PROS & CONS OF PETROLEUM INDUSTRY ON GLOBAL WARMING

Abstract

Global warming is the increase in temperature of the earth surface air and oceans, caused by the green

house gases (GHG), which include water vapour, carbon dioxide, methane, nitrous oxide. Rising sea levels,

glacier retreat, arctic shrinkage, and altered agriculture are the direct consequences of global warming.

Secondary and regional effects include extreme weather events, expansion of tropical diseases, changes in

climate systems and drastic economic impact.

The petroleum industry activities involve burning, processing, flaring and transporting using fossil fuels ,

which emit the CO2 is one of major sources for GHG emissions. Therefore, petroleum industry needs to

adopt initiatives in mitigating GHG emissions, monitoring & controlling. Proposals for stabilizing the

atmospheric concentration of CO2 about 500-550 ppm brings Carbon Capture and Storage (CCS).

Separation, compression, transportation and deposition of CO2 will increase the electricity cost by

approximately 50%, but the use of CO2 to recover additional oil may offer a significant value for large

quantities of CO2. CO2 can be stored in geological formation or in Deep Ocean or to react with minerals

(mineral carbonation). Geologic storage options include the depleted hydrocarbon reservoirs, saline

aquifers, and coal beds. Storage of CO2 in producing oil & gas reservoir leads to enhanced oil recovery by

increasing the mobility of the fluid or by maintaining the reservoir pressure. This process involves the

injection of fluid into the formation and monitoring the injected CO2. Petroleum industry has a long time

experience with all the activities involved with transportation and injection of fluid into underground. It

offers new business opportunity for the petroleum industry. CO2 can be stored in the ocean either as a deep

lake or as dissolution method. Alternatives under consideration include capture by micro algae, iron

fertilization, non biological capture from air and utilization.

Author: K.Thangarasu, PE 2’nd year, Rajiv Gandhi College of Engineering. 2008-2011

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Green House Effect

The Earth receives energy from the Sun mostly in the form of visible light. The bulk of this energy is not

absorbed by the atmosphere since the atmosphere is transparent to visible light. 50% of the sun's energy

reaches the Earth which is absorbed by the surface as heat. Because of its temperature, the Earth's surface

radiates energy in infrared range. The Greenhouse gases are not transparent to infrared radiation so they

absorb infrared radiation. Infrared radiation is absorbed from all directions and is passed as heat to all gases

in the atmosphere. The atmosphere also radiates in the infrared range (because of its temperature, in the

same way the Earth's surface does) and does so in all directions. The surface and lower atmosphere are

warmed because of the greenhouse gases and makes our life on earth possible. This is called natural

greenhouse effect ( see fig-1 ).

Increased industrial activity (fossil fuel burning) and other human activities such as cement production and

tropical deforestation, electricity generation has increased the concentration of these green house gases in

the atmosphere.These excessive emission of the anthrobogenic greenhouse gases trap the heat within the

earth’s atmosphere and thus results in increasing the temperature of the earth (see fig -2). This is we call as

the Global Warming.

To counter greenhouse gases, plants take the gases from the air, turn them into new growth, then

release them through respiration. In the ocean, the gases are stored as dissolved carbon dioxide. So carbon

dioxide and other gases are continuously being exchanged between land and atmosphere. However, the

plants and the rest of the land –based ecosystem, as well as the ocean, soak up less than 50% of all gases

that humans release through fossil fuels. Thus, the excess gasses (like CO2) build up as a heat blanket in the

atmosphere, thereby warming the planet. NASA scientists have stated that CO2 levels in the atmosphere

have shot up from 285 parts per million (ppm) to 377 ppm. Historically, CO 2 levels had only averaged

between 180 and 290 ppm. Every 10 ppm increase on CO2 concentration is associated with a half a degree

Centigrade increase in temperature

Effects of Global Warming

Polar ice caps melting

It will raise sea levels. There are 5,773,000 cubic miles of water in ice caps, glaciers, and permanent snow.

According to the National Snow and Ice Data Center, if all glaciers melted today the seas would rise about

230 feet. Luckily, that’s not going to happen all in one go. But sea levels will rise.

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Melting ice caps will throw the global ecosystem out of balance. The ice caps are fresh water, and when

they melt they will desalinate the ocean, or in plain English - make it less salty. The desalinization of the

gulf current will “screw up” ocean currents, which regulate temperatures. The stream shutdown or

irregularity would cool the area around north-east America and Western Europe. Luckily, that will slow

some of the other effects of global warming in that area (see fig-3).

Temperature rises and changing landscapes in the artic circle will endanger several species of animals.

Only the most adaptable will survive.

Global warming could snowball with the ice caps gone. Ice caps are white, and reflect sunlight, much of

which is reflected back into space, further cooling Earth. If the ice caps melt, the only reflector is the ocean.

Darker colors absorb sunlight, further warming the Earth.

Glacier retreat and disappearance

Currently glacier retreat rates and mass balance losses have been increasing in the Andes, Alps, Pyrenees,

Himalayas, Rocky Mountains and North Cascades due to the global warming. The loss of glaciers not only

directly causes landslides, flash floods and glacial lake overflow, but also increases annual variation in

water flows in rivers. Glacier runoff declines in the summer as glaciers decrease in size. Glaciers retain

water on mountains in high precipitation years, since the snow cover accumulating on, glaciers protects the

ice from melting. In warmer and drier years, glaciers offset the lower precipitation amounts with a higher

meltwater input.

Of particular importance are the Hindu Kush and Himalayan glacial melts that comprise the principal dry-

season water source of many of the major rivers of the Central, South, East and Southeast Asian mainland.

Increased melting would cause greater flow for several decades, after which "some areas of the most

populated regions on Earth are likely to 'run out of water'" as source glaciers are depleted (see fig-4).

Ocean acicidification

The role of the oceans in global warming is a complex one. Ocean acidification is an effect of rising

concentrations of CO2 in the atmosphere, and is not a direct consequence of global warming. The oceans

soak up much of the CO2 produced by living organisms, either as dissolved gas, or in the skeletons of tiny

marine creatures that fall to the bottom to become chalk or limestone. Oceans currently absorb about one

tonne of CO2 per year. It is estimated that the oceans have absorbed around half of all CO 2 generated by

human activities since 1800 (118 ± 19 petagrams of carbon from 1800 to 1994).

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In water, CO2 becomes a weak carbonic acid, and the increase in the greenhouse gas since the industrial

revolution has already lowered the average pH (the laboratory measure of acidity) of seawater by 0.1 units,

to 8.2. Predicted emissions could lower the pH by a further 0.5 by 2100, to a level probably not seen for

hundreds of millennia and, critically, at a rate of change probably 100 times greater than at any time over

this period.

Global warming is projected to have a number of effects on the oceans. There are concerns that increasing

acidification could have a particularly detrimental effect on corals (16% of the world's coral reefs have died

from bleaching caused by warm water in 1998, which coincidentally was the warmest year ever recorded)

and other marine organisms with calcium carbonate shells.

Sea level rise

Sea level has been rising 0.2 cm/year, based on measurements of sea level rise from 23 long tide gauge

records in geologically stable environments (see fig: 5). With increasing average global temperature, the

water in the oceans expands in volume, and additional water enters them which had previously been locked

up on land in glaciers, for example the Antarctic ice sheet is expected to grow during the 21st century

because of increased precipitation.

Increased evaporation

Over the course of the 20th century, evaporation rates have reduced worldwide. This is thought by many to

be explained by global dimming. As the climate grows warmer and the causes of global dimming are

reduced, evaporation will increase due to warmer oceans. Because the world is a closed system, this will

cause heavier rainfall, with more erosion. This erosion, in turn, can in vulnerable tropical areas (especially

in Africa) lead to desertification. On the other hand, in other areas, increased rainfall lead to growth of

forests in dry desert areas.

Destabilization of local climates

We can experience the effect of climate change in our monsoon season itself. We are getting uneven

rainfall in summer in one year and during next summer we are getting to much incresed temperature. In the

northern hemisphere, the southern part of the Arctic region (home to 4,000,000 people) has experienced a

temperature rise of 1 C to 3°C over the last 50 years. Canada, Alaska and Russia are experiencing initial

melting of permafrost. This may disrupt ecosystems and by increasing bacterial activity in the soil lead to

these areas becoming carbon sources instead of carbon sinks. A study (published in Science) of changes to

eastern Siberia's permafrost suggests that it is gradually disappearing in the southern regions, leading to the

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loss of nearly 11% of Siberia's nearly 11,000 lakes since 1971. At the same time, western Siberia is at the

initial stage where melting permafrost is creating new lakes, which will eventually start disappearing as in

the east. Furthermore, permafrost melting will eventually cause methane release from melting permafrost

peat bogs.

