In my September 28 blog Can flow batteries solve the electricity storage problem? I discussed an innovative new technology for tackling the key problem for integrating renewable energy into the electric grid: storage. There are numerous other innovations to store electricity, both mechanical sytems (flywheels, gravity) and chemical systems (batteries, fuel cells). One particular system is another made-in-Canada story: Missisauga-based Hydrogenics Corp., a developer of hydrogen systems and hydrogen fuel cells, uses electrolysis.
As Richard Blackwell reported in the Globe and Mail on August 3, 2014 in his article Ontario seeks wind, solar energy storage options, the Idependent Electricity Systems Operator (IESO) of Ontario has selected five companies to build energy storage demonstration projects. Among them is Hydrogenics.
The power-to-gas (P2G) project will include a 2 Megawatt electrolyser. Power-to-gas is a hybrid system in which electricity is used to separate water into hydrogen and oxygen through a proton exchange membrane (PEM). The chemical reaction is \[ 2\cdot H_2 O \rightarrow 2\cdot H_2 + O_2 \] The hydrogen is then compressed and injected into the natural gas system, where it can be transported and stored along with the natural gas. Another option is to combine the hydrogen with carbon dioxide in a process known as methanization, and the resulting methane is fed into existing gas pipelines. The chemical reaction, known as the Sabatier reaction, is \[ CO_2 + 4\cdot H_2 \rightarrow CH_4 + 2\cdot H_2 O \] The advantage of the system is that large-scale storage already exists: the extensive network of natural gas pipelines. The disadvantage is that the process is not overly efficient. There are significant losses during the production of hydrogen, and again during the methanization.
The project in Ontario is not Hydrogenics's first. In 2013, the company also provided a 1 Megawatt electrolyser to a 140 MW wind farm with 28 turbines in Grazpow, Germany. This unit is able to store up to 27 MWh per hour of energy. The system can either feed hydrogen into the local natural gas grid, or orun an internal combustion engine to produce electricity.