need one to win a debate for prius against diesel where the diesel's supposed winning argument is that it can use biofuels.
Hi burritos, The biofuels that have been used in Diesels are oils. They are basically a good idea. While Ethanol can be mixed with diesel oil, and used as a diesel fuel, its usually not in North America. To win your arguement, the solution is that modern Tier 2, Bin 5 diesels are incompatible with high ratio present biodiesel fuels. I believe the limit is B5, (5 percent bio-diesel). Work out the fraction of bio-energy in B5, versus E10. Probably pretty close, or a slight advantage for E10. In which case, at the present state of technology, the Prius actually has the capability of using more Biofuel than present, minimally emissions legal Diesels. Still, nothing to crow about, until they let equatorial Ethanol into the country. I imagine you have already pointed out that besides the funky catalytic technology (where they burn fuel to clean it without generating motive power), that you pointed out that in order to get under T2B5 they also had to get NOX down, which means lower combustion temperatures, and worse heat cycle efficiencies. As a result, the new Jetta TDI is just not mileage competitive with the Prius, unless you tweak the computer to illegally up the waste gate pressure. Which is why you find such fervent support for diesels in the racer-boy comunity, in my opinion.
This is what he posted, and it the article was very interesting. Clean Diesel Cars Greener Than Hybrids - New Fuel Efficient Engines Coming to U.S. - Popular Mechanics Maybe a hybrid diesel should be in the works.
Someone has got to be kidding. The diesel Polo is 500 pounds lighter, but only get 5% less CO2 emissions/distance. NOx and particulates are not discussed, but we are supposed to buy the diesel-is-the-future argument ??! PM is pathetic.
Hi burritos, Nope, this is just stuff I have read over the past few months on here and elsewhere. You will need to go out and find the links to present it as a convincing comment.
Emission Facts: Average Carbon Dioxide Emissions Resulting from Gasoline and Diesel Fuel | US EPA Gasoline carbon content per gallon: 2,421 grams Diesel carbon content per gallon: 2,778 grams Same EPA article gives CO2 numbers. CO2 emissions from a gallon of gasoline = 2,421 grams x 0.99 x (44/12) = 8,788 grams = 8.8 kg/gallon = 19.4 pounds/gallon CO2 emissions from a gallon of diesel = 2,778 grams x 0.99 x (44/12) = 10,084 grams = 10.1 kg/gallon = 22.2 pounds/gallon [FONT="] [/FONT] 2007 Prius MPG: 54 CO2 Emissions: 0.369 lb./mile CO2 lb/Gallon = 19.926 ( .369 * 54) VW POLO MPG: 74.3 CO2 Emissions: 0.351 lb./mile CO2 lb/Gallon = 26.0793 (0.351 * 74.3) Both number are match fairly closely for Gasoline. So some numbers ( MPG or CO2 Lb/Mile) are obviously wrong for diesel. ( Unless of course diesel deposits a large portion of carbon as soot or particulate matter.)
The Polo mpg may be per imperial gallon, which is 1.2 US gallons. Applying this correction gives 21.73 lbs CO2/(US) gallon diesel. Here is a (small) discrepancy I cannot figure out: Diesel is 15% heavier than petrol, Imp gallon is 20% larger than US gallon, So Prius(us) = 54*1.2.1.15 = 74.52 mpg imperial, diesel equivalents. This is a tad *better* than the polo, not 5% worse. I think the discrepancy is from variation in diesel weight, but am not sure. If tailpipe emissions of CO2 are being measured, that seems like the authoritative answer though, and not back calculating from fuel weights.
You are confusing two different emission systems. The NOx catalyst does not use fuel. A NOx catalyst uses the same technology as a catalytic converter on a car. The exhaust flows through a honeycomb and the catalyst converts NOx to N2 and CO2. That is for small diesels like the Jetta TDI. For large diesels they use urea injection. Urea is injected into the exhaust stream and reacts to eliminate NOx. The reason catalysts aren't used on larger diesel engines is that the volume of exhaust flow makes the honeycomb needed to remove the NOx too large physically and too expensive. Some diesel particluate filters (DPF) capture diesel particulates and then when they are full inject diesel fuel to burn the large particles into smaller particles. These types of filters were mandated by CARB because they wanted a emission system that didn't need to be maintained by the owner. The other, much simpler, options is to simple collect the particultes in a replacable filter and then replace the filter. This was turned down by CARB because they were afraid that owners would simply remove the filter instead of replacing it. NOx catalysts are simply an adaption of gasoline technology to diesel vehicles. Catalytic convertors have been used in gasoline vehcile since the 70's. DPF's may create technology that will soon be used on gasoline vehicles. Starting in September, Euro emission regulations will start requiring gasoline vehicles using direct injection to pass the same particulate regulations as diesel vehicles. (Current in Europe and the US, gasoline vehicles are not tested for PM) Recent studies have shown that gasoline vehicles with direct injection put out more PM than diesel vehicles with DPF's so it may only be a matter of time before gasoline vehicles also use particulate filters. As to the OP's question of biodiesel vs. ethanol: As others have said, current diesels can only use B5 while standard gasoline cars can use E10.