Impact of Global Warming

Water scarsity

Sea level rise is projected to increase salt-water intrusion into groundwater in some regions, affecting

drinking water and agriculture in coastal zones. Increased evaporation will reduce the effectiveness of

reservoirs. Increased extreme weather means more water falls on hardened ground unable to absorb it,

leading to flash floods instead of a replenishment of soil moisture or groundwater levels. In some areas,

shrinking glaciers threaten the water supply. The continued retreat of glaciers will have a number of

different effects. In areas that are heavily dependent on water runoff from glaciers that melt during the

warmer summer months, a continuation of the current retreat will eventually deplete the glacial ice and

substantially reduce or eliminate runoff. A reduction in runoff will affect the ability to irrigate crops and

will reduce summer stream flows necessary to keep dams and reservoirs replenished. This situation is

particularly acute for irrigation in South America, where numerous artificial lakes are filled almost

exclusively by glacial melt. Central Asian countries have also been historically dependent on the seasonal

glacier melt water for irrigation and drinking supplies. In Norway, the Alps, and the Pacific Northwest of

North America, glacier runoff is important for hydropower. Higher temperatures will also increase the

demand for water for the purposes of cooling and hydration.

Limitability to manage wild land fires.

The Association for Fire Ecology advises that under future drought and high heat scenarios, fires may

become larger more quickly and be more difficult to manage. Fire suppression costs may continue to

increase, with decreasing effectiveness under extreme fire weather and fuel conditions. They are observing

wild land fire conditions previously considered rare, such as extreme wildfire events (high heat release and

severe impact to ecosystems, lengthened wildfire seasons, and large-scale wildfire in fire-sensitive

ecosystem.

Permofrost melting

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Similar to melting ice, melting Arctic permafrost is producing the colorless, odorless methane (which is 23

times more powerful than CO2) at five times faster than thought. Warming thaws the permafrost (mostly in

Siberia), which is soil that has been continuously frozen for thousands of years. When methane was

released 250 million years ago, scientists believed it killed 94% of all marine species known from fossil

records, taking 100 million years to recover. Today, monitoring of the tundra has shown that the amount of

time it is frozen in winter has been cut in half from 200 to 100 days. Already in Alaska’s Kenai Peninsula,

what were lakes and wetlands are giving way to woodlands.

Effects on Agriculture

It was hoped that a positive effect of global warming would be increased agricultural yields, because of the

role of carbon dioxide in photosynthesis, especially in preventing photorespiration, which is responsible for

significant destruction of several crops. In Iceland, rising temperatures have made possible the widespread

sowing of barley, which was untenable twenty years ago. Some of the warming is due to a local (possibly

temporary) effect via ocean currents from the Caribbean, which has also affected fish stocks.

Rising atmospheric temperatures, longer droughts and side-effects of both, such as higher levels of ground-

level ozone gas, are likely to bring about a substantial reduction in crop yields in the coming decades .

Moreover, the region likely to be worst affected is Africa, both because its geography makes it particularly

vulnerable, and because seventy per cent of the population rely on rain-fed agriculture for their livelihoods.

Flood defense

Many of the world's largest and most prosperous cities are on the coast, and the cost of building better

coastal defenses (due to the rising sea level) is likely to be considerable. Some countries will be more

affected than others—low-lying countries such as Bangladesh and the Netherlands would be worst hit by

any sea level rise, in terms of floods or the cost of preventing them. In developing countries, the poorest

often live on flood plains, because it is the only available space, or fertile agricultural land. These

settlements often lack infrastructure such as dykes and early warning systems. Poorer communities also

tend to lack the insurance, savings or access to credit needed to recover from disasters ( see fig-6).

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Ecosystems

Unchecked global warming could affect most terrestrial ecoregions. Increasing global temperature means

that ecosystems will change; some species are being forced out of their habitats (possibly to extinction)

because of changing conditions, while others are flourishing. Secondary effects of global warming, such as

lessened snow cover, rising sea levels, and weather changes, may influence not only human activities but

also the ecosystem. Studying the association between Earth climate and extinctions over the past 520

million years, scientists from University of York write, "The global temperatures predicted for the coming

centuries may trigger a new ‘mass extinction event’, where over 50 per cent of animal and plant species

would be wiped out."

Many of the species at risk are Arctic and Antarctic fauna such as polar bears and emperor penguins. In the

Arctic, the waters of Hudson Bay are ice-free for three weeks longer than they were thirty years ago,

affecting polar bears, which prefer to hunt on sea ice. Species that rely on cold weather conditions such as

gyrfalcons, and snowy owls that prey on lemmings that use the cold winter to their advantage may be hit

hard. Marine invertebrates enjoy peak growth at the temperatures they have adapted to, regardless of how

cold these may be, and cold-blooded animals found at greater latitudes and altitudes generally grow faster

to compensate for the short growing season. Warmer-than-ideal conditions result in higher metabolism and

consequent reductions in body size despite increased foraging, which in turn elevates the risk of predation.

Indeed, even a slight increase in temperature during development impairs growth efficiency and survival

rate in rainbow trout.

Rising temperatures are beginning to have a noticeable impact on birds, and butterflies have shifted their

ranges northward by 200 km in Europe and North America. Plants lag behind, and larger animals'

migration is slowed down by cities and roads. In Britain, spring butterflies are appearing an average of 6

days earlier than two decades ago.

Many species of freshwater and saltwater plants and animals are dependent on glacier-fed waters to ensure

a cold water habitat that they have adapted to. Some species of freshwater fish need cold water to survive

and to reproduce, and this is especially true with Salmon and Cutthroat trout. Reduced glacier runoff can

lead to insufficient stream flow to allow these species to thrive. Ocean krill, a cornerstone species, prefer

cold water and are the primary food source for aquatic mammals such as the Blue whaEle [15]. Alterations to

the ocean currents, due to increased freshwater inputs from glacier melt, and the potential alterations to

thermohaline circulation of the worlds oceans, may affect existing fisheries upon which humans depend as

well.

Spread of diseases

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Global warming may extend the favourable zones for vectors conveying infectious disease such as dengue

fever and malaria. In poorer countries, this may simply lead to higher incidence of such diseases. In richer

countries, where such diseases have been eliminated or kept in check by vaccination, draining swamps and

using pesticides, the consequences may be felt more in economic than health terms. The World Health

Organisation (WHO) says global warming could lead to a major increase in insect-borne diseases in Britain

and Europe, as northern Europe becomes warmer, ticks—which carry encephalitis and lyme disease—and

sandflies—which carry visceral leishmaniasis—are likely to move in. However, Malaria has always been a

common threat in European past, with the last epidemic occurring in the Netherlands during the 1950s. In

the United States, Malaria has been endemic in as much as 36 states (including Washington, North Dakota,

Michigan and New York) until the 1940s. By 1949, the country was declared free of malaria as a

significant public health problem, after more than 4,650,000 house DDT spray applications had been made.

GREEN HOUSE GAS EMISSION FROM PETROLEUM INDUSTRY

Greenhouse gas emissions from Refineries

In a given refinery, roughly 4-10% (depending on refinery complexity) of the energy equivalent in

incoming crude oil is consumed as fuel to run refinery processes. Major air emission sources include

combustion products from furnace stacks—SOX, NOX, CO, CO2 and particulates. Hydrocarbon emissions

come from a wide variety of sources including evaporative losses from feed and product storage, loading

operations, water collection and water treatment facilities, and fugitive losses from process equipment (see

fig-7). Consequently, refiners are a significant source of CO2 emissions. Worldwide refinery operations are

responsible for approximately 820 million tons of annual CO2 emissions, approximately 5.5% of the man-

made CO2 emissions worldwide. There are reasonable opportunities to reduce CO2 generation via energy

efficiency programs, and fuel switching, but many of these concepts have already been adopted in the

developed world. Except in very rare instances (CO2 recovery from hydrogen plant off-gases for example)

CO2 is not recovered, and the technology available today to do so is not cost effective.

