In a not too distant future, sleek, quiet ferries will speed across the waters of San Francisco Bay powered by hydrogen fuel cells. In this future, the black smoke and the rumbling vibration of diesel powered ferries have been relegated to quaint memories of the past, the same way we now view steam ships or paddle wheeled boats. The ‘California energy crisis’ will have faded from view as a distant episode of the ‘hydrocarbon age.’ As passengers traverse the white caps, some will work on laptop computers while others talk on cell phones or contemplate a weekend trip in their new car; all powered by fuel cells. Homes of the future will incorporate hydrogen fuel cell technology to generate their own power. The day may come when no one pays utility bills!
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A Proton Exchange Membrane type fuel cell (PEM). The plates with grooves channel hydrogen and oxygen on either side of the membrane. Hydrogen and oxygen circulate and are exposed to the surface of the PEM. In the exchanges of gases, protons pass through the membrane while electrons are captured by the nickel screen and conducted to an external circuit to perform work. Used by permission of Home Power Magazine Oct.-Nov. 2001
By Byron Anderson
Published: November, 2001
In a not too distant future, sleek, quiet ferries will speed across the waters of San Francisco Bay powered by hydrogen fuel cells. In this future, the black smoke and the rumbling vibration of diesel powered ferries have been relegated to quaint memories of the past, the same way we now view steam ships or paddle wheeled boats. The ‘California energy crisis’ will have faded from view as a distant episode of the ‘hydrocarbon age.’ As passengers traverse the white caps, some will work on laptop computers while others talk on cell phones or contemplate a weekend trip in their new car; all powered by fuel cells. Homes of the future will incorporate hydrogen fuel cell technology to generate their own power. The day may come when no one pays utility bills!
Does that seem too visionary a picture? Actually, all the elements needed to make this picture a reality are in development right now. The technology, though moving rapidly, seemingly remains low on the radar screen for the general public. For instance, readers of Bay Crossings may be surprised to know that fuel cell powered water transit has already been demonstrated on San Francisco Bay.
On October 2nd 2001, an otherwise conventional 14’ runabout equipped with a prototype fuel cell gently ‘ferried’ members of the press and the Water Transit Authority around China Basin for a day of excursions and animated technology discussions. The product used to power the boat was an EnableTM hydrogen PEM fuel cell capable of generating 1 kW continuously with peak power of nearly 2kW. This demonstration was hosted by DCH Technology, Inc. of Valencia California, a company known for its hydrogen sensing equipment. Arron Rachlin, company spokesman, explained that the event was one of several demonstrations DCH was engaged in through a grant from the California Air Resources Board. The state is in fact promoting a host of energy related studies and demonstration projects that involve hydrogen and fuel cell technology.
Today companies like Ballard are developing the latest generation of fuel cell engines for buses and cars while Fuel Cell Energy, Inc. and others put finishing touches on fuel cell based stationary power systems. Even Coleman, Inc. venerable makers of camping equipment, plans to produce a portable fuel cell within a year.
Fuel Cell Origins
Despite their modern high-tech aura, fuel cells actually have been known to science for more than 100 years. Though generally considered a curiosity in the 1800s, fuel cells have become the subject of intense research and development, especially since World War II.
In 1839, William Grove demonstrated the world’s first ‘fuel cell’ (or ‘gas battery’ as he called it) at the Royal Institution in London. Grove, a friend of Michael Faraday, had been experimenting with electrolysis, the process of putting an electrical current through a fluid, in this case sulfuric acid. What surprised him was that when he disconnected the apparatus it seemed to work backwards and he observed that he was now generating a small voltage. Unfortunately the materials that Grove used were unstable and public interest dwindled. It wasn’t until the 1960’s that fuel cells were revived for use on manned space flights. NASA developed fuel cells as the ideal supply of both power and drinking water.
Fuel Cells for the Uninitiated
For those not up to speed on what fuel cells are or why they are the ‘darling technology’ of choice for our transportation-energy future, let’s briefly examine how they work; the benefits they will bestow and some of the technology hurdles that must be overcome.
"I believe that water will one day be employed as a fuel, that hydrogen and oxygen will constitute it, used singly or together will furnish an inexhaustible source of heat and light of much greater power than coal possesses. Bunkers, ships and locomotive tenders will store these two condensed gases instead of coal, and they will burn in the boilers producing enormous heat…." Jules Verne, ‘Mysterious Island’ - 1870
Everyone is familiar with batteries, every car has one. A car battery has several cells that store an electrical charge. Combined they deliver 12 volts of direct current (DC). The difference between a battery and a fuel cell is that whereas batteries store electricity, a fuel cell generates electricity. Electricity from a fuel cell is generated by the electro-chemical reaction taking place between two gases, hydrogen and oxygen. The key to understanding the source of energy generated in a fuel cell is that the hydrogen - oxygen reaction can be ‘intercepted’ to capture small amounts of electricity. The byproduct of this reaction is the formation of water (H2O).
Application to Marine Vessels
At a recent board meeting of the Water Transit Authority, Bob Beadell, Business Development Manager of Zemar Ltd. explained the plans his company has for developing marine fuel cells. "Our focus for marine applications is currently on what we call "captive fleets". These are vessels which have a defined duty cycle which brings them back to their home port or berth at the end of each day, this includes such things as small ferries and water taxis. The reason for this is to allow them to refuel daily or as needed. As technology develops to allow greater volumes of fuel to be stored, without a weight or space penalty, then we shall begin to shift our focus to include offshore marine applications."
