Platinum offers ‘exponential’ boost to hydrogen electrolyser performance

31st July 2020

By: Martin Creamer

Creamer Media Editor

     

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Platinum provides an exponential improvement in the performance of electrolysers used to produce green hydrogen, says Hydrox Holdings CEO Corrie de Jager, who describes platinum’s uplift as being “amazing”.

“We tried a smattering of only 9% platinum and it provided a tremendous improvement in the electrolytic performance of the system,” De Jager told Engineering News & Mining Weekly.

“Suddenly, you get much higher current density when using platinum, which is what you want – a small unit with high current densities, so that you can lower your capital costs further.

“You can build a smaller system and bring the costs down. That’s on the capital side. On the operational side, the closer your electrodes can be, the higher the efficiency, and the less power they will consume, and that’s why we’re excited about the whole process.

“If you go from 1.7 V to say 2 V, it’s exponential. It’s just amazing how the platinum suddenly increases efficiency. It’s just ‘wow’. It’s mind-blowing,” De Jager added.

As reported by Engineering News & Mining Weekly in March, Hydrox, which is sponsored by Shell Energy, achieved a Proudly South African world first by building a hydrogen electrolyser at its Strydompark, Randburg, Johannesburg, premises, using its home-grown divergent electrode flow through (DEFT) technology, which allows electrolysers to operate without membranes at higher temperatures. This results in greatly improved electrical efficiencies, and promises to lower the production price of clean hydrogen, demand for which is growing by leaps and bounds globally.

A stroke of Hydrox genius was to innovate by perforating its electrodes, without any membrane or diaphragm in between. The flow of hydrogen and oxygen through the two perforated electrodes separates the hydrogen and oxygen gases from migrating or crossing over.

Nickel, not platinum, has been the main electrode metal used: “We really couldn’t afford the platinum. I must say, when we tested with platinum, we had to send our electrodes over to America and the guys plated the platinum on for us and sent it back, and it didn’t really last.

“But in the short spell of time, we got the reports back that were just amazing. We got over an amp back, 1 100 milliamps per square centimetre . . . normally you work at 200 milliamps, and we got a 1 100 milliamps per square centimetre back, on the performance level, from a little bit of platinum. And this is what we’re going to look at. What is the optimum. Platinum is obviously expensive, so you’ve got to look at what’s the least you can use, and there are other metals associated with platinum that can actually tie in with platinum. Molybdenum is one and there are a couple of others, not expensive, but they can all play a part. Iron can play a part, but it’s got to be worked out, it’s got to be experimented.

“We know how to do it, and we know how to get it to last, and how to get it attached to our electrodes. Also, we’re looking at different kinds of electrodes now, more surface area. It’s just amazing what we can do with our flow-through system now, and if we can get the catalyst on there, boy, we’re going to blow them away. It’s going to be mind- boggling, and then we’ll have efficiency second to none,” De Jager enthused.

Electrolysis splits water into hydrogen and oxygen electrochemically and, for more than a century, electrolysers have been limited to lower temperatures and pressures, with electrolysis basically being undertaken using some or other form of membrane to keep the gases separate.

Now the world has a new local system, which has been achieved with the financial support of the Gamechanger programme of petroleum giant Shell, which provides businesses with seed funding to advance unproven early-stage ideas that have the potential to enhance the future of energy.

Support from Shell has been vital to Hydrox, which is a recipient of South Africa’s National Science and Technology Forum Award for Innovation.

DEFT™ can use fluctuating currents: “Apparently, no other electrolyser can do that. We’ve tested from, say, 200 milliamps to 20 000 milliamps, 20 amps, per square centimetre, and we still get separation – obviously, we don’t get that high, because it will break the system apart, with all the shrinking effects, but we can use the fluctuating currents in our system, and we’ve tested it now as part of our Shell project. We’ve tested that so we can use the fluctuating currents from renewables.

“We’ve still got to link it to a wind farm or a solar plant and see exactly what it does, but, in theory, where we’ve tested it on the computer, this is what’s exciting and it’s another possibility, because we don’t have the membranes. Our gas bubbles travel over a very short distance. This is what’s so exciting about our technology. It’s so simple. It works so well; it’s got lots of potential. So, yes, fluctuating currents, renewables – it’s a great match,” said De Jager.

Standard electrolysers use a heat exchanger system to remove excess heat so that it does not supersede the maximum operating temperature of the membrane. But with DEFT™, this excess temperature can be ‘locked’ into the system to improve system efficiencies, resulting in lower operating expenditure and hydrogen costs. The new system can also handle fluctuating currents, which makes it ideal for renewable energy and ‘green’ hydrogen.

