Technology Idea of the Week

This week: is there a future for methane fuel cells? Methane hydrates have featured quite a lot recently while I researched for my posts on Arctic natural resources and in Anson Mackay's lecture on the crysosphere. It seemed deserving as this weeks technology focus!

Fuel Cells - A very brief introduction! 

• Convert chemical energy into electricity by an oxidising reaction
• Require a constant fuel supply 
• The ideal fuel is hydrogen because it doesn't produce greenhouse gases but the technological challenges in its cost and storage mean this currently not viable (Steele, 1999, Nature)
• Currently, the best fuel options are hydrocarbons (methane) and alcohols (methanol).  

Methane Hydrates

• Methane hydrates (clathrate) are crystalline solids composed of a mixture of water and light natural gas (methane, carbon dioxide, ethane). They are found in the shallow lithosphere (<2000m deep) where the surface temperature is less than 0 °C (Kvenvolden, 1993, Review of Geophysics)
• There are substantial natural deposits of methane hydrates in deep ocean sediments, permafrost and under frozen lakes. It is estimated that the global volume of methane hydrate is 10¹⁵ to 10¹⁷ cubic metres of methane which represents 53% of all fossil fuels ((Demiras, 2010, Energy Conservation and Management). The distribution of organic carbon can be seen in the image below. 

Distribution of organic carbon on earth (excluding kerogen and bitumen).
Source: Demiras, 2010, Energy Convservation and Management)

Advantages of Methane Fuel Cells

• Substantial deposits - it is estimated that the global volume of methane hydrate is 10¹⁵ to 10¹⁷ cubic metres. Deposits are found in widespread geographical locations including US permafrost, Lake Baikal in Siberia and Arctic sediments. (Demiras, 2010, Energy Conservation and Management)
• Low carbon energy - methane is a less carbon intensive fuel than coal or oil: it produces approximately half the amount of CO2 than coal for equivalent volumes. This can be seen the equation below. Therefore using methane hydrates as an energy source could help reduce anthropogenic emissions of carbon dioxide which may contribute to the greenhouse effect. 

Top equation - the combustion of coal. Lower equation - the combustion of methane hydrate
Source: Demiras, 2010, Energy Convservation and Management)

The Challenging side of Methane Fuel Cells

• Location and access - finding the deposits requires high level seismic imaging, we do not have detailed enough resolution for some deposits. In addition the deposits often cross national boundaries or are in international territories. This raises a lot of geopolitical issues in terms of researching the site and rights over the resources. (Kvenvolden, 1993, Review of Geophysics)
• Extraction - the gas can expand 160 times its volume as it is brought to the surface and is de-pressurised. This can cause explosions and leaks of methane gas (CH4) which contributes to the greenhouse effect. We currently need to do further research into drilling technology to ensure safe extraction of methane hydrates. (Demiras, 2010, Energy Convservation and Management)

It is possible...

In March of 2013, a Japanese drilling company successfully produced gas from frozen methane hydrates from the ocean floor. For equal volumes, this deposit holds 164 times the energy of conventional gas (NewScientist, 2013). The deposit is in the Nankai trough and could be a game changer for Japan's energy supply. Investigation into methane hydrates was fast tracked by the Japanese government after the Fukushima nuclear power disaster. Here is a film of the methane hydrate extraction in Wellington by a team of German Scientists (the video is in English)! 

In conclusion, methane hydrates could be a really important step in meeting our energy needs over the next 100 years. The ultimate goal still remains as the production of commercially viable hydrogen fuel cells.