South African company Hydrox Holdings has patented a water electrolysis method that is membrane-free.
“Our aim is eventually to produce hydrogen from renewable-energy sources, particularly solar and wind, and to have hydrogen readily available,” said Hydrox CEO Corrie de Jager.
Hydrox’s divergent electrode flow through electrolyser can operate at temperatures greater than conventional systems, owing to the absence of a temperature-limiting membrane.
Envisaged is the establishment of hydrogen producing plants outside the bigger cities to provide existing petrol filling stations with hydrogen from compressed gas cylinders.
Mining Weekly put these questions to De Jager:
Where is the membraneless electrolyser pilot plant being built to test your new technology?
Our facility is located in Strydompark, Randburg, where all testing is done. The electrolyser and all its components are being built by a number of local and international suppliers.
What do you hope to prove with this pilot plant?
To provide the world’s first scalable membraneless electrolyser that produces pure hydrogen and oxygen gas at good efficiencies. This pioneering unit has tremendous potential for further improvement. Fabrication, commissioning and stress testing of the pilot plant will be completed by December 2019, however, long-term testing to assess performance, durability and reliability will continue into the new year.
Who is funding the plant and how much will it cost?
Hydrox has been privately funded by individuals and Shell is currently providing us with further funding to complete the pilot plant. Although development costs of a specialised prototype system are quite high, the ultimate target is to achieve a total production cost of hydrogen of below $7.5/kg. This will make our system extremely cost competitive. Our DEFT technology allows for further optimisation which gives it a huge advantage over all other systems.
Is hydrogen a better fuel than petrol and diesel?
Hydrogen is mostly known for its application in the mobility sector, but it has numerous alternative industrial applications. The demand for affordable hydrogen is enormous. Hydrogen can be used as a means of storing and distributing renewable energy from wind and solar.
Hydrogen produced from renewable-energy sources can be chemically combined with carbon dioxide (CO2) from the air or from CO2 emission sources to produce carbon neutral methanol, dimethyl ether or other fuels or additives. Methanol can be used as a fuel or can be added to petrol to lower pollution levels. Hydrogen is a clean fuel as there are no greenhouse emissions associated with it.
Hydrogen contains 33.33 kWh lower heating value (LHV) of useable energy, while petrol and diesel only contain around 12 kWh LHV of energy. An internal combustion engine is known to have a thermal efficiency of between 20% and 40%. By contrast, a fuel cell has an electrical efficiency of between 50% and 60%.
How can it be made cheaper than petrol and diesel?
By reducing the capital expenditure (capex) and operating expenditure (opex) costs, through scaling of the system, increasing energy efficiency and using fluctuating energy loads provided from renewable-energy sources effectively.
The elimination of costly membranes and fewer working parts reduce capex resulting in lower production costs. The development of highly efficient catalysts will greatly enhance energy consumption and various possibilities are currently being explored in conjunction with local universities. The price of hydrogen does not necessarily need to be cheaper than the price of diesel or petrol, as the cost per unit distance travelled needs to be more cost effective.
Fuel cell electric vehicles are far more efficient compared with diesel or petrol vehicles and even if hydrogen comes at a slightly higher price than diesel or petrol, it would still provide more kilometres culminating into a cost saving. No CO2 is emitted from the water electrolysis process, nor is any produced when hydrogen is converted to usable energy in a fuel cell. However, it all depends on where your energy to produce the hydrogen originates.
Many countries still have electrical grids comprised of coal and oil power stations. In this case, the production of hydrogen will yield CO2, owing to the electrical energy source. If the source of electricity is renewable energy, or if the majority energy is from renewables, the CO2 production would either be negligible or minimal.
Will your electrolyser use platinum-group metals as catalysts?
At the moment DEFT electrolysis is targeted to be as simple and robust as possible, and nickel is the most reliable metal on the market commonly used in alkaline water electrolysis as an effective electrode substrate.
We are currently looking at catalyst options containing a small amount of platinum-group metals (PGMs), however, the biggest boost for the platinum market will not be from the generation of hydrogen but rather in the conversion of hydrogen to electricity in a fuel cell. The fuel cell catalyst is solely dependent on being fabricated from PGMs, owing to the acidic environment of the fuel cell.
Inexpensive available hydrogen would unlock the fuel cell industry by increasing the demand for platinum.
Why should we be producing hydrogen in South Africa?
Hydrogen is a logical means of storing renewable energy and can serve as an effective means of supplementing our local electrical grid. By converting to a hydrogen economy, we can eliminate the need to build additional power stations as excess power produced during times of low demand can be stored as hydrogen to provide the grid with power during peak demand.
By creating a hydrogen infrastructure, South Africa would unlock the full platinum potential as more fuel cells will be sold. There is already a huge demand for hydrogen from the mining industry for underground mining vehicles, power generation and ore purification.
Within South Africa, a number of large companies such as Sasol and Eskom have been cited as major point source CO2 and sulphur dioxide emissions, the CO2 can be recaptured and used in conjunction with hydrogen to generate more fuels. Hence, the reduction in CO2 emissions would be a possibility along with maximising the profits generated by these companies. Along with this, some companies rely on hydrogen to produce some of their more valuable products such as processes within Illovo sugar. Switching to hydrogen is going to have a lasting positive effect on our environment and country as a whole.
What is the advantage of your system?
One of the biggest advantages is that our system, being membraneless, can operate at much higher temperatures in contrast to current electrolysers using the temperature ‘limited’ membrane. Higher temperatures result in much improved electrical efficiencies.
The excess heat is typically removed from standard electrolysers using a heat exchanger system in order not to supersede the maximum operating temperature of the membrane. Within DEFT, this excess temperature can be ‘locked’ into the system and be used to improve system efficiencies, resulting in lower opex and hydrogen costs. We will be entering shortly into a collaboration agreement with an internationally funded consortium of scientists from various countries to develop just such a system.