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Energy Solutions

Bloom Box Rekindles Excitement About Fuel Cells

A new fuel cell from a well-financed California start-up is attracting a lot of attention

Image 1 of 3
These Bloom Energy Servers at the eBay headquarters provide 15% of the facility's power.
Image Credit: Bloom Energy
These Bloom Energy Servers at the eBay headquarters provide 15% of the facility's power.
Image Credit: Bloom Energy
Bloom Energy CEO K.R. Sridhar holding coated ceramic wafers, which are stacked with thin layers of a metal alloy to form the solid oxide fuel cell.
Image Credit: Jonathan Sprague photo
A 100 kW Bloom Energy Energy Server (Bloom Box) being installed.
Image Credit: Bloom Energy

The high-profile roll-out of the highly secretive Bloom Box fuel cell, on CBS’s 60 Minutes in February, ushered in a new round of excitement about fuel cells.

Fuel cells have been around for over 50 years. They are, in essence, chemical batteries that churn out electricity as long as a fuel, such as hydrogen or natural gas, is fed in at the other end. They have been a mainstay of power generation in NASA’s space program for decades and have slowly been making inroads for more earthly applications.

While President George W. Bush and many others have touted hydrogen fuel cells as the “energy source of the future,” a fuel cell is not an energy source at all, but rather a device that converts a fuel into electrical energy–and it does so quite efficiently and cleanly.

One of the problems with most fuel cells is that they require pure hydrogen for their operation, and hydrogen is a difficult material to store and transport. Being our lightest element, hydrogen has to be compressed to achieve a reasonable power density, so you’re usually dealing with very high pressures in storing it. Compressed hydrogen is explosive and can be quite dangerous.

What Bloom Energy has created with its Bloom Box, according to CEO K.R. Sridhar, Ph.D., is a novel fuel cell that doesn’t rely on rare-earth elements, such as platinum (as do most other fuel cells) and does not require pure hydrogen for its operation. The company makes thin ceramic wafers out of quartz sand, coats the wafers on both sides with special proprietary materials, and stacks these with layers of an affordable metal alloy between. A four-inch stack of these layered cells and metal will generate one kilowatt (kW) of power when a hydrogen-rich fuel, such as natural gas, and oxygen are forced through it. Sridhar claimed on 60 Minutes that two of these stacks could power a typical American home, while a single stack could power four homes in his native India.

Dr. Sridhar is a physicist who previously led NASA’s efforts to develop a system to generate oxygen for a mission to Mars. When that project was eliminated, he kept working on his invention, but reversed the process to create a “solid-oxide” fuel cell. In this process, oxygen is used rather than produced and electricity is generated. His work has been financed, starting in 2002, by about $400 million, most prominently from the venture capital firm Kleiner, Perkins, Caufield & Byers (famous for recognizing the potential of–and funding–such Silicon Valley success stories as Netscape, Amazon, and Google). Until February, though, the Bloom Energy’s technology was shrouded in secrecy. The February 21 edition of 60 Minutes removed that veil of secrecy with great fanfare.

The first commercial Bloom Boxes were installed at a Google facility in late 2008, and test installations have now been completed for WalMart, eBay, FedEx, Staples, and more than a dozen other companies. Most of these fuel cells are powered by natural gas, though the units at eBay’s headquarters–enough to provide 15% of the power needs–use landfill gas (a mix of methane, carbon dioxide, and other gases). These 100 kW units cost $750,000, or 7,500/kW of capacity, which is not a bargain in today’s distributed-generation market–but costs are expected to drop as production scales up. We’ll see how that goes.

According to an article in Greentech Media, The Bloom Box is 56% efficient, which is far higher than most natural gas generators, but waste heat is not captured, as it is from some competing fuel cells–a number of which have been around for years.

The Bloom Box isn’t the only “second-generation” fuel cell to come along recently (though it is certainly the most prominent). The Freemont, California company Oorja Protonics, makes methanol fuel cells that are initially being sold as power supplies for electric forklifts. Their OorjaPak Model III holds five gallons of liquid methanol (a type of alcohol) that will power a small forklift for two 8-hour shifts and can be refueled in about a minute–while standard electric forklifts can take up to four hours to recharge batteries.