Exhaust Gases

Exhaust gas and flue gas emissions (carbon dioxide (CO2), nitrogen oxides (NOX) and carbon monoxide

(CO)) in the petroleum refining sector result from the combustion of gas and fuel oil or diesel in turbines,

boilers, compressors and other engines for power and heat generation. Flue gas is also generated in waste

heat boilers associated with some process units during continuous catalyst regeneration or fluid petroleum

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coke combustion. Flue gas is emitted from the stack to the atmosphere in the Bitumen Blowing Unit, from

the catalyst regenerator in the Fluid Catalytic Cracking Unit (FCCU) and the Residue Catalytic Cracking

Unit (RCCU), and in the sulfur plant, possibly containing small amounts of sulfur oxides. Low-NOX

burners should be used to reduce nitrogen oxide emissions.

Fugitive Emissions

Fugitive emissions in petroleum refining facilities are associated with vents, leaking tubing, valves,

connections, flanges, packings, open-ended lines, floating roof storage tanks and pump seals, gas

conveyance systems, compressor seals, pressure relief valves, tanks or open pits / containments, and

loading and unloading operations of hydrocarbons. Depending on the refinery process scheme, fugitive

emissions may include:

· Hydrogen;

· Methane;

· Volatile organic compounds (VOCs), (e.g. ethane, ethylene, propane, propylene, butanes, butylenes,

pentanes, pentenes, C6-C9 alkylate, benzene, toluene, xylenes, phenol, and C9 aromatics);

· Polycyclic aromatic hydrocarbons (PAHs) and other semivolatile organic compounds;

· Inorganic gases, including hydrofluoric acid from hydrogen fluoride alkylation, hydrogen sulfide,

ammonia, carbon dioxide, carbon monoxide, sulfur dioxide and sulfur trioxide from sulfuric acid

regeneration in the sulfuric acid alkylation process, NOX, methyl tert-butyl ether (MTBE), ethyl tertiary

butyl ether (ETBE), t-amylmethyl ether (TAME), methanol, and ethanol.

Upstream Petroleum Industry GHG emissions sources

There are three principal categories of emissions sources pertinent to the natural gas industry.

1. Methane sources include routine operations, fugitive releases, field operations, pipelines, pneumatic

device vents, gas-oil separation plants (GOSPs), Kimray pumps, dehydrator vents, centrifugal and

reciprocal compressors, internal combustion engines, seals, flanges, meters, pipeline leaks, upsets,

incomplete flaring, and so forth.

2. Carbon dioxide from industry use of natural gas, diesel fuel, electricity, and (in some cases) steam.

3. Carbon dioxide vented from produced natural gas. Natural gas, while chiefly methane, also contains

entrained CO2, sometimes in high concentrations.

Gas Flaring

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Gas flaring can take place during various petroleum industry operations. In the upstream petroleum sector,

waste gases are flared at gas plants, natural gas batteries, pipelines, and during well tests. Gas processing

plants produce market ready natural gas by removing water, sands, hydrogen sulphide, carbon dioxide, and

natural gas liquids from the natural gas mixture produced at the wellhead. Waste gases, including hydrogen

sulphide-rich gases, and gases burned during emergencies are flared at these facilities. Natural gas batteries

collect and process gas collected from one or more wells. Flaring at these facilities and pipelines can occur

during emergencies, equipment upsets or failures, and maintenance operations. Flares are located at wells,

dehydrators, compressors, and gathering pipelines (see fig-8).

Well tests are used to determine the economic value, pressure, flow, and composition of the petroleum

products within a reservoir. The waste gas that is produced during well testing is disposed of in flares,

unless the testing occurs "in line", where the test gas is directed to a processing plant through nearby

pipelines. The average flare from well testing burns for 2.5 days.

The complete combustion of pure hydrocarbons produces only water and carbon dioxide. Low efficiency

flares do not completely combust all of the fuel gas and unburned hydrocarbons and carbon monoxide are

emitted from the flare with the carbon dioxide.

Flaring is an environmental concern with regards to global warming and acid deposition. Emissions of

carbon dioxide and unburned natural gas from flares contribute to the greenhouse gas effect and global

warming. Global emissions of carbon dioxide for 1989 from gas flaring were estimated at 202 million

tonnes, or approximately 0.8 percent of anthropogenic (man made) carbon dioxide emissions. The majority

of emissions due to gas flaring are from the oil-producing countries of Africa and Asia, as well as in the

former USSR.

Research is currently being conducted to make incinerators more adaptable and portable, thus they may

become a more viable option in the future. If operated properly, incinerators generally have more efficient

combustion than flares.

Alternatives to flaring include:

conserving the waste gas for processing at natural gas facilities,

re-injecting the waste gas underground to maintain reservoir pressure during production,

connecting well test gases to existing pipeline systems for in-line well testing,

using the gas to power micro-turbine generators for electricity production,

Ensuring flare systems are properly designed, constructed and maintained through guidelines,

codes of practice, or regulation.

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Carbon dioxide mitigation

The world has embraced the objective of dramatically reducing the risks of climate change. The downside

of the climate change is as apocalyptic as it gets: melting glaciers, water and foot shortage, rising sea levels,

droughts and floods, population displacement, the economic effect would be similar disastrous. A

prediction state that 20% of the world economy could be wiped out by the middle of the century if no

action is taken. The same report said there is still time to bring CO2 emissions-and, therefore global

temperature under control. IPCC estimated that emission must peak in the 10-20 years to limit global

temperature increases to 2.0-2.4C above pre industrial level-regarded as the threshold at which the more

extreme effects of climate changes will begin. It recommends measures are taken to reduce CO2 emission

by50-80% by 2050.

Proposals for stabilizing the concentration of CO2 to prevent the most harmful effects of climate change

have focused on the goal of a concentration of atmospheric CO2 of 500-570 parts per million (ppm). The

emission of CO2 could be reduced substantially without significant changes to the basic process .The

concept of stabilization wedges, developed by the Carbon Management initiative identifies a range of

existing technologies and energy conservation measures that could be applied on a large scale to stabilize

world emissions at their present value (see fig-9, 10). . They include more efficient of use of

transport, greater efficiency in energy production and wider deployment of renewable,

biofuels and nuclear energy (See box 1).

EFFICIENCY

Buildings, ground transport, industrial,

processing, lighting, electric power plants.

DECORBONISED ELECTRICITY

Natural gas for goal

Power from coal or gas with CCS

Nuclear power

Power from renewable

DECORBINISED FUELS

Synthetic fuel from coal, natural gas and

biofuels, with CCS

Biofuels

Hydrogen

From coal and natural gas with CCS

From nuclear energy

From renewable energy

FUEL DISPLACEMENT BY LOW CARBON

ELECTRICITY

Grid charged batteries for transport

Heat pumps for furnaces and boilers

NATURAL SINKS

Forestry (reduced deforestation, new

plantations)

Agricultural soils

METHANE MANAGEMENT

Landfill gas, cattle, rice, natural gas

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Box-1: the stabilization wedges

PETROLEUM INDUSTRY’S PART IN GHG REDUCTION

Fossil fuels have acquired, with a concern for climate change, entirely new connotations. The oil & gas

industry activities involve burning, processing, flaring & transporting fossil fuels, which emit CO2 is one of

major sources for GHG emissions The initial public reaction is understandably a negative one: the burning

of fossil fuel is the culprit. Greenhouse gas emissions from energy production can be reduced by the use of

alternative energy sources such as nuclear power and renewable energy. Renewable energy sources are

increasingly used, however, until these sources can reliably produce significant amounts of energy, the

immediate energy demand is likely to be met by conventional fossil fuel combustion. As many thing, the

promise of non-fossil energy in either renewable or nuclear form is limited extend. Renewable energy has

obvious attractions, but, unlike fossil fuel, is unable to supply base load electricity. IEA projection suggest

that growth in Coal fired generation is likely to be the single biggest contributor to new green house gas

emission over the next 15 years. We all want endless amount if renewable energy but the reality is we can't

jump to an end point tomorrow. In a tight race against time to combat an escalating climate problem,

devising a way to de-carbonize their use is a necessary matter of urgency. We must recognize that fossil

fuels still form the backbone of our energy infrastructure and their use is inevitable for some time to come.

