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$1/Gallon "Green Gasoline" In Sight

mattnyc99 writes "We've gotten excited here about the startup that claims it can make $1/gallon ethanol out of anything from trash to tires. But we've also seen how cellulosic ethanol is a better option, and how ethanol demand in general is only adding to the worldwide food crisis. So what about $1/gallon gasoline? NSF-funded researchers at UMass Amherst just completed the first direct conversion from cellulose using a new method of hydrocarbon refining, which they claim can be commercialized within 5-10 years and essentially make fuel out of anything that grows. Quoting: 'We already have the infrastructure in place to distribute liquid fuels. We're using them to power transportation vehicles today, and I think that's what we'll be using in 10 years and in 50 years,' Huber says. 'And if you want a sustainable liquid transportation fuel, biomass is the only way to go.'" The process is running at about 50% efficiency now; the $1/gallon figure is based on getting to 100%.

33 of 740 comments (clear)

  1. Re:I'm willing to pay $2/gallon by aliquis · · Score: 4, Interesting

    For the consumer or in some huge volume?
    1 US gallon = 3.78541178 litre

    Over here in Sweden the taxes put the gasoline price at something like 12.49-12.99/litre in this town right now according to a webpage.
    Say 12.70 sek / litre * 3.785 = 48.07 sek.
    8.36$ / gallon in the gasoline station.

    So yes, people would gladly pay 2$/gallon here. In face people already pay almost 1.5 $ / litre for etanol/E85. (And we do have tax reduction / no taxes(?) on that.)

  2. Re:I say! by Anonymous Coward · · Score: 5, Interesting

    Well, I can't say exactly how long it will take to commercialize, but the company I work for, which may or may not have been mentioned in the article (wink) has a production-scale run of the catalyst scheduled for later this year. I wouldn't scoff too hard at a 5-10 year projection.

  3. Re:doing research != speaking well by N1ck0 · · Score: 3, Interesting

    The 50% efficiency is how much of the biomass energy they can convert to the "high-octane liquid". Can they get to 100%? No...you cannot extract 100% energy from something, also the process that is getting you 50% yields will probably require much more energy then what you are doing right now.

    Also does this $1/gallon figure account for the energy needed to raise/cool this biomass the 1000 degrees per second? Also the cost of getting the biomass? And the cost of collecting (and probably liquifing/straining/etc this biomass. Is this $1/gallon number include current tax rates for transportation maintenance? I have a funny feeling that that might just be the cost to actually execute the refinement assuming everything else was free.

  4. I just tried this E85 stuff.. it sucks by bill_kress · · Score: 4, Interesting

    I just bought a car that happens to take this E85 ethanol combo gas.

    It dropped my mileage from city 22 to like 16, highway 30 to 22.

    It was a little cheaper due to government subsidies ($2.77 vs $3.30 at the time), but it didn't come close to breaking even with the drop in mileage.

    Overall very disappointed.

    Where are the plug-in hybrids?

    1. Re:I just tried this E85 stuff.. it sucks by bill_kress · · Score: 2, Interesting

      As I understand it, to recharge an electric car in your garage costs you an equivalent of less than $.50/gal--so screw green.

      But does anyone have validation of this?

  5. Re:Huh What? by jawtheshark · · Score: 2, Interesting
    *blink*
    I know that ethanol has some solvent properties, but corrosion? Yeah, it will dissolve the paint of your car.... Not nice, but don't spill. I have an ethanol powered oven. It's for decoration only, even though it puts out a substantial amount of heat. The ethanol I filled in the stainless steel furnace is still there. I can turn it on anytime I want. No rust (=corrosion) whatsoever.

    So, frankly, the typical concrete gas bunker won't corrode. It also won't corrode any of our modern car tanks because they're plastic and ethanol and plastic get along quite nicely.

    Yes, in pure gasoline cars it will attack the rubber in the engine. No, this has nothing to do with what you mention.

    I really must be missing something.

    --
    Ahhh...the great dumpster continuum. Many a free computer will be found there. -- sowth (748135)
  6. $2/gal to produce = $3/gal at the pump by Overzeetop · · Score: 3, Interesting

    That's rough, but at $118/bbl, the cost of refined gasoline is somewhere about $2.50/gallon. The $3.50 you're paying at the pump includes distribution and taxes. So you'd pay $3/gallon for a fuel that stores only about 60-65% of the energy as the $3.50/gallon gas your paying now. Not really economical. At their theoretical 100% efficiency, it's about a wash, though you'll still have to visit the pump half again as often to fill up.

