In a binge of hype that might make Dean Kamen blush, the world has been introduced to Bloom Energy, a new entrant to the fuel cell business that claims to be ready to revolutionize the energy economy. Plug a Bloom Box in to your building's natural gas line, the company claims, and you can start getting clean power at a price that beats the grid. Unfortunately, for the moment, that's about all it's saying.

Which is unfortunate, since the details are critical. Fuel cells are well understood technology, and already in use in some commercial deployments. There's a lot to like about fuel cells, as they're quite efficient and, when fueled with hydrogen, produce water as the only byproduct. Fuel cells haven't already swept the electricity market, however, for one simple reason: the hardware is ferociously expensive.

Ars contributor Adam Stevenson is familiar with the materials used in solid-oxide fuel cells (SOFCs), and he described some of the challenges to putting them together. SOFCs work by ionizing reactants at two electrodes. Ions then flow across the cell, while electrons travel around it, enabling a fuel cell to put them to use in the form of electric currents.

Reactions take place at a cathode and anode, which transfer electrons between reactants, typically hydrogen and oxygen. Oxygen ions then diffuse across the system, where they're paired with the hydrogen ions, forming water; the electrons create a standard electric current (We've got a diagram of the process in this article). Typically, this process operates at temperatures of hundreds of degrees celsius.

Nearly every aspect of putting something like this together is problematic. The catalysts usually involve the use of precious metals, like platinum, which significantly boosts the costs. The entire apparatus is put together with materials that have radically different properties, but have to form complete seals, and maintain that seal over a very large temperature range. None of that is easy to accomplish, and the results often have a relatively short lifetime in the field.

Adding to the complications, you generally can't simply dump natural gas and air on the appropriate electrodes and expect things to work. Purity of one or both of the reactants can be critical and, if methane is involved, the "front end" of the system tends to be more complex, as some reactions take place outside the fuel cell proper in order to liberate hydrogen. Most companies with hardware on the market have not disclosed the details of these preparatory steps.

Bloom Energy has revealed that it has developed new materials for use in the electrodes, and that its engineers think that it can bring production costs of the units down significantly below anything else on the market. This implies that its electrodes have ditched the requirement for precious metals, and may be able to use less pure input materials, or directly react methane at the anode. Bloom is also talking about an expected lifetime that significantly exceeds that of existing hardware, which will also lower costs. Without any details, however, it's impossible to judge whether any of this is accurate.

Some of the other claims being made, however, are clearly hype. Bloom has suggested that the box can be emissions-free, but that's only if you supply it with hydrogen. Feed it natural gas, and there is no way to avoid producing CO 2 , barring the use of a carbon-neutral source of methane, such as landfill gas. In fact, Bloom has also been proud to claim that the hardware produces fewer greenhouse gasses than burning coal. Given that coal is the absolute worst energy source in this regard, that's no surprise; the "lower emissions" claim is true for simply burning methane, as well.

Bloom has also suggested that their fuel cell can run in reverse—plug it into some solar panels, and you can produce fuel to store. But Stevenson said that, while this is technically true for most fuel cells, the performance is generally very poor, and can damage most cathode materials.

Then there's the pricing issue. Wired Science's Alexis Madrigal noted that the hardware costs are currently over $700,000, and a fuel cell researcher told him that this was "an order of magnitude higher than it needs to be, to be truly competitive." Bloom promises that the price will come down but, again, there's no way to evaluate that claim.

Right now, however, the units do appear to be delivering savings to the companies that have installed test versions. That's because a number of states have programs to encourage the use of fuel cells and non-polluting technology. These offset the cost of the hardware significantly, and can drop the costs of running a Bloom Box below the the price for grid power. Whether those subsidies will remain in place if the focus shifts from general pollution to carbon neutrality is anybody's guess.

Although it's not really possible to figure out whether all of Bloom's claims live up to its hype, the company appears to be setting itself a very high bar. Fuel cells are really difficult to do both well and cheaply, and there are a lot of very smart people—in industry, government labs, and academia—who are working on this problem. It's possible that Bloom has managed to make a breakthrough that will leapfrog it past all of them. Possible, but not exactly probable.