Energy Alternatives II: Non-renewables & renewables

Transcription

1 Energy Alternatives II: Non-renewables & renewables

2 Non-renewables: fossil fuels There is no global shortage of fossil fuels Petroleum: 50+ years left Coal: hundreds of years Natural gas: decades FF are easy to find, mine & consume FF prices are quite low Distributional issues Price issues Environmental issues

3 There is still lots of oil around the world

4 The problem remains: who has it, who wants it, and how will it get from one to the other

5 1 trillion cu. meters gas = 6.29 billion bbl oil There s also quite a bit of natural gas: about one trillion barrels of oil equivalent

6 1 billion metric tons coal = billion bbl oil And a lot of coal: 2-4 trillion barrels of oil equivalent

7 In principle, fossil fuel supplies are not a serious problem In practice, it appears that they are (or will be)

8 Nor can the political implications be ignored Even if oil is not really scarce, perception creates myths, and myths can lead to conflict Even if climate change proves not to be a problem, there s still a lot of pollution from ff And cheap energy fosters growing demand, which has to be supplied somehow We ll return to these points next week

9 What about energy alternatives? Hydroelectricity Geothermal Fuel cells Ocean energy Fusion Biomass Wind Solar Hydrogen Global oil use = 500 trillion liters/year

10 And don t forget how compact & convenient ff are

11 What should we look for in energy alternatives? Reduce vulnerability, increase flexibility Be environmentally-friendly or green Be cost-effective & efficient Be sustainable over the long-term Not introduce major lifestyle disruptions Not generate intractable waste problems Not solve one problem only to create others Not introduce intractable social problems

12 Hydroelectricity is one very effective & widespread renewable energy source

13 Total global electrical production = 20,000 TWh/yr. Its total potential is limited and large dams are not without environmental & social impacts

14 In theory, geothermal is widespread & could provide heat & electricity Energy in Iceland

15 In practice, again, accessible geothermal reservoirs are limited, and recent efforts to fracture bedrock to release geothermal heat appeared to cause earthquakes, leading to cancellation of projects in Switzerland & California

16 The oceans offer almost limitless energy potential Wave energy power note the very high energy potential in the North Atlantic, off the Irish coast: the Saudi Arabia of waves! So far, various technologies have not panned out or proven economical but that could change

17 It might also be possible to use ocean temperature differences to produce heat much like refrigerators No commercial-scale systems yet

18 Fuel cells can generate electricity directly, but require a fuel source to drive electricity production. A few small test plants appear to be in operation

19 And there s always fusion The fuel source is virtually unlimited But fusion is always 50 years in the future

20 Fusion reactors will involve very complex designs, and they will be very expensive Depending on fuel, they could also generate considerable amounts of radioactive materials

21 Depending on source, it might displace food production (as with corn ethanol). Biomass conversion involves chemical reduction into liquid fuels, which is already being done on a very large scale in the U.S. & Brazil

22 Solar energy is plentiful but diffuse, and must be collected, concentrated & stored

23 It can be used to heat or boil water, the latter to generate steam

24 Built onto buildings, on as part of the structure, it can generate electricity

25 But solar is diurnal, at best, and some kind of storage system is required for times when it is not available Global production of solar PV cells is growing, while cost is dropping

26 There is a lot of wind energy potential, especially out in the oceans

27 Wind is variable and diffuse and must be backed up by some other electrical source (could solar & wind back up each other?)

28 Wind resources are widely available

29 Costs of wind are decreasing, capacity is growing, but so is the average size of turbines. These tend to be quite noisy & to kill birds, and there is growing opposition to them

30 What about hydrogen? Solar in the desert could be used to make hydrogen, which could be piped to cities.

31 Technological progress projection Mtoe 25,000 20,000 15,000 10,000 5,000 Solar Hydro Biomass Nuclear N. Gas Coal Oil

32 This is one optimistic electrical generation projection note that it is only electricity; liquids not included