    --
    Is it just my observation, or are there way too many stupid people in the world?
    1. Re:$2/gal to produce = $3/gal at the pump by timmarhy · · Score: 2, Interesting
      $3/gal not economoical? fuck me i'm paying $1.5 a LITRE. that's about $6.6 USD/gal.

      sign me up if you can make fuel for $3/gal.... or maybe you need to realise there is more to the world then the USA

      --
      If you mod me down, I will become more powerful than you can imagine....
  7. Who wants to bet... by vivin · · Score: 1, Interesting

    ... that this may not see the light of day? I want to see this come to fruition as much as (most) anybody else and I don't want to be this cynical and/or conspiratorial. But I wonder how the oil companies would react to this, or even the US government - would it be apathetic. I mean... remember the Electric Car? My more optimistic side hopes for this to actually come true.

    --
    Vivin Suresh Paliath
    http://vivin.net

    I like
  8. You heard it here first... by rickb928 · · Score: 3, Interesting

    When we can make affordable fuel out of trash, garbage, and untreated sewage, then trash, garbage, and untreated sewage will nearly immediately be in short supply. Cost of the raw material will increase, and make the finished product less affordable.

    Pretty soon after that, we will cut down perfectly good trees for no other reason than to make liquid fuels. Darn. There goes the forest. And the parks, etc. Not so good.

    It's just not that easy. But it's attractive, and will keep us until we can do the electric car thing and do away with liquid fuels altogether.

    Maybe.

    --
    deleting the extra space after periods so i can stay relevant, yeah.
  9. I have a diesel engine, I run on almost anything. by Regul8or · · Score: 5, Interesting
    I've been putting used motor oil, hydraulic fluid, transmission fluid, gasoline, solvents, and misc. oils in my truck's tank for years now. I mix in these waste products with clean bio/#2 diesel at a rate of about 33%. Of course I filter down to 20 microns and check for water in my fuel.

    When I calculate my fuel mileage based on ONLY how much diesel I actually pay for, I get about 30-33 highway mpg in my 7900 pound 3/4 ton diesel truck.

    Gasoline engines are a flawed design and gasoline/ethanol is a flawed fuel. It does have a place such as in motorcycles or small engines. I'll take my diesel powered vehicle any day of the week over some inefficient gasoline powered vehicle.

  10. Re:I say! by Torsoboy · · Score: 3, Interesting

    Truth. The premise of the third movie was that they couldn't get the Delorean up to 88 MPH since they had no gasoline.

  11. Re:Thanks ethanol for world hunger and beer prices by CorSci81 · · Score: 2, Interesting

    Malted barley prices have been going up for microbreweries as a result of farmers planting corn instead of barley. My family runs a small craft brewery and we've been feeling this pinch firsthand along with the shortages/high-prices of hops. It's not just the big players that will have to raise their prices.

    And FYI corn can be a perfectly valid adjunct if you're trying to achieve a specific flavor. We produce a blonde ale that uses a corn adjunct for that purpose. It just shouldn't be used solely for the purpose of making the beer cheap by replacing as much malted barley as possible. Besides, rice is a more popular adjunct for that since it imparts less flavor/color.

  12. Re:Think again by cayenne8 · · Score: 4, Interesting
    "Even assuming we built enough reactors and the bacteria work fast enough, do you have any idea how much organic waste we have to rustle up to make 588 million gallons?"

    I do wonder how much organic waste we are just letting go in the garbage every year now, though? I mean, millions of yards get mowed weekly (or more depending on where you live)....not to mention golf courses, stadiums, parks...etc. Then as someone said, we have tons of paper and boxes that are garbage each day. How about recycling most all of that waste paper into fuel?

    I'd say at the start...that amount of ethanol, combined with the domestic oil reserves we have....could get us off the world 'grid' pretty quickly. Eventually..we could get off the fossil fuel altogether, but, this would be a huge stop-gap answer.

    I wonder how much organic waste we currently just throw in the trash now, which could go for this type of ethanol generation? We could quit using corn for ethanol (well, except for consumption) right away too.

