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Global Warming:. &. Strategies for overcoming Greenhouse Gas Emissions. What are Greenhouse Gases?. GHGs are the radiative force in the greenhouse effect: balancing the net radiation coming in and out of the atmosphere from the sun keeping the surface temp balanced - PowerPoint PPT Presentation


  • Global Warming: Strategies for overcoming Greenhouse Gas Emissions&

  • Global Warming: BasicsGlobal Warming is a type of climate change

    Climate change = total amount of the sun's energy absorbed does not equal the amount of energy released which causes an imbalancegreenhouse gases affect the balance!

    Earths climate has changed many times in its history

    Possible Reasons for Climate Change: Volcanic eruptionsThe Earth's orbit changingThe amount of energy released from the SunChanges in ocean circulationhuman activities

  • What are Greenhouse Gases?GHGs are the radiative force in the greenhouse effect: balancing the net radiation coming in and out of the atmosphere from the sun keeping the surface temp balanced

    Increasing concentrations of GHGs warms the Earths atmosphere (Global Warming)

    Major GHGs: ozone, water vapor, carbon dioxide, methane, nitrous oxide, and human made fluorinated gases

    Human influence on greenhouse effect is mainly through the release of CO2

  • Simple understanding of Greenhouse Effect

  • Main Types of Greenhouse GasesCarbon Dioxide (CO2): burning of fossil fuels (oil, natural gases, and coal), decaying organic material, industrial by-products, deforestation

    Methane (CH4): production and transportation of fossil fuels, livestock, agricultural practices, and decay of organic waste

    Nitrous Oxide (N2O): agricultural and industrial activities and burning of fossil fuels and waste

    Fluorinated Gases (very strong synthetic gases): industrial processes, includes chlorofluorocarbons

  • How Humans emit GHG Burning of fossil fuelsDeforestationLivestock IndustryVented septic systems and landfillsAgricultural ActivitiesUse of Synthetic gases like chlorofluorocarbons in refrigerating systems and manufacturing processes

  • World CO2 Emissionsfrom the Consumption and Flaring of Fossil Fuels 2005 in Million Metric Tons

    World Total: 28,192.74 MM tons

    USA: 5,956.98 MMtons21.2% of human emitted Carbon dioxide 20.14 metric tons per capita

    Asia/Oceania: 10,362.49 MMtons36.8% of all Human emitted CO2, BUT their per capita is only 2.87 metric tons

    USA CO2 emissions from Petroleum: 2,613.96 million metric tons Natural Gas: 1,201.37 million metric tons Coal: 2,141.66 million metric tons

    Stats from 2005, but posted in Sept. 2007 from EIA

  • CO2 Emissions U.S. carbon dioxide emissions have grown by an average of 1.3 percent annually since 1990

    CO2 growth is mainly from population growth

    Transportation sector is the largest source of CO2 emissions

    Anthropogenic CO2 emissions total roughly 7 billion tons of Carbon a year.

  • Methane Emissions27.8 million metric tons emitted in 2004 = 9% of total U.S. GHG emissions

    Where from?emissions from landfillsemissions associated with animal wastecoal mines, rice cultivation.

    The major sources are energy, agriculture, and waste management

  • Nitrous Oxide and Man-Made Gases Nitrous Oxide:

    U.S. human emissions in 2004 were 5 % of total U.S. GHG emissions.

    Major Source: Agricultural sources accounted for 75% of total U.S. nitrous oxide emissions in 2004. Man-Made Gases:

    Hydrofluorocarbons, Perfluorocarbons, and SulfurHexafluoridePFCs and SF6 have long atmospheric lifetimesPotent GHGs with global warming potential thousands of times higher than that of carbon dioxide


  • Greenhouse Gas historyCarbon Dioxide is up thirty percent since 1750 because of increasing population.In the mid-1800s during a high part of the Industrial Revolution you can see that the emissions of GHGs really begins to pick up.

  • Global TrendsKyoto Protocol is a way to reduce GHG by regulations and limits

    174 parties who have ratified the protocol

    36 countries are required to reduce GHG to specific levels

    The US is not apart of it! Some of the countries that ARE include the EU, Germany, Russia, Romania, Iceland

    Six Kyoto GHGs: carbon dioxide, methane, nitrous oxide, sulful hexafluoride, HFCs and PFCs

