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ACAL Energy Announces Successful Operation of Novel Fuel Cell With Recirculating Liquid Cathode Technology

ACAL replaces the cathode in a conventional PEM fuel cell (left) with a liquid, non-precious metal catalyst system (right). Click to enlarge.

UK-based ACAL Energy Ltd. has announced the successful operation of a new type of fuel cell system based on its proprietary recirculating liquid cathode technology, known as FlowCath. A 50W fully integrated multi-cell system incorporating the Flowcath technology was operated for the first time last week and produced higher power levels than expected, according to the company.

The FlowCath system replaces the standard—and expensive—platinum cathode found in conventional fuel cells with a liquid, non-precious metal catalyst system. This not only reduces the cost of the cell, but also humidifies the membrane naturally, eliminating the need for additional hydration systems, and better manages the heat which is generated.

The circulating catalyst solution was originally invented by Ford Motor in 1950s, but abandoned because the chemical system couldn’t deliver enough oxygen. ACAL leverages advances in detergent chemistry over the past 50 years.

ACAL’s core technology is the liquid catalyst chemistry. The company currently uses a polyoxometallate inorganic association complex that is very stable and robust, and offers the same power density as platinum (unpressurized), with an additional 100% performance improvement possible.

For its next-generation system, the company is developing a transition metal-ligand complex. This is a higher potential catalyst, capable of delivering 2-3x the performance of platinum, according to ACAL.

Drawing of the ACAL fuel cell system.

The fact that we have managed successfully to build a 10-cell stack, and get the integrated system working so quickly is down to our approach of changing only those parts of the system necessary to adopt our FlowCath technology, keeping everything else the same.

— Dr Andrew Creeth, inventor

ACAL will next try to scale up from the initial 50W system to a 1 kW unit, as well as running the system to demonstrate the expected long term durability advantages of the approach.

ACAL Energy Limited was co-founded in August 2004 by FlowCath inventor Dr Andrew Creeth and Amanda Lyne. The CEO is Dr Sb Cha, ex Commercial Director of CDT Inc. ACAL Energy is in the process of raising private equity funds in order to take the technology forward from small scale laboratory systems, into manufacturable prototypes.

Although ACAL is targeting a range of markets, including stationary, residential and automotive applications requiring larger than 1 kW of power, its initial target is diesel generator replacement ($4b+ market). Home CHP and automotive are longer term possibilities. ACAL thinks it will be ready for initial commercialization by 2010.

ACAL Energy is currently funded by CT Investment Partners LLP, Rising Stars Growth Fund (RSGF), NorthStar Equity Investors Ltd and Porton Capital Ltd. and Synergis Technologies Ltd.



Rafael Seidl

Or, you could just use an old-fashioned alkaline fuel cell cooled by circulating the electrolyte. The latter also has to be changed on a regular basis as any CO2 dissolved in it reduces performance. This would be analogous to an oil change in a regular ICE-powered vehicle.

Of course, like all low-temperature fuel cells, AFCs require hydrogen fuel. That is the fundamental barrier to market entry and, likely to remain so for the foreseeable future.


Well, fuel cells might have a place in the world as power plants, or grid storage.

Not really as transportation devices though.


"Of course, like all low-temperature fuel cells, AFCs require hydrogen fuel. That is the fundamental barrier to market entry and, likely to remain so for the foreseeable future."

isn't it fairly simple to include a reformer to extract the hydrogen from natural gas?

Paul F. Dietz

This replaces the platinum on the oxygen side, but weren't there always non-precious-metal electrodes available there? I thought the problem was on the hydrogen side, at least in acid fuel cells.


I agree with the alkaline fuel cell comments, why did people forget those, CO2 poisoning was not a serious problem.

Lou Grinzo

eric: Yes, it's technically doable (including a reformer on board, or in someone's garage, for that matter), but the problem is the CO2 emissions. When you reform methane you get over 5 times as much CO2 (by weight) as you do hydrogen. That's a lot of CO2 to try to capture, transport, and then sequester permanently. And that's not even taking into account the fact that natural gas (i.e. methane) supplies will be problematic in many places, likely including North America, in not too many more years.

That leaves you with making hydrogen via electrolysis, which gets expensive because of the amount of energy involved.


