Blue hydrogen can help protect the climate – Eurasia Review

An international group of researchers led by the Paul Scherrer Institute and Heriot-Watt University have conducted in-depth analyzes of the climate impact of blue hydrogen. This is produced from natural gas, with the CO2resulting from the captured and stored process. The study, published in the journal of the Royal Society of Chemistry Sustainable energy and fuels, concludes that blue hydrogen can play a positive role in the energy transition – under certain conditions.

Hydrogen is an energy vector of the future: water is the only by-product of its use, whether to power a car or to produce heat for homes and industry. In fact, the method used to produce hydrogen is what determines its environmental performance. The optimum form is green hydrogen, produced by electrolysis of water. For hydrogen to be effectively green, the electricity used in this process must come from renewable sources, such as hydro, wind or solar power, making it virtually carbon neutral. At present, however, the hydrogen produced in this way is expensive and not available everywhere – due to the lack of renewable electricity and electrolysis capabilities.

“The increasing demand for hydrogen will probably not be able to be satisfied in the foreseeable future”, one can read in the conclusion of this international study. Today, most of the hydrogen is produced from natural gas or other fossil fuels. This is called “gray hydrogen” and does not benefit the environmental performance because its production has a negative impact on the climate and energy is lost during the conversion.

Blue hydrogen offers a kind of compromise and its role in the energy transition has been more widely discussed in recent months by experts and policy makers. Like gray hydrogen, it is also produced from natural gas using a process called 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 part of it is captured and permanently stored underground in order to reduce the greenhouse effect. This process is known as carbon capture and storage (CCS) and helps improve the environmental balance.

Leaks weaken the climate benefit

A joint study published last August by researchers at Cornell and Stanford universities in the United States, however, came to the conclusion that even when CSS is used, blue hydrogen for heat production is not better for the climate, but overall, it can be well over 20%. worse than using natural gas directly as an energy carrier. The main reason, according to the authors, was the leakage of natural gas into the atmosphere throughout the supply chain – from its production, to drilling, to transport by pipeline or ship, then to the plant. hydrogen production. Since the greenhouse effect of natural gas, or rather its main component methane, is about 30 times stronger than CO2, even leaks of a few percent can seriously weaken the climate balance of the hydrogen produced. In addition, the steam reforming of natural gas produces CO2 emissions, otherwise all of the carbon dioxide is captured, allowing some to escape into the atmosphere rather than being stored underground.

“This study gave us the chance to study the climate impact of blue hydrogen in much more depth,” says Christian Bauer of PSI’s Energy Systems Analysis Laboratory, the lead author of this study. In a short time, Bauer and Mijndert van der Spek, professor at the Research Center for Carbon Solutions at Heriot-Watt University, formed an international collaboration of researchers from different institutes to give the new study a broader base. . The collaboration with colleagues from ETH Zurich has been particularly close, as they have special models for the detailed simulation of processes such as carbon capture. “They used their simulation software to model the production of blue hydrogen, and then at PSI, we fed the results into our environmental performance models,” Bauer reports. “We were therefore able to reproduce the entire production chain, from natural gas extraction to carbon capture and storage. “

The climate impact assessment shows a nuanced picture: whether blue hydrogen actually benefits the climate, it depends to a large extent on the amount of methane lost between the point of extraction and the production of hydrogen, and on the amount of methane lost between the point of extraction and the production of hydrogen. efficiency with which carbon is captured during steam reforming. natural gas. “Methane emissions are very diffuse, as they can occur at many different points along the production chain,” says Bauer, making them difficult to identify. Depending on the production technology and the country of extraction, emissions can vary from a few tenths of a percent to several percent. And when it comes to capturing carbon dioxide, some methods are able to trap and store almost all of the CO.2, while others only reach about fifty percent. “With modern CO2 capture technologies, almost all of the CO2 products in the production of hydrogen can be captured, ”explains van der Spek. This means that blue hydrogen can play a key role in the transition to a carbon neutral society.

High-tech standard is the key

The key to generating blue hydrogen in the most climate-friendly way is therefore to ensure a high level of technology. “Countries like Norway are good role models,” says Bauer. They are already capable of extracting and transporting natural gas with virtually no loss and emissions of less than 0.5%. If almost all the CO2emissions are captured during the steam reforming process and stored underground in old natural gas fields in the North Sea, for example – a solution that has already proven to be safe and effective for many years – so this blue form of hydrogen is almost as climate friendly as the green form.

The PSI scientist emphasizes that his American colleagues were not necessarily wrong. “But they only studied the negative side of the spectrum when they studied the production of blue hydrogen. On the other hand, we were able to show that well managed, this type of hydrogen can make a valuable contribution to the energy transition. It could at least be a sort of stopgap solution until green hydrogen becomes widely available and at lower cost. “The continuously growing demand may require that the two types of hydrogen be used to complement each other over an extended period of time,” according to Bauer.

The natural gas industry has already recognized that only production with the lowest possible emissions can ensure its survival. It has set itself the goal of improving the technology used worldwide to such a high level that methane emissions do not exceed 0.2%. Policy discussions focus on the threshold values ​​that would qualify blue hydrogen as a low-carbon, environmentally friendly fuel source. “It is important here that such an emission threshold really takes into account the entire production chain”, warns Bauer. Critical factors should not be overlooked when assessing the climate balance.

Hydrogen color spectrum

In the energy sector, hydrogen has a different name depending on how it is produced. The color spectrum of hydrogen includes:

Green: produced with electricity from renewable sources

Turquoise: manufactured by pyrolysis of methane. Natural gas is heated and divided into hydrogen and solid carbon

Orange yellow: made from organic materials such as biomass, biogas and biomethane

Purple / red: made from electricity produced by nuclear reactors

Blue: made from natural gas, with the carbon dioxide by-product captured and permanently stored

White: natural geological hydrogen

Grey: produced from natural gas (“gray” often refers to all fossil fuels as well)

Brown: produced from lignite or lignite

Black: made from black coal (bituminous)

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