Building energy out of sand

But such was the razzmatazz that accompanied the unveiling of Bloom Energy’s eagerly awaited “energy server” on Wednesday at the California headquarters of one if its first customers, eBay.

A mini power station containing fuel cells that can run on anything from natural gas to the more renewable stuff, Bloom’s device,  invented by ex-Nasa scientist K R Sridhar, has received the level of hype in Silicon Valley normally reserved for a new product from Apple.

Fuel cells, which convert hydrogen and oxygen into electricity by an electrochemical process, are a promising source of energy while emitting less CO2 and other pollutants, as well as being much more efficient, than burning. But most modern designs use expensive materials, such as platinum, or corrosive chemicals that shorten their lifespan.
At the heart of Sridhar’s device is a thin fuel cell made from a plentiful resource, sand. The size of a floppy disk, it is painted with proprietary inks that allow the fuels to react with oxygen from the air, a chemical process that produces electricity.

According to Sridhar, a single cell can produce about 25W, enough for a low-energy lightbulb, and a stack of cells the size of a brick will power an average home. A single Bloom box, a unit the size of a chest freezer and which contains several stacks of fuel cells, will produce 100KW, enough for 100 homes.

“Compared to the US national grid, this is about twice as efficient,” said Sridhar. “So your carbon footprint is about half. If you use a renewable fuel, you’re carbon neutral.” Sridhar has spent eight years developing the fuel cells and has already sold the first units: the first customer was Google, which uses a Bloom box at its headquarters.

“Bloom fuel cells are powering a portion of Google’s energy needs at our headquarters here in Mountain View — this is another on-site renewable energy source that we’re exploring to help power our facilities,” said   Jamie Yood, a Google             spokesman.
Other customers include Walmart, Federal Express and Coca Cola. The former US secretary of state, Colin Powell, sits on the board and Bloom has received $400 m from venture capitalists.

But not everyone has been converted. Keith Pullen, co-director of the centre for energy and the environment at City University in London, said: “Although Bloom Energy cites four advantages over existing technology—low material costs, high efficiency, multiple fuel sources and reversibility—these are attributes that all fuel cell developers seek to achieve. So, whether the technology is worthy of the hype will depend on further data emerging through future testing and deployments.”

Martin McAdam of renewable energy company Aquamarine Power was more sceptical. He said living off-grid with the Bloom Box would still require an infrastructure to move the fuels around. “It still produces CO2 — it may be more efficient but that’s the question that needs to be asked, how much CO2 is emitted per MWh? If it’s using natural gas, it’s no different to a gas power station, even if it is more efficient.”

So far, the Bloom Boxes cost around $700,000 but this is expected to fall as more of the units are built at commercial scale. Sridhar says he already has plans for the future boxes in the home.