Carbon Capture and Storage

Carbon Capture and Storage (CCS), is an attractive CO2 emissions-mitigation option for a number of

reason. CCS alone can able to reduce 25% of the CO2 emission. But the process of separating CO2 from

industrial and energy-related sources, transporting it to a storage location and isolating it from the

atmosphere –is the key to large-scale de-carbonization and sustainable long term use of fossil fuels. As a

result, the Petroleum industry has the opportunity to reinvent itself. Petroleum industry already knows how

to transport the captured CO2 to the storage site and know very well about the geological formation

favorable for the storage. The CO2 capture process, of which there are a number of technical options at

various stages of development, typically enables some 70-95% of the co2 produced in an industrial process

to be captured. Although power plants equipped with CCS require more energy (10-40% more) , the net

CO2 savings still amount to some 80-90% compared with plants without CCS technology(sea fig -11)..

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CCS has the potential to make particularly significant contribution to carbon-emissions savings in the

electricity -generation sector. Power generation alone is responsible for 40% of the global man-made

anthropogenic emission of CO2 from the energy sector, generating about twice as much CO2 as

transportation.

Three Main Approaches to Capture CO2

Technologies that are being developed for CO2 capture and sequestration from combustion and gasification

technologies include:

CO2 capture from plants of conventional pulverized fuel (pf) technology with scrubbing of the flue

gas for CO2 removal, here called post-combustion capture (PCC).

Integrated gasification combined cycle with a shift reactor to convert CO to CO2, followed by CO2

capture, which is often called pre-combustion capture.

Oxy-fuel (Oxyf) combustion, with combustion in oxygen rather than air, and the oxygen is diluted

with an external recycle flue gas (RFG) to reduce its combustion temperature and add gas to carry

the combustion energy through the heat transfer operations in the current first generation

technology.

Oxy-combustion with an internal recycle stream induced by the high momentum oxygen jets in

place of external recycle. This technology is now widely used in the glass industry and, to a lesser

extent, in the steel industry.

Chemical looping which involves the oxidation of an intermediate by air and the use of the

oxidized intermediate to oxidize the fuel.

This review covers the first three options, as these are the closest to commercial application involving

carbon capture (see box: 2).

Box-2: CO2 capture options

Post Combustion

Post combustion capture (PCC) process separate CO2 from the exhaust gases produced by the combustion

of fuel (coal, natural gas, oil or biomass) in air. The concentration of CO2 in the exhaust gases is low

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Energy Conversion

Capture of CO2

Fossil Fuel Energy Conversion

Capture of CO2

Storage/use of CO2

Gasification of Reforming CO Shift Fuel gas

Extraction

Energy/power

Energy/power

Post combustion capture

Oxyfuel combustion

Pre-combustion capture

(typically 3-15% by volume) and the pressure is typically ambient. PCC can use established technology

applied in chemical and natural gas processing for CO2 and SO2 removal, with Amines such as

monoethanolamine (MEA) and Methyldiethanolamine (MDEA) are primarily considered. CO2 is captured

by using a liquid amine solvent. Once absorbed by the aqueous amine solution, the CO2 is then released by

heating. This technology is widely used to capture CO2 from exhaust gas for use in the food and beverage

industry and as a feedstock for fertilizer manufacturing. The fundamental reaction for this process is:

C2H4OHNH2 + H2O + CO2 ↔ C2H4OHNH3+ + HCO3

-

During the absorption process, the reaction proceeds from left to right; during regeneration, the reaction

proceeds from right to left (see fig-12).

Post combustion capture has been carried out successfully, in chemical and food & beverage

industry and fertilizer manufacturing.

Retrofitting is also likely to result in the additional utility systems to meet the higher energy

demands of CO2 capture.

Challenges

Post-combustion CO2 capture technology can be retrofitted to existing power plants or introduced

into existing industrial process. However integration of the process equipment and associated

infrastructure within existing plant raises issues of technical practicality and cost on account of the

scale and complexity of the equipment needed.

Require a large amount of energy to regenerate the solvent (in the solvent stripper), this being as

much as 80% of the total energy of the process. As generation efficiency loss results, requiring the

use of additional fuel.

CO2n the flue gas also causes degradation of the amines with the byproducts leading to corrosion

problems, necessitating chemical inhibitors or process modification involving de-oxidation of the

CO2-rich amine solution.

The capture process requires the extraction and use of steam, which significantly reduces the

power plant's gross generating capacity.

In order to reduce the capital and energy cost, and the size of the absorption and regenerator (stripper)

columns, new processes are being developed. One example is the membrane-absorption process, where a

micro porous membrane made of polytetrafluoroethylene separates the flue gas from the solvent. The

membrane allows for greater contacting area within a given volume, but by itself the membrane does not

perform the separation of CO2 from the rest of the flue gases. It is the solvent that selectively absorbs CO2.

The use of a gas membrane has several advantages: (a) high packing density; (b) high flexibility with

respect to flow rates and solvent selection; (c) no foaming, channeling, entrainment and flooding – common

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problems in packed absorption towers; (d) the unit can be readily transported, e.g. offshore; (e) significant

savings in weight.

It is possible to design a once through scrubbing process (i.e., no regeneration step). For example, one

could scrub CO2 from flue gas with seawater and then return the whole mixture to the ocean for storage.

However, to-date these approaches are not as practical as those using a regenerable solvent. In the seawater

scrubbing example, the large volumes of water that are required result in large pressure drops in the pipes

and absorber.

Other processes have been considered to capture CO2 from power plant and industrial boiler flue gases

includes

Membrane separation

Cryogenic fractionation,

Adsorption using molecular sieves.

Generally, these processes are less energy efficient and more expensive than the absorption methods.

Pre-Combustion

This process converts the fuel into a gaseous mixture of hydrogen and CO2. The CO2 is then separated and

hydrogen can then be burned without producing any CO2 in the exhaust gas. The conversion process for the

fuel start with a reaction with steam and air or oxygen in carefully controlled quantities and conditions to

produce synthesis gas (syngas)-a mixture of gases comprised mainly of carbon monoxide and hydrogen.

From the syngas, CO2 and additional hydrogen are then produced by reaction of carbon monoxide with

additional steam. The CO2 then can be separated from the resulting mixture of hydrogen and CO2 either by

absorption by liquid solvent or solid adsorbent such as Methanol and Polyamine glycol (commercial brands

are called Rectisol and Selexol) . The H2 is combusted in a gas turbine with heat recovery and a steam

turbine following. The CO2, then may be released either by heating or reducing pressure (see fig-13).

Advantages

Compared with post combustion processes, the pressure and concentration of CO2 in pre-

combustion processes is relatively high- making CO2 separation easier to achieve and offering the

potential to apply novel CO2 -capture technologies, such as membranes and liquefiers at low

temperature.

In contrast to post combustion processes, pre-combustion CO2 capture involves the production of

syngas and hydrogen. The hydrogen can be used for hydro-treating-a refinery process producing

cleaner fuels- whereas syngas can be used as a feedstock for liquid fuels or chemicals

15

manufacturing. By these alternative means, plant using pre-combustion processes can provide

many valuable products in addition to heat and power.

The technologies required for pre-combustion CO2 capture have been applied in various industrial

processes, such as in ammonia and hydrogen production. Natural-gas reforming, which uses

similar technology, has been widely applied in refining and petrochemicals industries. This

approach would also be used in power stations using Integrated Gasification Combined Cyclone

Technology, in which coal is satisfied.

Pre combustion is largely proved and already being used in large-scale industrial processes

Challenges

The fuel conversion steps required for pre-combustion are more complex than the processes

involved in the post-combustion; this make the technology more difficult to apply to retrofits.

Oxyfuel Combustion

This process use oxygen rather than air for combustion of fuel. This produces exhaust gas that is mainly

water vapour and CO2. The exhaust gas has a relatively high CO2 concentration (>80%). the water vapour

produced can be removed by cooling and compressing the gas stream. The oxygen for combustion can be

produced by cryogenic distillation of air in air-separation units (ASU), which are used extensively in

process industries. Oxyfuel combustion systems are being developed in on a small scale, in laboratory or

pilot projects .In addition to applying oxyfuel-combustion in boilers, these approaches are being studied in

gas turbine systems (See fig-14).

The characteristics of oxy-fuel combustion with recycled flue gas differ with air combustion in several

aspects primarily related to the higher CO2 levels and system effects due to the re-circulated flow,

including the following:

To attain a similar adiabatic flame temperature (AFT) the O2 proportion of the gases passing

through the burner is higher, typically 30%, than that for air (of 21%), necessitating that about

60% of the flue gas is recycled.

