Energy Alternatives II: Non-renewables & renewables.
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Energy Alternatives II:Non-renewables & renewables
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
There is still lots of oil around the world
The problem remains: who has it, who wants it, and how will it get from one to the other
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
1 billion metric tons coal = 2.45-4.9 billion bbl oil
And a lot of coal: 2-4 trillion barrels of oil equivalent
In principle, fossil fuel supplies are not a serious problem
In practice, it appears that they are (or will be)
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
What about energy alternatives?
• Hydroelectricity• Geothermal• Fuel cells• Ocean energy• Fusion• Biomass• Wind• Solar• Hydrogen
Global oil use = 500 trillion liters/year
And don’t forget how compact & convenient ff are
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
Hydroelectricity is one very effective & wide-spread renewable energy source
Its total potential is limited and large dams are not without environmental & social impacts
Total global electrical production = 20,000 TWh/yr.
In theory, geothermal is widespread &
could provide heat & electricity
Energy in Iceland
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
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
It might also be possible to use ocean temperature differences to produce heat much like refrigerators
No commercial-scale systems yet…
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
But fusion is always 50
years in the future
And there’s always fusion
The fuel source is virtually unlimited
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
Biomass conversion involves chemical reduction into liquid fuels, which is already being done on a very large scale in the U.S. & Brazil
Depending on source, it might displace food production (as with corn ethanol).
Solar energy is plentiful but diffuse, and must be collected, concentrated & stored
It can be used to heat or boil water, the latter to generate steam
Built onto buildings, on as part of the structure, it can generate electricity
Global production of solar PV cells is growing, while cost is dropping
But solar is diurnal, at best, and some kind of storage system is required for times when it is not available
There is a lot of wind energy potential, especially out in the oceans
Wind is variable and diffuse and must be backed up by some other electrical source (could solar &
wind back up each other?)
Wind resources are widely available
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
What about hydrogen? Solar in the desert could be used to make hydrogen, which could be piped to cities.
1990 2020 2050 2100
Technological progress projection
This is one optimistic electrical generation projection—note that it is only electricity; liquids not included