Some of these other fuel cell manufacturers are actively pursuing the combined heat and power (CHP) market, in which both electricity and useful heat are being delivered. While the Oorja fuel cell is only 35-37% efficient, according to Greentech Media, by capturing the waste heat, overall efficiency can be boosted to 70-75%. Panasonic and ClearEdge Power offer residential-scale CHP fuel cells with overall efficiencies of 80% and nearly 90%, respectively, according to the same article.

I am excited about fuel cells as energy conversion systems that cleanly and efficiently produce electricity (and often heat) from an energy input, such as natural gas. We need to remember, though, that these are not renewable energy systems–since they have to have a fuel source–and they are not likely to revolutionize our power generation infrastructure quickly. But if they can generate electricity from natural gas and other hydrogen-rich fuels more affordably and more efficiently than other generation sources, they can be an important part of the many-faceted energy future we need.

I invite you to share comments on this blog. Are fuel cells going to be the next great thing to come along?

— Alex Wilson is the executive editor of Environmental Building News and founder of BuildingGreen, LLC. To keep up with his latest articles and musings, you can sign up for his Twitter feeds.


  1. Jan Juran | | #1

    A Possible Renewables Complement
    Hi Alex: you are correct to highlight the high cost of this new invention: $7.50/watt capital cost exceeds the cost of complete PV systems, and the latter use free sunshine rather than natural gas for fuel. However a (much cheaper) future-edition Bloom Box could provide possible back up for intermittent wind power, thereby facilitating what is already a low cost renewable electricity source in plenty of appropriately windy North American sites. Capturing the waste heat for district hot water or district heating could approximately double the efficiency of a Bloom Box. A distributed electricity source also may avoid the approximate ten cents per kilowatt-hour grid distribution cost to a home or neighborhood, regulatory hurdles notwithstanding. A Bloom Box can generate electricity when electricity prices are very high during peak times of day and season. Distributed electricity sources are inherently scalable and blackout and terrorist resistant. Dr. Sridhar, we are cheering from the sidelines as you pursue manufacturing learning curve (hopefully a steeply downward sloped curve) efficiencies to significantly lower the cost of a Bloom Box.

  2. User avater GBA Editor
    Martin Holladay | | #2

    $7,500 per kW of capacity
    The standard backup source of power (burning fossil fuel) for off-grid homeowners or construction crews is the 5-kW Honda generator, which currently costs $420 per kW of capacity. So this fuel cell costs 18 times more. The Honda burns gasoline, but is easily converted to burn propane or natural gas -- just like the fuel cell.

  3. User avater
    James Morgan | | #3

    Breaking News ...
    Still no free lunch.

  4. User avater
    Alex Wilson | | #4

    On the cost of fuel cells
    But what's the efficiency of that Honda generator? My guess is that it's about half that of the Bloom Box. And how much pollution does the Honda emit? The high cost of this fuel cell is clearly an issue today, but it's not unusual for early versions of a new technology to be quite expensive and later iterations to bring the cost down considerably. if the cost can be reduced significantly--and if reliability is demonstrated (long a problem with solid-oxide fuel cells)--then the Bloom Box and its cousins could represent a significant advance. I'm excited about that possibility, though I'm not sure I'd give that 50% odds. If we always opposed new technology because it was too expensive (remember the early CFLs and PV modules in the 1980s?), we wouldn't make very many advances.

  5. User avater GBA Editor
    Martin Holladay | | #5

    PV costs in the 1980s
    Since the 1980s, the cost of PVs has dropped by a factor of 2 or 3 -- not 18.

    You may be right in the very long run, but count me a skeptic. I have heard a physicist give a very convincing presentation on why the economics of hydrogen will never beat the economics of other fuels, including PVs plus batteries (which have their own significant problems).

    Hydrogen is a pipe dream and a distraction from the important work we face.

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