    Now, if we could just do away with the fscking corn subsidies, and lift the sugar tariffs we could also kick the HFCS problems we have, get food prices back down a bit, and have real Coke with real sugar again in the US.

    --
    Light travels faster than sound. This is why some people appear bright until you hear them speak.........
  13. Terra Petra - burying your stable carbon biomass by filmotheklown · · Score: 4, Interesting

    This is being done/worked on. It's called Terra Petra "Black Earth" and is being developed for use in biomass gasification.

    Basically you gassify carbonaceous materials such as wood or other biomass. Instead of allows all the biomass to be consumed in the process, you pull a portion of the charcoal out of the gasification stream and then disc it into the earth. Charcoal, being a fairly stable version of high density carbon will remain in this state for a very long time and in a sense becomes fertilizer for the soil (over time). Charcol is a more stable form of carbon than just raw biomass which will otherwise decay into CO2 as it rots

    In fact, in the amazon, this has been going on for 1000s of years and is a way to make otherwise not so great tropical soils fertile.

    Gasification combined with Terra Petra has the possibility of not only being carbon neutral, but carbon negative. If you gassify existing biomass (in particular the waste wood and garden clipping stream of most municipal wastes) you start out carbon neutral. The carbon in the waste stream is already destined to either be incinerated or 'mulched' which releases the carbon as CO2 either way.

    If during the process of gassifying this biomass stream, you extract a portion of the charcoal that is created, you can then sequester it in the soil. Thus becoming carbon negative to the extent you pull from your gassifier. The trade off is that you have less carbon to convert to CO for use as a producer gas.

    --
    Filmo The Klown
  14. Incinerator by CustomDesigned · · Score: 5, Interesting
    Here in Fairfax, VA we have an incinerator. It burns the trash to make electricity, and separates out glass and metals for resale, and traps and separates gases in the exhaust for resale. All the separation is run by its own electricity - and it sells the excess of that also. It is a highly successful installation. They are digging up landfills for more trash to feed it.


    The only drawback is that the landfills are being refilled with ash, and eventually will run out of room again.

    1. Re:Incinerator by lorenlal · · Score: 2, Interesting

      How bad is the ash? Could it be used (say in fertilizer or household items)?
      Or am I a moron for asking?

  15. Re:I say! by Mr.+Slippery · · Score: 5, Interesting

    Those CFLs are *mercury free*, right? And that electric car isn't going to be charged from a coal plan, is it?

    If you trashed the CFLs, the amount of mercury released would be less than the mercury released by coal-fired plants to power the equivalent in incandescent lights.

    And CFLs can - and should be - recycled, so no mercury is released except for the occasional broken bulb. If you break one, you just take some simple precautions to clean up. They have about 1/100th of the mercury in a old thermometer, the type everyone had in their house not very long ago.

    Environmentally, mercury in CFLs is a very very small issue.

    And an electric car powered by a coal-fired generating plant still emits much less pollution than a gasoline car.

    So what's your point?

    --
    Tom Swiss | the infamous tms | my blog
    You cannot wash away blood with blood
  16. Re:I say! by Skillet5151 · · Score: 4, Interesting

    Post to undo accidental modding. A long set of dropdown boxes that take effect immediately with no way to confirm or change...what could go wrong?
    (Or have I missed something?)

  17. Econ 101 by jmorris42 · · Score: 1, Interesting

    > So in theory we could be seeing this with $2 or $3 a gallon gas fairly soon...

    No. Even assuming that at 50% efficiency they can produce a gallon of fuel for $2 we still need to figure in a profit for the manufacturer, transportation and a profit for the retailer. Now add in taxes at each level, regulations, polution controls, etc. Might squeek in at $4 by the time it hits the pump. Of course in five years there might be a market for a $4/gallon alternative fuel.

    If you want to understand the overhead involved look at gas. When oil was selling for $15-25/barrel gas was retailing between $1 and $1.50/gallon. Oil is now selling for >$110/barrel and gas is averaging $3.50/gallon. Kinda gives you an idea how much of the gas you are pumping goes to the terrorists in the middle east and how much is being eaten up in refining, taxes, profit and misc overhead.

