Liquid Fuel from Sunlight, Seawater and Fresh Air
My idea for using seagoing vessels to photosynthesize hydrocarbons,
thereby using current solar income for a no-net-gain-in-carbon-emissions
option that allows us to keep using some of the current fossil-fuel
infrastructure, is described in more detail below.
What I envision is oil-tanker ships with inflatable leaves. They
set out from harbor with furled leaves, empty tanks, and some
cultures of algae or cyanobacteria bred to produce abundant lipids
(oils). Once out at sea, they unfurl their enormous leaves, pumping
them full of seawater to provide the H2O
and nutrients the algae needs. The water is slowly circulated,
filtered to intake mostly water and minerals (and no "grazers"
that might eat the bio-diesel crop), and to release water but
few or no crop organisms back to sea. The leaves also have stomata,
allowing the exchange of CO2 and O2.
As the leaves fill with oily greenery, the crew begins harvesting
this quick-growing crop. The tankers are internally equipped with
an extraction press to separate bio-diesel from "chaff"
(the remaining cellular material of the living oil factories),
without nasty extractive chemicals. Harvesting and processing
are gradual, just keeping pace with crop production. The oil should
be clean enough that it could safely be used not only for fuel
and lubricant, but also for cooking oil. The financial officer
onboard the ship monitors the going rates for oil at various ports,
then consults with the meteorologist and the navigator to choose
the best course for the ship as it fills its tanks.
The ship itself, of course, would run on a combination of bio-diesel,
wind, and direct photovoltaic power. Because the bio-diesel the
ship produces is being harvested from current solar energy income,
and with current CO2 uptake, the oil it
produces and sells is a completely renewable resource, and burning
that oil would merely balance out some of the CO2
that was sequestered as it was produced. The other byproducts
of the ship (the chaff from extraction) contain some carbon, so
the ship probably draws down more carbon than it releases (in
the form of marketable oil). The effluents from the ship should
all be clean and safe to release into the sea; even oil-spills
should be much less frightening than they are with fossil fuel
tankers. The ship is fairly self-sufficient for as long as it
remains at sea, though an economy of small trading vessels (exchanging
fresh fish and produce for some oil, and perhaps even exchanging
crew) may grow as bio-diesel plants spend longer at sea.
Because the bio-diesel these ships produce is a combustible liquid
fuel source, it should be able to exploit the existing use patterns
and infrastructure already established for fossil fuel. While
toxic refineries should go extinct, the ports, fuel stations,
factories and vehicles currently dependent on fossil fuel should
be fairly easily converted to transport and run on this clean-grown
bio-diesel from the sea.
The key to this process (as propounded in the excellent book
Cradle to Cradle by William
McDonough and Michael Braungart) is to consider all phases
of production as part a closed life-cycle, a circulation of resources
through members of an interlinked community, such that the waste
from one process becomes the raw material for other processes.
In this case, all waste must be returned to the sea (where other
organisms can safely break it down into component parts for their
own processes) or the air (as oxygen that will be used by aerobic
organisms like us, or be consumed in burning the fuel produced,
both of which will release the carbon and the energy from sunlight
that was captured during the growth of the fuel organisms).
There's no reason not to start trying to breed high-lipid algae
or cyanobacteria right now! This is the same kind of crop creation
that led to corn, wheat, rice and soybeans.