May 23, 2008

Damn Gas Prices....

 One of the Brickmuppets' Crack team of Science Babes returns briefly from the beach to review a few things regards that thing that's on everyones mind right now.... GASOLINE ALTERNATIVES.

There is a lot of talk regards Robert Zubrin's plan.
Zubrin is a talented engineer and has an amazing out of the box imagination. His plan is laid out here and there is a typically literate discussion of it going on at Jerry Pournelle's place here.

One big quibble I have is that Zubrin seems dismissive of fears that corn to ethanol processes will lead to food shortages, and indeed it is likely that a lot of the current spike in domestic food prices is due to petrol induced transportation costs.
However, both directly and indirectly, burning food will raise its cost and scarcity. (It's Science!)
Zubrins plan is interesting in other ways. While he is a biofuel advocate, his focus is on methanol. Methanol has a few disadvantages...
It's got poor energy density and it is corrosive, (eating aluminum and rubber) thus it requires  specially designed engines. It is also toxic but given that gasoline is not exactly FDA approved either this at least seems to be a silly gripe. Methanol (like Ethanol) is unsuitable for diesel engines and is generally used in otto cycle engines which exacerbate its poor energy density...One can go ~ half as far on a tank of methanol...assuming you don't have an aluminum engine block in which ones trip is shorter still.

(Much is occasionally made of the fact that Methanol can be refined (via dehydration) into dimethyl  ether which is a diesel fuel with a substantially higher cetane rating which gives it even better energy density in a compression engine than regular diesel. This is actually a superb diesel and jet fuel with spectacular energy density per volume...rather too much in fact as, unlike other such fuels it is highly  flammable, making it a safety hazard for ships and jets.It also is a gas at normal temperatures and pressures which nullifies  its energy density advantage and imposes handling problems. Thus I am very skeptical that CH3OCH3 is the answer to our fuel needs.)

   Note though that methanol has the very large advantage that it can be made from most types of trash as well as the inedible portions of crops....in fact it can be made  from virtually any bio-organic matter.

(This is an good place to remind people that non-edible portions of crops are not technically trash, they are normally recycled into the soil as fertilizer, so alternate fertilization methods are necessary...this is not insurmountable of course, but it is a nontrivial concern)

Methanol is, despite its disadvantages, a vastly better idea than corn based ethanol which is ranked by efficiency on this chart that will...er...spoil the lunch of ethanol fanatics.

Ascending order
Crop kg oil/ha litres oil/ha lbs oil/acre US gal/acre
corn (maize) 145 172 129 18
cashew nut 148 176 132 19
oats 183 217 163 23
lupine 195 232 175 25
kenaf 230 273 205 29
calendula 256 305 229 33
cotton 273 325 244 35
hemp 305 363 272 39
soybean 375 446 335 48
coffee 386 459 345 49
linseed (flax) 402 478 359 51
hazelnuts 405 482 362 51
euphorbia 440 524 393 56
pumpkin seed 449 534 401 57
coriander 450 536 402 57
mustard seed 481 572 430 61
camelina 490 583 438 62
sesame 585 696 522 74
safflower 655 779 585 83
rice 696 828 622 88
tung oil tree 790 940 705 100
sunflowers 800 952 714 102
cocoa (cacao) 863 1026 771 110
peanuts 890 1059 795 113
opium poppy 978 1163 873 124
rapeseed 1000 1190 893 127
olives 1019 1212 910 129
castor beans 1188 1413 1061 151
pecan nuts 1505 1791 1344 191
jojoba 1528 1818 1365 194
jatropha 1590 1892 1420 202
macadamia nuts 1887 2246 1685 240
brazil nuts 2010 2392 1795 255
avocado 2217 2638 1980 282
coconut 2260 2689 2018 287
oil palm 5000 5950 4465 635
note that of all biofuels listed, corn ethanol has the absolute WORST yield of any listed crop...naturally it is the one congress is pursuing with the utmost vigor.

Zubrins other big proposal is to mandate flex fuel vehicles.
 This is a very sensible idea and would mean that any car sold in the US would have to be capable of running on a wide variety of fuels including corrosive ones like methanol. This would allow consumers to buy whatever fuel was cheaper (perhaps seasonally) and solve a lot of the chicken/egg problem with alternative fuels....namely that people won't buy an alternate fuel car if they cant get fuel for it...and gas stations wont install methanol or other alternate fuel pumps if there are no cars to sell the fuel to. The downside to flexfuel vehicles is a slight reduction in efficiency since tolerances are necessarily lower. Also it has been pretty much accepted by now that it is challenging to say the least for any flexfuel otto engine to be made that will run on kerosenes like diesel fuel.

Ignoring, for now,  the potential represented by steam cars, this is bothersome because not only is the diesel cycle extremely efficient but the kerosenes and vegetable oils they have historically run on have very high energy densities.


Now two companies, Scania and Transonic Combustion have gone at this intractable problem  from the opposite direction and produced diesels that will run on alcohols...and unmodified on regular diesel...and on biodiesel! The Transonic development is rather closely guarded at the moment, but there is a bit of info here. Also, there is a good write-up on the Scania design (which is already commercially available)over at Green Car Congress.

Not only that...biodiesel, particularly from algae is an exceedingly promising fuel that need not interfere with crop production in any way. Brickmuppet Blog has ranted on this from time to time but there have recently been a  promising  development or two in this area.

Algael oil is 50 times as productive as the best non-algael  biofuel crops. There are hurdles to be sure, but certain species of algae produce oil as a energy storage medium and it requires very little refining to be used as fuel. The algae needs water, light, fertilizer and a sealed environment to keep competing , less "oily" breeds of algae, out, but its tanks need not be associated with farmland in any way, thus no food crop displacement. With artificial lighting (and assuming a way to mitigate the kerosene smell) the algael farms and pressing/refining rigs can be located in industrial parks or even cities. It is the only crop that can potentially replace petroleum in cars without turning the entire planet into farmland.

There is a very comprehensive overview of Algeal Oil theory here.

Note that with flexfuel vehicles, one need not worry about the need to replace ALL of the oil we consume. A mixture of algael oil, alcohols from trash and even our own domestic oil production would render us energy independent. The competition between the three would likely drive down prices over time as well.

Of course there is no such thing as a free lunch. None of the biofuel proposals will work without electrical input of some sort, either to facilitate fermentation or provide light, ventilation or just press the algae. Thus an external power source is needed. If one is serious about biofuels one is going to need to increase power generation capacity as our grid is already under strain.

If one is serious about biofuels one is likely enthusiastic about reducing pollution. Thus one is going to have to look at relatively non polluting sources of said power.

If one is not living in a fantasy land one needs to dismiss SOLAR and wind except for certain regional/ niche applications...our hydro is about at capacity and geothermal is useful in limited areas.

Thus if one is serious about biofuels one is going to be foursquare for  a crash program to increase our nuclear power infrastructure.

Ultimately, when it comes to alternattive energy, nuclear is the only alternative.

Nuclear is the future.

A rant from last year on THAT topic is here.

Today's 'Science Babe' is actually Emma Sky from the Phoenix Wright games. I believe it is  official artwork despite her summer attire.

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