Renewable Energy Resources CONTENTS:

1. Overview

2. Definition

3. Types of Renewable energy

4. Wind

5. Solar Energy

6. Hydropower

7.

1. Introduction

In today's world of climbing fuel prices, approaching the peak oil supply limit, and discussions

of global warming, renewable energy is gaining more public attention and receiving more

financial and legislative support. We need to learn more about the different types of renewable

energy so that you can help educate your family, friends, and policymakers about ways to help

our country move towards energy independence and environmental sustainability. According to

a USAID report, Pakistan has the potential of producing 150,000 megawatts of wind

energy, of which only the Sindh corridor can produce 40,000 megawatts .

2. Definition

Renewable energy is generally defined as energy that comes from resources which are naturally

replenished on a human timescale such as sunlight, wind, rain, tides, waves and geothermal heat.

Renewable energy replaces conventional fuels in four distinct areas: electricity generation, hot

water/space heating, motor fuels, and rural (off-grid) energy services.

3. Types of Renewable Energy

Most Countries currently relies heavily on coal, oil, and natural gas for its energy. Fossil fuels

are non-renewable, that is, they draw on finite resources that will eventually dwindle, becoming

too expensive or too environmentally damaging to retrieve. In contrast, renewable energy

resources such as wind and solar energy are constantly replenished and will never run out.

Most renewable energy comes either directly or indirectly from the sun. Sunlight, or solar

energy, can be used directly for heating and lighting homes and other buildings, for generating

electricity, and for hot water heating, solar cooling, and a variety of commercial and industrial

uses.

The sun's heat also drives the winds, whose energy, is captured with wind turbines. Then, the

winds and the sun's heat cause water to evaporate. When this water vapor turns into rain or snow

and flows downhill into rivers or streams, its energy can be captured using hydroelectric power.

Along with the rain and snow, sunlight causes plants to grow. The organic matter that makes up

those plants is known as biomass. Biomass can be used to produce electricity, transportation

fuels, or chemicals. The use of biomass for any of these purposes is called bioenergy.

Hydrogen also can be found in many organic compounds, as well as water. It's the most

abundant element on the Earth. But it doesn't occur naturally as a gas. It's always combined with

other elements, such as with oxygen to make water. Once separated from another element,

hydrogen can be burned as a fuel or converted into electricity.

Not all renewable energy resources come from the sun. Geothermal energy taps the Earth's

internal heat for a variety of uses, including electric power production, and the heating and

cooling of buildings. And the energy of the ocean's tides come from the gravitational pull of the

moon and the sun upon the Earth.

In fact, ocean energy comes from a number of sources. In addition to tidal energy, there's the

energy of the ocean's waves, which are driven by both the tides and the winds. The sun also

warms the surface of the ocean more than the ocean depths, creating a temperature difference

that can be used as an energy source. All these forms of ocean energy can be used to produce

electricity.

4. Winds

History: Societies have taken advantage of wind power for thousands of years. The first known

use was in 5000 BC when people used sails to navigate the Nile River. Persians had already been

using windmills for 400 years by 900 AD in order to pump water and grind grain. Windmills

may have even been developed in China before 1 AD, but the earliest written documentation

comes from 1219. Cretans were using "literally hundreds of sail-rotor windmills [to] pump water

for crops and livestock.

Working Mechanism: Wind turbines, like windmills, are mounted on a tower to capture the

most energy. At 100 feet (30 meters) or more aboveground, they can take advantage of the faster

and less turbulent wind. Turbines catch the wind's energy with their propeller-like blades.

Usually, two or three blades are mounted on a shaft to form a rotor.

A blade acts much like an airplane wing. When the wind blows, a pocket of low pressure air

forms on the downwind side of the blade. The low pressure air pocket then pulls the blade

toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much

stronger than the wind's force against the front side of the blade, which is called drag. The

combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a

generator to make electricity.

How fast wind blows, how often, and when, factors play a significant role in its power

generation and costs. The power output from a wind turbine rises as a cube of wind speed. In

other words, if wind speed doubles, the power output increases eight times. Therefore, higher-

speed winds are more easily and inexpensively captured.

