19-May-2017: Ecological concerns over combustible ice

Commercial development of the globe’s huge reserves of a frozen fossil fuel known as “combustible ice” has moved closer to reality after Japan and China successfully extracted the material from the sea floor off their coastlines.

Combustible ice is a frozen mixture of water and concentrated natural gas. Technically known as methane hydrate, it can be lit on fire in its frozen state and is believed to comprise one of the world’s most abundant fossil fuels.

Methane hydrate has been found beneath seafloors and buried inside Arctic permafrost and beneath Antarctic ice. Estimates of worldwide reserves range from 280 trillion cubic metres up to 2,800 trillion cubic metres, according to the U.S. Energy Information Administration. That means methane hydrate reserves could meet global gas demands for 80 to 800 years at current consumption rates. Yet efforts to successfully extract the fuel at a profit have eluded private and state-owned energy companies for decades.

Methane hydrate is an attractive energy source due to its high energy density: one cubic meter of combustible ice contains about 164 cubic meters of regular natural gas. This high energy density is due to the fact that methane is trapped within the hydrate crystal structure and greatly compressed.

There are environmental concerns. If methane hydrate leaks during the extraction process, it can increase greenhouse gas emissions. The fuel also could displace renewables such as solar and wind power.