Hydrogen Production – how much will be sustainable, how sustainable, when, and how?

August 6, 2019 |

The pursuit of hydrogen applications is a story of vehicles, plants, and refineries where hydrogen will be used, and the trucks and pipelines via which it might be supplied to those end users. It all starts — and, failing some innovation, might find itself stillborn — at the point of production. Creating another fossil economy, even if it uses groovy hydrogen, is not the aim of our industrial societies. We want new methods of production, new sources that justify the time, money and aggravation of building out a hydrogen infrastructure. So, affordable production is the first hurdle, but by no means the easiest.

The hydrogen production landscape today

As the IEA informs us, “around 70 Mt of dedicated hydrogen are produced today, 76% from natural gas and almost all the rest (23%) from coal, most of that in China. And for that reason, hydrogen production corresponds to the CO2 emissions of Indonesia and the United Kingdom combined — and massively increasing hydrogen’s applications would magnify that by several times.

Source: IEA

The other source we use tight now — and not much of it — is water-splitting, using electrolysis. The costs are high because for one, the yields are low. A ton of water contains about 220 pounds of hydrogen. By comparison, a ton of natural gas (purified to methane) contains 500 pounds of hydrogen. One of the reasons you’ll rarely hear about hydrogen in biomass circles is the yield, as well. A ton of sugar has roughly 130 pounds of hydrogen, and lignin too.

Alternative water-splitting from renewable power

The strategy for some time to come is going to involve waste recovery. In the case of electricity, finding excess no-cost renewable power, mostly. There are certainly excess hours available from “peak” solar and wind production, so that’s a good start.

But the volumes get daunting. As the IEA observes, “If all current dedicated hydrogen production were produced through water electrolysis (using water and electricity to create hydrogen), this would result in an annual electricity demand of 3 600 TWh – more than the annual electricity generation of the European Union. Water requirements would be 617 million m3, or 1.3% of the water consumption of the global energy sector today; this is roughly twice the current water consumption for hydrogen from natural gas.”

So, there’s a roadblock to consider. Having noted that, let’s not think of the future of hydrogen as requiring 100% renewable generation. A more reasonable case would be that all future expansion of production would come from renewables, and over time the dependency on fossil would be reduced.

Using renewable methane

And there’s the option to form methane from waste biomass.

One attractive aspect, there’s a lot of existing technology to tap. For example, anaerobic digesters to produce biogas, and steam methane reformation to produce hydrogen. As the IEA observes, “Steam methane reformers using [methane] are the workhorse of dedicated hydrogen production in the ammonia and methanol industries and in refineries. Natural gas accounts for around three-quarters of the annual global dedicated hydrogen production of around 70 million tonnes of hydrogen (MtH2 ), using around 205 billion cubic meters (bcm) of natural gas (6% of global natural gas use).”

SMR produces a lot of CO2.  Lowering carbon intensity through carbon-capture is an option. The IEA notes, “CCUS can be applied both to SMR and ATR hydrogen production. Using CCUS with SMR plants can lead to a reduction in carbon emissions of up to 90%, if applied to both process and energy emission streams. Several SMR-CCUS plants are already operational today, producing around 0.5 MtH2/yr between them.”: Two methods are separating CO2 from syngas, and CO2 can also be captured from the flue stack in a more diluted form.

Another option is methane splitting

As the IEA observes: 

The main technology is based on alternating current three-phase plasma, and uses methane as a feedstock and electricity as an energy source. It produces hydrogen and solid carbon, but no CO2  emissions.

Methane splitting requires high-temperature plasma and significant thermal losses reduce its efficiency advantage, but it uses three to five times less electricity than electrolysis for the same amount of hydrogen produced. It has very low CO2  formation and creates solid carbon in the form of carbon black. It requires more natural gas than electrolysis, but could create additional revenue streams from the sale of carbon black for use in rubber, tires, printers and plastics. The US firm Monolith Materials operates a pilot methane splitting plant in California and is building an industrial plant in Nebraska; the Nebraska plant will ultimately be run on low-carbon electricity and sell hydrogen to the Nebraska Public Power District, which plans to convert a 125 MW coal plant to burn hydrogen instead of coal. Although the total efficiency would be lower than using the natural gas directly in the power plant, the emissions from gas combustion would be avoided and the hydrogen would effectively be a “store” of input electricity for the power network.