It may be possible to use up to E-20 with no modifications. Minnesota is apparently investigating this. Of course ethanol has about 65% the energy/volume that petrol has. Bio-diesel is about the same as petro-diesel. Butanol would be a vastly superior choice to ethanol except that no one seems to know how to make large quantities of if in a cost effective fashion.
There was a small, only 4 cars, study done on various ethanol blends. At the 20 to 30 percent range, the Ford and Toyota were more efficient than straight gas. The standard and flex-fuel GM thew same or slightly worse than gas. Basicly, the % btu reduction in gasahol blends doesn't always equal to direct % reduction in fuel economy. Couldn't find the study I read about, but did find this: http://www.ethanol.org/pdf/contentmgmt/E30_Final_Report.pdf
That's true. If the engine can take advantage of the higher octane, fuel economy can be pretty similar. usually though, that's not the case and fuel economy suffers as a result.
Hi ShellyT, The data in that report (chart on Page 6) is pretty damming of E30. All vehicles used more fuel, and the fuel/mile cost more. Only 2 of the fully tested 11 vehicles used less BTU/mile (94 Buick Regal, and 92 Ford Taurus). All other vehicles used more fuel energy per mile with E30 versus E10. That pretty much says it all - E30 is a bad idea with present cars. Ethanol is a Fuel Oxidant. It is not a biofuel at this time. Heat Cycle modification of engines and relaxed importation are neccassary for that to be so.
Those numbers in the article are at best confusing and at worst flat-out wrong. They've quoted the Polo's combined MPG (Imperial gallon) correctly, but the 2G Prius number is not 54 but 65.7mpg(I). CO2 emissions are 104g/km for the Prius and 99g/km for the Polo. However, these are figures for a manual-transmission Polo - you can't get an automatic BlueMotion. They've also massively over-stated the Polo's price. It's now £13,695 (base price) in the UK, compared to Prius at £18,370. Both prices include 15% VAT, first 12 months' Vehicle Excise Duty (though this is £0 for the Polo and only £15 for Prius), cost of registration, and a certain amount of fuel - an 'on-the-road' price. Fuel economy should not be quoted in Imperial gallons for a US audience. If using EU New European Driving Cycle numbers this should be specifically made clear, so they aren't compared to US EPA cycle. EU testing does not include high-speed driving, does not test in cold conditions, and does not test air-conditioning. I'm not even sure that numbers off the dyno are discounted as they were in the US prior to 2008 (and may still be). The new Prius gets 72.4mpg and 89g/km CO2 on the same test. Extra-urban fuel economy is up 10%, urban fuel economy up 28% largely, I think, due to the exhaust heat recovery system. (We didn't have the coolant thermos on the previous model.) On-the-road pricing is the same for T3 and T Spirit grades, T4 has more features relative to T3 than the previous model and is correspondingly more expensive. To the original point, I don't see biofuel as an argument because it's generally using byproducts, and the energy cost of producing the base product is not included. There's only so much waste vegetable oil/excess corn/sugar byproduct available. Once you start growing crop for the sole purpose of producing biofuel, you have to factor in the energy cost of doing so, and the energy use in agriculture is vast. It's been estimated that for every calorie of food grown, 100 calories of energy has been used to grow it, through mechanized ploughing, sowing, fertilization, spraying and harvesting, and the energy used to make artificial fertilizers, including the energy content of the natural gas that produces the hydrogen to bond with nitrogen to form ammonia, for nitrogen fertilizer. (Sugar beet is a nitrogen-fixer, so can form part of a crop-rotation system, as are some varieties of sugar cane; soybeans are, too). Brazil manage with their cane-sugar ethanol, but planting and harvesting of cane is largely done through manual labour. In the West this is too expensive.
Good post there!! As far as bio fuels, using corn to create ethanol, to me is a not so smart idea, it pushes corn prices up, which trickles down to anything and everything that is made from corn. In addition, since not a heck of a whole lot can run on Ethanol, unless it is in small amounts such as 10% in gas, its wasteful to create huge amounts of it. OTOH, Bio Diesel, which can be created from many different products, can run, once refined, in just about any diesel engine older than 2007, and there are quite a lot of them, and the emissions from bio diesel are less than petrol diesel. In this case, bio diesel is a win in many ways. Now, there is technology that exists today that can be used to first reduce the amount of CO2 produced by power plants, converting it to O2, and the by-product can then be turned into Bio-Diesel, Ethanol and Fertilizer, a Quadruple play. That tech is Algae filtration. It can be retrofitted to existing power plants, provided there is enough area for the equipment. The one drawback of this is the fact a large area is needed for it to work efficiently, but with time I am sure they can overcome it. With more of these systems being installed, the overall cost should also come down. The Energy Blog: Vertigro Algae Bio-Fuel Oil/C02 Sequestration System