    --
    Democrat delenda est
  18. Recycling needs cheap oil by Simonetta · · Score: 1, Interesting

    Here in Portland Oregon we have manditory garbage recycling. Everybody has to seperate their plastic from the glass from the newspaper and so forth. It's a sham because it requires three times as many garbage trucks to collect the seperate catagories. There's three times as much diesel consumption to run these garbage trucks and three times as much noise pollution in the early-morning hours when they are collecting. The energy saved by the Mickey Mouse recycling schemes is less than the extra energy expended to truck out the seperated garbage to the distant landfills. So what's presented as advanced Green lifestyle is just more brown horseshit designed to make the latte-Volvo bohemenian boozhwah crowd feel good. Sad but true.

  19. Re:no way. by rcw-home · · Score: 2, Interesting

    a heat pump might only consume 500W of electrical power (I made that number up) in order to dump the same 1000W into the same room.

    Real numbers, for the curious: Not more than 303 watts, for Energy Star compliant geothermal heat pumps, and not more than 427 watts for Energy Star compliant air heat pumps. The ratio for the first is the Coefficient of Performance (COP) rating - the lowest mentioned there is 3.3, 1000/3.3=303. For the second, it's Heating Seasonal Performance Factor (HSPF), which is the same thing except in BTUs/hr per watt instead of watts per watt. The lowest HSPF is 8.0, or 2.34 watts per watt. 1000/2.34=427.

  20. Re:I have a diesel engine, I run on almost anythin by krazytekn0 · · Score: 2, Interesting

    Actually most of those things have less emission waste than diesel... He is probably prematurely gunking up his engine. but as far as gaseous waste he's most likely not doing any worse than running straight diesel. I had a diesel volkswagen that would go 40 miles on a gallon of canola... it smelled like french fries.

    also of note is the simple fact that diesel engines are so much more efficient than gasoline engines. For comparable power, a diesel engine will push a small car at least twice as far as a gasoline engine. In trucks the difference is not so pronounced because of their larger aerodynamic drag... Not until you get into heavy hauling situations where you're once again fighting the sheer weight of the vehicle much more than the air resistance. Also, diesels have fewer moving parts and typically will run at least 5-10 times as many miles as gasoline engines in similar applications. I've seen a 1991 Dodge D350 with 700,000 miles on it, and it still gets over 20 miles to the gallon.

    --
    Not all life is cyber. Extra Income
  21. Re:i couldn't have said it better myself by TheLink · · Score: 3, Interesting

    I figure a better way to store hydrogen would be with around a chain of carbon atoms ;). There's a lot of hydrogen you can store that way.

    Either we burn the result, or we figure out how to build filters, fuel cells and catalysts that can handle the result in an environmentally friendly way.

    A big benefit of having an electric subsystem is for the regenerative braking.

    The benefit of sticking to hydrocarbons would be backward compatibility.

    One of the problems is if we use rare catalysts - there might not be enough to go around to put in every vehicle (assuming a believable catalyst recycle rate when the vehicle is scrapped).

    --
  22. Re:i couldn't have said it better myself by drinkypoo · · Score: 4, Interesting

    And you have plutonium factories all over the place. If you don't see the problem with that. Google the news for "Iran nuclear". >

    Actually, you're wrong. That's a POSSIBLE consequence, but not a necessary one. The reactors do not need to be of a type useful for making weapons-grade material in order to be useful for making useful nuclear reactor fuel.

    And the waste problem remains unsolved.

    The reprocessed waste has a half-life which at least seems manageable on a human time scale, and is not nearly as nasty in any case.

    Skip uranium entirely. Go to an "energy amplifier", where thorium is hit with a proton beam. It's subcritical - pull the plug and it shuts down. It's proliferation-resistant, and it can even be used to burn up plutonium. And it produces a lot less waste.

    Per your source, This design is entirely plausible with currently available technology, but requires more study before it can be declared both practical and economical.

    --
    "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
  23. Re:I say! by drinkypoo · · Score: 3, Interesting

    Saving energy is not even in the top three reasons for recycling, although if there are cases where you *can* save energy by doing so, that's a pretty nice benefit.

    Actually, quite a bit of the environmental cost of using steel or aluminum is related to the energy cost of refining it.

    It would make more sense to stop making so much plastic shit than to recycle it. We can make compostable hemp plastics. No shit. You can make them with corn too, but corn is not a good feed stock for reasons which should be obvious.

    Given that most of our energy comes from Coal in this country, you should be concerned about the energy cost issue.

