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Compact Solar Unit Yields 250 Liters of Hydrogen per Day

Photo Credit: © KU Leuven - Rob Stevens and Tom Bosserez

The amount of energy needed to produce hydrogen, as well as the required materials has long been a challenge for renewable power researchers in order to make it scalable for industrial or consumer use.

Now, bioscience engineers at Katholieke Universiteit (KU) in Leuven, Belgium, have created a compact hydrogen gas panel that produces hydrogen gas from moisture in the air using solar panels. After ten years of development, a single unit now produces 250 litres per day – a world record, according to the researchers. Twenty of these panels could provide electricity and heat for one family for an entire winter. The technique is already being adopted by Toyota and put to a field test for residential energy use.

Under a watery sun, Professor Johan Martens and his research team roll the hydrogen gas panel onto the lawn in front of the Centre for Surface Chemistry and Catalysis at KU Leuven. The device looks like an ordinary solar panel. The engineers have attached a flask with water to the device so that we can see the hydrogen bubbles escape. A meter indicates the quantities. After a couple of seconds, the first bubbles begin to rise to the surface.

Hydrogen gas is an energy vector that can easily be stored and transported, and it can be converted at will into both electricity and heat. The gas doesn’t release any greenhouse gases or toxic substances, provided that you use clean energy to produce it. That’s what Professor Martens’s team has developed: a device that turns sunlight and water vapor into hydrogen gas in a sustainable way.

“It’s a unique combination of physics and chemistry. In the beginning, the efficiency was only 0.1 per cent, and barely any hydrogen molecules were formed. Today, you see them rising to the surface in bubbles. So that’s ten years of work – always making improvements, detecting problems. That’s how you get results.” The team is unable to be too specific about the technology used in the units, as they have a number of patents pending.

A traditional solar panel converts between 18 to 20 per cent of the solar energy into electricity. If you then have to use that electric power to split the water into hydrogen gas and oxygen, you lose a lot of energy. The KU Leuven bioscience engineers solved this exact problem by designing a hydrogen gas panel of 1.6 m² that converts 15 per cent of the sunlight straight into hydrogen gas. This is an unprecedented development in the category of devices that don’t require precious metals or other expensive materials.

Hydrogen gas from renewable energy sources – green hydrogen gas – has been a promising prospect on the energy market for years, but the industry is lacking a real breakthrough. Hydrogen is considered expensive and difficult to produce and store. Today, most hydrogen is produced using oil and gas, sometimes called ‘grey’ hydrogen because production is not environmentally clean. The KU Leuven researchers believe this is about to change.

Tom Bosserez and Johan Martens © KU Leuven – Rob Stevens 

Last week, Toyota announced that it wants to produce hydrogen gas with a prototype designed by Johan Martens’s team in 2014. This device is a little screen (10 cm2) that the engineers will scale up to a large panel.

In Leuven, they already have one of these large panels. On campus, we see the meter rise steadily on the device in front of us. The bubbles keep coming, despite the watery sun. “The panel produces around 250 litres per day over a full year. That’s a world record,” says KU Leuven researcher Jan Rongé. “Twenty of these panels produce enough heat and electricity to get through the winter in a thoroughly insulated house and still have power left. Add another twenty panels, and you can drive an electric car for an entire year.”

The predictions are still based on calculations. However the researchers will are beginning a pilot project to field-test the theory.

Hydrogen gas does come with risks of its own. Like most fuels, the gas is highly flammable. This poses a danger, especially in closed spaces. At the same time, it’s also a light gas, so when it escapes, it rises immediately instead of spreading over the ground.

The team’s prototype is ready for field testing outside of the campus. The first project is in Oud-Heverlee, a rural town in Flemish Brabant. The house is well insulated and gets most of its power from solar panels, a solar boiler, and a heat pump. It is not connected to the gas grid. It only uses power from the grid in the winter. Twenty hydrogen gas panels will be added to this mix. If all goes well, more panels will be installed on a piece of land in the street. This will allow the other 39 families in the street to benefit from the project as well. The hydrogen gas produced in the summer will be stored and converted into electricity and heat in the winter.

Hydrogen gas is easier to store than electricity, because buffering electricity requires batteries that are expensive and that slowly lose voltage as well. For this reason, buffering electricity in batteries from summer into winter is inefficient. With hydrogen gas, it’s a different story. The hydrogen gas produced in the summer can be stored in an underground pressure vessel until winter. One family would need about 4 cubic metres of storage. That’s the size of a regular oil tank.

For Johan Martens, a test project like the one in Oud-Heverlee is what he and his team have been working towards for years. “We wanted to design something sustainable that is affordable and can be used practically anywhere. We’re using cheap raw materials and don’t need precious metals or other expensive components.”

The actual cost of the hydrogen gas panels is still unknown, as the mass production is yet to start. The researchers, however, say that it should be affordable. This invention could completely change the future of green energy. The emphasis will not so much be on large production units, but rather on the combination of smaller, local systems. It will also require less energy-guzzling transport of energy, whether it’s gas, oil, or electricity. The researchers, in any case, are optimistic: “the sky is the limit.”

Source: KU Leuven, Cleantech Concepts. Translated by Katrien Bollen and Shana Michiels, with permission from the original authors, Ben Vanheukelom, Luc Pauwels, and William Laenen. 

About Tom Breunig (203 Articles)
Tom Breunig is principal at Cleantech Concepts, a market research firm tracking R&D projects in the cleantech sector. He is a technology industry veteran and former international marketing and communications executive who has worked with organizations in semiconductor design, water monitoring, energy efficiency and environmental sensing. He has spoken at numerous technology and energy conferences.
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