A fuel cell development company is celebrating 8,000 hours of continuous use of its product with no degradation.
ACAL Energy, based in Cheshire, UK, has developed a novel fuel cell technology that cuts costs and boosts the durability of hydrogen fuel cells by replacing the fixed platinum catalysts on the cathode of a traditional proton exchange membrane (PEM) fuel cells with a liquid regenerating catalyst system.
PEM fuel cells degrade by approximately 28mV per 1,000 hours – a key barrier to their widespread adoption – but ACAL’s FlowCath system bypasses the issues that cause degradation at the same time as making a 25 per cent cost saving due to the reduced need for platinum.
And with their test model now having passed the equivalent of 250,000 road miles with zero degradation, the founder of the company and inventor of the system Dr Andrew Creeth is keen to highlight the benefits of their approach.
“It’s not a new idea. Ford had a look at it in the early 1980s but their catalytic system was inefficient and it meant they would have had a trailer to carry something like 5,000lb for a 20kW fuel cell system,” said Dr Creeth.
“What was new was to find the right catalyst system and having had the idea we found it fairly soon after. Clearly it’s the key to the whole thing.”
Dr Creeth, who has a PhD in electrochemistry from Imperial College London, came across the idea for his “secret sauce” while working for multinational Unilever.
“A thought occurred to me,” he said. “There might be an opportunity for using an oxidation catalytic system for fuel cells.”
A conventional PEM fuel cell strips hydrogen atoms of their electrons at the anode, ionizing them and releasing negatively charged electrons to provide electrical current.
Oxygen in the form of air enters the fuel cell at the cathode, combining with electrons returning from the electrical circuit and hydrogen ions that have travelled through the membrane, separating the anode and cathode to create water.
But in ACAL’s FlowCath system, while hydrogen is catalysed on the anode in the conventional fashion, the electron and proton are absorbed into a solution containing redox catalyst systems, which flow continuously from the stack to an external regeneration vessel.
In the regenerator the solution comes into contact with air and the electron, proton and oxygen react to form water, which exits the regenerator as vapour with the solution flowing back to the cell.
Dr Creeth likened the system to the human body’s oxygen transportation system, with the regenerator representing the lung and the liquid catalyst representing haemoglobin.
“Clearly life is incredibly efficient at managing the whole process so yes, I would say that we have looked to see how life does things,” he said.
“But because life is so sophisticated the details tend to be based around concepts coming from life rather than mimicking the concept.”
By using a liquid system and carrying out the oxygen side of the reaction outside of the fuel cell stack the system has managed to address the durability problems caused by unwanted oxidation reactions occurring in the cell, degradation of the membrane through repeated drying and degradation of the catalyst.
The system is also far simpler than most PEM fuel cells requiring no air compressor or humidity control and the liquid catalyst is able to act as a coolant reducing volume and cost.
The firm is already in discussion with several auto companies about commercialising the technology for use in fuel-cell-powered cars.
Dr Creeth said: “The reason auto companies are so interested is that getting commercial durability with low platinum levels is really hard. You get systems working at the appropriate durability with a high level of platinum but you really can’t get the durability while getting the platinum level down.”
But the company believes that with a range of 1 to 200kW their product has other applications from combined heat and power for homes and businesses, to back-up power generation for mobile networks or computer systems, or even as a replacement for the diesel generator.
Dr Creeth said: “There is a very significant market that is starting to appear in Japan where they are concerned about energy supply having given up nuclear power.”