Can't you just use solar to make the Hydrogen via electrolysis? and even though you could only make it durung the daylight hours the goodthing is its always sunny somewhere around the world all the time. So we would be making hydrogen 24 hours a day. Now we would just need to figure out the storage and shipping of it.

Rafael Seidl

@ Eric -

in terms of well-to-wheels efficiency, you might as well drive a CNG vehicle, which costs a lot less and is very nearly as clean.

@ What2do -

currently, the cheapest ways to capture solar power for transportation is to grow plants or algae and produce biofuels from them. Biomethane can be produced from cellulosic feedstocks today, fed into the natural gas grid and used to run CNG vehicles.

According to Dr. Craig Venter, advances in genetic engineering techniques will before long deliver single-celled organism that can not only produce fuel compounds directly from CO2, H2O and sunlight but also excrete rather than accumulate them. This will eliminate the post-processing required for ethanol and biodiesel.

Craig Venter's TED talk

If the excreta are hydrophobic, they can be removed continuously from the aqueous growing medium using mild centrifuges. This lets the algae live longer, so less time and effort goes into growing the protein structure of the cells. Further increases would be possible if photosynthesis relied not only chlorophyll but also
accessory pigments
sensitive to other wavelengths.

Al Fin

Venter is promising more than he is able to deliver in a timely fashion. Waiting for Venter would be a bad idea.

There is nothing wrong with reforming methane to hydrogen for fuel cells. Better to approach the ideal incrementally than to postpone the good and the do-able in favor of a mythical ideal.

CO2 hysteria is all the fashion, but it is making humans stupid.

Healthy Breaze

Fuel cells and batteries and biofuels, oh my!

I'm an algae fan, but am concerned that where most of the flue gas is produced (the NorthEast) will not be where the algae grows best (the SouthWest). Also, raise your hand if your power plant has 1,000 acres of land nearby available for growing algae.

My sense is algae is an opportunistic fuel production pathway, that mostly buys us time for 14 years while we replace the hydrocarbon-based transportation fleet with a mostly-electric fleet. Batteries with Silicon nanowires, solar cells with quantum dots, high-altitude wind power and the like should provide terrawatts of renewable energy over the next 15 years. That's my hope, anyway.


"CO2 hysteria is all the fashion, but it is making humans stupid."

Al, how you can deny the geophysical impact of a trace gas representing .038% of the Earth's atmosphere is hard to comprehend.


mithbustr, I suggest you take your "myth-busting" abilities elsewhere, as no-one here (including me) is that bored that we feel the need to rise to your sophomoric bait. There are plenty of other sites that can rectify your ignorance (or amplify it, your choice). A wise man once said most people only choose to hear the echoes of their own opinions, and he was right.

Rafael Seidl

@ HealthyBreeze -

don't forget King Coal has a lot of political clout and will do all he can to prevent renewable electricity from ever encroaching on his turf. Also, algae would let him earn money twice off each carbon atom he drags out of the ground.

Note that photosynthesis can only use a few percent of incident light intensity on a sunny day, so even diffuse ambient winter light in the Northeast will permit significant production volumes - provided only that the temperature inside the bioreactors is high enough.

If required, CO2 can be piped over significant distances, so the land used for the algae wouldn't need to be immediately adjacent to the power plants. Alternatively, you could increase surface area by going vertical (e.g. Valcent Vertigro). Insulate the pipelines and you can even use the CO2 to transport low-grade heat to the bioreactor farm at a remote location.

Finally, consider that electric vehicle technology is expensive. Even then, relative to ICEs, you have to sacrifice either performance or range, two features the average consumer has become very accustomed to.

Michael McMillan

50 watts? great. Can I get one for my laptop?


Nice job indeed and quite promising for clean electric generation. Not relying on Pt is definitely a big step but that doesn't solve all the problems of producing, storing and distributing the H2 which make H2 impractical for transportation any time soon.

But nice job indeed


Did anyone above read the introduction presentation? I'm not a fuel cell expert, but it mentions fuelling with methanol...


They have done work on Direct Methanol Fuel Cells. The slide set talks about the work done to reduce the need for expensive catalysts. CO and CO2 both poison that catalyst in PEM fuel cells and if you change the catalyst, you might just reduce the sensitivity.

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