Want fuel cells? Think outside the hydrogen tank

Nov 18, 2011 By Kyle Todd
One of Professor Eric Wachsman's solid-oxide fuel cells (SOFCs)

(PhysOrg.com) -- When most people hear the words "fuel cell," they think of eco-friendly, hydrogen-powered cars that emit nothing more than water.

And that, says Professor Eric Wachsman, director of the University of Maryland Energy Research Center (UMERC), is one of the reasons we're all not driving one.

The U.S. Department of Energy's (DOE) recent decisions about how to fund research, he says, are putting the country at risk of falling behind in the development and implementation of the most efficient means of converting fuel to electricity. Fuel cells have up to three times the efficiency of an internal combustion engine.

"There is a problem in the perception of the public and policy makers, and in the funding of our fuel cell programs, that hydrogen and fuel cells are linked," says Wachsman, a faculty member at the university's A. James Clark School of Engineering. "Hydrogen-based fuel cells are the technology that has gotten all of the press and as a result we're still waiting for a future . Yes, fuel cells can run off hydrogen, but they don't have to."

Another problem, Wachsman says, is America's fixation on vehicles. "It will take decades to create a nationwide hydrogen distribution and , and to convert every gas station into a hydrogen filling station. That reality has turned fuel cells into a 'future technology' and has resulted in a drastic reduction in the funding of fuel cell research by the DOE in favor of developing , when in fact fuel cells can be used right now in many stationary and , including centralized and power generation for homes, businesses, and industry."

Most people are unaware that there are two kinds of fuel cells. The one in the public eye, the (PEM) fuel cell, uses hydrogen to generate power. The type of fuel cell Wachsman and his colleagues have worked to perfect, the (SOFC), has a distinct advantage over its PEM-based sibling.

"Solid oxide fuel cells are unique because they can oxidize any fuel," Wachsman explains. "They can run off of gasoline, diesel and natural gas today, and biofuels and in the future, whenever that infrastructure is in place."

Hot Technology

Still, nothing's perfect, and Wachsman can sum up the reason why SOFCs aren't in large-scale production in a word: temperature.

"That is the issue," he explains. "It's the reason why the automotive companies are using PEM fuel cells. PEM fuel cells operate at around 80 degrees Celsius [180 degrees Fahrenheit], which allows them to startup fairly quickly. Current solid oxide fuel cells currently operate at 800 degrees Celsius [1500 degrees Fahrenheit], so it takes a long time to warm up to operating temperature, making them more applicable to stationary power generation."

Wachsman and his colleagues are working to change that. In an article in the November 18 issue of Science, the team outlines the technology behind a new world record power density SOFC that generates two watts of power per square centimeter at 650 degrees Celsius [1200 degrees Fahrenheit]. The cell uses a bi-layer electrolyte developed by Wachsman that is more than 100 times more conductive than the conventional zirconia-based electrolyte operating at the same temperature also a world record. When the cells are assembled into a stack they should produce three kilowatts of electricity per kilogram of material, more than an at approximately one-third the size.

The paper lays out a strategy to further lower temperature. The team believes its improvements to SOFC electrolytes and nanostructured-electrode designs could ultimately reduce the cells' operating temperature to only 350 degrees Celsius [660 degrees Fahrenheit]. At that temperature they could start up fast enough for automotive applications, and would be more efficient and more affordable than current SOFCs because they could be manufactured from less expensive materials.

Explore further: Team improves solar-cell efficiency

More information: See Eric D. Wachsman and Kang Taek Lee. "Lowering the Temperature of Solid Oxide Fuel Cells." Science, 2011, forthcoming.

See Eric D. Wachsman, Craig A. Marlowe and Kang Taek Lee. "Role of solid oxide fuel cells in a balanced energy strategy." Energy and Environmental Science, 2011. Read the advance article online here.

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User comments : 18

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PPihkala
4.3 / 5 (6) Nov 18, 2011
Make that car a hybrid like Prius with smallish battery and drive with electricity until SOFC is hot enough. SOFC warming up can also be aided with EL heater.
Tomator
4 / 5 (3) Nov 18, 2011
Linked with nanotube supercapacitor would work pretty cool and be quite durable.
Eikka
3.5 / 5 (10) Nov 18, 2011
Make that car a hybrid like Prius with smallish battery and drive with electricity until SOFC is hot enough. SOFC warming up can also be aided with EL heater.


