Slashdot Mirror
Hydrogen Fuel Cells Running On Sunflower Oil
tigersaw writes "You've heard about Biodiesel , Greasecars, and Fuel Cells for a while now. At yesterday's meeting of the American Chemical Society, researchers from the University of Leeds in England described a novel approach that combines these ideas in a fuel cell device that employs steam and two separate catalyts to generate hydrogen using sunflower oil. Experimental results show a hydrogen yield of 90 percent, versus 70 percent in other hydrogen fuel cell technologies. 'The sunflower oil used is the same type found on grocery shelves. "We would happily toss our salad with it," says the researcher, who adds that the process can also work with other types of vegetable oils.'"
So how much energy is required to generate the steam that produces the hydrogen? Do you get enough H2 to make it worth the cost and effort?
It's like an all-electric car... sure it uses no gas but that power has to come from somewhere to begin with. You've only moved the problem to someone else's back yard.
At least with Biodiesel you get out more energy than you put in to make the conversion (the balance of the energy comes from the sun, which the plants have collected and turned into the raw oil).
=Smidge=
I disagree. On Alan Alda's "Scientific American Frontiers," they showed a novel approach in which hydrogen is produced "on site." That is, it uses a reverse fuel cell in every "hydrogen station" to develop hydrogen, then it is liquified, and delivered via hydrogen pumps, much like the way you pump gas, but with a slightly different hookup. That, in my opinion, is a better means of distribution as it completely eliminates the need for transport, pipes, large factories, and so forth.
A blog like any other.
But where does the energy to make the H2 come from? Currently, it takes a cubic assload of electricity to generate hydrogen, so the distributed production model would need huge increases in the electrical power generating infrastructure, which is already near maximum utilization.
The alternate is producing the H2 at a location with cheap power (hydro, desert solar collectors), and then shipping the H2 where it needs to be. But that has its own issues, as you pointed out.
I'll be honest - I'm not holding out for the "hydrogen economy" in my lifetime. Sounds to much like shale oil - grand idea, sounds good politically, and goes precisely nowhere. (Kind of like Carter's other big idea - Middle East Peace)
"As God is my witness, I thought turkeys could fly." A. Carlson
You don't know? Didn't even stop to ask?
I didn't think so.
Being a wet blanket bugs me sometimes, but somebody has to do the dirty work of dragging everything back down to earth and facing facts. Here are some:
- The reactor doesn't generate hydrogen with 90% efficiency, it generates hydrogen of 90% purity. Given that the off-gas is about half methane (RTFA) it appears to me to be very inefficient. (Note: neither the author nor your Slashdot editor bothered to RTFA either.)
- There are already engines, and even fuel cells, which can burn hydrocarbons directly. Sunflower oil makes reasonable diesel fuel as-is. Solid-oxide or molten-carbonate fuel cells can reform fuels internally, and while they might coke up on straight sunflower oil they'd probably work just fine after it had been steam-reformed a bit.
- Hydrogen as a motor fuel suffers from huge problems with storage. People see it as sexy but for all the wrong reasons.
I could see this as another technology for making compact laptop power supplies whose fuel couldn't be used to bring down an airplane (just TRY making a fuel-air bomb with sunflower oil). The key to renewable energy? Gimme a break.Time is Nature's way of keeping everything from happening at once... the bitch.
Why don't americans stop living in the suburbs and move back into the cities where they could perhaps bicycle or *gasp* walk to locations instead of insane hour long commutes. Perhaps all that hydrogen could inspire a blimp comeback - who needs anti-grav when we already have balloons? Sure they're flammable, but with helium that's not an issue. I'd like to see an antagonist element try to take out a building by crashing an airbourne bouncy-castle into it...
Why not use a fuel that's liquid at STP? Ethanol, say? The energy-per-unit-mass is lower, but it's so much denser you end up with a far higher energy-per-unit-volume. Storing and pumping liquids is a solved problem; you can use the existing infrastructure built by the petrochemical industry. Ethanol can be burnt and synthesised by fuel cells, too.
So what's with the hydrogen obsession?
one point to filter for emissions
That's not necessarily a good thing. Basically you would be concentrting all of the resulting pollution in one area instead of spreading it out more or less evenly. Assuming nature cleans up the pollution at a certain rate (say, as by density of plant life and large bodies of water to absorb and recycle CO2) then you actually made the problem much worse in some areas.
no car pollution in cities
Ah, well, as long as it's not in your back yard I guess it's okay then!
an easy upgrade path when you replace your coal plant with biodiesel or solar or fusion or whatever
Except that the existing power distribution system is already strained and aging such that it can barely keep up with peek demands today. It would cost billions upon billions to construct new powerplants and additional infastructure to handle the additional demand of the now millions of electrical vehicles feeding off of it.
possible economies of scale
See above. In general you try not to build powerplants too far from where the power is used (obvious?). And you will definately need more of them right from the start.
Now take a straight biodiesel economy model:
Virtually no infastructure costs. Everything you need to produce, transport and distribute liquid fuel is already in place.
Less pollution on the grand scale. BD burns cleaner than the oil and coal (especially coal) used in powerplants, and the resulting pollution is spread out evenly such that nature can process it more effectively. If you're worried about soot (which BD produces less of anyway) there are already very effective filtering systems for small vehicles in widespread use.
