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Microbiological conversion of renewable electricity and CO2 to a natural gas quality bio-fuel

Periodic Reporting for period 1 - ELECTHANE (Microbiological conversion of renewable electricity and CO2 to a natural gas quality bio-fuel)

Reporting period: 2015-06-01 to 2016-05-31

The increase in variable renewable energy sources such as wind turbines or photovoltaic panels leads to an ever increasing occurrence of periods where the supply of renewable electricity exceeds the demand. This imbalance puts a strain on the power grid infrastructure and it even leads to situations where renewable electricity generators are forced to stop feeding electricity to the grid (i.e. curtailment). This affects the profitability of renewable energy generation systems and thus it becomes less interesting to invest in e.g. wind farms.
The idea behind power-to-gas is to use the surplus renewable electricity to power an electrolyser and to split water in oxygen and hydrogen. In this manner, the excess renewable electrical energy is stored as chemical energy in the form of hydrogen. Since hydrogen is difficult to store and manipulate, it makes sense to convert this hydrogen gas with carbon dioxide to synthetic methane. This methane does not differ from the methane in natural gas and therefore it can be stored, transported and used in the existing natural gas infrastructure. For instance, it can be injected in the natural gas grid or it can be used for CNG vehicles. Power-to-gas connects the electricity and the natural gas grid. The loss of efficiency due to the conversion of hydrogen to methane is compensated by the ease of using the synthetic methane in the existing natural gas infrastructure. OWS developed a process that uses microorganisms to catalyse the conversion of hydrogen and carbon dioxide to methane. This biological methanation process has significant advantages over the catalytic conversion process. This study investigates to what extent power-to-gas with the biological methanation process developed by OWS is feasible and how it can be brought to the market.
In this project, OWS assessed the feasibility of power-to-gas with the biological methanation technology developed by OWS.

From a technical point of view, there are no impediments for the full-scale implementation of a power-to-gas plant using the biological methanation technology developed by OWS.

A preliminary risk assessment did not come up with any risks that would form a barrier for the implementation of power-to-gas with biological methanation.

OWS’s technology is sufficiently innovative to avoid any patent infringements.

At is unclear to what extent synthetic methane produced in a power-to-gas plant with methanation meets the EU criteria for sustainable biofuels. In our view, synthetic methane is sustainable, regardless of the origin of the carbon dioxide used in the process (fossil or biogenic), as long as the electricity used for the electrolysis process is excess renewable electricity that cannot be stored and returned to the power grid at a sufficiently high efficiency. Once the synthetic methane from power-to-gas meets the EU’s sustainability criteria, it has de facto the same status as biomethane. Concerted efforts with the biomethane sector could help facilitate the use and the trade of synthetic methane.

For the time being, there is no market demand for power-to-gas with biological methanation. This may change in the future, when the share of RES in the EU’s electricity consumption exceeds 80 %, but this is likely a matter of decades and there are several other technologies available that may prove more efficient and less expensive than power-to-gas with biological methanation.

The economic viability of power-to-gas depends a lot on the annual hours that storage of renewable energy in the form of methane will be required. It is estimated that power-to-gas with biological methanation needs to run for at least 4000 hours a year to achieve the optimal levelized cost of energy. Even then, additional revenues would be required to make the process profitable. The most important revenue besides synthetic methane sales would be the price that power grid operators are willing to pay for ancillary services required to maintain the grid balance. Yet, at current imbalance tariffs, it is unlikely that this will be sufficient and power-to-gas with biological methanation may not even be the best option to fulfill this role.
OWS concludes that it’s power-to-gas concept with biological methanation has currently no potential to be developed to the level of investment readiness or market maturity. For the time being, there is no positive business case for power-to-gas and therefore it is irrelevant to develop a business plan. Still, the increase in variable sources of renewable electricity may lead to a future where excess renewable energy becomes the default. In that case, storing this renewable electrical energy as chemical energy in the form of methane may prove to be necessary. So, in the coming decades it may be possible to have a positive business case for power-to-gas with biological methanation.