01-10-2021 | | By Robin Mitchell
It is a well-known fact that the renewables industry faces challenges with energy availability, and the million-dollar question is what technology will help to act as an energy store for renewables. Electrolyzed hydrogen could be the answer to this, but its production goes beyond energy storage.
Renewable energies such as solar and wind can produce electricity with no carbon emission (not taking into account CO2 produced during manufacturing processes). Still, while they may produce clean energy, their sources of energy are not consistent. As the energy sector has historically been reliant on more reliable energy sources such as coal, oil, and nuclear, energy storage technologies have seen virtually no development.
Now that countries worldwide are starting to tackle the climate crises, the search for appropriate energy storage technologies has begun with some candidates, including pumped-hydro, compressed air, and flywheels. However, in particular, one is showing real promise, which is hydrogen, as it can be easily converted to electricity with the use of a fuel cell. It can be quickly produced using a direct electrical process (electrolysis) and produces heat when being produced and used, which can further be used to store energy.
Trying to reduce the amount of CO2 produced by society must target all aspects of life, and the production of electricity is just one of many contributors to CO2 production. Another primary source of CO2 output comes from central heating in homes. This problem persists whether the heating is provided via electricity or natural gas (as the energy still needs to be produced). Furthermore, heating homes presents a challenge for renewable energies as home heating is often required most when sources of renewable energies (solar and wind) are at their minimum.
While stored hydrogen can provide renewable energies with energy storage, it can also be directly used to heat homes. Currently, gas supplied to homes is primarily natural gas which itself is mostly methane. However, boilers currently in service can operate on a gas blend of methane and hydrogen (up to 80/20 ratio). This means that hydrogen could be directly injected into the gas network generated from renewable sources of energy, which would reduce the amount of CO2 produced.
Using hydrogen in the gas network has the added benefit of reducing the number of conversion steps from energy production to heat production. For example, other energy storage technologies such as flywheels can only turn their energy back into electricity, requiring homes to have electrical heaters to take advantage of. In the case of gas, existing infrastructure can handle a gas blend.
While hydrogen produced from renewable sources can heat homes, it is not without its faults. The biggest challenge faced by hydrogen for use in heating is that the current boiler used in homes cannot operate on 100% hydrogen. This means that switching entirely to 100% hydrogen would require all connected homes to have their boilers decommissioned and replaced with hydrogen boilers, which is expensive.
The second challenge faced with hydrogen is that the existing infrastructure cannot handle 100% pure hydrogen. This is because pure hydrogen gas damages the metallic piping used in the natural gas industry. As such, all existing pipework would need to be replaced if natural gas was eliminated entirely.
Overall, hydrogen could be a major player in the energy storage business and help renewable energies to become more reliable. Furthermore, running current boilers on a hydrogen blend may also help reduce CO2 production sourced from stored hydrogen.