Using ethanol

One technology we find very interesting is splitting hydrous, low-cost ethanol. There’s a glut of ethanol on the market right now — so the production of hydrogen in this way has the dual impact of giving us a molecule we can use, and reducing oversupply of ethanol and thereby improving the price outlook and giving farmers a break.

More on that early-stage technology from SBI Bioenergy and you can learn more about it here.

The costs

The costs are all over the map. The IEA indicated in their Future of Hydrogen report that “natural gas without CCUS is currently the most economic option for hydrogen production” with costs as low as $1/kg in the Middle East. The leader on the low-carbon side is electrolysis, which needs electricity prices of $10-$40/Mwh to work cost-competitively. That’s high, compared to where we are on renewables at the moment, which range more in the $60-$200 region. But, we’re talking about marginal hours, down time — so, that’s the play that will be on the minds of many when thinking about production at world-scale.

Source: IEA

Making fuels from hydrogen — the attraction as a form of renewable power storage is potent, but the IEA cautions that “for synthetic liquid fuels from electrolytic hydrogen, however, electricity costs of $20/MWh translate into costs of $60–70/bbl without  without\ taking account of any capital expenditure or CO2  feedstock costs.” The problem is hydrogen begins with its low energy density in a gas state — liquefaction is where it’s at. That could some in the form of storage as ammonia, diesel or jet fuel. 

Let’s perk up our ears at the mention of ammonia. Yes, it makes an excellent fuel, and when combusted creates no CO2 emissions at all. But it’s as toxic as it comes, and the handling issues would be completely daunting. Something to study as a problem — the handling — and reminds us that with hydrogen, it is more than just figuring out a production technology. Materials handling, distribution and so forth are a huge part of the equation.

The diesel option is probably part of a syngas story more than a hydrogen story — right now, we generally produce diesel from hydrogen and carbon monoxide via a Fischer-Tropsch synthesis. It’s costly at the moment, and embryonic. Hydrogen production may well prove useful if there’s a CO source and not enough hydrogen. Be interesting to see if LanzaTech takes an interest in ethanol splitting technology — clearly the company has sourced lots of carbon monoxide through its partnerships and knows how to make lots of ethanol — so, the potential is there.

Capturing CO2 for low-carbon hydrogen production

As the IEA observes, “for very low CO2  pathways, non-fossil CO2  sources would be needed. One option is to use CO2 formed at high purity during the production of biogas and bioethanol. Capturing CO2  from these processes requires only moderate additional investment and energy, and has CO2  capture costs as low as $20–30/ton.”

Where to produce

Ideally, many have noted that the hydrogen production is best sited at the point where a low-carbon fuel is produced — that is, the hydrogen should either be the finished fuel, or should be co-located with the finished fuel production. Saves on distribution infrastructure. And in the case of ethanol production, there are the advantages of being able to capture zero-cost CO2 which improves ethanol’s carbon-intensity, and then use that in fuel creation. In the case of ethanol splitting, you also have the potential benefit of using lower-carbon, lower cost hydrous ethanol (no need to distill down the broth to an anhydrous or dry ethanol, ethanol splitting uses a very wet ethanol, almost a stiff whiskey).

The Bottom Line

For some time, hydrogen is going to be fossil-based production, and enthusiasts will haver to decide on the lower-cost route of building an infrastructure for fossil hydrogen then switching over to renewables, or the higher-cost, slower route of going all out for renewables from the get go. 

In terms of renewables-based sustainable hydrogen, for some time its going to be about capturing waste streams. Low value renewable power, low value water, low value biomass, cheap waste industrial gases, cheap wet ethanol, and so forth. 

And we remain intrigued about the possibilities of ammonia as a fuel though the toxicity is for most a complete red-flag, hard stop. We wonder. 

You can read the IEA’s breakthrough report, The Future of Hydrogen, here.

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  1. Venkat says:

    Very interesting report from IEA. Hydrogen is the only alternative to Carbon. Sourcing Hydrogen from fossil fuels and biomass is leading to rejecting Carbon in the air in some form or other.

    Water splitting by electrolysis is the best albeit its low yield , but then it should use electricity from renewable sources such as Solar and Wind.

    In the above figure 7, in the bottom line, should it not be water and not electricity , followed by electrolysis?