## Siemens demos long-term stability of high-temperature electrolytic cells; role in energy storage systems

##### 14 February 2014

The use of electricity to generate hydrogen is considered potentially to be a key technology for the storage of surplus energy from renewable sources (e.g., Audi’s e-gas, earlier post); it could also play an important role in the transition of the energy system and the stabilization of grids. In a project funded by the German Ministry of Economics, scientists at Siemens’ global research unit Corporate Technology (CT) have developed ceramic electrolytic cells for high-temperature electrolysis. This technology could be more efficient than the conventional approach, since electrolysis reactions require a much lower cell voltage at high temperatures.

Another interesting property of high-temperature electrolysis is that the flow of the electricity can be reversed, allowing users to switch back and forth between efficient electrolysis processes and fuel cell operation. Such a system could use natural gas, biogas, or hydrogen to generate electricity or produce combined heat and power.

A future high-temperature electrolyzer could also be coupled with a system for synthesizing chemicals such as methane (e.g., an e-gas system). The resulting waste heat could be used to generate the water vapor needed for high-temperature electrolysis. According to the researchers’ simulations, hydrogen generation and methane synthesis would each have an efficiency of about 75% relative to their respective calorific values. This already takes into account the compression of the gases to 80 bar.

In the project, the CT researchers worked together with the ceramics manufacturer Kerafol and Forschungszentrum Jülich to optimize electrochemical cells that use an oxygen ion-conducting electrolyte as a substrate. The main challenge was to prevent the oxygen electrode from becoming detached, which had previously caused aging effects.

The researchers improved the electrode’s stability by making it from a material that conducts electrons as well as oxygen ions. In a CT lab in Erlangen, ceramic electrolytic cells ran for more than 8,000 hours at 850 °C. The cells had a current density of 0.5 amperes per square centimeter and a cell voltage of up to 1.1 volts.

In this endurance test, the researchers noticed that the voltage-related aging amounted to only 0.2% per 1,000 hours of operation.

The researchers also demonstrated a concept for constructing the cell stacks. However, further development work is needed before larger cell stacks will have a sufficiently high level of long-term stability.

I had my high for today. I've always said to make electrolysis of water, this is productive, efficient, money-making and non-polluting. Im ready to buy as soon as it hit the market. My current gas car is becoming a burden, is it possible to wait patiently before getting at last a better car and fuel.

Why there is no comments for an article like this??

MY level of adrenaline is higher then it was.

So this is a solid-oxide (electrolyte) fuel cell, running as a reversible electrolysis cell.  Degradation is low; 1.7% per year allows a considerable lifespan before it needs replacement.

Unfortunately, this doesn't fit with the current "RE or die" paradigm.  Ceramics often don't stand up well to thermal cycling, and use as a dump load for storage of wind/PV generation peaks means widely varying power throughput.  Keeping the unit hot when not in use means parasitic losses.

I'd really love to see one of these things come to market, but after waiting decades I'm no longer the optimist I once was.

Forecourt based production of hydrogen using HT electrolysis is shown here as $3.12/kg. Clearly no distribution costs are incurred with this model of production, and using the small Toyota SUV as a reference which gets 68 miles/kg/gallon equivalent the costs to drive would be well under half of that in a petrol car. Sorry, forgot the link! Here: http://www.inl.gov/technicalpublications/Documents/5436986.pdf It should not be assumed that 'hydrogen and fuel cells just mean fossil fuels' either. Sure, it is the cheapest way of making hydrogen, but then again the cheapest way of making electricity is by burning gas. Here are some costs for various ways of making hydrogen: http://www.hydrogen.energy.gov/pdfs/progress12/ii_0_dillich_2012.pdf Even using the most expensive way of generating hydrogen, and using 2011 figures, then it costs from biological sources$6.90kg, or around the same as petrol on a per mile basis.

At the Californian mix where a third of transport hydrogen is to come from renewables and ignoring the much cheaper electrolysis from renewable, which costs $4.10/kg, the mix comes out to ($3.12*2 + $6.90)/3 =$4.38/kg

That is a pretty reasonable price if you are getting 68mpge

Does anybody know why clean energy sources should cost less the dirty burning fossil and/or bio-fuels?

"Does anybody know why clean energy sources should cost less the dirty burning fossil and/or bio-fuels?"

As long as we don't fear climate change enough to put a price on carbon or to voluntarily pay more for clean energy we will not give up fossil fuels.

If we're really lucky the price of clean energy will drop below the price of fossil fuels and we'll switch earlier.

If that doesn't happen then we probably won't switch over until we start experiencing a lot more hurt than we are today. Once the pain level gets high enough we'll demand that our governments outlaw fossil fuel via one route or another.

If we have to wait that long we'll be leaving a nasty future for those who follow.

Well said BW..

The pain level may already have been reached in many large Asian cities. People will soon get tired of wearing mask and getting very sick from air pollution.
Lung cancer cases are going up at the same rates as ICEVs.

Americans are very resistant to pain. Guns are killing 35,000+/year and the love affair is still going strong.

We'll only get cheap, clean energy if emissions-free is the only criterion.  If the Greens are allowed to add "and not that icky nuclear" to the definition, it will be expensive and unreliable.

Guns are killing 35,000+/year and the love affair is still going strong.

Ascribing agency to inanimate objects is a hallmark of insanity, Harvey.  I know it's politically incorrect to name the actual agents, but that's because ethnomasochism/"anti-racism" and PC in general is a form of insanity.

In the USA, the people who own and carry most of the guns and the people who commit most of the murders are disjoint sets.  The violent groups are violent with or without guns.  The non-violent groups own guns in no small part to keep the violent groups at a safe distance.  It's not a "love affair", it's survival.

The non-violent groups own guns in no small part to keep the violent groups at a safe distance. It's not a "love affair", it's survival.

Balony. Violent groups will be violent without rationally considering the consequences, and the incentive is to be more violent if the other guy might have a gun. Gun groups do love guns. So let them have them, but hold the gun owner (or posessor) responsible. Use a gun to commit a crime and you go to jail. Let someone else use your gun (or allow it to be borrowed, lost, or stolen) to commit a crime and you go to jail. Rights come with responsibilities.

JMartin, look at the murder rates for Vermont, Montana and even dirt-poor West Virginia.  Then look at their gun-ownership rates vs. states like Illinois and New York.  You'll be shocked—SHOCKED!—to see that loving guns has such a strong negative correlation to criminal lack of restraint.

Guess who's objecting to the "stop, question & frisk" program to keep crooks from carrying guns in NYC?  It's not the NRA.  Minority juries are refusing to convict their co-ethnics on gun-possession charges and even murder charges.

Violent people can often be deterred, it just takes more of a deterrent than e.g. common decency.  A gun works wonders as a deterrent, and most defensive uses of guns end without shots fired because the aggressor saw the wisdom of retreat.

E-P, I am not convinced correlations prove cause and effect.

But I am not arguing for gun control, just gun responsiblity. If ti is true that "guns don't kill people, people kill people," then hold the people responsible. That is my position.

We tried that.  We got told in no uncertain terms that it's racist.

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