But if the SOFC can just reach temperature as you reach your destination, what's the point? The longer it takes to start up, the more energy you waste.

Heating up a kilogram of iron for example by 650 degrees takes 300 kJ of energy. Now, if your "engine" weighs 25 kilograms for 100 HP on the pedal, and you need all that warmed up before you go, that's 2 kWh or 1/4 a liter of gasoline wasted right there. With that amount of fuel, you would already be 2 miles down the road, or 5-6 miles if we assume that the fuel cell has three times the fuel economy.

So it's quickly apparent that the efficiency of the car suffers a lot on short trips. Could work for a taxi, because it doesn't have time to cool down.
Eikka
3 / 5 (5) Nov 18, 2011
The main issue of cold starting such an engine is however, that it requires a lot of power to do quickly. Suppose you have a 5 kilogram version of the hypothetical fuel cell that is made of iron; it needs 417 Wh to come online, which is just about what you could pull out of a regular car battery.

The trouble is that it would take 10-15 minutes at a reasonable rate so that the battery doesn't boil over, and the battery would be empty after just one start.
Noodle_Naut
1 / 5 (4) Nov 18, 2011
Seems to me it could be insulated in an advanced thermos of some kind and simply maintained at the high temperature whether the car is running or not. If it can operate in say a 200 degree range and it looses say .5 degrees per hour it should remain operable for quite a while. It could use a battery to keep it above the minimum temperature all the time.

If the charge gets low then the fuel cell just turns on and charges up the battery.

If you are going to go on vacation or put it in storage or it is being garaged where the CO2 buildup could be a problem then there is a switch to shut it down. You simply use an outlet to get it hot again in say 20 minutes.

A simple CO2 external air sensor could recognize when CO2 buildup is becoming a risk and shut down automatically to avoid danger if someone forgot to turn it off and it has been left for a few hundred hours.
Noodle_Naut
2.7 / 5 (7) Nov 18, 2011
I think if you can make this tech reasonably affordable and reliable, semi tractor tailor operators would defiantly want it even if it could not be insulated as I suggested. It could make driving far more efficient and save a lot of money. They often keep them running 24 hours a day anyway.
that_guy
5 / 5 (1) Nov 18, 2011
I'm pretty skeptical of this whole thing, but according to the DOE, it should be able to achieve better efficiency than gas, at 50%. With a turbine to gain energy from the exhaust, it should hit 70%. Typical gas engines only hit 15-20%

http://www.fossil...ide.html

http://en.wikiped...n_engine

an aside - as it turns out, rocket engines are about 70% efficient if the expansion chamber is big enough.

default_ex
3.3 / 5 (6) Nov 18, 2011
How about...

Power up the car with the SOFC, when parked plug it into the house to provide power, sell back excess to the power company. If the entire country were to do this, we'd likely find our big power generation facilities worthless.
Jaeherys
not rated yet Nov 18, 2011
Even if it takes a half an hour to heat up to operational temperatures, as mentioned before, a hybrid setup would go a long ways in fixing that. Simply having a timer in the car that starts 45 min before you have to leave, alleviates the warmup problem for typical use.

For short journeys the battery would be used only and depending on the total distance needed to travel, the car would start the warm-up process to recharge the batteries while you do your food shopping for example.

With enough programming and great insulation around the fuel cell, I'd be surprised if this type of technology would actually inhibit your everyday life.

Sure it might slow you down in some situations but there is a simple way to deal with that, suck it up and stop complaining!

In time things will be more convenient and efficient than they are now but we can't keep denying all these technologies on the premise that they are not 100% as "great" as what we have today.
jerryd
1 / 5 (1) Nov 18, 2011

bullhocky. Those foolcells are no where near 50% eff nor are they are eff as ICE's can be. They don't include the pumps, etc in either the weight or input energy.