    --
    "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
  24. Re:I say! by Rei · · Score: 4, Interesting

    not sure where you pulled that from? Their seams to be one clean coal plant in the US, and with batteries not being exactly green, and a pure electric car costs more to run than the same car running on hybrid (if battery replacement cost is not subsidized.) Throw in all the radio-active emissions of coal plants (none in gasoline.)

    It's very, very simple. Gasoline engines are very inefficient. Non-hybrids average less than 20% tank-to-wheel efficiency. Hybrids, just over. Fuel-burning power plants, 30-50% efficiency. Transmission losses, ~8%. Charger losses, ~7%. Battery losses, ~0.1% in Li-ion. Motor losses, ~10%. Do the math. I can give you several peer-reviewed studies on the topic if you're prefer.

    As for batteries, you're just not up to date with the technology. These aren't lead-acid or nickel-cadmium batteries here. For example, my Aptera is to use lithium phosphate batteries. These last 10-20 years and are almost completely nontoxic. Their raw ingredients are things like iron, phosphoric acid (the same stuff as in soft drinks -- made from fluoroapatite, the same stuff as in well cared-for teeth, plus sulphuric acid, which is an oil industry *byproduct*), graphite, and even sugar (for the carbon binding). These aren't "in a few years" -- they're already here. They're becoming the new standard for cordless power tools, for example.

    Considering low emission gas vehicles currently exhaust cleaner air than they take in

    That's nearly always a myth promoted by the manufacturers. If you look at the actual numbers, they usually lower one pollutant by a tiny amount (say, particulate matter caught up in the air filter) while still emitting the other pollutants.

    --
    I just invaded Grammar Czechoslovakia and duped Grammar Neville Chamberlain; now it's on to Grammar Poland.
  25. Re:I say! by nickname29 · · Score: 4, Interesting

    (and was used to make gasoline in SA),

    The sentence should read: Is still used to make gasoline (petrol, diesel) in SA, and Qatar.

    however it's not energy efficient, and i hardly believe that this process is either.

    CTL and GTL is energy efficient. It is cheaper to manufacture gasoline from gas or coal than to pump it out of an oil field. SASOL (the company in SA that makes gasoline from coal and gas) has grown considerably during the high oil prices. Their stock price doubled in a year. They made huge profits at $40 dollars/barrel - imagine what they are making now. There were even calls for a special tax on this company (since it makes humongous profits).

    Here is a stock chart for SASOL (on the LSE). As you can see, the stock price is 6 times what it was in 2004.

    Just a side note, making cellulistic ethanol is a much harder and difficult beast â" it is more difficult (by a few orders of magnitude) than making ethanol from corn.

  26. Re:Yield != efficiency by electrictroy · · Score: 1, Interesting

    Here's a quick way to reduce consumer consumption by one-third:

    - Get everyone to drive 88 mpg VW Lupo 3L's. There's enough room to carry a family of 3, plus groceries or soccer equipment. (Or a 70mpg Honda Insight; perfect commuter vehicle.)

    But no, instead people keep driving their 20mpg Ford Living Rooms.

    --
    The government is not your daddy. Its purpose is not to raid middle-class neighbors' wallets and give it to you.
  27. Re:I say! by prisoner-of-enigma · · Score: 2, Interesting

    For example, my Aptera is to use lithium phosphate batteries. A quick Google search yields the following website: http://www.aptera.com/. I'm assuming that's the source of the car you're referring to. Digging around in it a bit, I find the following:

    What will be the battery life and cost replacement?

    This depends largely on usage and if you have an "All Electric" or an "Electric Plug-in Hybrid" version of the Aptera. We will share these exact numbers when they become available closer to the start of Aptera production.


    So your 10-20 year lifespan of the battery isn't documented on the website anywhere that I can find.

    To its credit, Aptera does say its car will cost between $26,900 and $29,900. I wonder how much of that is subsidized, though. And paying $30K for a car that does 0-60 in 10 seconds, carries two passengers, and practically no cargo isn't exactly a screaming bargain. You'd be far better off buying a more conventional gas/electric hybrid like the ones currently available.

    I also note on the Aptera site that the car isn't designed for cold climates. Availability is almost non-existent as well. Last, and perhaps most distressing, Aptera offers no warranty on the vehicle. Sure, they're working on something, but as of now you get nothing. Remind me again why anyone except the most die-hard tree hugger with deep pockets and no family would ever want to buy this thing?