Efficiencies: Harnessing the wind is one of the cleanest, most sustainable ways to generate

electricity. Wind power produces no toxic emissions and none of the heat-trapping emissions that

contribute to global warming. This, and the fact that wind power is one of the most abundant and

increasingly cost-competitive energy resources, makes it a viable alternative to the fossil fuels

that harm our health and threaten the environment. The United States installed a record 13,351

MW of wind power in 2012, capable of producing enough electricity to power more than 3

million typical homes. While wind energy accounted for just fewer than four percent of U.S.

electricity generation in 2012, it already generates more than 10 percent of the electricity in nine

U.S. states. Thanks to its many benefits and significantly reduced costs, wind power is poised to

play a major role as we move toward a sustainable energy future

Uses: Wind turbines can be used as stand-alone applications, or they can be connected to a

utility power grid or even combined with a photovoltaic (solar cell) system. Several electricity

providers today use wind plants to supply power to their customers. Stand-alone wind turbines

are typically used for water pumping or communications. However, homeowners, farmers, and

ranchers in windy areas can also use wind turbines as a way to cut their electric bills.

Latest Research: Scientists have developed the first autonomous industrialized public

lighting system that works with solar and wind energy

Source: http://www.sciencedaily.com/releases/2015/01/150120085819.htm

References

http://www.ren21.net/Portals/0/documents/Resources/GSR/2013/GSR2013_lowres.p

df

http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-

wind-energy-works.html

http://www.renewableenergyworld.com/rea/tech/wind-power

http://www.sciencedaily.com/news/matter_energy/wind_energy/

http://www.altenergy.org/renewables/wind.html

5. Solar Energy

The sun is probably the most important source of renewable energy available today.

Traditionally, the sun has provided energy for practically all living creatures on earth, through

the process of photosynthesis, in which plants absorb solar radiation and convert it into stored

energy for growth and development. Scientists and engineers today seek to utilize solar radiation

directly by converting it into useful heat or electricity.

Working mechanism: Following types of solar energy systems are in use today:

a) Solar photovoltaic cell Photovoltaic systems convert solar radiation to electricity via a

variety of methods. The most common approach is to use silicon panels, which generate an

electrical current when light shines upon it. When sunlight hits a cell, the energy knocks

electrons free of their atoms, allowing them to flow through the material. The resulting DC

(direct current) electricity is then sent to a power inverter for conversion to AC (alternating

current), which is the form in which electric power is delivered to homes and businesses.

a) Solar thermal collectors use heat-absorbing panels and a series of attached circulation tubes

to heat water or buildings.

b) Solar concentration systems use mirrors -- usually arranged in a series of long, parabolic

troughs, a large round dish, or a circle surrounding a "power tower" -- to focus the sun's

reflected rays on a heat-collecting element. The concentrated sunlight heats water or a heat-

transferring fluid such as molten salt to generate steam, which is then used conventionally to

spin turbines and generate electricity.

c) Passive solar design is the creative use of windows, skylights and sunrooms, building site

and orientation, and thermal construction materials to heat and light buildings, or to heat

water, the natural way.

Advantages of Solar Energy

a) Sunlight is free and infinitely renewable.

b) Unlike conventional fossil fuel and nuclear power, solar power produces no polluting

emissions, including those that cause global warming.

c) With no moving parts, solar panels are silent, easy to operate, and rarely need maintenance.

d) Solar power can slash utility bills for both residential and commercial consumers

e) Solar panels can help utilities avoid brownouts and blackouts. When demand for electricity

is high, utilities can use the panels to generate extra energy rather than fire up expensive and

polluting "peak" power plants that otherwise lie dormant.

f) Many solar panel manufacturers are based in the United States, employing more than

27,000 Americans in high-earning, high-tech jobs. This domestic industry helps reduce our

dependence on foreign oil, coal and natural gas.

g) It will increase countries' energy security through reliance on an indigenous, inexhaustible

and mostly import-independent resource, enhance sustainability, reduce pollution, lower

the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise.

Disadvantage

The main disadvantages are that it is currently more expensive than traditional energy, and the

availability of solar radiation varies from day to day, and from season to season.

Uses

a) Solar power remains, after hydro and wind, the third most important renewable energy

source in terms of globally installed capacity. In 2012, more than 100 GW of solar

photovoltaic (PV) power was installed in the world an amount capable of producing at least

110 TWh of electricity every year

b) Solar photovoltaic are especially valuable for remote rural applications where it would be

prohibitively expensive to supply electricity from a utility line.

c) New commercial concentrating solar power plants are being built throughout the

Southwest, but solar power can be used wherever the sun shines. The 32-megawatt Long

Island Solar Farm at Brookhaven National Laboratory, currently the largest solar farm on

the East Coast, produces enough electricity annually to power nearly 4,500 homes. The

project created more than 200 locally sourced construction jobs and maintains two full-time

workers for operations and maintenance.

d) Homeowners, farms and businesses across the country are installing solar panels to reduce

their electric bills. Many farms and businesses, with their open acreage and/or large

buildings, can install enough solar to pay their entire electric bill, or at least reduce costly

summer electricity rates, which is often the case for northern states.

