The recent Marine Technology Notes column on fuel cells for boats (Are fuel cells poised to become a serious option for voyagers? Issue 127, Jan./Feb. 2003) provided an interesting look at fuel cells. It will be interesting to see how fuel-cell technology matures over the next few years.
However, there are certain facts of life that the reader needs to be aware of, and these facts are perhaps not sufficiently clear in the article. The issue concerns limitations on the technology imposed by thermodynamics. Fuel cells are terrific in space capsules and similar applications, where the hydrogen is pre-loaded in tanks. A boat floating on the sea is, in fact, on a vast ocean of fuel, as the article points out. However, breaking down the water to hydrogen and oxygen will consume more energy than that recovered by the fuel cell, no matter what technology is contained in the cells. If this were not so, we would have a perpetual-motion machine. While the article mentions the impossibility of such machines, it does not go on to say that more energy will be consumed than produced in the overall process. Clever engineering can improve the efficiency of the process, but it will always be a net loss. A further prediction of thermodynamics is that if it were possible to generate the hydrogen from seawater by consuming less energy than that produced in the fuel cell, then there would be some spontaneous natural process that would break down seawater, and the oceans would dry up, making sailing less fun.
On my admittedly low-tech sailboat, there are three sources of energy available: solar power (which includes wind power, which is simply solar power in another guise), muscle power, and my trusty Westerbeke that consumes diesel fuel. That’s it. If I install a fuel cell, I will need to either utilize solar power, eat a lot of Wheaties or burn diesel fuel in order to produce my hydrogen, and the energy produced by the fuel cell will be less than it took to produce the hydrogen, so I start with a net deficit. Any additional energy required to turn electric motors, run electronics, etc. will also have to be ultimately provided by one of these sources. The bright spot in all this is that it may be possible to produce hydrogen under favorable circumstances and store it for later use, or alternatively to generate electricity in the fuel cell and store that for later use in battery banks. But those batteries are also less than 100 percent efficient.
It is worth noting that numerous other efforts are underway to explore the practical side of a hydrogen economy — e.g., using geothermal heat in Iceland to produce hydrogen. Other ways of producing hydrogen — e.g., passing steam over coal — may also have possibilities, but one of their by-products is large amounts of carbon dioxide. All of these processes are governed (and limited) by the laws of thermodynamics.
Mark Van Baalen sails a Hinckley Pilot 35 and teaches geology at Harvard.
To the editor:
The recent column on fuel cells was interesting but raised some questions.
The only energy coming into the cycle described comes from wind and sun. All the ways of getting it are available to cruisers now. Solar cells, wind turbines and propeller generation can charge storage batteries. If they are used to separate hydrogen, the hydrogen separation becomes part of the energy-using side of the process. It has an efficiency less than 100 percent, like every other stage.
If hydrogen were available, an internal combustion engine could burn it, just as natural-gas buses do today. And they would only emit water vapor. In this context, the fuel cell’s requirement for really clean hydrogen is an impediment, not a virtue. Its principal virtue is lack of noise and vibration, which everyone would appreciate. But it is not a source of energy otherwise unavailable.
Rodney Myrvaagnes lives in New York and sails a J/36.
Craig Schmitman of HaveBlue responds:
Mark Van Baalen accurately points out that more energy will be consumed than produced in the HaveBlue process. As Tim Queeney can attest, we unequivocally acknowledge that there are losses at each step.
The same critique can be applied to the petrochemical industrial process. The diesel fuel for Mr. Van Baalen’s trusty Westerbeke must first be pumped from the ground as crude oil (using energy), then shipped (using energy), then stored (using energy), then refined (using energy), stored, and finally delivered to the consumer with energy (as well as economic) losses all along the way.
Most engineers agree that it is more efficient to convert stored hydrogen via a fuel cell into the energy necessary to power an electric drive (and the propeller) than it is to burn diesel or gasoline to power an engine, which in turn sends power to a propeller via a transmission. Obviously, whenever the propulsion system is operating, you are expending more energy than you can make and store, and thus the hydrogen tank level goes down. The HaveBlue system is predicated upon capturing energy from the wind and sun (or taking it from shore power), converting that energy to the most useful storable form (hydrogen), storing that hydrogen, and efficiently using that fuel when needed. On HaveBlue systems, the fuel cell does not power the electrolyzer. Rodney Myrvaagnes should be pleased to know that HaveBlue technology can be applied to hydrogen-consuming internal combustion engines as a cost-effective alternative to fuel cells.
For the record, HaveBlue does not consider water to be a fuel. It is one feedstock (electricity being the other) required for the production of hydrogen via electrolysis.
Craig Schmitman is president of HaveBlue in Oxnard, Calif.