    --
    In the end they will lay their freedom at our feet and say to us, Make us your slaves, but feed us. - Fyodor Dostoyevsky
  28. Re:i couldn't have said it better myself by Eivind · · Score: 2, Interesting

    Oh really ? You don't feel a -TINY- bit dishonest here ?

    I state "perhaps 1% of the energy-density", you quote a site that says: The best mass-market rechargeable batteries today have an energy density of ~160Wh/kg. Next generation cells are expected to have energy densities of a few hundred Wh/kg. Gasoline has an energy density of ~12,000 Wh/kg In case your math-skills are down, 160/12.000 is pretty much in the 1% ballpark I mentioned.

    I was talking about actual existing batteries by the way, not fantasy-ones. There are no cars available powered by fantasy-batteries. When there are, these things may change.

    Furthermore, the article compares hypothethical FUTURE battery-cars with poor examples of TODAYS internal-combustion engines. For example, it quotes tank-to-wheel efficiencies at 20%, which is not even state of the art TODAY.

    A perfectly normal modern diesel does 30%. More radical designs (still ones on the market TODAY) like hybrid diesels can do 45%. And there is no reason to assume that batteries will shortly more than double in performance whereas internal combustion based vehicles will make no progress whatsoever.

    It is even -more- wrong in areas where heating is desireable, like 2/3rds of the year where I drive: Some of the "loss" in tank-wheels efficiency is used in heating the interior of the vehicle, defrosting windows etc.

    So, in short, the article claims "equal" performance (86Kwh delivered from 350Kg of machinery), whereas the reality, if you buy best-of-breed from internal-combustion and batteries TODAY is more like, the battery-powered thingie will have 1:6th the range of the IC-one, and it'll spend twice the mass-budget to do that. Which isn't so bad. Where it gets ugly is when you add in that the IC can be completely retanked in a minute, whereas TODAYS electric vehicles need multiple hours to even do a 75% recharge. (the last few percents take even longer)

    But yeah. My 2001 (not even current) Toyota does 750km, and refill in a minute. If an electric vehicle could do atleast 160km (100 miles) and recharge similarily quickly, it'd have a chance. If it could do 250km, recharge in a minute, the IC-cars would be dead.

    You're right that people should take breaks when driving anyway, but the thing is, with 100 miles range, it means the thing is empty in a -single- hour of driving (okay, make that 1.5 for those of you not in germany), and with gas-stations being spread thin in some areas, there's a small margin. Signs with "last gas-station for 50miles" aren't rare where I live, so it WOULD be very impractical to need to stop at precisely timed intervals, and very often.

  29. Re:"out of anything that grows" ... by Profane+MuthaFucka · · Score: 2, Interesting

    Great, we'll get central planning on this right away, and our farmers will receive their new growing orders from the national directorate this winter.

    Oh wait, that won't work. Corn and potatoes are going to sell for X dollars a pound, and switchgrass is going to sell for 10X dollars a pound. Farmers with good land are going to grow corn and potatoes when they can grow shitloads of switchgrass on their very fertile land? Come on.

    Plus, switchgrass cannot supply our needs. Demand is too high. That means that the prices will NEVER come down to make growing food profitable in relation. Even the holy invisible hand of the market won't save us.

    This is a recipe for mass starvation in the world.

    --
    Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
  30. Re:I say! by BlackSnake112 · · Score: 2, Interesting

    Define needs. Just going to work every day, then a small car would work. Hauling all the gear for the small car doesn't fit the bill. Now if you can afford to have more then one car then good for you. A lot of us out there cannot. Renting the bigger car is not an option for a lot of us.

    I moved closer to work. Paying more for a lot less just to cut the commute down. I fill up 1-2 times a month with my bigger car. The two prius people fill up once a week at least (according to them). So 47.6 (11.9*4) gallons a month vs 32 (assuming both fill ups). Who is burning more fuel? Usually I fill around 1/2 tank not empty so it is more like 8-10 gallons a fill not the full 16. I figured I give the full amount on both to be fair. The prius people were quite pissed off at me. When I told them how often I fill up. Both prius people have a second bigger car for family trips. The prius is too small for all of them plus their stuff at the same time.