  • US Greenhouse Gas Abatement Mapping Initiative Executive ReportThe USA abatement programs have been hypothesized to be full blown by 2030Areas of Focus:Reducing Carbon Intensity of Electric PowerCCS, Wind, Nuclear, Solar Photovoltaics, Natural Gas-fired powerExpanding and Enhancing Carbon SinksAfforestation of pastureland and croplandConservation tillageForest management practicesWinter Crop CoversFuel Efficiency and Hybrid developmentBiofuels (cellulosic)Improving conventional vehiclesHybrid and Plug-in Hybrid developmentEnergy and Building EfficiencyCombined Heat and Power Application (CHP)Residential Heat Power

  • Strategies for Reducing GHGsResearch and Development of Renewable Energies Solar EnergyWind EnergyBiomass/BiofuelOcean (Wave and Tidal)Hybrid systems Fuel Cell TechnologyNuclear EnergyHigher Efficiency for IndustriesMixture of all!Clean CoalCarbon Capture and Sequestration

  • What is Carbon Capture and Sequestration (CCS)?CCS is the capturing of carbon dioxide from the atmosphere and emission streams and then storing it back in the Earth.

    Estimates suggest that storage potential in geological formations of around 2000 GtCO2 (about 80 years of current global emissions)!

    3-step processCO2 Capture from power plants, industrial sources and natural gas wellsCompression and Transportation by pipeline or tankersStorage in Geological Reservoir Sequestration, Terrestrial Sequestration and Ocean Sequestration

  • Carbon CaptureCapture is possible at different times and using different processes:Before combustion (pre-combustion) decarbonization of fossil fulesAfter Combustion (post-combustion) capture from flue gasCO2 can be separated from the following during both pre and post combustionNatural Gas Flue gases from: SC-PCC plants (Supercritical Pulverised Coal CombustionSC-PCC with Oxyfuel CombustionIGCC plants (Integrated Coal Gasification Combined Cycle)NGCC plants (Natural Gas Combined Cycle)

  • Pre-Combustion CaptureCoal, or other fossil fuels, is gasified which converts the coal into a gaseous fuel by reacting it with high temperatures and certain amounts of oxygen.

    Through conversion it becomes a gas known as synthesis gas (syngas) which mainly consists of CO and H2 and the CO2 can be separated and captured

    A few ways to do this:IGCC PlantsNGCC Plants

  • Post Combustion CaptureChemically absorbing CO2 from flue gas in SC-PCC plants and NGCC plants using Amines and other chemical absorbents

    Oxyfuel combustion which produces almost pure CO2 that can be easily separated.

    Side note: Other separation methods such as membranes are being considered as a potential longer-term option for both pre/post combustion capture alone or in combination with other absorption techniques

  • Supercritical Pulverized Coal Combustion (SC-PCC)Pulverized coal combustion is the dominate coal generation in the US at the moment and uses very finely ground coal37 % Net Energy EfficientHHV: 9,300 Btu/kWh

    Capture from Flue Gas: captured by chemical absorbents that are heated to release CO2 and regenerated. The high CO2 concentration is what facilitates the capture.Amines are the common chemical absorbent Energy required for solvent regeneration and CO2 compression are highEfficiency losses are about 8-12 percentage points, with net efficiencies of about 35%

    Plant Types:

  • Oxyfuel combustion is the process of burning coal with a gas mixture that is mainly oxygen instead of just using air. 95% oxygen and the rest is recycled flue gasThe exhaust consists primarily of CO2 and H2O great for CCS

    CO2 is captured by cooling and water condensation

    Avoids costly CO2 gas separation but creates an additional cost for the pure O2

    Net efficiency are similar to that of the SC-PCC capture from Flue gas (approx. 35%)

    Advantages:About 75% less flue gas, leading to less heat being lost to the flue gas. Suitable capture of CO2 for sequestration. Less nitrogen oxide producedPower Plants can be retrofit for this new processPotentially lowers the cost for achieving a near net zero emissions from coal-based electricity generation with Carbon Capture by Oxyfuel Combustion


  • IGCC Plants: Integrated Gasification Combined CycleIGCC systems combine a coal gasification unit with a gas fired combined cycle power generation unit.

    Coal gasification: the process of converting coal to a gaseous fuel through partial oxidation. Carbon dioxide and Sulfur are removed

    The second part takes the cleaned gas and burns it in a conventional gas turbine to produce electrical energy

    Exhaust gas is recovered, used to boil water, creates steam for a steam turbine which also produces electrical energy.

    In typical plants, about 65% of the electrical energy is produced by the gas turbine and 35% by the steam turbine.

    3 main basic types of coal gasifiers: Fluidised Bed, Fixed Bed, Entrained Flow

  • IGCC continued.Advantages:

    achieves up to 50% thermal efficiency.

    It uses 20-50% less water than a conventional coal power station.

    It can utilize a variety of fuels, like heavy oils, petroleum cokes, and coals.