Orbit City, the Jetsons’ hometown, gets all its power from renewable energy. When the wind blows and the sun shines, it makes the electricity that keeps the city humming. But what happens at night, or when the air is still?
When the sun and wind provide more power than needed, the excess is used to electrolyze water into hydrogen and oxygen, with no carbon emissions. When sun and wind power are insufficient, stored hydrogen feeds into fuel cells whose only output is power and water vapor. While this may sound like science fiction, all the components needed to make it happen have been around for decades.
So what are fuel cells?
Several types exist, using various electrochemical reactions to make power without combustion, fission, or turbines. Find a good comparison table at http://energy.gov/eere/fuelcells/comparison-fuel-cell-technologies. Initially used in spacecraft, the technology has gradually come down to earth to run cars, buildings, and remote sites off the grid. However, like many new energy technologies, the ride has often been bumpy. In the last decade, some fuel cell firms have gone under or performed poorly, disappointing both stockholders and advocates.
Adoption of the technology has also been much slower than renewables. According to FuelCells2000, a non-profit promoter of this technology, over 170 Megawatts (MW) of fuel cells are running in the U.S., many at customer sites (e.g., 35 Walmart stores have fuel cells). However, by comparison, California has over 2,000 MW of rooftop solar photovoltaic (PV).
At present, nearly all commercial fuel cells consume natural gas to make power by first “reforming” it into hydrogen and carbon dioxide. While still venting some carbon, other fuel cell emissions (e.g., the nitrous and sulfur oxides that cause acid rain and other problems), are extremely low. Unlike the combustion-based power plants that produce such emissions, fuel cells do not need the scrubbers, smokestacks, sound attenuation, vibration isolation, and other support systems common to them.
Building operators and owners have asked if a fuel cell may be profitable for them. Depending on a variety of specific issues, the answer is a qualified “maybe”.
Cells are also more efficient (40-60% of gas’s energy is converted into kilowatt-hours) than other on-site power sources. Even higher overall efficiency is possible when a cell’s waste heat is utilized in a Combined Heat and Power (CHP) system. But, as Jesse Hayes, the product manager for Doosan Fuel Cells points out, sometimes the extra installation cost to make that heat useful outweighs the extra dollar savings. See the comparison table mentioned earlier for the waste heat temperatures produced by each technology. Hayes also stated that, unlike many other types of CHP technologies, fuel cells have excellent turndown ratios, meaning they run quite efficiently across the variable loads common in buildings. He also touted cells’ fast startup during an outage, 10 seconds, which rivals the startup time of diesel.
Where power quality and reliability outweigh dollar savings, fuel cells may be ideal: banks, military and research facilities, and data centers have installed many of them. Where significant rebates or financial incentives are available (e.g., California, New York, New Jersey), other types of facilities have seen acceptable paybacks.
So why are fuel cells not taking off like solar PV, which takes up much more space and only works when the sun shines? Hayes attributes much of the difference to successful lobbying by the solar industry as it secured many financial perks like net metering, rebates, and renewable portfolio standards that are not presently available for fuel cells.
To make the case for fuel cells at your site, start by determining what financial benefits, aside from energy cost reduction, may be available. Federal tax credits are generous, some states and utilities offer rebates and tax abatements, and other vendors have offered novel financing methods including one company that offers a discount when also buying stock in the fuel cell vendor. In states such as New York, fuel cells are considered renewable resources and provide the same favorable public recognition as wind and solar.
Do not forget about a cell’s capability in an outage. Unlike solar PV systems which automatically shut off when utility power is unavailable, fuel cells can quickly “island” themselves to provide nearly instant backup power at any time of the day. All of this makes them excellent candidates for integration into microgrids. Hayes refers to this as “the point where sustainability and resiliency meet.”
A good source for unbiased fuel cell data and links is the home of FuelCells2000, www.fuelcells.org.