In speaking of the near term future of the technology Beadell said, "Most of these (fuel cells) are currently very expensive but all of the manufacturers expect costs to fall rapidly once they are mass produced….we expect even greater cost reductions due to the elimination of expensive catalysts and improvements in power density. This, taken into consideration with greatly reduced maintenance costs, will make Alkaline fuel cells very competitive with diesel or gas engines." Zemar intends to return to the Bay Area early next year to demonstrate its alkaline fuel cell technology in a marine application.
As Renewable as Rain
One great appeal of fuel cells, as mentioned, is that they generate electricity with no pollution and few if any moving parts. The hydrogen and oxygen used in generating electricity through this method ultimately combine to form water as a byproduct. Since fuel cells use hydrogen, one line of reasoning taken by economists and technologists envisions our whole economy based on hydrogen. This scenario, in which hydrogen is as renewable as rain, has been referred to as the "hydrogen economy." A stable energy cost is a must for economic productivity. A decrease in the cost of energy will have a marked positive effect on the economy just as every Californian knows firsthand what the reverse brings.
Technology and Infrastructure Challenges
There are several technological hurdles that must be overcome. Materials are expensive right now. Platinum is used in fuel cells as a catalyst but there are many promising materials that are less expensive being looked at. Hydrogen storage has also been a historical problem because of low density of the gas.
Robert Hayden of the California Fuel Cell Partnership in West Sacramento recently wrote, "The technological development of fuel cells as electricity generators for transportation and stationary sources is complex. Equally daunting is the matter of fueling. Where are we going to get the hydrogen needed to power fuel cells? How are we going to put the infrastructure in place that will make it as convenient and safe for consumers to get hydrogen as it is today to get gasoline and other fuels?"
From the standpoint of availability, the good news is that hydrogen is relatively easy to obtain from a number of sources and processes. Fossil fuel resellers need not fear because there are many R & D efforts underway to find the best ways to reform gasoline, natural gas, diesel and even coal.
The purest ideal though, is to derive hydrogen from only renewable resources. The electrolysis of water by use of renewable energy such as solar or wind is the model most often mentioned. There is nothing to prevent such a plan from being put in place except the will to do so.
Fortunately, for us, the state of California is very interested in encouraging the development of alternative energy including fuel cells. "Widespread use of fuel cells in water craft would certainly help California’s efforts to reduce air pollution," said Dr. Alan Lloyd, Chairman of the California Air Resources Board in a recent press statement. The state department of energy has just recently announced a Request for Proposal (RFP) to study the whole issue of developing a hydrogen-refueling infrastructure for fuel cell vehicles and vessels. The study will run two years and will be published in a series of reports. The recommendations of the final report may very well facilitate the future mentioned at the top of the article.
Byron Anderson is an Advanced Transportation Technology Project Coordinator at City College of San Francisco. He has written articles for "Hydrogen Today", "Advanced Transportation Technology" and is webmaster and ‘AnswerGuy’ for www.clean-air.org. On the weekends he teaches a course on electric vehicles and hydrogen fuel cells at Sacramento City College.For more information, including details about different types of fuel cells, see www.baycrossings.com.
Types of Fuel Cells
Since the revival of interest in fuel cells several different types have been developed. Each type has operating characteristics and temperatures that are suitable for certain applications but not for others.
Proton Exchange Membrane (PEM) fuel cells work with a polymer in the form of a thin, permeable sheet coated with a TeflonTM like material. The solid, flexible membrane will not leak or crack, and these cells operate at a low enough temperature to make them suitable for boats, cars and homes. But their fuels must be purified, and a platinum catalyst is used on both sides of the membrane, raising costs.
Alkali fuel cells operate on compressed hydrogen and oxygen. They generally use a solution of potassium hydroxide as their electrolyte. Alkali cells were used in Apollo spacecraft to provide both electricity and drinking water. They require pure hydrogen fuel, however, and their platinum electrode catalysts are expensive. And like any container filled with liquid, they can leak.
Molten Carbonate fuel cells (MCFC) use high-temperature compounds of salt carbonate of sodium or magnesium... Their nickel electrode-catalysts are inexpensive compared to the platinum used in other cells. But the high temperature also limits the materials and safe uses of MCFCs—they would probably be too hot for home use.
Phosphoric Acid fuel cells (PAFC) use phosphoric acid as the electrolyte.. PAFCs tolerate a carbon monoxide (a poison for other fuel cells) in concentrations of about 1.5 percent, which broadens the choice of fuels they can use. Platinum electrode-catalysts are needed, and internal parts must be able to withstand the corrosive acid.
Solid Oxide fuel cells (SOFC) use a hard, ceramic compound of metal oxides of calcium or zirconium as electrolyte. At such high temperatures a fuel reformer is not required to extract hydrogen from the fuel, and waste heat can be recycled to make additional electricity. However, the high temperature limits applications of SOFC units and they tend to be rather large.
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A fuel cell stack made up of two cells using the same components. In practice, many fuel cells are assembled into a ‘stack’ of cells (think of the several cells in your battery) which can be added upon to attain the required current. Used by permission of Home Power Magazine Oct.-Nov. 2001 In these two Figures we are looking at a Proton Exchange type fuel cell (PEM). There are however, different kinds of fuel cells.