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Finding scalable, affordable and zero emission forms of energy is now a global priority. The International Energy Agency (IEA) predicts that our demand for power will increase by 25-40% by 2040 – which will only exacerbate climate change and its impacts if we can’t find new zero emission alternatives.
Three sustainable energy sources offer potential solutions. Renewable energy; biofuels (bioethanol and biodiesel derived from plants, agricultural, domestic or industrial waste products); and green hydrogen (GH2).
Hydrogen isn’t as energy dense as petrol, diesel or the other hydrocarbons we use as fuel, but there are vast quantities of it in ice packs, oceans, rivers, lakes and the atmosphere, so it holds promise. It makes a universal, light, and highly reactive fuel, but is hard to extract in a usable form. Importantly, the process of extraction mustn’t lead to further CO2 emissions if hydrogen is to become a new energy source for the net zero era.
A viable solution?
The largest proportion of hydrogen used for energy is ‘Grey Hydrogen’ at 99.9%, produced by the steam reforming of natural gas. This process generates relatively high carbon emissions, and certified green hydrogen must attain an emission reduction of 60-70% below that of grey hydrogen.
Green hydrogen production uses electrolysis to separate water into hydrogen. When this process is powered by renewable energy we approach the ideal outcome: truly sustainable fuel, sustainably produced. However, the cost of production is high ($6/kg in 2015). Once this cost reduces to the tipping point of $2/kg (predicted for 2025), green hydrogen could become a competitive fuel source. Goldman Sachs predicts that the market for GH2 could be worth $1 trillion/year by 20501 as more and more investment in the sector comes on stream to meet the demand for sustainable energy sources.
The uses of green hydrogen are many. For industries that are hard to electrify, such as the cement and steel production sectors, green hydrogen is an ideal solution to their heavy carbon-based energy demands. Hydrogen fuel cells can be used to power engines in trucks and cars, and hydrogen powered aircraft are already being developed by Airbus, although they do not foresee their use becoming common before 2050.
GH2 could also be used for domestic and commercial heating and cooking, with the British government proposing it as an alternative power source for most UK homes by 2050. Green hydrogen could be transported through the existing natural gas network, although some pipelines would have to be upgraded. GH2 can also make up for the shortfalls of power supply from renewable energy sources; when the wind doesn’t blow or the sun doesn’t shine, GH2 could meet some of the baseload capacity.
There are many challenges to developing a truly green hydrogen production system at scale, with the transmission network to bring the fuel to the places that need it. But given the pressing nature of climate change, it’s understandable that so many researchers and utility companies are already exploring how this promising energy source could be made viable at scale.