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Energy and Global Change

Energy and Global Change

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Energy and Global Change

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  1. Energy andGlobal Change

  2. State of the Planet “A dynamic interactive system of bio-geo-chemical cycles that are being significantly influenced by an emerging intelligent life-form. This life-form has some serious limits in cognition and self-awareness as well as a number of other intellectual and physical constraints.” Michael Crow

  3. Impact of Humankind • Eliminated 20% of all bird species • Increased atmospheric CO2 by 30% • Using over 50% of freshwater runoff • Overexploiting over 60% of marine fisheries • Increasing atmospheric CH4by 140% • Introduced over 70,000 synthetic chemicals into the environment W. Clark

  4. Impact of Humankind "The balance of evidence suggests a discernible human influence on global climate." Intergovernmental Panel on Climate Change, United Nations Most projections now suggest that the degree of change will become dramatic by the middle of the 21st century, exceeding anything seen in nature during the past 10,000 years.

  5. Challenges of the 21st Century • Eliminating weapons of mass destruction. • Preventing the population of the planet from exceeding 9 billion people. • Sharply reducing the global rate of loss of biodiversity. • Meeting global energy needs while limiting the atmospheric concentration of carbon dioxide.

  6. Global Warming There is now general agreement that the Earth’s temperatures are increasing, and the primary cause is humankind. 15 of the warmest years worldwide have occurred since 1980. It is likely that 1998 was the warmest year in the last thousand (from ice cores). The Arctic ice cap is melting. So are the glaciers. The sea levels are rising (10 inches in the past century). With rather high confidence one can now say that global warming is being experienced and that greenhouse-gas increases from human activities are its primary cause.

  7. The Greenhouse Effect CO-2 remains in the atmosphere for a century or more. Such greenhouse gases trap some of the solar radiation that the planet would otherwise radiate back to space, creating a blanket that insulates and warms the lower atmosphere. The inevitable result of pumping the sky full of greenhouse gases is global warming. This dries the planet by evaporating moisture from the oceans, soils, and plants. Additional moisture in the atmosphere provides a swollen reservoir of water that is trapped by all precipitating weather systems, including tropical storms, thunderstorms, snowstorms, and frontal systems. Human activities aside from burning fossil fuels also wreak havoc. The conversion of forests to farmland eliminates trees that would absorb carbon from the atmosphere. Fewer trees also mean greater rainfall runoff, thereby increasing the risk of floods.

  8. Global Climate Disruption Before the industrial revolution, the concentration of carbon dioxide was about 280 parts per million by volume (ppmv). Today we are releasing about 7 billion tons of carbon into the atmosphere each year, and the atmospheric concentration has increased to 370 ppmv. At the current rates, carbon release would increase to 15 billion tons per year with concentrations at 550 ppmv by 2050. The impact on climate would be extraordinary … and perhaps not reversible (runaway greenhouse effect).

  9. Global Energy Use

  10. Current Energy Supply System • In 2000, world’s 6 billion people used about 450 exajoules (billion-billion or 10^18) • 35% from oil • 23% from coal • 20% from natural gas • 6% from nuclear power • 6% from hydropower • 13% from biomass fuels (e.g., wood) • About 30% of primary energy was used to generate electricity. Fossil fuels provided 63%; nuclear provided 18%. • The United States, with 4.5% of world’s population, accounts for 23% of global energy use and 27% of electricity production.

  11. Current Energy Supply System • In 2000, world’s 6 billion people used about 450 exajoules (billion-billion or 10^18) (1 EJ ~ 1 quad = 10^15 BTU) • 35% from oil • 23% from coal • 20% from natural gas • 6% from nuclear power • 6% from hydropower • 13% from biomass fuels (e.g., wood) • About 30% of primary energy was used to generate electricity. Fossil fuels provided 63%; nuclear provided 18%. • The United States, with 4.5% of world’s population, accounts for 23% of global energy use and 27% of electricity production.

  12. The Current Situation Importance of energy: Energy costs typically absorb 7 to 10% of the cost of living (and are key factors in inflation and recession). Energy is a major contributor to dangerous and complex environmental problems at every scale. Energy issues can trigger issues in international security, from conflict over oil and gas reserves to nuclear weapons proliferation. In 2000, more than 75% of world's energy was produced from fossil fuels.