The high proportions of CO2 and H2O in the furnace gases result in higher gas emissivities, so

that similar radiative heat transfer for a boiler retrofitted to oxy-fuel will be attained when the O2

proportion of the gases passing through the burner is less than the 30% required for the same AFT.

The volume of gases flowing through the furnace is reduced somewhat, and the volume of flue gas

(after recycling) is reduced by about 80%.

16

The density of the flue gas is increased, as the molecular weight of CO2is 44, compared to 28 for

N2.

Typically, when air-firing coal, 20% excess air is used. Oxy-fuel requires a percent excess O2

(defined as the O2 supplied in excess of that required for stoichiometric combustion of the coal

supply) to achieve a similar O2 fraction in the flue gas as air firing, in the range of 3–5%.

Challenges

The lack of experience in applying these techniques on a significant scale means that knowledge

of the cost implications of implementing CO2 -capture is uncertain and often theoretical.

Without removal in the recycle stream, species (including corrosive sulphur gases) have higher

concentrations than in air firing.

As oxy-fuel combustion combined with sequestration must provide power to several significant

unit operations, such as flue gas compression, that are not required in a conventional plant without

sequestration, oxy-fuel combustion/sequestration is less efficient per unit of energy produced.

The air separation unit (ASU) alone may consume about 15% of a power plant’s electric output,

requiring a commensurate increase of fossil fuel to be consumed for achieving the rated electric

output of the plant.

According to various studies, the incorporation of CO2 -capture technology in new builds increase the costs

of electricity generation typically by 505 or more, depending on the type of plant and fuel involved. For

retrofitting, the cost complications are closely linked to the site-specific factors, such as the plant's age and

efficiency, and its size and capacity for expansion.

The approach taken to capture will be influenced by the type of fuel used in the industrial process and the

nature of configuration of the plant in question. In all three carbon capture routes, the processes require

additional energy -between 10% and 405, according to most estimates, depending on the type of plant.

Taking account of the additional CO2 emission resulting from increased energy use, capture systems

typically result in the net CO2 saving of 70-90%.

Transportation of CO2

Captured carbon dioxide should be transported to the favorable site for its storage. CO2 pipelines have been

in operation for around 30 years and experience suggest that there is no significant barrier to pipeline –

transportation of CO2.technically the non corrosive nature of the dry CO2 makes it a comparatively cheap

gas to transport.

17

Deployment of CCS on large scale will require new transportation infrastructure to link sources and links.

Ideally the co location of the plants generating CO2 directly above the geologic storage sites (i.e oil & gas

reservoir), eliminates the need for the transportation infrastructure.

Moving the volumes of CO2 required may also involve the use of shipping, particularly over long distances.

Like liquefied petroleum natural gas, CO2 can be liquefied and carried in bulk in shipping and pipelining

the hydrocarbon gases, the design and construction standards have meant that serious incident have been

rare. So there is no way to believe that the transport of CO2 will cause hazards, anymore significant than,

those that have been identified and successfully managed already.

Carbon Storage

Once captured and transported, most CO2 will be stored in geological reservoirs. Detailed knowledge and

understanding are needed as to where and how CO2 can be stored. This understanding must include, for

example, geographical locations, capacities, future behavior in reservoirs, and associated risks, together

with both national and international legal constraints. Storage media include geologic sinks and the deep

ocean. Geologic storage includes deep saline formations (sub-terrene and sub-seabed), depleted oil and gas

reservoirs, enhanced oil recovery, and unminable coal seams. . Deep ocean storage includes direct injection

of liquid carbon dioxide into the water column at intermediate depths (1000-3000 m), or at depths greater

than 3000 m, where liquid CO2 becomes heavier than sea water, so it would drop to the ocean bottom and

form a so-called “CO2 lake.” In addition, other storage approaches are proposed, such as enhanced uptake

of CO2 by terrestrial and oceanic biota, and mineral weathering. Attention must be given to the

development of a monitoring methodology capable of building trust and confidence amongst citizens living

in the vicinity of storage sites.

The Petroleum industry has been managing gas injection and storage in the subsurface for nearly a century.

Analogues show CO2 can remain in the ground for million of years. Our next step to reducing the Global

Warming is to increase the scale of storage: this will require better mapping of sources and sinks, and for

storage sites to be selected, operated and monitored in a standardized way.

Geological storage

Geological storage of CO2 is widely held to be s route with great potential. It involves the injection of CO2

in dense form into a rock formation below the Earth's surface. The most studied and tested options involve

injection into oil and gas reservoirs, deep saline formations, or un-minable coal beds (sea fig: 15 ) The

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initial choice of storage site is likely to be determined by factors including the location of major sources of

CO2, and secure storage sites, and the availability of existing redundant infrastructure.

The technologies and knowledge required for carrying out geological storage- involving well drilling,

injection technology, seismic imaging, understanding reservoir dynamics and mineralogy, monitoring and

risk management-are already very familiar to our petroleum industry.

Geological storage in depleted hydrocarbon reservoirs:

When it comes to storing gas underground, the petroleum industry is the home of much of the expertise.

Geological storage in hydrocarbon reservoirs involves the injection of CO2 in physically trapped

underground beneath an impermeable cap-rock. We know how to locate appropriate rock formations,

determine the storage capacity of the rock, assess the ease with which gas can be injected and immobilized

with time, and determine the maximum gas pressure that can be sustained without risk of fracturing or

exceeding the sealing capacity of the cap rock. The rock acts as an upper seal and prevents fluid or gas

from leaking out. This storage typically occurs in formations deeper than 800 meters.

Enhanced Oil (and Gas) Recovery

For oil and gas reservoirs, the presence of hydrocarbon proves the existence and effectiveness of the trap

and its seal for oil and gas, typically on a timescale of millions of years. The injected CO2, which displaces

the oil or gas already present in the reservoir, dissolves in the water within the formation and sinks to the

bottom .Modeling studies have shown that up to 20-60% of the injected CO2 could be dissolved within

1000 years. The injection of CO2 into oil and gas reservoirs can lead to enhanced oil recovery, maximizing

the output from the known resources, reducing reliance on new exploration and discovery, and prolonging

the life of the existing fields (See fig 16).

Geological storage in Saline aquifers

Deep saline formations, both sub-terranean and sub-seabed, may have the greatest CO2 storage potential.

These reservoirs are the most widespread and have the largest volumes. These aquifers are sedimentary

rocks (usually sandstone and less frequently limestone or other rocks), which are porous enough to store

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great volumes of CO2 and permeable enough to allow the flow of fluids. These reservoirs are very distinct

from the more familiar reservoirs used for fresh water supplies. Research is currently underway in trying to

understand what percentage of these deep saline formations could be suitable CO2 storage sites.

The density of CO2 depends on the depth of injection, which determines the ambient temperature and

pressure. The CO2 must be injected below 800 m, so that it is in a dense phase (either liquid or

supercritical). When injected at these depths, the specific gravity of CO2 ranges from 0.5 to 0.9, which is

lower than that of the ambient aquifer brine. Therefore, CO2 will naturally rise to the top of the reservoir,

and a trap is needed to ensure that it does not reach the surface. Geologic traps overlying the aquifer

immobilize the CO2. In the case of aquifers with no distinct geologic traps, an impermeable cap-rock above

the underground reservoir is needed. This forces the CO2 to be entrained in the groundwater flow and is

known as hydrodynamic trapping. Two other very important trapping mechanisms are solubility and

mineral trapping. Solubility and mineral trapping involve the dissolution of CO2 into fluids, and the reaction

of CO2 with minerals present in the host formation to form stable, solid compounds like carbonates. If the

flow path is long enough, the CO2 might all dissolve or become fixed by mineral reactions before it reaches

the basin margin, essentially becoming permanently trapped in the reservoir.

Storage of CO2 will take place at depths below some 7-800 meters where CO2 behaves as a fluid, and where

the pores of the sediments are filled with salt water.

Geological storage in Un-minable Coal seams

Abandoned or uneconomic coal seams are another potential storage site. These offer another opportunity to

store CO2 at a low net cost. CO2 diffuses through the pore structure of coal and is physically adsorbed to it.

This process is similar to the way in which activated carbon removes impurities from air or water. The

exposed coal surface has a preferred affinity for adsorption of CO2 than for methane with a ratio of 2:1.

Thus, CO2 can be used to enhance the recovery of coal bed methane (CMB). In some cases, this can be very

cost effective or even cost free, as the additional methane removal can offset the cost of the CO2 storage

operations.

