Hydrogen Production – How Much Will Be Sustainable, How Sustainable, When, and How?

(Hydrogen Digest) ... 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.

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.

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.”

Using renewable methane

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

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.

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.

The costs

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.

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).