Published on March 22nd, 2012 | by Nicholas Brown


Solar Powering Cars without Batteries

March 22nd, 2012 by  

Fraunhofer ISE has inaugurated a new hydrogen refueling station demonstration project. The refueling station is publicly accessible, providing one more place for fuel cell electric vehicles or vehicles with hydrogen-burning combustion engines to get their hydrogen fix.

Solar-Powered Hydrogen Refueling Station – Obtained from

Different types of fuel cells that can utilize different fuels, but this refueling station is just for hydrogen fuel cells, which generate electricity that then powers the electric vehicles’ motors.

Due to the intermittency of wind and solar power, it is good to find ways in which these renewable power supplies can be utilized without energy storage systems such as batteries, compressed air (CAES), etc. One way is the production of hydrogen via electrolysis, which is what the Fraunhofer hydrogen refueling station does. At this refueling station, electricity form the solar panels is used to power an electrolyzer, which passes an electric current through water, causing it to liberate hydrogen. (If you don’t remember, water (or H2O) is made up of water molecules, each of which contains 2 hydrogen atoms and 1 oxygen atom. During electrolysis, hydrogen bubbles out of the water at the cathode, and oxygen bubbles out at the anode.)

The hydrogen produced while the sun is shining is stored in tanks for later use at night, or during cloudy weather.

Apart from the above, the solar panel system Fraunhofer is using for this station is a grid-tie setup, meaning that the solar panels supply electricity to the power grid and reverse the electricity meter to offset the power consumption of the station. The Fraunhofer setup only partially offsets its power consumption, but it is a start. Innovatively, the solar panels also act as the roof and ceiling of the station.

The main components of this hydrogen station are an electrolyzer that operates at a pressure of 30 bar (435 psi), a 700-bar (10,152 psi) hydrogen compressor, puffer storage at two different levels, and hydrogen pumps.

Hydrogen fuel (when produced by renewable and clean energy) certainly has some advantages over battery electric vehicle technology, but it has its downsides as well. Hydrogen fuel cells are extremely expensive, but reasonably efficient; combustion engines, which hydrogen can power, are affordable, but inefficient and unreliable.

What do you think of this new refueling station and hydrogen-fueled combustion engine vehicles?

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About the Author

writes on CleanTechnica, Gas2, Kleef&Co, and Green Building Elements. He has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

  • Gwesleyk

    Instead of H20 electrolysis to give you H2 and O2, why not use a chlor-alkali nafion membrane cell to generate H2, CL2, and a ton of NAOH for 2500 kwh? That’s how you pay the light bill if you want to generate H2: you sell the CL2 and NAOH as value added by products and use that money to pay for your 2500 kwh of electricity.

  • Drowlison

    This is all great… but a tall order currently for sure with existing conversion losses as noted. I believe in H2 futures as well, but coming in a balanced manner through (for example) Waste to Energy operations – allowing large quantities of H2 to be captured, stored and replenned to vehicles / whatever uses – converted to community electric power as needed.

    • Bob_Wallace

      Waste -> electricity. I see that.

      But think about the amount of organic waste you toss and poop each day. Do you think there’s enough recoverable energy in that bucket to fuel a car?

      It’s like vehicles running on restaurant-sourced biodiesel. There’s enough french fry grease to power the odd pickup, but not the whole city.

  • dcmeserve

    Let’s see, from the picture it looks like the solar array is maybe 8kw. Drop that in half due to 50% energy loss in making H2, then half again for the fuel cell efficiency in the car. Then let’s be optimistic and say it can deliver full power (for example, when they knock down that building next to it) for 8 hrs/day. So this should be able to deliver enough miles per day to be equivalent to about a 16kwh EV battery charge.

    In other words, this station should be able to provide 1 car per day with enough hydrogen for an average (U.S.) commuter’s daily round-trip.

  • Ross

    There was a story on cleantechnica a few days ago about a way of combining the hydrogen with CO2 to produce formic acid which it claimed is more easily transportable and useable in a fuel cell.

  • Bob_Wallace

    It’s an interesting concept, but until we see affordable, long-life fuel cells in our near future it’s only a concept.

    There’s a race on between hydrogen/fuel cells, biofuel/ICEs, and electric cars. Currently my money is on EVs.

    It appears that we are close to affordable EV batteries. When/if that happens then EVs will set the entry level for fuel cells and biofuels.

    EVs will cost about 3 cents a mile to drive. That’s the equivalent of driving a 40MPG ICEV on $1.20/gallon fuel.

    Biofuel will need to get close to that price while not having a significant impact on food prices. That’s a very hard goal to meet, but a biofuel drop-in gas/diesel replacement would have the advantage of an existing distribution infrastructure and a mature ICE manufacturing system in place.

    Hydrogen fuel cells have an even tougher nut to crack if EV battery prices fall. They would have to present some very significant use/cost advantages over EVs because we have no hydrogen generation/distribution infrastructure. There would need to be a major reason for immense capital expenditure to build a brand new infrastructure. Liquid fuel and electricity have a huge advantage over hydrogen – they already have their infrastructures up and running.

  • youareme7

    I definitely think hydrogen has a place in our future transportation, it feels like there are many new technologies racing to fruition this decade that will (I hope) truly transform how we generate energy and transport ourselves. The MIT direct solar electrolysis is a big one. Imagine having PV and electrolysis panels on the roof of your house that would store hydrogen for your car and for powering, heating and cooling your house. We could be rapidly approaching the decline of the all powerful “utility” that just has too much inertia to change fast enough.

    • dcmeserve

      The MIT technology I think you’re talking about is not some kind of “direct” solar electrolysis. It’s just regular electrolysis, using a conventional solar panel to provide power. The comparison with photosynthesis is mostly just hype.

      The actual innovation there, from what I understand, is that this is a platinum-free electrolysis technology, which could reduce the cost considerably. However they still have a lot of work to get the electricity-to-hydrogen efficiency up even to the rather modest 50% level generally achieved with platinum electrodes. I believe their record so far is more like 20%.

      And keep in mind that fuel cells have similar efficiency problems, making the electricity –> H2 –> electricity loop roughly 25% efficient. Which means that you have to really be using electricity that is pretty much going to be discarded if not used for H2 production, for it to make any economic sense currently. Those efficiencies need to get much, much higher before H2 can start to compete with battery technology, especially for automotive applications.

      • Bob_Wallace

        Without extremely efficient hydrogen production (and cheap fuel cells) we won’t build hydrogen infrastructure.

        You’re standing there with a bucket full of cheap electricity. Do you pour it into a 25% efficient water -> hydrogen cracker and then loose even more power in the vehicle or do your pour it into an ~80% efficient EV?

        (10% loss in charging battery, 10% loss in the EV drive train.)

        The cost of charging an EV is so cheap that it sets a bar very difficult for any other system to cross. Its efficiency makes the chore even more difficult.

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