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SafetyOccupational safetyTransportation safetyWell control

EnvironmentalImpactsGroundwaterEcosystemsHuman healthSeismicityStorage

LocalEffectivenessGreenhouse gas controlSeepage back to atmosphere

Requirements for Geologic Storage

Figure 2: Example requirements for geologic storage of CO2.

Leak Detecting and Monitoring

Effective monitoring of CO2 underground is a vital link in the chain of CCS activities, ensuring safety,

maximizing performance and limiting risk. Various equipments needed for the monitoring CO2 is already

present in the petroleum industry as it monitoring the injected CO2 and water for the enhanced oil recovery

A variety of technologies are available to monitor the behavior of injected CO2 through its different

operational phases. Monitoring programs are site specific and their complexity is determined by the level of

risk associated with a particular geological structure. Once injected into subsurface, CO2 can be tracked

using various monitoring techniques. Monitoring is used for:

The control of storage performance in terms of capacity, injectivity and containment (plume

location, trapping mechanisms and leak detection).

The control of risks associated with leakage (contamination of shallower formation and releases at

surface) and as support for remediation.

In addition to these primary factors it may also in some cases be desirable to monitor other parameters that

could be helpful in assessing the performance of the storage project, or, in the event of leakage, assess the

source of leakage, design a remediation scheme and assess environmental impacts, specifically:

evaluate how effectively the storage volume is being used,

provide information on the extent of solubility and mineral trapping,

locate faults or other features that may be leaking CO2 ,

assess groundwater quality,

detect and monitor CO2 concentrations in the vadose zone and soils,

monitor ecosystem impacts,

monitor micro-seismicity associated with CO2 injection.

While potentially of secondary importance, knowing that monitoring approaches are available to

provide information about these parameters could provide greater assurance that geologic storage

could be accomplished safely and effectively

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Leakage and Seepage of CO2Injection wells leakageLeakage from the primary storage reservoirSurface seepage from the ground and abandoned wells

The monitoring program is a continuous process and is subdivided into three phases:

Operational monitoring, focusing on the storage reservoir;

Verification monitoring, aiming to characterize the displacement of CO2 plume and its behavior in

the reservoir, as well as to identify losses of isolation in the primary barriers (cap rocks, fault and

wells);

Environmental monitoring of the shallower sub-surface, the surface and/or the atmosphere.

Operational monitoring

During this phase monitoring activities focus on fine tuning injection pressure to optimize the injection rate

without compromising the cap rock integrity and jeopardizing storage safety. Measuring the injection rate

is by wire line logs or by venturi type flow meter.

Pressure measurements can be performed using a variety of conventional pressure sensor or by new reliable

optical sensor that can provide real time measurement of pressure and temperature.

Microseismicity is commonly used for hydraulic fracture monitoring to avoid fracturing cap rock.

Verification monitoring

The objectives of verification monitoring are to control the displacement and distribution of the CO2 in the

reservoir; to improve the characterization of the trapping mechanisms; and to verify the quality of the

containment. These observations will be used to benchmark and calibrate forward modeling and simulation

tools.

Geochemical Methods and Tracers

Geochemical methods are useful both for directly monitoring the movement of CO2 in the subsurface and

for understanding the reactions taking place between CO2and the reservoir fluids and minerals Fluid

samples can be collected either directly from the formation using a down hole sampler or from the wellhead

if the well from which the sample is collected is pumped. Down hole samples are considerably more costly,

but have the advantage that they are more representative of the formation fluids because they are not

depressurized as they flow up the well. Methods for collecting down hole and wellhead fluids samples are

well developed and geochemical sampling is conducted on a routine basis. Fluid samples can be analyzed

for major ions (e.g. Na, K, Ca, Mg, Mn, Cl, Si, HCO3-and SO4) pH, alkalinity, stable isotopes (e.g. 13C,

14C, 18O, 2H), and gases, including hydrocarbon gases, CO2 and its associated isotopes. Standard

22

analytical methods are available to monitor all of these parameters, including the possibility of continuous

real-time monitoring for some of the geochemical parameters.

While it is comparatively straightforward to measure the parameters listed above, interpreting these

measurements to infer information about geochemical reactions is much more challenging. In particular,

little attention has been given to understanding the impact of mineral/ CO2 interactions on enhanced oil

recovery. Only recently, and as a result of recent interest in geologic storage of CO2, has a great deal of

attention been paid to understanding reactions between CO2and deep geologic formations shortly after

CO2is introduced into the environment. Much remains to be learned about the kinetics of mineral/ CO2

interactions and how monitoring data can be used to predict the extent and rate of mineral and solubility

trapping. IPCC workshop on carbon dioxide capture and storage

Indirect Measurement Methods for CO2 Plume Detection

Indirect measurements for detecting CO2 in the subsurface provide methods for tracking migration

of the CO2plume in locations where there are no monitoring wells, or for providing higher resolution

monitoring in between wells or behind the cased portion of a well. Such indirect methods fall into four

categories, namely: well logs; geophysical monitoring methods such as seismic, electromagnetic, and

gravity; land surface deformation using tilt meters, plane or satellite- based geo-spatial data; and satellite-

based imaging technologies such as hyper spectral and IR imaging. The utility of these indirect methods is

determined by (1) their threshold for detection of the presence of CO2, (2) the extent to which the signal is

uniquely related to the presence of CO2 (e.g. distinguish the effects of a pressure increase from the presence

of CO2) and the (3) the degree of quantification that is possible (e.g. what is the fraction of the pore volume

occupied by CO2).

To date, 3-dimensional seismic reflection surveys have been used to monitor, with excellent success,

migration of the CO2 plume injection. The success of this project bodes well for the ability of indirect

methods to track plume migration in the subsurface. However, 3-D seismic reflection surveys may not

always be so successful; costs for these surveys are high compared to other available monitoring methods,

and in some cases, the spatial resolution or the detection threshold may not be adequate. Therefore,

additional methods for plume detection are being evaluated.

Well Logs

One of the most common methods for evaluating geologic formations is the use of well logs. Logs are run

by lowering an instrument into the well and taking a profile of one or more physical properties along the

length of the well. Wide varieties of logs are available and can measure many parameters - from the

23

condition of the well, to the composition of pore fluids, and mineralogy of the formation. For geologic

storage of CO2, like for natural gas storage and disposal of industrial wastes in deep geologic formations,

logs will be most useful for detecting the condition of the well and ensuring that the well itself does not

provide a leakage pathway for CO2 migration. Several logs are routinely used for this purpose, including

temperature, noise, casing integrity and radioactive tracer logs.

Time –lapse seismic survey

The purpose on time laps seismic survey is to image and monitor differences of reflectivity from the

reservoir and the surrounding formations, characterizing the evolution of the matrix and fluid distribution in

the porous media. The change in wavelet attributes can be associated with fluid propagation.

The three main objective of the time lapse seismic monitoring is

To generate an image of CO2 displacement inside the reservoir during injection;

To validate the sealing efficiency of the cap rock

To monitor plume stability during and after injection

Electrical and Electromagnetic

This measures the resistivity of the formation. Increased resistivity will occur, for example, with

displacement of saline fluids by CO2, while the dissolution of minerals in the formation will produce a

decrease in resistivity.

Is CO2 storage safe?

Yes, obviously it is the safest. Since CO2 (as a supercritical gas) is to be stored in reservoirs for thousands

of years, it is vital to ensure that there is a low risk of it migrating out of the reservoir. To achieve this,

considerable work is being carried out on the safety of CO2 storage. Significantly, a number of reservoir

modeling studies have been carried out, in order to evaluate the potential migration of injected CO2 from

aquifers through the overlying water saturated rock strata. The general conclusion is that, by upward

molecular diffusion alone, it would take many thousands of years for the CO2 to reach the surface following

the end of injection. It is also important to note that many reservoirs have safely held hydrocarbon gases or

liquids over whole geological eras, as this suggests that injected CO2 can remain in such structures for

similar periods of time. Indeed, many oil and gas reservoirs also hold appreciable quantities of CO2 mixed

24

with the hydrocarbons. This should further raise confidence that the CO2 can be stored safely. Another

factor is that many existing oil and gas reservoirs have been successfully adapted to store natural gas as a

peak smoothing mechanism. This is a more demanding activity than CO2 storage, because the gas is

regularly injected and removed to meet consumer demand. There is already a considerable bank of

information on the adaptation of geological reservoirs for natural gas storage that can be drawn upon to

assist the development of CO2.

