Why we should NOT use blue hydrogen as fuel
Blue hydrogen might be worse for the climate than natural gas
The hydrogen rainbow
Grey hydrogen is the most common form. The color simply denotes how it’s made, and this kind is generated from natural gas (which mostly consists of methane and ethane), the fossil fuel which powers most gas boilers and stoves and which scientists have identified as an important source of carbon emissions that governments need to eliminate.
Brown hydrogen uses lignite coal (also known as brown coal, generated over millions of years by compressed peat deposits) or oil. Black hydrogen is produced using bituminous coal – a tar-like substance.
The process of extracting hydrogen from all of these options emits CO₂ to differing degrees, and so they are not a suitable pathway for reaching net-zero emissions with hydrogen.
Green hydrogen, meanwhile, is produced by using zero-carbon electricity – such as that generated by wind turbines or solar panels – to split water into hydrogen and oxygen. The process is carbon-neutral, but green hydrogen is very expensive, and is expected to remain so untilat least 2030.
But blue hydrogen, it’s hoped, particularly by theUSandUKgovernments, is different. Blue hydrogen is produced using the same reforming process that is used to create grey, brown and black hydrogen, but the CO₂ that would ordinarily be released is captured and stored underground. Carbon capture and storage equipment is expensive, raising the price of the fuel, but it at least provides for low-carbon fuel production at a lower cost than green hydrogen.
Or does it?
Out of the blue
The process of making blue hydrogen also requires a lot of energy. For every unit of heat in the natural gas at the start of the process, only70-75%of that potential heat remains in the hydrogen product. In other words, if the hydrogen is used to heat a building, you would need to use 25% more natural gas to make blue hydrogen than if it was used directly for heat.
And as reported by the USEnvironmental Protection Agency, methane – the primary component of natural gas and a byproduct of using it to produce blue hydrogen – is a much more potent global warming gas than CO₂ over shorter timescales. On a 100-year basis, methane has a global warming potential 28-36 times greater than CO₂, so one molecule of methane in the atmosphere has the same effect as around 30 molecules of CO₂.
In the first study of its kind to consider blue hydrogen’s environmental impact over its entire lifecycle, the US researchers found that methane emissions released when the fossil natural gas is extracted and burned are much less than blue hydrogen. More methane needs to be extracted to make blue hydrogen, and it must pass through reformers, pipelines, and ships, providing more opportunities for leaks: enough, the research indicates, to make blue hydrogen20% worsefor the climate than just using fossil gas.
The new study casts doubt on the role that blue hydrogen might play in cutting greenhouse gas emissions from sectors like heating and heavy industry.
As these new findings are picked over by the energy community, it’s worth wondering how the news will be received in Westminster and Washington. The UK government is due to publish their delayed hydrogen strategy, which should set out where hydrogen will feature in the country’s decarbonization strategy. What is certain is that blue hydrogen may not be as green as it once appeared.
This article byTom Baxter, Honorary Senior Lecturer in Chemical Engineering,University of Aberdeenis republished fromThe Conversationunder a Creative Commons license. Read theoriginal article.
Story byThe Conversation
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