Excellent scaling economics. Unlike electricity you CAN produce/refine all of the BD in one spot for the entire country (even though you probably wouldn't want to). There is basically no restriction on the location of the refineries, and the distribution infastructure of trucks, boats and pipes is more flexible than high voltage transmission lines.
The only problem is "where does te energy come from in the first place?", which the centalized electric system doesn't address either. Fusion power has to actually exist before you can even consider it, and all of the other possibilities such as oil, coal and nuclear all rely on the very same sources we're trying to get away from.
I have read articles about the possible use of algae for BD production. According to the article (which I found a version of on google) you can farm a high-oil content algae species for the purpose, which eliminates basically all of the problems of cultivating and fertilizing land for growing plants (algae doesn't need tilling...) Simply excavate a shallow lake somewhere relatively low and let gravity fill it with seawater, then start growing. If you're clever you can use a system of dykes to let the tide purge the lake for you and filter off the algae as the lake drains. Then you run it through a giant juicer and add a little methanol and lye to remove the glycerin from the product, and you got Biodiesel ready to burn in just about any existing vehicle.
=Smidge=
Do you have any concept of the amount of infastructure currently devoted to gasoline delivery that would largely be wasted in hydrogen distribution, or the amount of new infastructure required? And that is beside the point that they only way we can currently produce hydrogen on any sort of efficient scale is to strip it from crude or natural gas. I'd put a guess that the new h2 infastructure would cost two orders of magnitude byond your Iraq cost figure, and we would still be getting the h2 from oil (stripping h2 in a factory and burning it in your car produces less polution than burning fossil fuels in your car).
Degaussing scares the bad magnetism out of the monitor and fills it with good karma.
If I recall correctly, the efficiency of the electrolysis/fuel cell cycle is about 50%. Some types of batteries do much better, at 80% or so. You're going to need a lot more power to run cars on electrolytic hydrogen than on batteries, and the difference between the two is something like 30% of current consumption - far from trivial.
On the other hand, with the current market penetration of electric vehicles you could do things either way and it would be cheap, especially if you used off-peak electricity exclusively. It's when you begin converting substantial parts of the vehicle fleet that the impact would be felt; you'd have to make big investments in the generating part of the infrastructure, mostly to replace low duty-cycle peaking generators burning expensive fuel with high duty-cycle or base-load plants burning cheap fuel.
Sustainability and energy independence essay
While I agree with your assessment of biodiesel being a good alternative to fossil fuels, I think you've missed some points on centralized production.
Yes, all of your pollutants would be centralized as well. But a modern oil burning power plant will release dramatically less pollutants than the equivalent (ICE) internal combustion engines. With a power plant, weight doesn't matter. That allows them to focus on production efficiencies and reducing pollutants. As new technologies are invented they only have to be installed in one place rather than 50-100,000 privately owned vehicles. And there are also benefits in regulating. For most people, if they didn't insist on driving huge SUVs, current electric technology would be more than sufficient. And for most, charging could be scheduled during off peak hours, reducing stress on the grid.
Economies of scale. In the 80's an ICE was only about 20% efficient. I'm sure that has increased with on-board computers and fuel injection, but since most of the inefficiencies were from heat loss, I doubt that it has increased dramatically. Steam generation and electric motors, OTOH, are extremely efficient. There will be losses in power transmission, but those are known variables.
I'm going to have to agree with others here, there is no one alternative to fossil fuels. Electric, whether with fuel cell or battery technology is one of them. Biodiesel and Ethanol is another. They address different market segments.
It is amazing what you can accomplish if you do not care who gets the credit. -- Harry Truman
For most people, if they didn't insist on driving huge SUVs, current electric technology would be more than sufficient.
:) And while it generally pays to "build bigger" (large powerplants having much better efficiencies) and electric motors nowadays are approaching 90%+ efficiency, battery storage systems are still extremely inefficient. By the time you get from the fuel to the road I'm not sure if you're spending the energy any wiser.
There are frequent brownouts in many urban areas during the summer because people are running their air conditioners. It's less frequent where I am, but it still happens. If the existing system can't fully satisfy peak demands, then switching everyone to electric cars is only going to make the problem worse - even "off-peak" charging, since off-peak will then become peak as millions of people plug their cars in to juice up. Lots of infastructure upgrades will be required to make it work...
Economies of scale. In the 80's an ICE was only about 20% efficient. I'm sure that has increased with on-board computers and fuel injection, but since most of the inefficiencies were from heat loss, I doubt that it has increased dramatically.
It hasn't
Doing some googling on the subject:
Coal powerplant: 45%
Transmission lines: 92% overall
Battery Charging: 87%**
Battery Discharging: 33%**
Electric motor: 98%
* It says "thermal" efficiency, but I'll take it as overall fuel->electric efficiency
** For lead-acid batrery. Depends on battery construction, charge and condition.
Multiply that up and you get an overall fuel->road efficiency of just under 12%. Ouch... if you have any other sources of information please share.
I'm going to have to agree with others here, there is no one alternative to fossil fuels. Electric, whether with fuel cell or battery technology is one of them. Biodiesel and Ethanol is another. They address different market segments.
Yes, exactly. My feeling is, though, that trying to replace petrolium fuels as directly as possible will be more sucessful than trying to replace/augment the existing infastructure. The "system" works pretty well and if it can be used it wold be worth it.
=Smdige=