Green hydrogen: what is it and is it better than blue hydrogen?

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One potential form of clean energy is green hydrogen, which is derived from renewable sources like water, rather than fossil fuels, and can be used to power heavy industry and power large vehicles, like airplanes and the boats.

But green hydrogen critics say using solar or wind power to produce another fuel right now is a waste of precious renewables, as the world struggles to move away from fossil fuels. At the same time, plans to use blue hydrogen – which is produced using fossil fuels – are coming under increasing scrutiny.

Much of moving away from fossil fuels involves electrifying some of the daily machines we use that run on oil and gas – cars and local transport, and heating homes in some countries, for example. For those who are already electrified, such as computers and appliances, nuclear power and renewable energies like wind and solar are replacing coal.

But some industries require so much energy that traditional renewables cannot meet their demand. This is a problem, because these industries are among the largest emitters of greenhouse gases.

This is where experts say green hydrogen has huge potential.

“Electricity from sources such as wind, solar and nuclear is essential to decarbonize our energy system – but it cannot do it alone, and long-haul transport and heavy industries harbor the most difficult emissions. to reduce, ”said Uwe Remme, an energy analyst at the International Energy Agency.

“Hydrogen is versatile enough to fill some of these critical gaps – providing vital raw materials for the chemical and steel industries or critical ingredients for low-carbon fuels for airplanes and ships,” said Remme at CNN.

Operating an airplane or large ship, for example, requires so much energy that any battery used to store solar or wind power would likely be too large and heavy for the ship. Green hydrogen, on the other hand, can be in liquid form and is lighter. According to Airbus, which is developing a zero-emission commercial aircraft, the energy density of green hydrogen is three times that of the jet fuels we use today.
While liquid green hydrogen would emit no carbon, it does have certain limitations. When burned in the open, it releases a small amount of nitrous oxide, which is a potent greenhouse gas. However, if the hydrogen is powered by a fuel cell, it will only emit hot water and air.
Some small planes have managed to fly on fuel cells powered by hydrogen, although the technology has not yet been developed commercially.

Green, blue or gray?

Hydrogen is the most abundant element on Earth. It is found in many things, including fossil fuels, water, plants, animals, and even humans, but it never occurs naturally in pure form. This means that in order to get pure hydrogen, it must be separated from other molecules by processes that also require energy.

Green hydrogen is produced when renewable energy is used to extract hydrogen from a clean source. This most often involves the electrolysis of water – sending an electric current through the water to separate the molecules.

Gray hydrogen is the most commonly used form of hydrogen today. He is relatively inexpensive, but is derived from natural gas and generally uses fossil fuels as an energy source. It is mainly used in the chemical industry to make products like fertilizers and for oil refining. In the process of extracting hydrogen from natural gas, the remaining carbon dioxide is allowed to escape into the atmosphere, which further contributes to climate change.

Blue hydrogen is generated with the same process as gray hydrogen, but most of the carbon emitted during its production is “captured” and not released into the atmosphere, which is why it is described as a low emission gas.

So what is the best climate solution?

It ultimately depends on the energy used to produce it.

Gray hydrogen has long been seen as a cleaner ‘transition’ alternative as the world wears off from coal and oil, but it remains a major contributor to climate change.

Recent studies have also shown that gray hydrogen emits more greenhouse gases than energy experts initially thought. Methane, a potent greenhouse gas and the main component of natural gas, often escapes from pipelines into the atmosphere.

A hydrogen electrolysis plant operated by Linde AG in Mainz, Germany on July 17, 2020.

If the green hydrogen generated from water and the electrolysis process to extract the hydrogen molecules are powered entirely by energy from renewable sources like solar and wind power, then green hydrogen could be a zero emission option.

But it’s not there yet.

The machines used to carry out this electrolysis are expensive and the process is not particularly efficient.

In 2020, of all low-carbon hydrogen produced, 95% was blue, according to a recent IEA report. But by 2050, as the green hydrogen industry grows, it is expected to be more readily available, easier to produce and competitive with blue hydrogen by 2030, reports the IEA. By 2050, the share is expected to be 35% blue hydrogen and 62% green, provided governments and companies are successful in developing the industry.

Jess Cowell, a Friends of the Earth activist in Scotland, opposes any use of blue hydrogen, saying it simply allows fossil fuel companies to stay in business and keep emitting. There may be a future for green hydrogen, Cowell said, but now is not the time to invest in it.

“You run the risk of diverting existing renewable capacity to green hydrogen production, and right now it’s an incredibly inefficient process,” Cowell told CNN.

A gray hydrogen powered bus in London, England on September 11, 2020.

It doesn’t make sense at the moment, Cowell explained, to use hydrogen for purposes such as heating homes, which is being discussed in the UK as an option. If renewable sources of electricity are used to create hydrogen.

“So what we want to see is use this renewable electricity for direct electrification,” said Cowell, explaining that gas boilers typically used to heat homes in Scotland and the UK should be electrified and run on wind and solar power, rather than hydrogen.

Why is blue hydrogen controversial?

Blue hydrogen has been the subject of controversy in many countries, including the UK, where the government recently released its ‘two-way’ hydrogen strategy, which showed heavy use of the blue type alongside development. green hydrogen.

UK Hydrogen and Fuel Cell Association chairman Chris Jackson resigned in mid-August after the plan was published, said in a statement to CNN the strategy was not consistent with his “personal views on the role of hydrogen in the transition to a net zero world”. Jackson is also the CEO and Founder of Protium Green Solutions, which focuses on renewable energy and green hydrogen.

Jackson said in the statement that he appreciates the fact that green hydrogen is not a quick fix.

“Likewise, I cannot ignore or argue that blue hydrogen is a viable and ‘green’ energy solution (a fact also validated by external studies),” he said.

Scientists say this invisible gas could seal our fate on climate change

One such study, published in Energy Science and Engineering in early August and peer-reviewed, found that while blue hydrogen emits 9-12% less carbon dioxide than gray hydrogen, it actually emits more methane than natural gas itself.

Overall, the greenhouse gas footprint of blue hydrogen was 20% greater than that of burning natural gas or coal for heat, and 60% greater than that of burning diesel for heating, according to the study.

There are also questions about whether the storage of carbon after its capture, which usually involves its injection into the soil, is sustainable.

“Our analysis assumes that the captured carbon dioxide can be stored indefinitely, an optimistic and unproven hypothesis. Even if this is true, the use of blue hydrogen seems difficult to justify for climatic reasons,” the study concludes.

Remme, of the IEA, however said that this study made assumptions that underestimated how much greenhouse gases could be captured, and that while the blue hydrogen was not as clean as the green type , it had a place in the world’s transition away from fossil fuels. fuels.

“There is a role for blue and green hydrogen, but we have to make sure that blue hydrogen is produced with the highest environmental standards,” he said. “The technologies are already available today to prevent these emissions, and they are often just as cost effective and save money.”


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