Power-to-methane in a Bioelectrochemical System

Interest in electricity storage technologies is on the rise with the increasing implementation of renewable energy into the electricity market and consequential fluctuations between electricity supply and demand. Power-to-methane in a bioelectrochemical system (BES) is a novel electricity storage concept inspired by research on methane producing BES, with the intent of recovering methane from electrical energy. Methane can then be stored or transported through existing natural gas pipeline infrastructure. The energy efficiency of the system quantifies the methane recovery as of electrical power input and is calculated as the product between current-tomethane efficiency and voltage efficiency. With this said, the higher the energy efficiency the less energy is lost between conversions and the more efficiently electricity is stored.


Technological challenges

So far the energy efficiency of methane-producing BES is below 25%, low in comparison to currently implemented electricity storage technologies.

In this context, the main challenge is to increase the energy efficiency while at the same time ensuring a highly productive system. This meaning without compromising methane production rates. Current-to-methane efficiency is highest when no other reactions occur besides methane production and voltage efficiency is highest the lowest the losses within the BES. These losses can be associated to cathode overpotential, anode overpotential, ion movement, pH gradients and other transports through the membrane.


With this said the main goals are:

  1. To develop a biocathode at minimum overpotential;
  2. To design a state-of-the-art (highly productive) methane-producing BES;
  3. To study the influence of intermittent electricity supply (characteristic of electricity storage applications) in the stateof- the-art system;
  4. To evaluate the most valuable CO2 containing waste streams;
  5. To understand the applicability of the stateof- the-art system as an electricity storage technology based on all above.