[Image above] Credit: alec boreham; Flickr CC BY-NC-ND 2.0
It’s the first and lightest element in the Periodic Table and the most abundant chemical in the universe. An atom of hydrogen contains just one proton and one electron—and that could be all that’s needed to cleanly power our future.
A team of scientists from CoorsTek Membrane Sciences (Golden, Colo.), the University of Oslo (Norway), and the Institute of Chemical Technology (Spain) has developed a promising new ceramic membrane that could reduce the cost and enhance the feasibility of hydrogen generation far enough to bring the technology to the forefront of clean energy solutions.
The new ceramic membrane—made from oxides of barium, zirconium, and yttrium—can separate hydrogen from natural gas in a one-step process with incredibly high efficiency. Incorporated into a protonic ceramic fuel cell, the membrane can generate high-purity compressed hydrogen using just natural gas and electricity. The team recently published its results in Nature Energy.
“By combining an endothermic chemical reaction with an electrically operated gas separation membrane, we can create energy conversions with near zero energy loss”, Jose Serra, co-author of the paper and professor at the Institute of Chemical Technology, says in a CoorsTek press release.
The membrane consists of a dense film of a BaZrO3-based proton-conducting electrolyte on a porous nickel composite electrode, a combination that has high proton conductivity at 400ºC–900ºC—allowing it to separate primarily hydrogen protons out of methane, the primary component of natural gas, with incredibly high efficiency.
According to the paper’s abstract, the scientists report that the membrane removes 99% of formed hydrogen from methane at 800ºC.
One potentially promising application for protonic ceramic fuel cells is to power low-emission vehicles. Natural gas is so abundant and low-cost and the separation process is so efficient that the ceramic membrane could make hydrogen the best all-around option to fuel future automobiles in terms of emissions and cost.
“Our breakthrough ceramic membrane technology makes it possible for hydrogen-fueled vehicles to have superior energy efficiency with lower greenhouse gas emissions compared to a battery electric vehicle charged with electricity from the grid,” Per Vestre, CoorsTek Membrane Sciences managing director, says in the press release.
According to a CoorsTek infographic, the ceramic membrane could allow overall hydrogen production efficiency for fuel cell vehicles of 41%, whereas fuel cell vehicles that rely on water electrolysis to generate hydrogen have an overall efficiency of just 17%.
In terms of overall efficiency, not far behind protonic ceramic hydrogen fuel cell vehicles is battery electric vehicles, with an estimated overall efficiency of 37%. But protonic ceramic hydrogen fuel cell vehicles are also superior in terms of lower emissions and lower driving cost—more than 20% lower emissions and 25% lower driving cost than battery electric vehicles.
Ceramic membranes can offer even more vast improvements over the vehicles most of us still drive around, those powered by internal combustion engines—protonic ceramic hydrogen fuel cell vehicles emit 65% less emissions and have 81% lower driving cost than vehicles powered by internal combustion engines.
Plus, the ability to easily generate compressed hydrogen could enable compact hydrogen generating installations, helping solve the problem of lagging hydrogen infrastructure that currently limits adoption of hydrogen fuel cell vehicles. While the infrastructure for electric charging stations is more rapidly expanding, hydrogen fueling stations are few and far between. In fact, there are currently only 39 in the entire U.S. (all of which are situated on the periphery of the country), despite commercial availability of hydrogen fuel cell vehicles.
“The potential for this technology also goes well beyond lowering the cost and environmental impact of fueling motor vehicles,” Vestre adds in the release. “With high-volume CoorsTek engineered ceramic manufacturing capabilities, we can make ceramic membranes cost-competitive with traditional energy conversion technology for both industrial-scale and smaller-scale hydrogen production.”
Small-scale hydrogen production is perfect for residential use, where such a protonic ceramic fuel cell could be installed similarly to a water heater. And because 61% of single family homes in the U.S. use natural gas heating, installations could be relatively straightforward for many homes.
The scientists report in the paper’s abstract that modelling of a small-scale hydrogen plant that produces 10 kg H2 per day—a typical family is estimated to need just 0.4 kg daily to power a fuel cell electric vehicle, for example—has an overall efficiency of more than 87%.
The team also indicates that the ceramic membranes are industrially scalable as well, even for high-volume hydrogen production to power applications such as manufacturing of ammonia-based fertilizers, the largest current industrial application of hydrogen with consumption of up to 200–600 tons of hydrogen per day.
Potential applications for the ceramic membrane are likely to get creative as well. “When you have the technology to convert energy from one form to another with almost no loss of energy, this opens up new ways to think about energy systems,” Serra says in the release. “For example, we can use the ceramic membrane technology to produce hydrogen from water. This will require more electric power than reforming of methane, but if electricity is available from renewable sources we can make hydrogen without CO2 emissions. You can also think one step further and design energy systems that are not only low carbon or zero carbon, but even have negative carbon emissions. This will be the case if you use renewable electricity to reform biogas to hydrogen, and store the produced carbon from the biogas underground. In this way, hydrogen can one day become a negative emission energy carrier.”
The paper published in Nature Energy, is “Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss” (DOI: 10.1038/s41560-017-0029-4).
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