That would require more corn acreage for cars than for feed and food.
Wind, Cellusose Ethanol, and Solar
Just the Facts:
Renewable energy will remain a very limited part of our total energy supply for a long time to come. But it's still important. Everything important starts small. The two most promising renewable sources are probably wind and eco-ethanol, though in Brazil sugar-cane ethanol seems to be making a significant contribution.
Total U.S. energy use was 100 Quads* in 2004, of that, 0.2 Quads was from wind and solar. That value doubled in the last 10 years. (DOE Monthly Energy Review, Table 1.3) At that rate wind and solar will supply 1% of our energy by 2028.
Ethanol supplied 0.296 Quads in 2004, but its production consumes 3/4 that much in energy, so its net contribution was less than 1/10 of 1%, but its use tripled in the last ten years. So it should also supply 1% of our energy by about 2028.
But ethanol from corn is quite expensive and not very ecological, so we probably do not want it to increase to the 1% level. That would require more corn acreage for cars than for feed and food.
That’s where eco-ethanol comes in. That’s ethanol made from cellulose, which is all the unused parts of plants. This is far more energy efficient and ecological because that is now wasted—well not quite. The unused parts of crop plants are usually returned to the soil to enrich it, or more accurately, to avoid impoverishing it. There is still a cost to using plant cellulose, but much less than from growing corn just to make gas for our cars.
* A Quad is a quadrillion (15 zeros) Btu.
http://zfacts.com
Just the Facts:
Renewable energy will remain a very limited part of our total energy supply for a long time to come. But it's still important. Everything important starts small. The two most promising renewable sources are probably wind and eco-ethanol, though in Brazil sugar-cane ethanol seems to be making a significant contribution.
Total U.S. energy use was 100 Quads* in 2004, of that, 0.2 Quads was from wind and solar. That value doubled in the last 10 years. (DOE Monthly Energy Review, Table 1.3) At that rate wind and solar will supply 1% of our energy by 2028.
Ethanol supplied 0.296 Quads in 2004, but its production consumes 3/4 that much in energy, so its net contribution was less than 1/10 of 1%, but its use tripled in the last ten years. So it should also supply 1% of our energy by about 2028.
But ethanol from corn is quite expensive and not very ecological, so we probably do not want it to increase to the 1% level. That would require more corn acreage for cars than for feed and food.
That’s where eco-ethanol comes in. That’s ethanol made from cellulose, which is all the unused parts of plants. This is far more energy efficient and ecological because that is now wasted—well not quite. The unused parts of crop plants are usually returned to the soil to enrich it, or more accurately, to avoid impoverishing it. There is still a cost to using plant cellulose, but much less than from growing corn just to make gas for our cars.
* A Quad is a quadrillion (15 zeros) Btu.
http://zfacts.com