Latest News

Prime Minister Nawaz Sharif inaugurated Pakistan’s first solar power park, which will start

generating 100 megawatts of electricity in December this year and by 2016 add 1,000 megawatts

to the national grid. The Quaid-e-Azam Solar Park project is a joint venture of the government of

Punjab, Bank of Punjab and M/s TBEA Ltd of China.

http://tribune.com.pk/story/706555/alternate-energy-pakistans-first-solar-park-rolled-out/

#SolarImpulse, the world's only solar-powered aircraft, will make a stop over in Ahmedabad

tomorrow as a part of its maiden global journey!

http://thelogicalindian.com/story-feed/tech/worlds-first-solar-powered-aircraft-takes-off-on-

round-the-world-flight/

References

http://en.wikipedia.org/wiki/Renewable_energy

http://www.renewableenergyworld.com/rea/tech/home

http://extension.psu.edu/natural-resources/energy/solar-energy

http://www.nrdc.org/energy/renewables/solar.asp

http://www.renewableenergyworld.com/rea/tech/solar-energy

http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-solar-

energy-works.html#.VP8wn_mSzFA

http://www.altenergy.org/renewables/solar.html

http://energyinformative.org/where-is-solar-power-used-the-most/

http://en.wikipedia.org/wiki/Renewable_energy#Solar_energy

6. Hydropower

Hydropower is considered a renewable energy resource because it uses the Earth's water cycle to

generate electricity. Water evaporates from the Earth's surface, forms clouds, precipitates back to

earth, and flows toward the ocean. 26% of total power capacity is obtained by hydropower in

Pakistan.

How it works

Most hydroelectric power plants use dams to impound river water in a reservoir, and then

release it in a controlled fashion to spin a turbine and generate electricity. Some “run-of-river”

facilities operate with just a small dam, but these still divert, or “bypass” a portion of a river.

Bypass reaches can be miles long. Other projects simply use water in an existing canal, taking

advantage of already available flow.

Types

Hydropower is used primarily to generate electricity. Broad categories include:

a) Conventional hydroelectric, referring to hydroelectric dams.

b) Run-of-the-river hydroelectricity, which captures the kinetic energy in rivers or streams,

without the use of dams.

c) Small hydro projects are 10 megawatts or less and often have no artificial reservoirs.

d) Micro hydro projects provide a few kilowatts to a few hundred kilowatts to isolated homes,

villages, or small industries.

e) Conduit hydroelectricity projects utilize water which has already been diverted for use

elsewhere; in a municipal water system for example.

f) Pumped-storage hydroelectricity stores water pumped during periods of low demand to be

released for generation when demand is high.

Efficiencies

a) Hydropower accounts for approximately 75% of the nation’s total renewable electricity

generation, making it the leading renewable energy source of power.

b) The annual hydropower output is equivalent to the energy produced from burning 200

million barrels of heating oil.

c) The National Hydropower Association estimates that more than 160 million tons of carbon

dioxide emissions were avoided in the United States in 2004 because of hydropower

generation.

d) The hydroelectric dams on the Snake and Columbia River systems provide the Pacific

Northwest with some of the cleanest and cheapest electricity in the country. The removal of

the Snake River dams would add 5.4 million tons of CO2 to the atmosphere each year and it

would take three nuclear, six coal-fired, or 14 gas-fired power plants to replace their energy

output.

e) Hydropower turbines are capable of converting more than 90% of available energy into

electricity, making it the most efficient form of electricity generation. By comparison, fossil

fuel plants are only approximately 50% efficient.

f) In addition to providing low-cost electricity, multi-purpose dams provide water for irrigation,

wildlife, recreation and barge transportation and flood control benefits.

Advantages to hydroelectric power:

a) Fuel is not burned so there is minimal pollution

b) Water to run the power plant is provided free by nature

c) Hydropower plays a major role in reducing greenhouse gas emissions

d) Relatively low operations and maintenance costs

e) The technology is reliable and proven over time

f) It's renewable - rainfall renews the water in the reservoir, so the fuel is almost always

there

Challenges

Hydroelectric reservoirs present a number of challenges, including: reservoirs produce

greenhouse gas emissions because of decaying vegetation from flooded lands, particularly in

tropical regions

Reservoirs typically result in higher levels of naturally occurring mercury in water resources,

which is released from land that is flooded

Silt deposits can shorten the operational lifespan of hydroelectric reservoirs.

