Oil of algae  Oil prices are soaring as supply chains in the
Middle East become fragile. BP's quest for deep-water reserves
in the Gulf of Mexico last year proved calamitous. Where will
alternative energy supplies that are compatible with our oil
infrastructure come from?  Algae, the plant-like creatures that
make slime in ponds, hold promise. They can produce up to 100
times more combustible liquid energy than crop plants, such as
wheat. Huge, water-filled, light-permeable plastic reactors
allow algae to use the sun's energy to clip carbon-dioxide
molecules together into oily chains that can be purified and
release energy from combustion.  Depleting carbon dioxide and
creating liquid energy at the same time sounds good. But can we
do it on the scale that is needed? Billions have been invested
in the technology, but this year Shell has abandoned its work
with the algal energy firm Cellana. Others, too, are looking
nervous. Genetic technology to optimise algal biochemistry
towards fuel production is exciting b