Leave it to Texas to come out with a fascinating idea that combines methane production, carbon capture and geothermal energy in an area offshore the Gulf Coast. Here is how it would work. (Scientific American, November 2013, Pp. 72-77)
Offshore Texas and other oil-producing regions, there are deep saline aquifers rich in methane, actually holding an incredibly large amount of this resource. These three-kilometer deep aquifers are under considerable pressure and are hot enough to be a source of geothermal energy. And brine can also hold dissolved carbon dioxide. So, now a combination of these circumstances could conceptually lead to the following type of installation. Deep wells bring up the methane-containing brine, with the gas liberated when pressure is released. Carbon dioxide from a number of power plants would be piped to the location and injected into the brine which is then pumped down again. And the heat contained in the brine could be captured to provide local heating or to produce electricity.
This system works on paper, but faces a number of hurdles. Carbon dioxide is not as soluble in brine as methane. Building such a system would be very expensive, paid for by rate increases to customers. Since methane is a key greenhouse gas, much care would have to be taken to avoid methane leakage.
It seems clear that such an operation would make no economic sense under current conditions. But if it were to become clear that the world must start to sequester and store carbon dioxide if we continue to burn fossil fuels, then the brine-methane-carbon storage approach would have to be compared to replacing fossil fuel- burning power plants with thousands of large wind farms and solar installations or hundreds of nuclear power plants.
One interesting aspect of the scheme is that it avoids the controversies associated with the fracking process: It is done offshore or close to shore, it does not involve injection of chemicals and it would not involve dealing with thousands of land owners and lease rights.
According to the article, Sandia and Lawrence Livermore Laboratories are studying this system and two companies are considering building small pilot plants on the Gulf Coast.