CO2 Storage and Geothermal Co-Production Has a Bright Future (New Scientist)
So say Tom Buscheck from the Lawrence Livermore National Laboratory in California and his colleagues who presented a design for this type of energy storage at the European Geosciences Union general assembly last week in Vienna, Austria.
Their design would be able to store the excess energy produced by renewable and conventional power sources when demand is low and, at the same time, lock up the major cause of global warming – carbon dioxide.
"The only way you can decarbonise the fossil-fuel energy systems is if you can devise an approach where the economics makes sense," says Buscheck, who thinks their design, which is funded by the Geothermal Technologies Office at the US Department of Energy, does just that.
Buscheck team's proposes storing that excess energy in two forms: pressure and heat. Excess electricity would power a pump that injects supercritical CO2– a hybrid state of liquid and gas – into underground brine in sedimentary rocks between 5 and 10 kilometres below the surface. Supercritical CO2 can drive turbines much more efficiently than steam and can take a lot of squeezing and heating – improving its capacity to store energy.