Ocean Storage of CO2

The release of CO2 to the atmosphere can be prevented by storing it in the deep ocean at depth greater than

1,000 meters, where most of it would be isolated from the atmosphere for centuries. By far, the ocean

represents the largest potential sink for anthropogenic CO2. It already contains an estimated 40,000 GtC

(billion metric tons of carbon) compared with only 750 GtC in the atmosphere and 2200 GtC in the

terrestrial biosphere. Apart from the surface layer, deep ocean water is unsaturated with respect to CO2. It is

estimated that if all the anthropogenic CO2 that would double the atmospheric concentration were injected

into the deep ocean, it would change the ocean carbon concentration by less than 2%, and lower its pH by

less than 0.15 units. Furthermore, the deep waters of the ocean are not hermetically separated from the

atmosphere. Eventually, on a time scale of 1000 years, over 80% of today’s anthropogenic emissions of

CO2 will be transferred to the ocean. Discharging CO2 directly to the ocean would accelerate this ongoing

but slow natural process and would reduce both peak atmospheric CO2 concentrations and their rate of

increase.

In order to understand ocean storage of CO2, some properties of CO2 and seawater need to be elucidated.

For efficiency and economics of transport, CO2 would be discharged in its liquid phase. If discharged above

about 500 m depth, that is at a hydrostatic pressure less than 50 atm, liquid CO2 would immediately flash

into a vapor, and bubble up back into the atmosphere. Between 500 and about 3000 m, liquid CO2 is less

dense than seawater, therefore it would ascend by buoyancy. It has been shown by hydrodynamic modeling

that if liquid CO2 were released in these depths through a diffuser such that the bulk liquid breaks up into

droplets less than about 1 cm in diameter, the ascending droplets would completely dissolve before rising

100 m. Because of the higher compressibility of CO2 compared to seawater, below about 3000 m liquid

CO2 becomes denser than seawater, and if released there, would descend to greater depths. When liquid

CO2 is in contact with water at temperatures less than 10oC and pressures greater than 44.4 atm, a solid

hydrate is formed in which a CO2 molecule occupies the center of a cage surrounded by water molecules.

For droplets injected into seawater, only a thin film of hydrate forms around the droplets (see fig:17).

There are two primary methods under serious consideration for injecting CO2 into the ocean.

25

One involves dissolution of CO2 at mid-depths (1500-3000 m) by injecting it from a bottom

mounted pipe from shore or from a pipe towed by a moving CO2 tanker.

The other is to inject CO2 below 3000 m, where it will form a "deep lake".

Benefits of the dissolution method are that it relies on commercially available technology and the resulting

plumes can be made to have high dilution to minimize any local environmental impacts due to increased

CO2 concentration or reduced pH. The concept of a CO2 lake is based on a desire to minimize leakage to the

atmosphere. Research is also looking at an alternate option of injecting the CO2 in the form of bicarbonate

ions in solution. For example, seawater could be brought into contact with flue gases in a reactor vessel at a

power plant, and that CO2-rich water could be brought into contact with crushed carbonate minerals, which

would then dissolve and form bicarbonate ions. Advantages of this scheme are that only shallow injection

is required (>200 m) and no pH changes will result. Drawbacks are the need for large amounts of water and

carbonate minerals.

Discharging CO2 into the deep ocean appears to elicit significant opposition, especially by some

environmental groups. Often, discharging CO2 is equated with dumping toxic materials into the ocean,

ignoring that CO2 is not toxic, that dissolved carbon dioxide and carbonates are natural ingredients of

seawater, and as stated before, atmospheric CO2 will eventually penetrate into deep water anyway. This is

not to say that seawater would not be acidified by injecting CO 2. The magnitude of the impact on marine

organisms depends on the extent of pH change and the duration of exposure. This impact can be mitigated

by the method of CO2 injection, e.g. dispersing the injected CO2 by an array of diffusers, or adding

pulverized limestone to the injected CO2 in order to buffer the carbonic acid.

CO2 Mineral Sequestration

What is Mineral Sequestration?

Mineral sequestration involves the reaction of CO2with minerals to form geologically stable carbonates, i.e.

mineral carbonation. This idea was first proposed by Seifritz in 1990. There have been several methods

suggested to achieve carbonation:

an aqueous Scheme by Kojima; an underground injection scheme by Gunter et al;

the processes via mineral derived Mg(OH)2 suggested by Lackner et al; and most recently,

The carbonic acid process, using olivine and serpentine directly proposed by O’Connor et al.

Mineral carbonation reactions are known to geologists and occur spontaneously on geological time scales.

For example, the reaction of CO2 with common mineral silicates to form carbonates like magnetite or

26

calcite is exothermic and thermodynamically favored. For illustrative purposes, general and specific global

mineral carbonation reaction pathways are shown below.

The family of reactions represented by Reaction 1 has the potential to convert naturally occurring silicate

minerals to geologically stable carbonate minerals and silica. This process emulates natural chemical

transformations such as weathering of rocks to form carbonates over geologic time periods. Reaction 2

illustrates the transformation of the common silicate mineral serpentine, Mg3Si2O5(OH)4, and CO2 into

magnetite, MgCO3 silica and water. Using this ideal case, one ton of serpentine can dispose of

approximately one-half ton of CO2. Reaction 3 illustrates the transformation of forsterite, which is the end

member of the common silicate mineral olivine. One ton of olivine can dispose of approximately two-thirds

of a ton of CO2. Again, the reaction is exothermic and releases 90 KJ/mole of CO2

(1) (Mg, Ca)xSiyOx+2y+zH2z + x CO2 x(Mg,Ca)CO3 + ySiO2 +zH2O

(2) 1/3 Mg3Si2O5(OH)4 + CO2MgCO3 + 2/3 SiO2 + 2/3 H2O + 64 kJ/mole.

(3) 1/2 Mg2SiO4 + CO2 MgCO3 + 1/2 SiO2 + 90 KJ/mole

As illustrated CO2from one or more power plants is transported to a carbonation reactor, combined with

crushed olivine or serpentine from a nearby mine and held at the appropriate reaction conditions until the

desired degree of carbonation is reached. Then products of the reaction, which might be slurry of

carbonated minerals and residues in aqueous CO2, are separated. The CO2 is recycled, useful materials are

collected and the carbonated materials and residue are returned to the mine site.

There are adequate mineral deposits to support mineral sequestration. The tonnage of silicate mineral

necessary to carbonate 100% of the CO2 emissions from a single 500 MW coal-fired power plant can be

estimated based on the following assumptions: 1) a mean magnesium oxide (MgO) content in the

magnesium silicate ore mineral of 40 weight percent (wt pct); 2) 90% ore recovery; 3) 80% efficiency of

the carbonation reaction; and stoichiometry of equation 1. Based on these assumptions, a single 500 MW

power plant, generating approximately 10,000 tons/day of CO2, would require just over 30,000tons/day of

magnesium silicate ore.

Pipeline

Advantages of Mineral Sequestration

The major advantages of CO2 sequestration by mineral carbonation are:

Long Term Stability - Mineral carbonation is a natural process that is known to produce

environmentally safe and stable material over geological time frames. The production of mineral

carbonates insures a permanent fixation rather than temporary storage of the CO2 thereby

guaranteeing no legacy issues for future generations.

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Vast Capacity – Raw materials for binding the CO2 exist in vast quantities across the globe.

Readily accessible deposits exist in quantities that far exceed even the most optimistic estimate of

coal reserves (~10,000 -109 tons).

Potential to be Economically Viable - The overall process is exothermic and, hence, has the

potential to be economically viable. In addition, its potential to produce value-added by-products

during the carbonation process may further compensate its costs.

Challenges

Slow reaction:-The major technical challenge now hindering the use of minerals to sequester

CO2is their slow reaction rate. Weathering of rock is extremely slow. The highest priority is given

to identifying faster reaction pathways.

The optimized process to be economical:-Although many carbonation reactions are exothermic,

it is generally very difficult to recover the low-grade heat while the long reaction time and

demanding reaction conditions contribute to process expense.

Environmental impact:-the environmental impact from mining minerals and carbonation

processes must be considered.

Program Goals

The program goals are specifically designed to address these challenges, including

Identifying favored technical processes,

Determining the economic feasibility of each sequestration process identified, and

Determining the potential environmental impacts of each process.