  13. The Current Situation The reliability of energy supplies is decreasing because of political instability and increasing demand, at a time when many countries are becoming more dependent on those supplies. The United States is heavily dependent on foreign oil, and natural gas prices have doubled in recent months. Overall consumption of electrical power is increasing, and is likely to rise from 40% to 70% by 2050 (think computer!) During the next decade, the role of renewables, particularly wind and biomass, will increase, but not nearly enough to fill present requirements. The U.S. and other developed countries will find it necessary to devote far more attention, including increased R&D, to multiple risk and energy trade-offs involving coal, nuclear power, petroleum, natural gas, and electric power.

  14. Coal

  15. Coal U.S. coal reserves are enormous–an order of magnitude larger than oil and gas reserves (140,000 EJ). Unfortunately, coal is a dirty, inconvenient fuel for most uses which causes significant environmental impact and danger to public health due to pollutants released during the direct combustion (flyash particulates, SO-2, CO-2, NO), materials handling problems, and the environmental and health problems associated with coal mining.

  16. Oil

  17. Oil and Gas During the first half of the 20th Century our society made a transition from wood and coal as its primary energy sources to petroleum and natural gas. These resources are limited. Some believe that the prospective scarcity of oil combined with the instability of the regimes of oil-rich nations will cause a steep rise in hydrocarbon prices over the next two decades. Some believe that depletion is now close to the psychologically important half-way mark. But optimists believe that htis turning point is still decades away, and that with new technologies, reserves are far larger (particularly with tar sands).

  18. Oil and gas Exxon believes "that for the next 25 to 50 years, the oil available to the markets is for all intents and purposes infinite." But scarcity is not the only reason why the world might move away from oil. The unnerving votality of oil prices, together with growing concern about the environmental imapct of hydrocarbons, is already spurring the search for alternatives. "The stone age did not end because the world ran out of stone, and the oil age will end long before the world runs out of oil!"

  19. M. King Hubbert’s Peak • U.S. oil production peaked in the 1970s • The imbalance between domestic production and consumption has led to our extreme dependence on Middle East oil • When will global oil production peak? • Certainly some time during this century. • Within next few decades? • Within next decade? • Note the disruption that will occur when global consumption exceeds production!

  20. Natural Gas • Natural gas has become the preferred fuel for new generating capacity. • Thus far, at least, the discovery of new reserves is increasing faster than our consumption. • Gas-turbine plants are relatively inexpensive to build and much cleaner than coal. • But, natural gas supplies are limited, and the cost of natural gas fluctuates widely (currently about twice as expensive as coal).

  21. United States Energy Vulnerability The fraction of U.S. oil imports from the OPEC cartel and, within it, from the politically volatile Persian Gulf, is likely to increase over time. Currently the U.S. gets half of its oil imports from OPEC and half of that amount from the Persian Gulf. The Persian Gulf has almost 30% of world oil production, 43% of exports, and 65% of proven reserves.

  22. Biomass

  23. Biomass • Wood, crop residues, dung, and other combustible wastes are the main source of energy for a majority of the world’s population (65 EJ or 15%). • 60% of biomass supplied by wood, most of which is cut and burned faster than it is replaced. • Furthermore, biomass contributes to CO-2 buildup, both through deforestation and combustion.

  24. Hydroelectric

  25. Hydroelectric Power • One of only two sources of carbon-free energy (the other being nuclear fission) currently producing a significant fraction of the world’s energy supply (currently 7% or 27 EJ per year). • Further expansion is limited by geography and environmental impact. (In fact, pressure is building to dismantle dams and return rivers to natural flows.)

  26. Geothermal

  27. Geothermal The thermal energy contained in the upper 10 km of the earth’s crust can be tapped in a variety of ways: dry steam fields (e.g., the Geysers plant in California); wet steam fields, pumping fluids through hot igneous rocks associated with recent volcanism, and tapping geopressurized basins containing large volumes of trapped geofluids under abnormally high temperature and pressure.

  28. Problems • Fields are of limited magnitude and rapidly depleted over a few decades. • Geothermal fluids withdrawn from the earth contain a variety of noxious substances, including CO-2, H2S, arsenic, mercury, and even radioactive materials. (In fact, the Geysers plant has the highest radioactivity level of any power plant in the United States!) • The environmental and safety impact of geothermal plants are very high.