On December 13, Audi celebrated its synthetic methane (e-gas) vehicle fuel plant, which is under construction in Werlte, Germany. Audi says that it is the world's first industrial plant for generating e-gas from CO2 and renewable electricity. Its end product will be hydrogen and synthetic Audi e-gas, which will be used as climate-friendly fuel for vehicles such as the new Audi A3 Sportback TCNG. E-gas production will begin in the spring of 2013.

The Audi e-gas plant will utilize renewable energy for electrolysis. The electrolysis process splits water molecules into oxygen and hydrogen, or Audi e-hydrogen, which at some point can be used to power fuel-cell vehicles. Since there's not much of a hydrogen fueling infrastructure in place yet, Audi can react the hydrogen with CO2 in a methane-processing unit to generate renewable synthetic methane, or Audi e-gas. The e-gas can be delivered to fueling stations through the local natural-gas network, since chemically speaking, the e-gas is nearly identical to fossil-based natural gas.

Audi unveiled the 2013 A3 Sportback in Munich, right before the 2012 Paris Motor Show in September. The five-door hatchback features a bi-fuel powertrain as part of the Audi e-gas project. Since compressed natural gas fueling stations are hard to find, the A3 also makes use of a 13-gallon gasoline tank to help give the car an effective range of around 745 miles.

The e-gas initiative is part of Audi's strategy of bringing cleaner, carbon-neutral fuel to internal combustion engines. The Werlte plant will generate enough CO2-neutral e-gas to power 1,500 new Audi A3 Sportback TCNG vehicles 15,000 kilometers (9,320 miles) each year. This compact five-door hatchback is scheduled to arrive at dealerships in late 2013.

Audi gets the CO2 to power the e-gas plant from a nearby biogas plant, operated by energy company EWE. The CO2 is made climate neutral by being chemically bonded into the fuel at the Audi e-gas plant, so that it won't pollute the atmosphere. Audi's new e-gas plant will be able to annually produce about 1,000 metric tons (1,102 US tons) of e-gas, and will chemically bind about 2,800 metric tons of CO2. That's roughly the equivalent to the amount of CO2 that can be absorbed by about 224,000 beech trees in a year.

Audi was given an award for its e-gas project in November. The Working Group for Efficient and Environmentally Friendly Energy Use honored Audi with an award and 15,000 euros.


