A US start-up says it has developed an emissions-free process that will make hydrogen from natural gas at such a low price it could give away the H2 for free.
This is because the technology will also produce high-value carbon-based products and chemicals at the same time as the hydrogen — and the income from selling those would be enough to render any project profitable.
The microwave plasma pyrolysis technology developed by Pittsburgh-based H Quest uses electricity to generate microwaves that moves methane (CH4) into a plasma state, stripping off hydrogen atoms and initiating a chain reaction that creates solid carbon or petrochemical compounds such as acetylene (C2H2) and ethylene (C2H4).
“Thanks to the high value of the carbon co-product, under the currently prevailing natural gas and electricity prices, H Quest could essentially give the hydrogen away for free, and still make a profit,” chief executive George Skoptsov tells Recharge.
Natural gas is used to produce most of the hydrogen currently used around the world today in the fertiliser, oil refining and chemicals sectors, but the steam methane reforming process used produces nine to 12 tonnes of CO2 per tonne of H2. This is because the carbon molecules combine with oxygen in the air, but take air out of the equation, and methane will split into hydrogen and solid carbon.
Heating natural gas in the absence of air, mainly inside so-called pyrolysis ovens, has long been discussed, with any H2 produced in this way being labelled as “turquoise hydrogen”.
But pyrolysis ovens are still in their infancy and currently very expensive, with the high temperatures needed — which require burning a fraction of the hydrogen produced — not exactly keeping costs low. Consequently, no commercial turquoise hydrogen plants are yet in operation.
By contrast, H Quest’s microwaves require four times less electricity than required for the green-hydrogen electrolysis process that splits water molecules into H2 and oxygen, the company says.
But the start-up’s technology has further advantages over pyrolysis ovens — it is able to produce different and higher-value forms of carbon, including super-strong nanotubes and graphene, as well as petrochemicals used in heavy industry that are normally derived from unabated fossil fuels.
“It’s very difficult to make a high-value carbon product, which is why a lot of people [looking into turquoise hydrogen] will say, ‘well, there's so much carbon], it's low quality, with poor structure and impurities, we'll bury it under our plants’,” says Skoptsov. “And our carbon is fundamentally different and that's what makes us, what makes this process, different.”
There are many forms — or allotropes — of pure carbon that differ according to how the atoms are arranged, including diamonds; carbon black, which is used in the production of tyres, printer inks and reinforced plastics and batteries; graphite, used in pencils; one-atom-thick graphenesheets; and carbon nanotubes, the strongest material yet discovered.
According to information seen by Recharge, low-quality graphite costs about $5/kg, graphene comes in at roughly $175 per kilo, while carbon nanotubes can fetch up to $2,300/kg.
But Skoptsov says the “real advantage” of the company’s technology “has to do with the complexity of the pyrolysis process, which most people don’t recognise”.
“After you activate methane, it doesn’t simply start losing hydrogen [atoms], leaving carbon behind. What it does is it starts combining with itself — and through that process it loses hydrogen. So it starts making chemicals, more complex chemical compounds, which sort of keep assembling themselves into larger and larger structures.
“If you are very skilled, you can take that process to [produce even] graphene, it’s actually doing to form a large graphene sheet.”
“But you can also freeze it at the chemical stage before it goes all the way to carbon. So you reduce your hydrogen output, but then you can go to make ethylene, for example.”
Ethylene (C2H4), the key ingredient in the polyethylene plastic, is the world’s most produced organic compound, and mainly derived by heating natural gas or petroleum — processes that are said to account for about 0.8% of global greenhouse gas emissions.
“Really we see ourselves as a company that doesn't just make hydrogen or a company that makes carbon black.” Says Skoptsov, a former robotics engineer who founded H Quest in 2014. “We see ourselves as a sort of more broad-scale sustainability purveyor.
“We’re making a product that already exists, is difficult to decarbonise, is made conventionally with a lot of CO2 emissions, and we’re doing it in a fundamentally zero-CO2 way. And we have a stream of hydrogen that can feed directly to decarbonise existing processes, as a source of energy or as a chemical feedstock.”
Why has no-one done this before?
With so much focus on clean hydrogen around the world right now, and oil & gas companies working on blue hydrogen, where not all the CO2 emissions can be captured and stored, why has no-one else thought of using microwaves in this way?
“The problem is it’s actually very difficult to get something to be heated with microwaves,” says Skoptsov. “Water is great in the microwave oven, but ice doesn’t heat in the microwave at all. If your TV dinner is half frozen, that half is going to stay cold and the other half will be steaming hot. And especially industrial materials — chemicals, oil, organics, they’re impossible to heat effectively in the microwave.
“We haven’t invented the process of creating microwave plasma. But what we have done is develop a way for it to be industrially relevant.”
Microwave ovens in people’s homes work by using an electron tube called a magnetron to produce microwaves — a form of electromagnetic radiation with short wavelengths and extremely high frequencies of up to 100GHz (100 billion oscillations, or vibrations, per second). These microwaves cause water molecules in food to vibrate at speed, causing it to heat up.
It is the same basic mechanism in the H Quest process. A magnetron fires microwaves at 2.4GHz at methane, causing the few naturally-occurring free electrons within the gas to vibrate rapidly, causing them to collide with other electrons that are then freed by that collision, causing a chain reaction that eventually frees a lot more of the electrons.
