Wednesday, 12 August 2020

Hydrogen – The future of zero-carbon fuels?

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As the debate over how to combat climate change becomes ever more urgent, one company says it has found a way to produce carbon-neutral hydrogen on an industrial scale. In November, Heliogen, an American clean energy company backed by Bill Gates, announced that it had concentrated solar energy to exceed temperatures greater than 1,000 degrees Celsius. At this temperature, Heliogen can split CO2 or water molecules to make hydrogen in a carbon-neutral way for industrial processes.

Producing hydrogen without the use of fossil fuels wasn’t a concern until recently, but now this is arguably one of the biggest challenges to making it a viable fuel of the future, says Yury Melnikov, senior analyst at the Energy Centre and the Moscow School of Management 

“For many decades, all around the world we’ve been getting cheap and reliable hydrogen almost only from fossil fuels – coal, gas and oil. Until recently, there were no serious reasons to look for an alternative production method. But the fight against climate change, which governments, companies, cities and people are now involved in, has changed the problem at the root. Now we need not only a cheap and reliable hydrogen production method, but also a carbon-neutral one,” Melnikov says.


Logistical challenges

“The production of hydrogen is actually very easy: two electrodes are put into water and electricity is led to the electrodes. This simple process releases hydrogen from water. The challenge comes when sustainable production is needed,” says Juha Kytölä, Director of R&D and Engineering at Wärtsilä. “Electricity from ’green’ sources like wind or solar is not widely available at this moment and it still has rather high cost, though it is decreasing.”


Kytölä adds that creating hydrogen – even in a carbon-neutral way – isn’t the biggest challenge to using it as a fuel. The logistics of transporting and storing hydrogen is difficult due to the size of the tanks needed and the very low temperatures required for liquifying it.


It would be useful for the maritime industry in particular if the hydrogen produced through the Heliogen concept could be used efficiently for creating synthetic methane, he says. Ships currently running on liquefied natural gas (LNG) could use it without any modifications to the ship systems. Alternatively, hydrogen could be used as-is as a fuel in combustion engines or fuel cells, but that would require further development in terms of hydrogen storage and logistics concepts.


“Heliogen has introduced one potential way to produce hydrogen. Practice will show if this method is commercially successful. If the resulting cost for hydrogen will be very low, the hydrogen may be attractive for further processing purposes like for production of synthetic methane, thus replacing the use of fossil methane,” Kytölä says.


Scaling up

Is Heliogen’s breakthrough the solution to transforming sunlight into fuel at scale?


“Heliogen is proposing an alternative process to produce hydrogen. Instead of electrodes and electricity, Heliogen is using extremely high temperatures to split water to hydrogen and oxygen. Common to both processes is that hydrogen can be released from water by using a lot of external energy. When later combusting hydrogen (combining hydrogen and oxygen), that energy is released again (due to process losses, the energy is somewhat less than was needed for the split),” explains Kytölä.


Heliogen declined via email to comment for this story, but in a press release announcing the breakthrough, Bill Gross, CEO and Founder of Heliogen, said that his company has made a technological leap forward in addressing the energy demand in industrial processes like making cement, steel and other materials (which are responsible for a fifth of all emissions) and transportation, which are still heavily dependent on fossil fuels.


Indeed, any industry could benefit from this process in order to utilise hydrogen to produce heat, to produce mechanical or electrical energy or for chemical processes.


Melnikov has several reservations about the Heliogen technology’s readiness for commercialisation. He sees electrolysis as a more promising option for hydrogen production from renewable sources.


“With Heliogen, everything will depend on whether the company will succeed in the face of the challenges posed by the technology itself and offer the market a competitive solution,” Melnikov says.


He identified three main challenges that clean energy providers like Heliogen must overcome, which are similar to the challenges Kytölä identified for the use of hydrogen as a fuel overall: difficulties in terms of scaling, difficulties in transportation, and difficulties in storage and matching production to demand.


An industrial level system that could be used to produce heat for one factory using such technology would need dozens of square kilometres of space next to it. Additionally, Heliogen technology, like many technologies that capture renewable energy source, only works at full capacity a few hours each day. Most industrial processes work according to a very different schedule, so storage solutions will be key to viability. At the moment, however, there are no high-value heat storage technologies.


Solution of the future?

The expert community is of two minds about whether Heliogen is the non-linear technology we’ve all been waiting for.


“I would say that this is an interesting and potential step forward for creating sustainable societies. It remains to be seen if this becomes the commercially most attractive way. We are all awaiting low-cost solutions to meet that target,” Kytölä says.


Melnikov believes that it is still much too early to assess Heliogen’s full potential and come to any verdict because it is just one of many different methods of heating something to a high temperature without burning fossil fuels and has no direct relation to hydrogen production. However, cheap, flexible, and reliable green energy production will be a real game changer for the deep de-carbonisation of the global economy. Should Heliogen succeed, it will have carved out an important niche in the future global energy market.

Source: Wartsila

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