"How much of a dent can these sources make, and at what cost, compared to other sources?"
Well, I think it is clear that ethanol from corn is a bad idea.
Ethanol from sugar cane is better. Ethanol from cellulose has great potential if the problems are ever solved. That is potentially a very large source. However, the political hurdles are high. The corn producers have locked up the ethanol market in the US, and there are severe restrictions on importing ethanol and sugar. No doubt if there is a breakthrough in converting cellulose to ethanol, it would be blocked also.
Wood fuels are limited. In areas where trees are processed, it could be used and solve a disposal problem. But it isn't a general solution. Now a related technique, burning of biomass, has broader applicability. Again, it shows the most promise when integrated with existing industries as a waste disposal method.
Algae holds some promise, however. Currently production is limited and species choice is not ideal. But, with selective breeding, if not bio-engineering to up the lipid content it could be a very economical source. Especially when integrated with sewage treatment. Now, if the algae is burned as biomass instead of having the lipids extracted for biodiesel, then it has a more immediate viability.
So what is the bottom line? With current technology it can only account for a few percent if costs are to be minimized. With some development, it could be a lot more. There isn't a silver bullet, though. |
