An international group of researchers, including Professor Jon Gibbins from UKCCSRC, TERC and the Energy Institute, has carried out in-depth analyses of the climate impact of blue hydrogen. The study confirms that blue hydrogen, produced from natural gas and using carbon capture and storage processes, can play an essential positive role in the energy transition, when used with certain conditions.
Hydrogen is an energy carrier of the future: water is the only by-product from its use, whether it be to power a car or to generate heat for homes and industry. When producing hydrogen, the method used to produce the hydrogen is what determines its environmental performance. The optimal form is green hydrogen, produced by the electrolysis of water. For hydrogen to be green, the electricity used must come from renewable sources, such as hydro, wind or solar power, which makes it close to carbon neutral. At the moment, however, hydrogen produced in this way is expensive and not universally available – due to the lack of renewable electricity and electrolyser capacity.
Today, most hydrogen is grey hydrogen, produced from natural gas or other fossil fuels,which does not benefit the environmental, as its production has a negative climate impact and energy is lost during conversion.
Blue hydrogen offers something of a compromise, and its role in the energy transition has been more widely discussed in recent months by experts and policymakers. Like grey hydrogen, it is also produced from natural gas using a process known as steam reforming, which heats and then splits the gas into hydrogen and carbon dioxide. In this case, however, the CO2 is not allowed to simply escape into the atmosphere, but is captured and stored permanently underground in order to reduce the greenhouse gas effect. This process is known as carbon capture and storage (CCS) and improves the environmental balance.
A joint study published last August by researchers at the US universities of Cornell and Stanford came to the conclusion, however, that even when CCS is used, blue hydrogen for heat generation is not better for the climate, but overall can be well over 20 percent worse than using natural gas directly as an energy carrier. As a result, researchers wanted to study the climate impact of blue hydrogen in much greater depth.
This study, published in the Royal Society of Chemistry’s journal Sustainable Energy & Fuels, was led by Heriot-Watt University and the Paul Scherrer Institute (PSI) in Villigen, Switzerland and carried out with an international collaboration of researchers from different institutes in order to give the new study a broader base. The group used specific models for detailed simulation of processes such as carbon capture in order to model the production of blue hydrogen. The results were then fed into environmental performance models in order to be able to replicate the entire production chain, from natural gas extraction to carbon capture and storage.
The evaluation of climate impacts shows a nuanced picture: whether blue hydrogen actually benefits the climate depends to a large extent on how much methane is lost on the way from the point of extraction to hydrogen production, and how effectively carbon is captured during the steam reforming of the natural gas.
Christian Bauer from PSI’s Laboratory for Energy Systems Analysis, the lead author of the current study, said of the results: “The methane emissions are very diffuse, as they can occur at many different points along the production chain, making them hard to identify. Depending on the production technology and the country of extraction, emissions can vary between a few tenths of a percent to several percent. And when it comes to capturing the carbon dioxide, some methods are able to trap and store almost all the CO2, while others only manage around fifty percent.
Dr. Mijndert van der Spek, Associate Director CO2 utilisation at the Research Centre for Carbon Solutions at Heriot-Watt University said: “With modern CO2 capture technologies, virtually all the CO2 produced in the hydrogen plant can be mitigated and, therefore, blue hydrogen can play a key role in the transition to a carbon neutral society, until there are sufficient renewable resources to produce green hydrogen in the large amounts needed”.
The key to generating blue hydrogen in the most climate-friendly way is therefore to ensure a high standard of technology. “Countries such as Norway are good role models,” Bauer said. They are already able to extract and transport the natural gas with virtually no losses and emissions of less than 0.5 percent. If almost all the CO2 emissions are captured during the reforming process and stored underground in former natural gas fields in the North Sea, for example – a solution already proven to be safe and effective over many years – then this form of blue hydrogen is almost as climate friendly as the green form.
The PSI scientist stresses that his American colleagues did not necessarily miscalculate. “But they only studied the negative side of the spectrum when investigating the production of blue hydrogen. By contrast, we were able to show that if managed correctly, this type of hydrogen can make a valuable contribution towards the energy transition. It could at least be a type of interim solution until green hydrogen is widely and cheaply available.”
Read a full press release from Heriott-Watt on this study here: https://www.hw.ac.uk/news/articles/2021/blue-hydrogen-can-help-protect-the-climate.htm
View the full original publication here: https://doi.org/10.1039/D1SE01508G