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More "Miles Per Acre" From Bioelectricity Than Ethanol
CarnegieScience writes "Scientist calculate that, compared to ethanol used for internal combustion engines, bioelectricity used for battery-powered vehicles would deliver an average of 80% more miles of transportation per acre of crops, while also providing double the greenhouse gas offsets to mitigate climate change."
Miles per acre? What's that in rods per hogsheads?
The problem with using biomass to generate electricity to run cars is that you've got to get the electricity into the car and store it there, usually in a lithium-ion battery. That whole process probably diminishes your efficiency by an order of magnitude. If this guy's taken all that into account, well, so far so good. But I think we're going to need literally quantum advances in energy storage technology (think molten salts and carbon nanotube supercapacitors) before we can get fossil fuels completely out of our transportation system.
The real advantage of producing ethanol right now is that you can just mix it into gasoline and sell the combination fuel (E85) for use in most post-2004 model year cars. It doesn't require a total revamp of the energy distribution network for vehicles.
...now all we need is a fuel that comes in the form of a long string, and we can finally express fuel efficiency as a dimensionless number.
BTW, 20 miles per gallon works out to 3.4409911e+10 inverse acres. Or, to look at it another way, one gallon per 20 miles is 2.9061395e-11 acres, or about 0.12 square millimeters. That's the diameter of the imaginary thread of gasoline that your vehicle is gobbling, Pac-Man-like, as you drive down the highway.
Comparing energy production density to Corn-based Ethanol is like stealing candy from a baby. Corn-fueled Ethanol has a tough time doing much better than just burning fossil fuels outright in systemic carbon footprint, and in some studies, is actually WORSE than strictly burning gasoline/oil.
Yes, the average is a net improvement of anywhere from 25% to 70% return on investment, but even then, you have to consider the value of the farmland itself! We'd probably do much better by simply growing wild grass on prime farmland, harvesting it, and burying it, when looking in terms of carbon footprint!
So saying that NNN technology is X% better than bioethanol is like saying that doing X is less painful than scraping off your penile foreskin with a cheese grater.
Truthful, but not very useful. Come back when you have something that actually works. For example, what's the benefit of bio-electricity over Photo-voltaics? Now that the latter technology is down to (or better than) $1/watt, this becomes a very, very tough technology to beat, and actually works better on craptastic, rocky soil off in the desert someplace with 3 inches of rainfall per year.
Meaning, we can get back to using farmland for growing food, and stop with this silly "let's raid the kitchen cupboard to feed our guzzling SUVs!" craze that's been on for the last few years.
I have no problem with your religion until you decide it's reason to deprive others of the truth.
Food crops as energy sources was never a good idea, we didn't breed them for their modern harvestable energy content, and even if we did we'd be offsetting fuel crops. Algal Oil is a MUCH better biofuel solution as it can be build anywhere you have the following things:
A) Land [cheaper the better] .. so cannot pull it straight from the air, have to filter it.. but pretty much everywhere]
B) Source of Water [doesn't neccesarily need to be fresh or particularly clean, in fact fertilizer polluted water might even be a good thing]
C) Source of Carbon Dioxide [clean CO2
D) Sunlight
And it already works, we have "pilot plants" already cranking it out.
Don't have to offset prime forest or prime agricultural - vast stretches of the semidesert southwest would be usuable.
If you cannot keep politics out of your moderation remove yourself from the Mod Lottery.. NOW!
We can get fossil fuels out of our energy system right now with drop in non-fossil replacements like Algal Oil [ see my discussion of it in this thread http://tech.slashdot.org/comments.pl?sid=1225951&cid=27864987 ]
If you cannot keep politics out of your moderation remove yourself from the Mod Lottery.. NOW!
I'm driving a home-converted electric car right now. I didn't even choose my components for efficiency, and according to my kill-a-watt meter, I'm still running more than twice as efficient as an internal combustion engine.
There have been several studies comparing overall efficiency, including power transmission losses. The EV wins every time.
For geek dads: Contraction Timer
The real blow-it-out-of-the-water numbers are when you eliminate "bio" from the equation, period. Corn yields 300-450 gallons of ethanol per acre. Sugarcane, about 550-850 gallons or so. Switchgrass can theoretically yield over 1000 gallons per acre and algae 5000, although those numbers are likely to get way smacked down by reality (especially the algae numbers). But let's just go with them. CAFE average is ~24mpg, and you get less mpg on ethanol, but hey, let's just say our cars get 40mpg. The average driver goes 12k miles per year, so corn can support 1.3 drivers/acre, sugarcane 2.3 drivers/acre, switchgrass 3.3 drivers/acre, and algae a way-over-optimistic 16.7 drivers/acre.
A compact linear fresnel reflector solar thermal generating station produces about 1MW nominal capacity for every 4 acres and has about a 20% capacity factor (in non-optimal sites). That's an actual MW per 20 acres, or 488,288,000Wh/acre-year. The Volt and Tesla Roadster both use about 200Wh/mi, so let's go with a more pessimistic 300Wh/mi after losses and with less efficient designs. That's 121.7 drivers per acre. I.e., it beats the pants off even the highly speculative numbers for algae. And it uses no water or fertilizer -- and we use *way* too much water as it is.
If you want land efficiency, converting the sun directly to electricity and using that electricity directly rather than having the intermediary stage of "plants" is the way to go. And we farm too darn much of this planet as it is already.
You're not made of Tuesday!
Aglae can produce oil instead of ethanol. Oil that can be treated just like light sweet crude at the refinery, with a lot less impurities [so it's easier to refine].
So to not do something stupid like Algae Ethanol and do Algae Oil the biggest advantage is it's a potentially carbon neutral drop in replacement that can be used in existing gasoline and diesel engines.
If you can get efficient storage of electricity (like hopefully EEStor isn't full of it) a pure-eletric system will be better - but at the same time we can cut our greenhouse gas emissions massively by using Algal Oil as a drop in replacement for fossil oil.
Now as gas/diesel demand drops down in about 50 years we can do other things with that algae production infrastructure I'd imagine.
If you cannot keep politics out of your moderation remove yourself from the Mod Lottery.. NOW!
Of course, the obvious NEXT questions are annoying things like:
1. What kind of numbers do you get with nuclear and/or fusion reactors, instead of biomass reactors or cornfields?
It is worth mentioning that the MIT Nuclear Engineering senior project recently was the engineering design of a fusion reactor to produce hydrogen for automotive fuel. One of the reasons given for producing hydrogen rather than electricity is that we don't have anything remotely resembling a power grid in the Northeast that could handle the output of a commercial-size fusion reactor.
And their design was apparently conservative: you could build it, starting TODAY.
2. How do you distribute the electricity from your biomass reactor or your solar field to the cars? See previous paragraph about power grid issues.