Download
1 / 38
380 likes | 579 Views
Energy. Energy Use, California, 1972. Energy Use, California, 1979. Energy Use, California, 1993. Energy Use, California, 1994. Energy Use, California, 2003. Everything You Need to Know About the Energy Crisis. Geothermal Energy: A Free Lunch?. Environmental Problems of Geothermal Energy
E N D
Geothermal Energy: A Free Lunch? Environmental Problems of Geothermal Energy • It is Finite • Heat Sources Can Be Exhausted (Geysers, California) • Sulfur Emissions • Disposal of Mineralized Brines Technical Problems of Geothermal Energy • Corrosion • Mineral Deposition in Pipes • Non-Productive gases (Carbon dioxide, methane, etc.) • Low Temperatures • Low Thermodynamic Efficiency
Thermodynamic Efficiency • Eff. = (Ti - Tf)/Ti • T = Degrees Kelvin = Degrees C + 273 • Ti = Initial temperature • Tf = Final temperature • Ti-Tf = Temperature drop
Thermodynamic Efficiency Automobile Engine • Ti = 1200 C = 1473 K • Tf = 500 C = 773 K • Eff = (1473 - 773)/1473 = 48% Typical Steam Power Plant • Ti = 700 C = 973 K • Tf = 200 C = 473 K • Eff = (973 - 473)/973 = 51%
Thermodynamic Efficiency Geothermal Power Plant • Ti = 150 C = 423 K • Tf = 80 C = 353 • Eff = (423 - 353)/423 = 17% Actual achieved efficiencies • Automobile on Highway: about 5% • Geothermal Plant: 5% or So, Sometimes less than 1%
Coal • Delta, continental environments • Carbonized Woody Material • Often fossilized trees, leaves present
Petroleum A hydrocarbon molecule What organisms make these? Answer: None
Petroleum • Lots of organisms make these, however • Fatty Acids • Probable source: Marine plankton
Hubbert Curves • In 1956, Oil geologist M. King Hubbert noted that rates of oil production follow a bell-shaped curve. • Cumulative production follows a slanting S- curve • Production lags discovery by about ten years.
What if We Find More Oil? • Even a huge increase in total oil has very little effect on the peak and decline of production. • Why? We waste most of it on inefficient uses.
Is There a Lot More Undiscovered Oil? • 80 per cent of oil being produced today is from fields discovered before 1973. • In the 1990's oil discoveries averaged about seven billion barrels of oil a year, only one third of usage. • The discovery rate of multi-billion barrel fields has been declining since the 1940's, that of giant (500-million barrel) fields since the 1960's. • In 1938, fields with more than 10 million barrels made up 19% of all new discoveries, but by 1948 the proportion had dropped to only 3%.
Gas Hydrates • Hydrocarbons trapped in cage of water molecules • Freeze above 0 C under moderate pressure • Solid gas hydrates occur in marine sediments (“yellow ice”) • Potentially huge energy resource • Possible role in climate change?
Some Relevant Quotes The internal-combustion engine used for automobiles is a fragile device compared with other prime movers -- even compared with the internal combustion engines used for diesel- electric locomotives that have been known to go over a million miles without mechanical overhauling.
Some Relevant Quotes ... the energy-system efficiency of the motor car with petroleum motor fuel is, thus, 5 percent ... no one is proud of this accomplishment -- least of all the automotive-design engineers ... The trouble is, every time the design engineer manages to save a few BTU it is more than spent answering the clamor for softer tires, for radio, for better heaters, more lights, cigarette lighters and possibly even air conditioning.
Some Relevant Quotes Histories written a few centuries hence may describe the United States as a nation of such extraordinary technologic virility that we succeeded in finding ways of dissipating our natural wealth far more rapidly than any other nation. At any rate, we are having a wonderful time doing it. From the discussions in the earlier chapters of this book it is clear that the problem of energy for the United States is not one of the dim future. It is upon us now.
Some Relevant Quotes Our imports of petroleum are small but each year they become larger. By 1960 they are likely to be quite substantial. By 1970 they will almost certainly be huge -- if foreign oil is still available then in sufficient quantity... This tiny period of earth's life, when we are consuming its stored riches, is nearly over ... Fortunately for us there is still time for fundamental research [on alternative energy sources]. But not too much time.
Some Relevant Quotes: Source Eugene Ayres and Charles A Scarlott, 1952; Energy Sources -- The Wealth of the World, McGraw-Hill, 344p.
Petroleum is a Syllogism • There is a finite amount of it in the world • We are using it and not replacing it • Therefore we will eventually run out of it • Any of this not clear?
The End of Cheap Oil • Known petroleum can last at least a couple of centuries more, but… • It only flows through the rocks so fast. • No amount of drilling will make it flow faster, and careless drilling can shorten the lifetime of an oil field. • Sometime in the 21st century, global demand will outpace production capacity and… • Oil will go to the highest bidder.
Some Final Thoughts What have you personally done to deserve access to petroleum at any price? If you think energy is such a scam, get up off your butt and do something about it. • If you think there is undiscovered oil out there, study geology and engineering and find it! • If you think synthetic oil is the answer, major in chemistry and make it happen. • If you think the answer is alternative energy sources, major in physics and engineering and develop them. • Don’t major in Plain Vanilla Studies and then complain when other people don’t provide you with energy for free.
