Hydrogen fuel cell vehicle technologies have surpassed important performance targets, according to the findings of a seven-year study just released by the U.S. Department of Energy's National Renewable Energy Laboratory (NREL). Out of several car makers and energy companies that worked together in teams in the study, one achieved a 254-mile driving range for fuel-cell electric vehicles (FCEVs), and one team achieved average fuel cell stack durability of 2,521 hours.
The "National Fuel Cell Electric Vehicle Learning Demonstration Final Report" reviews the largest demonstration worldwide to date of fuel cell vehicle and hydrogen infrastructure.
These new research findings could give impetus to legislative efforts to revive federal support for hydrogen technologies. As reported recently by ThomasNet.com Green & Clean writer Tracey Schelmetic, a bipartisan group of senators is moving to reconvene the Senate Fuel Cell and Hydrogen Caucus, which has been inactive since 2010.
In a statement, the senatorial group said:
Credit: National Renewable Energy Laboratory
The fuel cell and hydrogen energy industry is a true American success story. Domestic fuel cells and hydrogen energy systems have achieved significant advances in power generation, portable applications, transportation, back-up and material handling. Across the nation, fuel cell and hydrogen energy technologies are creating jobs, reducing emissions and improving efficiency.
3.6-Million-Mile Hydrogen Torture Test
The DOE project, conducted from 2005 to 2011, is referred to as the National Fuel Cell Electric Vehicle Learning Demonstration. In the project, the DOE selected four automotive original equipment manufacturers (OEMs) that paired up with energy partners into teams. They collectively deployed 183 FCEVs and 25 project fueling stations. The vehicle manufacturers were GM, Daimler, Hyundai-Kia and Ford; Shell, BP and Chevron served as energy partners.
The DOE's California Hydrogen Infrastructure Project contributed its fueling stations to the project. Vehicles made more than 500,000 trips covering 3.6 million miles, consuming 152,000 kg of hydrogen.
During the project period, test results show a steady increase in fuel cell stack durability, i.e., resistance to degradation. The project tested three progressive generations of stack technologies, and the average time to 10 percent voltage degradation increased progressively from 821 hours to 1,062 hours to 1,748 hours. The project's target fuel cell durability figure was 2,000 hours, so the third-generation technologies came close.
Vehicle driving range also showed steady improvement during the test period. The DOE's high-level target for the teams was a 250-mile range, and the second-generation group of vehicles achieved 196 to 254 miles. The project also conducted an evaluation of Toyota's FCHV-adv fuel cell vehicle, which achieved an impressive 431-mile range.
The third high-level target for the project was a $3 per gallon gasoline equivalent (gge) hydrogen production cost. Under the project's testing, on-site natural gas reformation led to a cost of about $8 to $10 gge; on-site electrolysis led to $10 to $13 gge. These results did not come near the project's targets. However, the report notes that two independent review panels have found that distributed natural gas reformation could lead to a cost of $2.75 to $3.50 gge and distributed electrolysis could lead to $4.90 to $5.70 gge.
The DOE report discussed some of the high-level strategies of hydrogen infrastructure development:
NREL hydrogen lab in Colorado. Credit: National Renewable Energy Laboratory
Recent discussions within the hydrogen community indicate that there will be two major thrusts of hydrogen infrastructure build-out. The first will focus on geographic coverage by the stations to ensure that early adopters will have convenient fueling within a reasonable distance from where they live or work. The second stage of the deployment will focus on fueling capacity expansion and allowing the quantity of vehicles supported by the infrastructure to rise rapidly as the OEMs accelerate their production of the vehicles.
The demonstration project operated within the geographic-coverage stage, in which, the authors wrote, "the stations will necessarily have excess capacity and appear to be underutilized." Currently, the stations are "serving six or fewer vehicles per day on average, with several stations serving between 10 and 23 cars on their busiest days." However, after the hydrogen infrastructure shifts from "coverage" to "capacity" mode, "many of these demonstration stations will quickly become saturated and will need to be upgraded or replaced to allow for increased capacity and vehicle usage."
Hydrogen and the Environment
Hydrogen is often promoted as a green-energy alternative to conventional gasoline. The Fuel Cell and Hydrogen Energy Association wrote:
When using pure hydrogen, there are zero greenhouse gas emissions. When using other hydrocarbons as fuel, the emissions are still far less than with conventional combustion technologies (think ounces of carbon monoxide instead of pounds). In fact, fuel cell power plants are so low in emissions that some areas of the United States have formally exempted them from air permit requirements.
In a previous article, "The Damage Done - Hydrogen Vehicles, Good for the Planet?" I examined the environmental impacts of hydrogen as a transportation fuel. In my research, I found that FCEVs do, indeed, operate with very low emissions. The problem is that hydrogen is not a naturally occurring resource; it must be produced using an energy source. In the case of the NREL demonstration, the energy source is natural gas, so the environmental effects of hydrogen have to be determined by accounting for the life-cycle environmental damage of the natural gas that is used to produce the hydrogen. In other words, hydrogen "inherits" the environmental impacts of its parent energy source.
A 2010 report from the National Academy of Sciences (NAS), "Hidden Costs of Energy: Unpriced Consequences of Energy Production and Use," found that on a life-cycle basis hydrogen produces lower levels of greenhouse gas (GHG) emissions, 341 CO2 equivalents per vehicle mile traveled (CO2eq/VMT) compared with 552 CO2eq/VMT for a conventional light-duty gasoline vehicle. Beyond GHGs, NAS estimates that hydrogen results in higher health and environmental damages than gasoline, $0.67/gge versus $0.30/gge for gasoline.
It's likely, though, that greater reliance on renewable energy sources would reduce the life-cycle environmental effects of hydrogen. The Fuel Cell and Hydrogen Energy Association said:
A hydrogen fueling station in California. Credit: National Renewable Energy Laboratory
Hydrogen is most commonly generated from renewables with a device called an electrolyzer, which uses electricity to separate water into hydrogen and oxygen. By converting renewable electricity into hydrogen, the intermittent power of wind and sunlight can be stored for long periods and used in a fuel cell for power at any time, day or night. Electrolysis can also leverage the surplus generation from renewables that would otherwise be wasted. Currently, wind turbines are shut down on windy days when electricity generation outpaces demand. By simply installing electrolyzers, that surplus power could be put to use generating hydrogen.
This suggests that hydrogen fuel cells might be used as an element of a distributed power generation model. Renewables might be used at the community, neighborhood or even household level to generate energy that is then stored in hydrogen fuel cells for later use -- even the fuel cell in a homeowner's automobile might be used for this purpose.
A fuel cell bus in California. Credit: National Renewable Energy Laboratory