BY MIKE STONE:
Israeli manufacturer GenCell has developed an ammonium storage and hydrogen fuel cell combination for off-grid power applications.
The system is aimed at providing off-grid power to isolated communities, public buildings and mobile telecommunication base stations, which has traditionally been supplied by polluting diesel gensets.
By 2020 a projected 400,000 base stations alone will be burning though USD$19bn of diesel, generating 45 million tonnes of carbon, every year.
One way to reduce the bill and its associated carbon footprint is with renewable energy plus battery storage. Another is fuel cells, topped up with renewable-generated hydrogen.
One major problem with the fuel cell route is the lack of cheap, easily-available hydrogen. To get around this, fuel-cell maker GenCell has built a system that can get hydrogen from a more readily available precursor, ammonia.
Ammonia is the second most commonly produced chemical on the planet, making it a potentially cheap and easy source of fuel-cell hydrogen.
In the GenCell system, ammonia fuel is stored in a tank at normal pressure and simply flows into a reformer unit. There it is cracked into a mixture of 75% hydrogen and 25% nitrogen, with a conversion efficiency of 70%.
The hydrogen is then fed into a GenCell A5 fuel cell that unit continues running, self-powered, around the clock, for as long as the ammonia lasts. Unconverted ammonia is cycled back into the reformer to reduce waste.
The process is initiated using power from a battery and takes around two hours to power up.
Cost-wise, GenCell calculates that a telco with 1,000 base stations would save anything between $28m and $230m over 10 years by switching from diesel gensets to the ammonia-hydrogen combination.
Savings for base stations
The wide spread in the company’s figures depends on where in the world these notional deployments take place.
The company sees base stations as a natural market for its offering, which includes maintenance, financing and refuelling with ammonia.
But any off-grid application currently served by diesel could benefit from GenCell’s technology, said the company. An A5 unit could keep a small rural school running at 5kW for a whole year on just one 12-tonne tank of ammonia.
Power demand is scalable, and the fuel cell can cater for peaks in demand by simply consuming more ammonia, GenCell said.
Having only one delivery of fuel a year compared, to the dozens that would be needed with a generator, would immediately save money, said GenCell CEO Rami Reshef, as would the lower price of ammonia vis-à-vis diesel.
How green is my fuel cell?
If the territory is prone to equipment theft, that threat would be reduced, and security costs lowered, too, Reshef said. Unlike gensets, fuel cells would only have scrap value for a thief.
As well as combusting carbon-free hydrogen gas, the unit avoids the spillages and leaks that cause diesel gensets to contaminate the ground where they are sited.
However, the savings and green credentials that GenCell claims for its ammonia and hydrogen hybrid could be subject to debate.
The current preferred method of ammonia manufacture is from natural gas, so fluctuations in the price of gas are reflected in the market cost of ammonia.
What’s more, the production of one tonne of ammonia emits almost three tonnes of carbon. The ammonia industry contributes to around 1% of all carbon emissions worldwide.
GenCell counters that the company is involved in the development of carbon-free ammonia production. And indeed, every major ammonia technology licensor is currently working towards the same goal.
Another potential criticism of GenCell’s approach is that its price advantage is dependent on the relative cost of diesel.
This tends to be lower in many developing countries, meaning the business case for GenCell’s systems may be shakier in areas where there is greater need for off-grid power supplies. The company’s response is twofold.
First, Reshef said, plenty of developed economies with reliable grids also have a need for off-grid power sources.
Even in the UK, according to Reshef, telecommunication base stations in remote locations are mostly served by diesel gensets. Second, diesel is being eased out in these developed economies.
The UK telecoms regulator has stipulated that diesel gensets need to be replaced without sacrificing coverage.
As a result, Reshef said GenCell had received plenty of interest from the UK’s largest phone company, BT, for the A5 fuel cell. This trend away from diesel is one which will spread to developing economies, too, Reshef hopes.
The A5 has attracted interest from around the globe, Reshef said. GenCell hopes to finalize its first orders soon.
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