Improving the storage of biogas

Biogas is a valuable energy resource for many in the developing world. In areas where main grid electricity is non-existent or unreliable, biogas is a safer and more dependable alternative. Conventional wood collecting is the most popular way to gather fuel but it is highly polluting to the surrounding environment and time consuming for those collecting it.

Biogas stoves are more environmentally friendly and socially sustainable; helping to reduce health issues caused by smoke inhalation and producing useful by-products such as manure fertiliser. However, biogas is not the most suitable solution in a developing context because it is difficult to store and not easily, or cheaply, manoeuvred.

The technology the i-Team investigated referred to using Metal-Organic Frameworks (MOFs) in storage tanks. MOFs are composed of organic structures with metal ion clusters attached. Part of the reason that these are so effective in this instance is that they allow gas to be stored at lower pressures. Previously, methane gas had to be stored in a tank at 250 bar pressure. Using a MOFs tank, the same volume of gas can be stored at 30-40 bar. Storing the same volume of gas at a lower pressure increases the safety of the system. It also significantly reduces the high cost of compression that is characteristic of storage at high pressures.

The team aimed to identify whether this technology was viable in China and India, especially with regards to competitor technology. Methane makes up 29% of India’s greenhouse gas emissions and so utilising this excess could be a sustainable option. The limitations for MOFs technology in India is that the high costs of the technology might outweigh the potential benefits. The MOFs are 1.5x the price of existing fuel tanks despite being the better transportable option. Biogas bottling plants currently use high pressure seamless CNG cylinders that are approved by PESO, so competing with this would be difficult. However, the growing domestic market, with government support for bottling, indicates that it might have potential in the future.

In China, there has been a very strong push for natural gas vehicles (NGVs) as it reduces oil consumption, air pollution, and carbon emissions. The government are aiming for 8 million vehicles by 2020, with 3.2 million already being used in 2014. As MOFs are lighter and cheaper gas cylinders, using the technology could not only be better for the environment, but could increase driving range and have cheaper operational costs. This proves very promising, although limitations on implementing the technology do prove to be substantial. The lack of refuelling infrastructure and current fuel prices make the technology less viable on a larger scale, and furthermore there are significant regional variations in the acceptance and use of NGVs.

Given the insights that the i-Team produced, they recommended the following: the technology needed to be made cheaper where possible and large-scale infrastructure development programs need to be investigated.

i-Teams website link:

Improving the storage of biogas