Energy question of the week: Can burning ice solve our energy problems?
Crude oil, coal and natural gas are not the only fossil fuels hidden deep below the surface of the Earth. Right around the globe, enormous quantities of methane hydrates can be found as many people already know, especially since Frank Schätzings famous novel 'The Swarm' (Der Schwarm). This white combustible ice consists of water and methane gas. If thawed in a controlled fashion, many billions of tons of methane could be obtained from it. The question is: do methane hydrate have a genuine role to play in our energy future?
Based on current estimates, known reserves comprise roughly 12,000 billion tons of methane hydrates. Substantial deposits are located on continental shelves in the Pacific around Japan, off the Pacific coastline of America and to the North of Canada and Siberia. These deposits are located deep down in the seabed and locked into land-based permafrost for a very good reason: methane hydrates cannot form solid ice crystals until the pressure exceeds 20 bar and temperature fall below four degrees Celsius. The ice evaporates at lower pressure or higher temperature, and in the process, releases 164 times its own volume in the form of gas.
Swapping carbon dioxide for methane
In Japan, Russia, USA and Germany, intensive efforts are under way to find ways to exploit these reserves. However, this methane ice, which has formed over millions of years, would have a devastating impact on our climate: it locks in about twice the volume of carbon as the sum total of all reserves of crude oil, natural gas and coal combined. As methane burns, this carbon is converted into the greenhouse gas carbon dioxide. On the other hand, it can be used efficiently in modern gas-fired power stations to generate electricity. At this time, researchers are working on the possibility of separating carbon dioxide from the combustion gases of future power stations, and pumping it separately into subterranean storage facilities.
A gas hydrate block from 1200 metres under water (approx. 600 fathoms), source: Wikimedia Commons. Top image: Burning ice, source: IFM - GEOMAR.
The approach adopted by German researchers at the IFM-Geomar Institute (Leibniz Institute of Marine Sciences) at the University of Kiel is very interesting. As part of the SUGAR project (Submarine Gas hydrate Reservoirs), they wish to run tests to establish if the methane extracted from methane hydrates can be replaced by pumping in carbon dioxide. The principle being that water, through a chemical reaction with carbon dioxide, should form a stable and solid compound of carbon dioxide hydrates.
If methane hydrates were ever extracted from continental shelves without appropriate precautionary measures being taken, the disaster scenario painted by Schätzing in ‘The Swarm’ could occur: without methane hydrates, the shelves on the coasts could become unstable, gigantic landmasses could start to slip and that in turn could trigger tsunamis. Experts are taking these risks seriously and are only experimenting on the extraction of methane hydrates in flat storage locations far from continental shelves.
Extraction unlikely to prove economically viable
There are still many technical questions to answer before the methane in burning ice can be brought to the surface in a usable form. This year, a test extraction operation is scheduled to commence in Alaska during which an attempt will be made to introduce carbon dioxide as a stabilising element. Similar pilot projects on storage deposits on the seabed off the coastline of Japan may be initiated a few years later. At present, it is not possible to predict when or even if at all it will be possible to exploit methane hydrate reserves in an economically feasible manner, with acceptable levels of risk to climate and geological stability.
Weitere Information: SUGAR Project at IFM-GEOMAR
The DLR Energy question of the week in 'The future of energy' Year of Science
The Federal Ministry of Education and Research (BMBF) has given the Year of Science 2010 the motto 'The future of energy'. For this reason the science journalist Jan Oliver Löfken will this year answer a question on the subject of energy in his blog each week. Do you have a question about how our energy supply might look in the future? Or do you want to know, for example, how a wave power plant works and how it can efficiently generate electricity? Then send us your question by email. Science journalist Jan Oliver Löfken will investigate the answers and publish them each week in this blog.