ALTERNATE APPROCHES

A. Capture by Micro algae

The concept is to grow algae in artificial ponds, add the necessary nutrients and fertilize the ponds with

CO2 from flue gas. Under these conditions it is possible to enhance the growth of micro algae, harvest the

algal biomass and convert it to food, feed or fuel. At present, about 5000 tons of food- and feed-grade

micro algae biomass is produced annually in large open pond systems. As such, this approach cannot be

considered as a sequestration method because the CO2 will be returned to the atmosphere upon digestion

and respiration of the food or feed. What is even worse, when used as a feed to ruminating animals, some

of the ingested carbon may be converted to methane which is a stronger greenhouse gas than carbon-

28

dioxide. But if the biomass is converted to biofuels and subsequently combusted, then it replaces fossil fuel,

and thus the commensurate emission of fossil fuel generated CO2 is avoided. However, for this approach to

be viable as a greenhouse gas control method, it is necessary to significantly lower the cost from today’s

level. Despite some intensive efforts, primarily from Japan, little progress has been made towards this goal.

B. Ocean Fertilization

It has been hypothesized that by fertilizing the ocean with limiting nutrients such as iron, the growth of

marine phytoplankton will be stimulated, thus increasing the uptake of atmospheric CO2 by the ocean. The

presumption is that a portion of the phytoplankton will eventually sink to the deep ocean. Researchers have

targeted “high-nutrient-low-chlorophyll” (HNLC) ocean regions, specifically the eastern Equatorial Pacific,

the northeastern Sub arctic Pacific, and the Southern Oceans.

Four major open ocean experiments have been conducted to test the “iron hypothesis”, two in the

Equatorial Pacific (IRONEX I in 1993 and IRONEX II in 1995) and two in the Southern Ocean (SOIREE

in 1999 and EISENEX in 2000). These experiments, funded through basic science programs (not

sequestration programs), show conclusively that phytoplankton biomass can be dramatically increased by

the addition of iron. However, while a necessary condition, it is not sufficient to claim iron fertilization will

be effective as a CO2 sequestration option.

The proponents of iron fertilization claim very cost effective mitigation on the order of $1-10/tC, but

critical scientific questions remain unanswered. While iron increases uptake of CO 2 from the atmosphere to

the surface ocean, it needs to be exported to the deep ocean to be effective for sequestration. No

experiments have yet attempted to measure export efficiency, which is an extremely difficult value to

measure (some people claim that it cannot be measured experimentally). In addition, there are concerns

about the effect on ecosystems, such as inducing anoxia (oxygen depletion) and changing the composition

of phytoplankton communities.

C. Non-biological Capture from Air

The terrestrial biosphere routinely removes CO2 from air, primarily through photosynthesis. It has been

suggested that CO2 can also be removed from air via non-biological means. While some concept papers

have been published, no viable methods to accomplish this goal have been proposed. The problem is that

the partial pressure of CO2 in the air is less than 0.0004 atm, compared to about 0.1 atm in flue gas and up

to 20 atm in synthesis gas. The difficulty in capture increases as the partial pressure of CO2 decreases.

Therefore, one can question whether CO2 can be captured from air with acceptable energy penalties and

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costs. If so, it almost surely will take development of a capture process very different from those that exist

today.

D. Utilization

CO2 from fossil fuel could be utilized as a raw material in the chemical industry for producing commercial

products that are inert and long-lived, such as vulcanized rubber, polyurethane foam and polycarbonates.

Only a limited amount of CO2 can be stored in such a fashion. Estimates of the world’s commercial sales

for CO2 is less than 0.1 GtC equivalents, compared to annual emissions of close to 7 GtC equivalents. It has

been suggested that CO2 could be recycled into a fuel. This would create a market on the same scale as the

CO2 emissions. However, to recycle CO2 to a fuel would require a carbon-free energy source. If such a

source existed, experience suggests that it would be more efficient and cost-effective to use that source

directly to displace fossil fuels rather than to recycle CO2.

CONCLUSION

The world cannot continue to emit the CO2into the atmosphere in the way it is doing today. The combined

expertise and resources of the petroleum industry are enormous and its credentials in geological storage is

second to none. Petroleum industry is ready to use this expertise to ensure CCS can make a significant

contribution to tackling climatic change. our destiny is going to engineer the planet more and more- to

arrange the temperature, rainfall and sea level to suit our preferences. Indeed ,while today problem is

getting rid of CO2 the reverse may occur. We may start asking if we can put CO2 below the ground in a

retrivable fashion, so we can,warm the planet if we feel it’s getting to cold.

REFERENCES:

1. CO2 Mineral Sequestration Studies in US

Philip Goldberg, Zhong-Ying Chen, William O’Connor ,

Richard Walters and Hans Ziock.

2. Ocean Storage of CO2, IEA Greenhouse Gas R&D Program.

3. Monitoring to ensure safe and effective geologic sequestration of carbon dioxide

Sally M. Benson and Larry Myer, Lawrence Berkeley National Laboratory, Berkeley, California 94720,

smbenson@lbl.gov.

4. Long term strategies for mitigating climate change, Yoichi kaya, Director General, Research Institute

of Innovative Technology for the Earth (RITE), Japan.

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5. System-Level Modeling for Geological Storage of CO2

Yingqi Zhang, Curtis M. Oldenburg, Stefan Finsterle, Gudmundur S. Bodvarsson and

Lawrence Berkeley. National Laboratory, Earth Sciences Division, USA.

6. Fundamentals of carbon capture and storage technology, by the petroleum economist

7. Carbon capture and storage post note March 2005 Number 238.8 Carbon Capture and Storage from Fossil Fuel Use 1

Howard Herzog and Dan Golomb, Massachusetts Institute of Technology, Laboratory for Energy and the

Environment.

9. Global Warming: Effect, Solution, Opportunity By Carl N. Hodges.

10. Environmental, Health, and Safety Guidelines for Petroleum Refining by international finance

corporation, world bank group.

11.Electricity and Petroleum industries by Canada’s green house gas inventory 1990-1999.

12.Global Warming: A Scientific Overview By James M. Taylor Senior Fellow, Environment Policy,

The Heartland Institute.

13. A Report of Energy Trends and Green House Gas Emissions and Alternative Energy, by Exxon mobil 14. La Plata County Natural Gas Industry Greenhouse Gas Emissions Estimate, 2006, By Richard

Heede, Climate Mitigation Services, 19 February 2008.

15.Green house Gas Emissions: Policy and Economics, A Report Prepared for the Kansas Energy

Council , by Trisha Shrum, KEC Research Fellow, August 3, 2007.

16. EBRD Greenhouse Gas Assessment Methodology, Version 1.1, February 2005.

17. Green House Gas Emissions and Estimation inventories, IPIECA\API workshop, Belgium, 16

January 2007.

18. Green House Gas emissions control by oxygen firing in circulating fluidized bed boilers, from

project facts, US department of energy, National energy technology laboratory.

19. Review of the carbon Pollution reduction scheme white paper by Australian Petroleum Production

& Exploration Association.

20. Combustion processes for carbon capture by Terry F. Wall,

School of Engineering, the University of Newcastle, Callaghan, NSW 2308, Australia.

21. Monitoring to ensure safe and effective geologic sequestration of carbon dioxide by Sally M.

Benson and Larry Myer, Lawrence Berkeley National Laboratory, Berkeley, California 94720,

smbenson@lbl.gov.

22. Facts on CO2 capture and storage, Summary of a Special Report by the Intergovernmental Panel on

Climate Change.

23. U.S. Inventory of Greenhouse Gas Emissions and Sinks 1990-2000 (EPA 2002).

24. Global Warming unit presentation, 11/06, Beryl Flom.

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Figure 1: Green House Effect

Figure 2: increase in earth’s surface temperature.

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Figure 3: Ice gap melting.

Figure 4: Glacier disappearance

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Figure 5: Increase in sea level comparison

Figure 6: flood defences

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Figure 7: Petroleum Refinery GHG emission

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Figure 8: Gas Flaring

Figure 9: The Stabilization triangle

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Figure 10: seven wedges concept

Figure 11: Comparison of power plant with CCS to without CCS

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Figure 12: flow diagram of post combustion carbon capture

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Figure 13: flow diagram of pre-combustion capture

Figure 14: flow diagram of oxyfuel combustion

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Figure 15: Geological Storage options for CO2

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Figure 16: Enhanced oil recovery with CCS

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Figure 17: Ocean storage of CO2

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