One of the big unknowns in the decarbonization movement is the potential role of hydrogen. Hydrogen is a viable alternative to the electrification of the energy uses that currently use carbon-based fuels. Hydrogen is attractive as, when consumed in a fuel cell, the only output is water. No carbon.
One of the biggest challenges with hydrogen is that it does not exist in large quantities in nature; it must be created. Currently, the most common way to create hydrogen is from natural gas. As this process creates the carbon output that is trying to be avoided, that rather defeats the purpose. However, there are better alternatives described below so the use of hydrogen from natural gas can be a first step in a beneficial process.
Hydrogen is often referred to by a colour such as “blue hydrogen” or “green hydrogen”. This does not refer to the colour of the hydrogen itself but rather how it is created. Hydrogen has no colour and hydrogen is hydrogen no matter how it is created just like electricity is electricity no matter if it comes from a hydro plant, a fossil fuel plant or a nuclear plant.
The most commonly referred colours of hydrogen are grey, green and blue but there are a number of others:
- Grey Hydrogen is produced from natural gas using high temperature steam to react with the natural gas thereby producing hydrogen. This is the most common method of creating hydrogen in the world today.
- Green Hydrogen is created from water using electricity from renewable sources. The water is separated into hydrogen and water using electrolysis. The idea is to produce the hydrogen at the renewable energy sites (wind farms, solar farms or hydro dams) and the resulting hydrogen can be transported anywhere to be used as the source of energy. Some of the Atlantic provinces are hoping to create an industry by developing hydrogen plants near wind farms located in the ocean. Hydrogen from biomass, which essentially uses the process above on the water in the biomass, is considered green hydrogen.
- Blue Hydrogen is grey hydrogen (or brown/black hydrogen) where the carbon dioxide is captured and stored or repurposed.
- Black or Brown Hydrogen is extracted from coal using gasification. Black hydrogen is from black coal while brown hydrogen is from lignite.
- Purple or Pink Hydrogen is created from water using electrolysis with nuclear power as the source of the electricity.
- Yellow Hydrogen is created from water using electrolysis with grid power as the source of the electricity. The actual sources of the electricity will therefore vary by jurisdiction.
- Turquoise Hydrogen is created from methane using pyrolysis. Solid carbon rather than a carbon gas is the byproduct. Methane pyrolysis is a relatively new technology and has not been used at commercial scale yet. A market for the use of the solid carbon also needs to be developed for this process to be viable as the ratio of carbon to hydrogen produced is 3:1.
- White Hydrogen is the generic term for any other hydrogen coming from various industrial processes or in its natural form.
Hydrogen is viewed as an alternative to electrification for a number of reasons:
- Hydrogen is a known technology that has been in use for over a century.
- Hydrogen is a gas that can be used for both transportation and heating; the two major carbon replacement objectives of electrification. Hydrogen has been used to power some bus fleets for decades. Some of the auto manufacturers, such as Toyota and Honda, have been heavily investing in hydrogen powered vehicles as well as EVs.
- Hydrogen is easier to transport over large distances than electricity. In a sense, it is a method of transporting electricity as electricity can be used to create hydrogen in one location and then this hydrogen can be used to create electricity in another. As an alternative, hydrogen can be converted to ammonia which is even easier to transport over long distances.
- Hydrogen has greater energy density than natural gas so is more energy efficient. As such, it is a potential alternate source of energy for industrial users trying to reduce their carbon emissions.
- Hydrogen can be mixed with natural gas in pipelines so as to reduce the emissions from natural gas. This technology is still being developed and it is not known how high a mixture can be tolerated but a 20% hydrogen blend is being actively planned. I should note that this only reduces emissions by less than 10% due to their different energy density.
However, hydrogen also has some downsides:
- Hydrogen is very flammable. More so than gasoline.
- Hydrogen is not very dense. Storage facilities would have to be 8.5 times bigger than those for natural gas, or the hydrogen would have to be cooled to make it a liquid or the hydrogen has to be compressed to reduce the amount of storage needed. All of these have a cost and add risk.
- The biggest downside is that the infrastructure for hydrogen does not exist. The existing natural gas infrastructure could be adapted to some degree but that would be difficult. Comparatively, while the electricity infrastructure would have to be expanded, that is the expansion of a fully understood environment.
Hydrogen represents another opportunity to replace carbon-based energy. Whether it will be fully or partially adapted will depend on relative costs and general technology breakthroughs. I have always felt that there will be a role for hydrogen, maybe to fuel fleets, but that this role will be in parallel with electrification.