Session 7 sustainability and fossil fuels


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Session 7 sustainability and fossil fuels

  1. 1. Session 7 – Sustainability and Fossil Fuels
  2. 2. Definitions of Sustainability One definition: • For renewables: Usage rate < generation rate • For non-renewables: Usage rate < sustainable use rate of substituted renewable • For a pollutant: Emission rate < rate of recycling, absorption, or neutralization The ideal requires complete reliance on renewables. Another definition related to GHGs: • Sustainability means meeting energy needs w/o adverse warming
  3. 3. Sustainability – Who Cares? • Life is day-to-day in many countries • However, all countries face a global market for primary fuels – price is a force • Pie charts, p 264: China, Middle East/Africa will outpace US energy use by 2095 – will all three adopt the ideal? • If sustainability erodes economies, can we maintain or improve human condition?
  4. 4. A Conundrum • Human Development Index (HDI) of United Nations: Humans need > 4 MWh annually of electricity for well being • Yet, the UN IPCC predicts temp rises of 1.4 to 5.8 °C by 2100 • Do we meet basic human needs and suffer climate change consequences, or leave needs unmet with a more stable environment?
  5. 5. Assessing Technology for Sustainability • Engineering may yield an answer that is not mutually exclusive! • Comparing conversion systems is difficult • UN uses three general indicators to measure sustainability: • Environmental • Economic • Social • Let’s compare wind and nuclear using these indicators
  6. 6. Cornerstones of Sustainable Energy Policy Customers (Regulatory or market-based?) Technology Capital (Technically feasible at required scale? Public or private development?) (Who will invest, what risk/return profile?)
  7. 7. Fossil Energy • Recall: About 80% of US energy is fossil; 70% of US electricity is fossil based • Recall: Fossil = coal, natural gas, petroleum • P. 296: “A fossil fuel is a substance that releases energy by a chemical reaction.” – This is a necessary but not sufficient definition – Also needs to be organic, have covalently bonded Carbon, and be produced over geological time periods – Consider how biofuels meet parts of these definitions
  8. 8. Fossil Energy Reserves Example from Sample Problem 7.1 They appear huge . . . for Coal, 290,000 Quads (roughly) World annual energy use in 1995 was 325 Q If rate stayed constant, and if coal used exclusively, Reserves would last for 846 years
  9. 9. Fossil Energy Reserves Example from Sample Problem 7.1 However, with 2% annual growth in consumption, reserves shrink to 144 years. Are reserves increasing each year? Are countries and reporting entities trusted sources for national reserves?
  10. 10. Fossil Energy Reserves North Dakota Lignite Reserves •351 billion tons of known lignite reserves •25 billion tons that are economically recoverable – good for 800 years •32 million tons produced annually – steady production for a decade or more •At 7000 Btus/pound, North Dakota reserves contain 4.8 E 18 Btus or 4800 Quads Enough to power the world for over 10 years. Source: North Dakota Geological Survey; Lignite Energy Council