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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."
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.
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 ]
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Agreed... pump em full of Algal Oil produceed biodiesel... instant carbon neutrality [assuming all energy used for pumps, etc in the production plant is carbon neutral which can be done]
That's the nice thing about using Algal Oil as a drop in replacement for fossil oil - it's chemically identical but all that carbon in it was sucked out of the atmosphere.
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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.
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Well, if you want to get all units-nazi about it, it's the annual output of an acre. So 15000 miles per acre per year (for the bio-electric option), or 321.7 microhertz per smoot.
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.
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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.
Yes, I was also disappointed that they use bioelectricity as a euphemism for "burning crops in a power plant". Wiring together a huge field of cucumbers stuffed with zinc and copper disks would have been so much cooler.
like, say, hemp, which is a nitrogen fixer.
Or use land that isn't suitable for crops like marginal land.
i know the phtysics of UV degrading plastics, but then again most of the applications im seeing aren't using your normal plastics. They seem perfectly capable of turning a profit.
As for yuor "blah blah combine" combines don't exactly work on HYDROPONIC CROPS...
Yes you have some valid points about wear and tear, but apparently all analysts and people experimenting with it think that at $50/barrel that Algal Oil is perfectly economically viable.
BTW: bioplastics.
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"Shipping is responsible for 3.5% to 4% of all climate change emissions" from same article
It's not the carbon emissions that are the real problem with cargo ships, but the NO and SO pollution. As far as I can tell, these are not greenhouse gases so much as carcinogens. While, yes, they do need to be reduced, your post was very misleading in implying that the majority of air pollution and climate change comes from cargo ships. It doesn't.
Where does this notion come from? No, seriously. Current electric cars are about the same weight on average as current gasoline cars (they tend to be heavier than other cars in their class, but the lighter classes are overrepresented currently, so it's about a wash). Same amount of material, and therefore.... they're somehow incredibly resource hungry? Where does this come from?
Or is the notion that batteries somehow consume incredibly rare resources? You're thinking of fuel cells, which take platinum (trivia: so do catalytic converters). For example, one of the most popular chemistries for EVs today is lithium phosphate. It's made of lithium salts (which are so abundant that their prices generally range from $4 to $8 per *kilogram*, and which are available at essentially limitless quantities in the oceans for $20-35/kg), phosphoric acid (one of the world's most common industrial chemicals, and found in soft drinks), sugar, iron powder, a porous polyethylene membrane (polyethylene being one of the cheapest and simplest plastics), graphite or amorphous carbon, and bulk electrolytes (formulations vary), plus casing, wiring, etc. What exactly in this mix are you seeing as incredibly rare? The cost of lithium phosphate batteries (and spinel cells as well) are predominantly capital costs, not materials costs.
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yea, but can they convert to pipes?
That is the unit used to measure how long it took to cross a lake by the fur traders. How many pipes did they smoke? Would that not screw with their greenhouse gas calculations?
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