In our previous post, we outlined some of the ways that the Hydrogen Fuel cell is slowly making its way into the transportation energy mix. It’s benefits seem manifold: Hydrogen Fuel Cells release only water vapor, and once generated, Hydrogen can be stored for long periods with minimal loss. It also can be supplied very quickly to a vehicle, and  provide more range per “fill up” than most current battery technologies.

Yet, why isn’t there a fuel cell in every car by now? More to the point, if Fuel Cells can be used to generate emissions free electric mobility, why aren’t we using the technology to generate cleaner grid power?

In the past, the public’s safety concerns about hydrogen as a power source, the Fuel Cell’s lack of technology maturity, and the cost of building out an enhanced fuel delivery and storage infrastructure, each kept Fuel Cells from moving mainstream.

One large barrier to entry for a Hydrogen Fuel Cell is the catalyst. Currently, most catalysts are made from Platinum, which is quite rare and therefore expensive ($50,000 per kilogram). Other than some long-term (and admittedly out of the box solutions such a mining platinum from a nearby Asteroid!) Hydrogen Fuel cells which require a platinum catalyst remain a very high cost solution.

Finding more sources of  platinum, or engineering it’s replacement, are options clearly worth pursuing, yet neither is a near term solution to the Hydrogen Fuel Cell affordability issue. Also, putting aside for the moment the expensive platinum catalyst, there still remain the issues of cost and sustainability as well as the concomitant hydrogen generation, transport and storage challenges.

NGK of Japan- 63% efficient fuel Cell

Solid Oxide Fuel Cell Stack

Which bring us to a possible more near term Fuel Cell technology, the “Solid Oxide Fuel Cell“.

Rather than use a proton exchange membrane and  hydrogen (which must be generated somehow) – A Solid Oxide fuel cell features an advanced ceramic electrolyte to process fuel and  generate electricity.

One clear benefit of Solid Oxide Fuel cells (SOFC’s) is that they can generate power from existing hydrocarbon fuels.  Such a Ceramic based SOFC fuel cell is quite hydrocarbon friendly; meaning diesel, gasoline, and natural gas/methane fuels are each candidate sources of hydrocarbons for Solid Oxide.

Using Hydrocarbons directly, without reforming,  does not come without penalty. The process of conversion does create emissions, as well as generate copious amounts of heat- up to 800 Degrees Celsius!

Extremely high operating temperatures for Solid Oxide might be acceptable in a fixed location, where the excess heat can be easily vented, managed or used for a “combined heat and power” application, but the temperature is certainly not appropriate for a cramped, mobile platform such as an engine bay.

Bloom Energy is currently the most well known in the nascent industry of Solid Oxide Fuel Cell power. Bloom has found a profitable niche by creating so called “energy servers” which offer cloud based information companies an extremely reliable source of power.  Bloom gets it’s hydrocarbons from an easily understood source: the natural gas pipeline. Such a solution offers flexibility, and in some locales, generating power from natural gas in this manner is cheaper than buying it from the grid. Also, in future, given the near 900 degree c operating temperature, their Fuel Cell technology has many possibilities for reuse of waste heat. For those that would like to dig a bit deeper,  Bloom hosts a clever animation, which clearly illustrates its process.

Bloom Energy Servers

Recently, Apple Computer has signed an agreement with Bloom Energy for provision of  its Fuel Cell “energy servers” to partially power it’s North Carolina Data Center. This large cloud services data center is engineered to be highly sustainable. It features a white reflective roof, a solar panel farm, and Bloom energy servers powered by Methane Gas piped in from a nearby landfill.  By using methane gas in this manner, rather than wasting it by flaring, the environment scores a double win, as atmospheric  methane is a powerful contributor to climate change. In the bargain,  Apple gets a very reliable power source in order to send us all those movies, tunes, and apps.

So is that all? Solid Oxide- great for buildings, but too hot for the road?

Recent innovations have reduced the operating temperatures to 650 degrees c. Such applications include use as a Class 8 truck’s Auxiliary power unit.  This is a great start, as big rig trucks will no longer have to run their diesel engines all night long. In the past, the big diesel engines were left on  to provide so called “hotel power” – This power kept the driver’s cab cool in summer, warm in winter, and provided some measure of  electricity. The Solid Oxide Fuel Cell can now handle this function, and do it more quietly, while also significantly reducing fuel use.

Auxiliary Power Unit- Class 8 Truck

As promising as this development is, the Delphi technology is not quite suitable for primary motive power, as it’s high operating temperature requires a long start up/warm up time, and at it’s current size is not quite capable of generating the Horsepower/Torque needed for a big rig.

Perhaps then, there is room for another entrant:

Quite recently,  a team from the University of Maryland headed by Dr Eric Waschman, has proven that a lower temperature Solid Oxide Fuel Cell is possible. He and his team have managed to get the operating  temperature down to 350 degrees c.  Given it’s significantly lower operating temperature, such a fuel cell could be made using less exotic materials. Additionally, in a real world transport application, the technology would need little to no warm up time, and would require much less insulation and a smaller heat mitigation apparatus. Such a device could potentially fit in the engine bay as small that of a conventional automobile,  which can mean much wider acceptance in transportation :

The cell uses a bi-layer electrolyte developed by Wachsman that is more than 100 times more conductive than the conventional zirconia-based electrolyte operating at the same temperature. When the cells are assembled into a stack they should produce three kilowatts of electricity per kilogram of material – making it as efficient as an internal combustion engine at approximately one-third of its size

To recap-

A low emission fuel cell can generate electricity on the fly for efficient electrical motive power. Such a fuel cell can be powered by either hydrogen, or by today’s existing fuel infrastructure. Indeed, such a fuel cell can be powered by methane/methanol, which can come from waste landfill gas. Such a fuel cell can also be powered by Natural Gas (made up of methane, ethane, butane, propane) which the United States now seems to have in abundance.

Eventually, as we bring down the cost of hydrogen production, transport and storage, and as improvements are made in Solid Oxide chemistry and engineering, Fuel Cells will become more mainstream. It’s clear that in the very near future, practical Fuel Cell technologies can play a significant part in reducing our carbon emissions while increasing our energy security.