Hydrogen fuel: The catalyst that may open the floodgates

Hydrogen, the lightest and simplest element, presents an ideal source of power for fuel on our planet. Hydrogen is high in energy and produces a clean byproduct with almost no pollution. However, storing hydrogen at high densities is difficult, which creates challenges for using it as a transportation fuel. Hydrogen production can also create unwanted byproducts such as carbon dioxide. Yet, a new catalyst aims to solve these problems. Researchers from the US Department of Energy’s Brookhaven National Laboratory have developed a new fuel cell catalyst which uses CO2 and hydrogen to store its energy in liquid form; the only minor problem would be adjusting the pH or acidity of the liquid base. Hydrogen as a liquid form could be used more effectively and efficiently with the current fuel infrastructure than other alternative energy sources.

The Catalyst

The type of fuel cell that is used in an automobile requires pure hydrogen as an input and produces electricity as the output. Generally, the operation of a fuel cell is to convert fuel directly to electricity and heat using electrochemistry. The type of fuel can vary depending on the fuel cell. This new catalyst is the first to combine hydrogen and CO2 at room temperature and pressure, using water as the liquefying solution. The basic process allows the iridium-based catalyst to convert hydrogen and CO2 into formic acid, which is safer to handle than cryogenically stored dihydrogen. By adjusting the pH to acidic, the reaction frees the hydrogen from its carbon bonds, allowing it to be used in a fuel cell. Scientists and researchers from Brookhaven National Laboratory and the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, utilized this catalyst process, increased the pH solution and were able to regenerate the H2 at high pressure. According to the research team, no unwanted byproducts were found.

Hydrogen would be an ideal source of renewable fuel as it is the cleanest known alternative energy; nonetheless, developing a sufficient framework has proven to be problematic. Most research on hydrogen storage and transport has centered on materials called metal hydrides and their storage in metal-organic frameworks -- porous material structures that can be filled with gas. Placing hydrogen into these frameworks to make a fuel tank of reasonable size is not an issue with hydride technology. The key issue is the weight, and although the tanks would be a moderate size, they would be very heavy.

To further develop more background information on fuel cell research and hydrogen fuel storage, we reached out to Dr. Shane D. Stephens-Romero, Senior Scientist at the National Fuel Cell Research Center of UC Irvine. Dr. Stephen-Romero shared with us that, “the strategy used in fuel cell vehicles that are currently being demonstrated is to store hydrogen as a compressed gas. Because hydrogen is a low density molecule on a volumetric basis it needs to be stored at high pressure to store enough of it to achieve a 300 or 400 mile driving range.” He further explained the benefits as, “storing hydrogen as a liquid would get you the 300 or 400 mile driving range without needing the high pressures which would be logistically easier, both for the storage tanks on the vehicles, and for the equipment at the fueling stations.”

Beyond the Fuel Applications of Hydrogen Innovation

Dr. Stephen-Romero has pointed out that different fuel cell technologies are suitable for different applications -- for example, “Large stationary fuel cells generate electric power from a variety of fuels from natural gas, to biomethane, to hydrogen. However, these are fuel cells that operate at high temperatures, so they take a while to heat up when they turn on and then want to stay on.” Low temperature fuel cells present a key advantage for transportation applications compared to other types of fuel cells, because, “these types of fuel cells, which operate on hydrogen directly, can turn on and be ready for use immediately." Although fuel cell vehicles are scheduled to be launched commercially in 2015, the biggest remaining challenge is to get the fueling stations in place. Dr. Stephens-Romero views this dilemma as more of an issue of business and policy decisions than a technological limitation.

Dr. Stephens-Romero conveyed that many types of fuel cells are already commercialized for stationary power applications and are experiencing market success. However, the only remaining barrier for fuel cell automobiles is the lack of hydrogen fueling stations. According to Dr. Stephens-Romero, this is not a technology challenge, but rather a business and policy challenge, as “the market will not be prepared for the commercialization of fuel cell vehicles without some degree of retail hydrogen refueling stations in place.”

Since hydrogen fuel cells are a reliable power source, Dr. Stephens-Romero has assured us that they can be used for a broad array of applications. As he previously stated, there are many types of fuel cells suited for different applications, from commercial applications like stationary power generations, to upcoming applications like the automobile, laptop and cell phone. He adds that, “the hydrogen fuel cell in particular is being used commercially for residential power, backup power and in forklifts and will soon be commercialized for automobile applications.” When we asked what major companies were behind this technology and research funds, he mentioned some very familiar and renowned names -- Toyota, Honda, General Motors, Mercedes-benz, Nissan and Hyundai/Kia are all top contenders for industry-leading fuel cell vehicle development. Air Products & Chemicals, Inc., Linde, Praxair and Air Liquide are among the companies working on the equally important hydrogen infrastructure aspect of this clean technology.

Seizing the Liquid Frontier

One key advantage of hydrogen fuel tech is its cohesion with what is often referred to as the ‘liquid frontier’ -- the already prevalent infrastructure for liquid transport. The US, for example, has a network of over 150,000 miles of pipeline delivering liquid fuel products, and many other nations have similar networks. Liquid-fuel infrastructure dominates universal engine power; therefore, hydrogen liquid storage would be a key innovative tactic in mainstreaming hydrogen fuel. Liquid hydrogen requires extremely low temperatures of -423 F -- any hotter temperatures would cause a boiling point. The catalyst, which could transcend the limitations of this requirement, creates a liquid storage solution that is safe and stable at room temperature; it is thus able to utilize America’s existing infrastructure. The likelihood of creating a prosperous clean-fuel economy in the near future would require this type of simplified engineering, where renewable energy is smoothly integrated with existing systems. In a future hydrogen economy, liquids would also likely prove easier to move than gas. Safety issues concerning high-pressure gas is one of the reasons that liquefying hydrogen fuel effectively would provide a quantum leap.

Efficiency savings in infrastructure, while advantageous, are not the main draw of hydrogen fuel -- Dr. Stephens-Romero affirmed that fuel cell vehicles can be two or three times more efficient than a conventional gasoline car. He explains, “Demonstration fuel cell vehicles are currently demonstrating between 55 and 75 miles to the gasoline gallon equivalent (on an energy basis), and will likely improve as the vehicles are commercialized and further developed.” He also outlines the impact that it has on the automotive industry, as six major automakers have announced plans to commercialize fuel cell vehicles in the year 2015. “Since the cars have not been sold commercially, it is unclear as to what the market acceptance and penetration rate will be. However, signals from the industry suggest that the expectation is a better penetration than plug-in vehicles or CNG vehicles. It would probably be more on the order of what the penetration was for hybrid vehicles similar to the prius or the insight when they were first introduced.” Considering how popular the Prius and its various imitators have proven to be in the market, this bodes well for those vanguard automobiles that take advantage of hydrogen fuel.

The Quantum Leap

Although solar power, geothermal energy and smart grid electricity are viable clean tech innovations, they require fundamental infrastructure changes that are costly and take time to bear fruit -- the pipelines that hydrogen could take advantage of, on the other hand, are not disappearing anytime soon and are already in place for efficient distribution. Brookhaven’s fuel catalyst provides a storage platform that could facilitate the long awaited transition to a hydrogen-based economy by taking advantage of existing liquid-based distribution channels.