“Plasma is basically a gas that has had some of the electrons pulled off of their molecule,” says Skoptsov.
“One problem with the plasma is that these charged electrons will want to travel closer to the source of the electromagnetic radiation. So you have to confine them, otherwise they’ll get all the way to your magnetron — the thing that actually creates this bouncing electromagnetic field — and short it out. So what people have done is put it in a quartz tube — quartz is transparent to microwaves and it will contain the gases.
“But quartz tubes are a problem because, first of all, they don’t scale very well. They’re fragile. But most importantly, when you deal with hydrocarbon gases, that carbon tends to stick to the walls [of the quartz tube] — basically you clog the whole thing up with carbon, which starts heating up and your quartz tube is destroyed and your experiment is over.
“But we’ve been able to separate the microwave generation from the actual reaction in a way that doesn’t involve quartz tubes at all.
“We can actually make that process in our reactor go to completion.”
Skoptsov does not want to reveal how H Quest achieves this, describing the process as “our secret sauce that sets us apart from other folks”.
He explains that microwaves have not been widely used in heavy industry because “you cannot just scale them arbitrarily — there is a limit to how much energy a single magnetron can produce”.
So rather than building bigger and bigger machines for commercial projects — which could be built anywhere that has access to electricity and natural gas — H Quest will instead manufacture small-scale production units, but build multiples of these, according to the project size.
“We do have to scale by replication, which has intrinsic advantages,” Skoptsov explains. “If your process is profitable at that small scale, scaling by replication allows you to very quickly deploy and get to market.”
First commercial projects in three years
H Quest is due to complete a pilot project in the next 18 months that will be capable of producing 250kg of turquoise hydrogen and 750kg of carbon black per day.
A first commercial project, projected to cost $3m-5m to build, is due to be up and running within three years or less, with a daily output of one tonne of hydrogen daily and three tonnes of speciality carbon black.
Running costs depend on the price of green electricity and natural gas, but “we’re looking at something like a 40% return on capital per year from this first commercial project,” Skoptsov says.
H Quest will initially focus on carbon black for its early plants because it is fairly simple to produce and store at small scale, with ethylene being produced at larger follow-up plants, as the chemical tends to be bought and sold in large volumes.
The US company has largely been funded so far by research grants and is owned by Skoptsov, key employees and advisors and a handful of early investors, but will need additional investment to help fund the pilot and initial commercial projects.
So is H Quest going to build its own plants and sell the hydrogen and carbon, or license the technology to third parties?
“We’re looking to partner closely with the existing industry — what we want to sell them is the means of achieving their sustainability goals and decarbonisation,” Skoptsov explains. “What the partnership is going to look like, that’s really for us to work out. If they were to run it as part of their [existing] plant, they would need to license it, but also buy our equipment that’s made with our secret sauce.”
Most of the equipment is off-the-shelf, but the reactor itself — the place where the magic happens — has to be purpose-built by fabricators.
“There are multiple markets that we can address and I think the strategy would depend on each market.
The limits of the H Quest process
It would be easy to assume that H Quest’s process of making CO2-free hydrogen from natural gas could revolutionise the fast-growing H2 sector, that it would eliminate any need to produce blue hydrogen and allow a hydrogen economy to develop at speed, but the technology does have two small drawbacks.
One is that methane is a powerful greenhouse gas that often leaks upstream (see panel below), and the other is that there is a limit to the size of H Quest’s market, even if it is potentially large. For instance, the carbon black market, which the company wants to target first, requires 14 million tonnes of the stuff each year.
“What we're limited by is the market of the carbon co-product,” says Skoptsov. “We’re making three times as much carbon products [by weight] as hydrogen products. So we have to balance those. That’s the fundamental problem we have to solve, but we are already working on new use cases for our materials.”
The H Quest process releases no greenhouse gases, and if the electricity used is produced from 100% renewable energy, it is entirely emission-free.
However, methane is 84 times more powerful a greenhouse gas than CO2, and often leaks from pipelines.
According to recent scientific papers, up to 2% of the natural gas produced in Russia, Algeria and Libya leak into the atmosphere, while even the global leaders in methane-leak prevention, such as the UK and Norway, see significant proportions of their natural gas (up to 0.5%) unintentionally escape.
H Quest points out that if biogas is used in the process instead of fossil gas, the hydrogen and carbon-based co-products would have negative emissions.
And that methane leaks would be reduced to virtually nil if projects were built at fossil-fuel facilities that routinely flare natural gas.
“Regardless of what the spot markets tell you, the price of gas is so low that 650 million MCF (18 million cubic metres) of natural gas are flared — burned — every day in Texas alone because they don’t have a path to market,” says Skoptsov.
“But our plants can directly take that natural gas… and turn it into a useful product.”
He adds: “For the guys that are flaring right now, we might be selling a way to deal with their excess gas because it is a problem. If they’re prohibited from flaring, what are their options? They can stop producing, they can cap their well, they can try to store it, liquefy the gas and put it on a truck. Or they can tell us, ‘hey guys, can you set your thing up here, make your carbon — and you can use the hydrogen you’re making for electricity production to run your own process, so you’re basically a carbon black play’.”