Facts are good ICE's running 90% power in large sizes now are 50% eff and about 35% for car motors though only running near full power.

If you want an eff car, then a 50-100 mile battery range and a very small generator of 5kw/1,000lbs of car will give by far the best eff and fuel options.

What we really need is a 2hp Rankine heat engine so we can turn heating oil, wood, used veg oil, etc into heat and electricity during heating season.

If I was up north, in Fl so not worth it here, I'd by a water cooled 5-10hp diesel and run it on used veg oil, kerosene, biogas or whatever free/low cost fuel at 1200rpm for long life to replace the furnance.

And they have short lives.
PinkElephant
5 / 5 (2) Nov 18, 2011
@jerryd,
Those foolcells are no where near 50% eff...
Quoting from that_guy's first link:
This proof-of-concept system demonstrated an electrical efficiency of 53 percent.
As for this:
And they have short lives.
Again, quoting from that same link:
The turn of the century culminated in the current successful commercial prototype 150 cm cells, and a 100 kW cogeneration system that operated in the Netherlands, Italy, and Germany for more than 36,000 hours. Also, a world record for individual fuel cell operation (~8 years) still stands, and the prototype 150 cm cells have demonstrated two critical successes: the ability to withstand >100 thermal cycles and voltage degradation of less than 0.1 percent per 1,000 hours.
Seems you're a *just a tad* behind the times with your data...
Eikka
1 / 5 (2) Nov 19, 2011
Simply having a timer in the car that starts 45 min before you have to leave, alleviates the warmup problem for typical use.


But it would still halve your fuel economy, because you're only going to drive 10 miles to work. It would make it barely any better than regular hybrids.
jabailo
not rated yet Nov 19, 2011
America already has a hydrogen infrastructure...we make enough hydrogen to fuel something like 110 million vehicles. That hydrogen is now being injected into regular gasoline as an energizer. The effort now is to bring that hydrogen the last mile to a fuel pump, to standardize on pressure and storage technology. These are not problems that make hydrogen a future fuel as Toyota's decision to manufacture a hydrogen fuel cell car in 2013 amply demonstrates.

But yes, as Fuel Cell Energy has been showing for years now, you can make electricity with fuel cells from many energy sources such as natural gas...even wastewater!
wwqq
1 / 5 (1) Nov 19, 2011
How about...

Power up the car with the SOFC, when parked plug it into the house to provide power, sell back excess to the power company. If the entire country were to do this, we'd likely find our big power generation facilities worthless.


Asinine. You'd burn expensive, portable fuels in order to feed power into a grid that mostly uses cheap fuels. There's no future in fossil fuels and generating hydrogen takes an awful lot of energy which will come from ... big power generation facilities.
unknownorgin
1 / 5 (2) Nov 21, 2011
Even 1200F is workable and using a rechargeable battery to heat up a small feul cell that in turn heats a larger feul cell to start a system in a vehicle could be practical if an onboard timer is set to get the vehicle ready ahead of time. It is a matter of changing driving habits.
Eikka
1 / 5 (2) Nov 24, 2011
It is a matter of changing driving habits.


Which is why nobody will buy it unless they absolutely must. It's an inconvenience that nobody wants. It's the reason why steam cars didn't win over internal combustion - the latter would turn on and be ready at the turn of a key.
rawa1
1 / 5 (3) Nov 24, 2011
Fuel cells are indeed nice, but cold fusion technology could be miniaturized up to level, even the tiniest calculator would contain battery with capacity sufficient for its whole lifetime.

Under such a circumstances I'd definitely rather invest into research of nuclear sources, than into ineffective and bulky chemical energy sources - no matter which "green" technology they're actually using. BTW Andrea Rossi claims that a $24 million order has been sent to buy his cold-fusion device.

http://evworld.co...yid=2035
into the box
not rated yet Jan 16, 2012
If achieving the threshold temp is the only problem, the fastest would be a chemical reaction, which gives off heat. But I am not sure of the compatibility and suitability , for this application, as I am not an engineer.
The other option if using a power source is an option, radial heaters could be used. Which have limited heat loss and don't require any time at all to reach target temp.