This method, if it pans out, could not only be clean, it could make the
environment even cleaner.
Jonathan Trent, the lead research scientist on the Spaceship Earth
project at NASA Ames Research Center, has been working on a method to
produce oil from algae. Their Algal Biofuels Team appears to be
making progress.
NASA scientists have proposed an ingenious and remarkably
resourceful process to produce "clean energy" biofuels, that cleans
waste water, removes carbon dioxide from the air, retains important
nutrients, and does not compete with agriculture for land or
freshwater...
...Land plants currently used to produce biodiesel and other fuels
include soy, canola, and palm trees. For the sake of comparison, soy
beans produce about 50 gallons of oil per acre per year; canola
produces about 160 gallons per acre per year, and palms about 600
gallons per acre per year. But some types of algae can produce at least
2,000 gallons of oil per acre per year.
The illustration shows enormous bags made of plastic semipermeable
membranes, known as "forward-osmosis membranes." The float in the
ocean. The algae are fed with sewage. Algae eat the sewage
and produce oil. Fresh water leaches out of the bags and into the
ocean.
It is not clear to me how well this will scale up. 2,000 gallons
is about 47 barrels of oil. Currently, the world is producing
about 80 million barrels of oil per day. But that 47 barrels per
year per acre figure is for algae in installations on land.
Perhaps they can do a lot better in the ocean.
Of course, whenever an alternative energy project is considered, a
chorus rises up, proclaiming that it cannot replace our current
system. This is true, at least so far. It is likely that
nothing, in the near future, will replace oil, with the extent of
energy return on investment (EROI) that we are getting now.
But we have to do something. Most likely, that something will
come from trying a bunch of different things, followed by implementing
some subset of those things in a widely distributed network of
dissimilar technologies.
The algae might do better in the ocean, but wouldn't there be an issue with getting megatons of sewage to them? Preferably without spilling any!