My March 24 post on "Biodiesel from Algae" discussed this issue. The
idea that algae could provide all our road transport fuel has been
greatly hyped. The U.S. Department of Energy seems to have
extrapolated from the highest short term yields under lab conditions
and maximum algae oil contents to long term field conditions. They
were unable to obtain such high oil yields under long term field
conditions. They noted specifically that low night temperatures in
open ponds in New Mexico greatly limited algae productivity.
If biodiesel from algae was really so promising one wonders why the
U.S. Department of Energy only researched it from 1978 to 1996.
There is also a major technical problem that the algae ponds quickly
become filled with a variety of different species that vary in size,
shape and oil content. That lowers the oil yield and makes periodic
harvests of a small amount of the algae technically very difficult and
very expensive.
Biodiesel from algae also likely suffers from the same problem as
ethanol from corn, i.e. it requires substantial fossil fuel energy
inputs to produce including CO2 injection into the pond, temperature
control of the pond water, harvesting, oil extraction, transport to
market, etc.
David R. Hershey