These are the written replies that Hydrox gave to questions put to it by Engineering News & Mining Weekly:

Why has Hydrox been so obsessed about creating membraneless electrolysers?

Membraneless electrolysis has for many years been attempted by many scientists, as it opens the way to lowering the cost of electrolysis. Eliminating the membrane and its associated supporting components allow for not only a capital cost reduction but also greater operational flexibility. Membranes/diaphragms have a limited operating temperature. Going beyond this setpoint has an effect on the life span of the electrolyser and on the purity of the gas it produces. Membraneless operation does away with these limitations, giving rise to the potential to operate at more efficient operating conditions, such as high temperatures. Some conventional units can waste up to 40% of the electrical input, owing to heat production/removal. Our passion for membraneless systems stems from the fact that our unique patented approach resulted in the development of the world’s first fully functional membraneless electrolyser. All other kinds of membraneless technologies are still in the experimental stage. It is pleasing to note that our technology is being referenced in scientific publications. We are currently working on optimising our unit to surpass the performance of conventional systems, as it is our aim to be a leading hydrogen solutions company that can unlock green hydrogen.

How does Hydrox’s technology work and who will buy it?

All electrolysers use two electrodes – oxygen is produced on one and hydrogen is produced on the other. In order to keep the oxygen and hydrogen gases separated, some kind of membrane or diaphragm is required. These membranes/diaphragms, however, are not very conductive and hence add to the resistance of the cell. Hydrox has gone against the conventional way of thinking by employing diverging electrolyte flows exclusively through perforated electrodes. Injection into the centre of the electrode gap has allowed us to keep the produced hydrogen and oxygen gases separate and essentially the gases are swept away from one another, employing liquid flow. This allows for the operation of an electrolyser that does not make use of a separating membrane/diaphragm without a large increase in cell resistances. The target market is any industry/sector that can benefit from low-cost decentralised hydrogen production. This could include production as a feedstock into industries such as refineries or petrochemicals producers; production for the mobility market; for fuel cell vehicles, such as trucks; industrial vehicles for mines; or high-capacity flexible energy storage for renewable-energy farms. We are even getting enquiries from the farming sector to replace their current unreliable energy provider.

Why is the world moving towards the use of hydrogen?

Hydrogen has always been an important building block in chemistry. Almost every organic molecule contains hydrogen, thus forming an important part of organic chemistry. Most of the fuels we use are organic and thus contain hydrogen. This is important, as hydrogen can be used to manipulate and change fuel types. With hydrogen as a building block, reactions with available carbon and oxygen can form many of the fuels we use today. Hydrogenation reactions (reactions with hydrogen) are important to industry, often used to form valuable products from process by-products. Hydrogen is widely used to form ammonia, which is vital to the agriculture industry. In the mining sector, it can be used as a reducing agent in refineries to extract metals from their oxide forms. There are several important hydrogen- related processes which form part in the manufacturing of many of the chemicals and materials today. Beyond the use as an industrial feedstock, hydrogen is one of the most energy-dense fuels by mass, carrying an energy density of 39.4 kWh/kg. With the combustion of hydrogen, or its use in a fuel cell, the only emission that results is . . . water. Hydrogen produced from a renewable-energy source results in an energy-dense carbon-free fuel with the potential of zero-emissions upon use.

What are the factors leading to the demand for green hydrogen?

Renewable-energy sources, such as solar, wind, geothermal and hydropower, represent a promising alternative approach to energy production amidst growing concerns about diminishing fossil fuel reserves and harmful emissions contributing to global warming. Renewable-energy sources are unfortunately intermittent; therefore, for renewable energy to reshape the energy sector, effective energy storage mechanisms need to be in place. For widespread adoption of renewable-energy sources, energy storage methods need to offer more flexibility and higher storage capacities. For renewable energy to reshape the transportat sector, long-haul modes of transportat require an energy storage mechanism that has a superior power-to-weight ratio, compared to what is offered in existing storage methods. Decentralised green hydrogen production is a viable solution. Low-cost decentralised hydrogen will benefit wider society by unlocking renewable energy, allowing for the transformation of industries which currently contribute to global emissions and accelerate the rate of global warming.

Upcoming Hydrogen, Fuel Cells & the Green Economy Feature

Companies wanting to advertise in Engineering News & Mining Weekly’s upcoming Hydrogen, Fuel Cells & Green Economy feature should contact Creamer Media COO: sales and marketing Reinette Classen at reinette@engineeringnews.co.za, or at +27 11622 3744, or at +27 76508 2016, or at +27 11425 2004.

Edited by Creamer Media Reporter

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