Hydrogen fuel cells are emerging as key players in the clean energy landscape of the future, except for one problem: it takes a lot of energy to make hydrogen, and here in the US, the preferred source of that energy appears to be natural gas. That’s hardly a sustainable solution. However, not to worry. Researchers have been turning their attention to renewable energy for producing low-cost hydrogen. The most recent development is a low-cost photoelectrochemical cell that produces hydrogen bubbles in water with the help of a little iron oxide, aka rust.
A Low Cost Photoelectrochemical Cell
Photoelectrochemical cells (PECs) use solar energy to split water molecules into hydrogen and oxygen. They don’t produce electricity directly like photovoltaic cells do, but they could have a huge impact on the electric vehicle market by providing a path to cost-competitive fuel cells. That in turn would give the auto industry a low-cost, high-mileage alternative to conventional EV batteries.
The sticky wicket is to bring down the cost of PECs, and the latest breakthrough involves one of the cheapest materials around, in the form of iron oxide.
Researchers from Ecole Polytechnique Fédérale de Lausanne and Technion–Israel Institute of Technology teamed up on the hydrogen project, which involved the creation of an electrode based on nanostructured iron oxide particles described as “cauliflower-looking.”
The team was able to pinpoint the movement of electrons through the nanoparticles with the help of transmission electron microscopy, and identify the most efficient configuration.
This “champion” structure became the basis for a 10×10 cm prototype that creates oxygen bubbles in water as soon as it is exposed to sunlight.
That one-step process has the potential to cost far less than other solar-powered water-splitting devices, which typically involve hooking up an electrolyzer to a regular photovoltaic cell.
How much cheaper? According to the research team, in Europe, the lowest cost for producing hydrogen with the photovoltaic cell/electrolyzer combo currently comes in at about 15 € per kilo, and the team’s goal for its rust-based PEC is only about € 5 per kilo.
Dodging The Natural Gas Bullet
President Obama launched a national hydrogen fuel cell/fueling infrastructure initiative earlier this year called H2USA, which is all well and good but for now we’re giving it the sustainability stinkeye due to its emphasis on using natural gas, specifically shale gas, to produce hydrogen.
However, as we’ve previously noted, the initiative does not preclude the use of renewable energy, and that is already starting to become part of the picture.
On a large scale, we’ve been following one company called HyperSolar for a couple of years, which envisions a network of solar powered hydrogen “farms.” The company announced plans for its first commercial-scale facility last March.
At the other end of the scale, there’s the “artificial leaf” concept of a low-cost, pocket-sized device that could be dunked in a jug of water to produce hydrogen. While not necessarily the most efficient solution, it could provide a renewable, off-grid alternative for households with low energy demands.
In the meantime, you can bet that fuel cells will become a far bigger part of the US vehicle market sooner rather than later. GM and Honda just launched a fuel cell development partnership, and these two companies happen to lead the world in vehicle fuel cell patents.
Dodging The Water Bullet
As far as long-term sustainability in the fuel cell market goes, energy for producing hydrogen is only half the equation. The other half is water, and in that regard the world’s water scarcity issues could become a stumbling block.
The problem is that conventional hydrogen production involves clean water as a raw material. Now consider the introduction of millions of fuel cell vehicles around the world and you can see trouble brewing on the horizon.
On the other hand, a solution is on the horizon. Researchers have been developing solar-powered systems that involve producing hydrogen directly from “dirty” water, and the aforementioned HyperSolar already has a wastewater process under its belt.
Another interesting example involves the “artificial leaf” device under development at Harvard, based on research initiated at MIT. In earlier iterations, it used clean water, but researchers have tweaked the surface to prevent film buildup by bacteria.
Speaking of bacteria, researchers are already on track to create high-efficiency wastewater treatment systems integrating hydrogen fuel cells with microbial fuel cells.
A good example of this trend is under development at the University of Colorado at Denver, where researchers are working on a system that uses microbial fuel cells to desalinate water and/or treat wastewater while generating electricity, which is used to split water into hydrogen and oxygen. The hydrogen can then be used in fuel cells to run equipment at the treatment facility.