Small run-of-river hydro plants are not exempt from challenges including

frazil ice (slush formed in water that is too turbulent to freeze over) and pipeline freezing must

be considered

seasonal flows affect revenues

Fish migration can be a concern in which case conservation measures (e.g., fish guidance, habitat

compensation) have to be implemented.

Latest news

Pakistan Awards US$1.4 Billion Contract for 720-MW Karot Hydroelectric

Project on Jhelum River

References

http://www.governing.com/topics/transportation-infrastructure/gov-hydropower-

renewable-energy.html

http://naturalresources.house.gov/issues/issue/?IssueID=8267

http://www.altenergy.org/renewables/hydroelectric.html

http://www.epa.gov/cleanenergy/energy-and-you/affect/hydro.html

http://en.wikipedia.org/wiki/Hydropower

http://www.nrdc.org/energy/renewables/hydropower.asp

http://www.renewableenergyworld.com/rea/tech/hydropower

http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-

hydroelectric-energy.html#.VQBxNPmSzFB

http://www.hawa-energy.com/energy-in-pakistan/electricity-generation-sources-in-

pakistan/

http://water.usgs.gov/edu/wuhy.html

7. Geothermal Energy

The word geothermal comes from the Greek words geo (earth) and thermal (heat). So,

Geothermal energy is heat from within the earth. We can use the steam and hot water Produced

inside the earth to heat buildings or generate electricity. Geothermal energy is a Renewable

energy source because the water is replenished by rainfall and the heat is continuously produced

inside the earth and Earth's heat is being constantly replenished. The earth's heat mostly

originates from the radioactive decay of elements such as uranium. Geothermal energy is

environmentally friendlier than fossil fuels because it is connected with far less greenhouse gas

emissions. The average geothermal power plant emits in average 122 kg of CO2 per megawatt-

hour of electricity, which is negligible amount compared to fossil fuels fired power plants.

History of Geothermal Electricity

Experiments began in Lardarello, Italy in 1904. First U.S. plant at The Geysers in 1920s; first

commercial plant in 1960. Native Americans have been using geothermal energy for many years.

Types of geothermal power plants:

a) Dry steam plants - use steam piped directly from a geothermal reservoir to turn the

generator turbines. The first geothermal power plant was built in 1904 in Tuscany, Italy at a

place where natural steam was erupting from the earth.

b) Flash steam plants - take high-pressure hot water from deep inside the earth and convert it

to steam to drive the generator turbines. When the steam cools, it condenses to water and is

injected back into the ground to be used over and over again. Most geothermal power plants

are flash plants.

c) Binary power plants - transfer the heat from geothermal hot water to another liquid.

The heat causes the second liquid to turn to steam which is used to drive a generator

Turbine.

Uses of Geothermal Energy

Some applications of geothermal energy use the earth's temperatures near the surface,

While others require drilling miles into the earth. The three main uses of geothermal energy

are:

a) Direct Use and District Heating Systems which use hot water from springs or reservoirs near

the surface.

2) Electricity generation in a power plant requires water or steam at very high temperature (300

to 700 degrees Fahrenheit). Geothermal power plants are generally built where geothermal

reservoirs are located within a mile

Advantages

a) Dispatch able, 24–hour, base-load electricity

b) Very reliable

c) 90 to 95% availability

d) Environmentally sound (e.g., low emissions)

e) Virtually inexhaustible with smart resource management practices

f) Relatively low cost (~4 to 8 cents/kWh) Improved technology

g) Reduced drilling costs

h) Experience reduces risk

References

http://earthsheat.blogspot.com/2012/10/why-is-geothermal-energy-renewable.html

http://srren.ipcc-wg3.de/report/IPCC_SRREN_Ch04.pdf

http://www.ei.lehigh.edu/learners/energy/readings/geothermal.pdf

http://www1.eere.energy.gov/tribalenergy/guide/geothermal_energy.html

http://pubs.usgs.gov/circ/2004/c1249/c1249.pdf

http://apps1.eere.energy.gov/tribalenergy/pdfs/geothermal_green_tep_nov03.pdf

http://iea-gia.org/