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    • 1 Second Ago
  • 41 Comments
      DaveMart
      • 2 Years Ago
      'The German energy industry can benefit from Audi’s e-gas strategy, as it addresses the nagging challenge of how to store renewable electricity efficiently and irrespective of location. The ability to store large quantities of wind or solar energy via the dual electricity/gas principle could significantly foster the expansion of renewable energies. The Audi e-gas project can be easily replicated in any country with a natural-gas network. The Audi e-gas plant in Werlte is being built on a site owned by energy provider EWE AG measuring 4,100 m2 (44,132 sq ft) overall. Ground was broken in September 2012. As owner, Audi is constructing the plant in cooperation with equipment manufacturer SolarFuel GmbH. They have prioritized the optimization of energy flows. Waste heat generated during electrolysis and methanation, for example, is used in the adjacent facility – thus tremendously enhancing overall efficiency.' http://fuelcellsworks.com/news/2012/12/20/topping-out-ceremony-for-the-audi-e-gas-plant/ Opponents of fuel cell vehicles should note that storage of electricity as hydrogen is regarded as essential in Germany, and also that the use of the waste heat knocks into a cocked hat the commonly trotted out but false notion that they are hopelessly less efficient than charging a battery.
      Brody
      • 2 Years Ago
      Seems complicated, and it seems that the EROEI would bee "why bother" low. Trouble words are, plant and infrastructure. You might as well use charge a EV or PHEV with the 'renewable' mentioned. CNG and Hydrogen are not that energy dense right, so for long range driving, where batteries won't do, you might as well go with a bio-diesel or syn gas, Right?.
        DaveMart
        • 2 Years Ago
        @Brody
        Wrong. Germany is not using hydrogen production for fun, but because it is the only way that they can see making renewables work. If you don't have electricity from renewables available when you need to use it, then you either use fossil fuels or store it. Using hydrogen even after reforming losses is still more efficient than using natural gas, with the 68mpge of the Toyota FCEV comparing to the 22/25 mpg of the Highlander on which it is based, and the energy use in natural gas vehicles is no better than for petrol, so they are coming up for 3 times as efficient, whilst conversion and compression is around 65% efficient: http://www.electrochemsci.org/papers/vol7/7043314.pdf That is current practise, and can be expected to improve, but that still means that after reforming the natural gas is used around twice as efficiently as burning it in an ICE. That is aside from the fact that, as my link shows, the waste heat is actually going to be used in Germany, so the total efficiency will be something in excess of 80%.
          Jesse Gurr
          • 2 Years Ago
          @DaveMart
          Oh, nevermind, I found it in the other article, the fuelcellworks article, that you posted. They still don't say what exactly the waste heat is going to be used for or how.
          DaveMart
          • 2 Years Ago
          @DaveMart
          @Jesse: Apologies. I thought I had given the link: 'The Audi e-gas plant in Werlte is being built on a site owned by energy provider EWE AG measuring 4,100 m2 (44,132 sq ft) overall. Ground was broken in September 2012. As owner, Audi is constructing the plant in cooperation with equipment manufacturer SolarFuel GmbH. They have prioritized the optimization of energy flows. Waste heat generated during electrolysis and methanation, for example, is used in the adjacent facility – thus tremendously enhancing overall efficiency.' http://fuelcellsworks.com/news/2012/12/20/topping-out-ceremony-for-the-audi-e-gas-plant/ I also relied on my knowledge of German plans to use waste heat in their excellent district heating schemes and in factories - that is part of their grand plan. For Panasonic and their home fuel cells, which Germany is trying to put in swarms: 'The 2011 model of Panasonic's household fuel cell (ENE FARM) released in April 2011 features high environmental performance including the world's highest(*1) rated electricity generation efficiency of 40% (LHV)(*2) and heat recovery efficiency of 50% (LHV), i.e., an 90% (LHV) total efficiency.' http://panasonic.co.jp/ap/FC/en_doc03_00.html This is not used in the fuel stack in cars except trivially for the car heating. It is possible that heat exchanger technology will help though.
          Jesse Gurr
          • 2 Years Ago
          @DaveMart
          "That is aside from the fact that, as my link shows, the waste heat is actually going to be used in Germany, so the total efficiency will be something in excess of 80%" Where does it say that in that link? I can't find it. It talks about the fact that less energy is required when water has a higher temperature before electrolysis. I could understand if the waste heat is used to heat the water prior to separation into hydrogen. I thought I saw that 80% efficient for fuel cell generators for commercial use. As in, apartment buildings or commercial buildings, factories or private homes. Since waste heat from the fuel cell process can be used to heat water for hot water systems. I don't think that waste heat system can be used for cars/trucks though. They have no need for it.
      pmpjunkie01
      • 2 Years Ago
      Since everyone is knocking renewable energy for it's intermittency I am wondering if they are able to profitably run this plant on an intermittent schedule. Is it going to be profitable to possibly have it idle for let's say 50% of the time while there is supposedly no renewable energy available. How does this compare to storing the electricity in millions of 16kWh packs (Volt size) controlled by a smart grid?
        DaveMart
        • 2 Years Ago
        @pmpjunkie01
        You seem to confuse knocking with describing the characteristics of renewables. This plant will not have a severe intermittency problem as it is clearly heavily involved with biogas, which is not intermittent and is used to even out the swings. There might be a problem at a big enough scale, but there won't be at this scale.
      JakeY
      • 2 Years Ago
      So this is basically renewable methane/natural gas repackaged under the marketing name of "e-gas". So an "e-gas" vehicle is no different from a CNG vehicle (except the marketing).
        DaveMart
        • 2 Years Ago
        @JakeY
        Plus a fuel cell car is as nice to drive as any other electric vehicle, and way better than driving a combustion engine car, including those running on natural gas! Zero pollution at point of use, too, although of course natural gas cars are way better than petrol ones.
        DaveMart
        • 2 Years Ago
        @JakeY
        The natural gas is used around 1.5-2 times as efficiently in a fuel cell car as in a ICE even after conversion losses. Hydrogen can also be produced from a huge variety of sources, including potentially from artificial photosynthesis, salt-water fresh water salinity gradients, and in storing an overbuild of solar or wind, as is being done here. I am an advocate of nuclear power, and that can manage just fine simply charging batteries, and it is a bit more complex to use it to produce hydrogen, although it can be done with present reactors and the high temperature pebble bed reactor being built in China for completion in 2016 will be much more efficient at it. Using nuclear power doesn't solve the range problem of battery vehicles though unless you lug around a very big battery pack as in the Tesla. That is fine if they drop in price and weight enough, but the way we know we can practically do long range at the moment with current technology is by using fuel cells. It is for renewables though that hydrogen really comes into its own. Somewhat amusingly people here who advocate a lot of solar etc tend to be against fuel cells as the work of the devil, or the oil industry or something. Well, every single scheme I have ever seen which is heavy on renewables relies on hydrogen otherwise intermittency overwhelms them. That is why they are building this in Germany. It is the only way they can use excess wind when it is blowing strongly.
      EZEE
      • 2 Years Ago
      Rocket Scientist here.... Okay, but electrolysis uses, by nature, a lot of electricity. Did the study mention where tht came from? I am not poo pooing what they are doing, but how much energy are they using , to create energy (the e gas)? This has always been the bane of hydrogen's existence. Also, where is the CO2 coming from that they are using? Would be really cool if they can recover it from something tht generates it normally, opposed to generating CO2 to save the world from....uhm....CO2.... Again, not putting this down, but curious... Oh hey everyone, Merry Christmas! Even Ford.... ;-)
        Dave
        • 2 Years Ago
        @EZEE
        "The conversion efficiency of water to hydrogen is shown in Table 3. Overall, the conversion efficiency is high, ranging from 80-95%." http://www.nrel.gov/hydrogen/pdfs/36734.pdf
          EZEE
          • 2 Years Ago
          @Dave
          Whoa....
          Dave
          • 2 Years Ago
          @Dave
          "The energy efficiency ranges from 56-73%."
          Jesse Gurr
          • 2 Years Ago
          @Dave
          HHV H2 = 39.5 kWh/kg LHV H2 = 33.3 kWh/kg The nrel link that dave gave explains it pretty nicely I think. It is found in appendix B towards the end. It basically says that they use HHV to calculate efficiency because it takes 39.5 kWh of energy to turn liquid water into hydrogen and oxygen. You could think of the reverse also, the combining of hydrogen and oxygen to produce liquid water gives off the heat equivalent of 39.5 kWh. The LHV refers to the combination of hydrogen and oxygen to create water in the form of steam. Which is why the EPA uses the LHV to calculate MPGe of hydrogen cars since the fuel cell produces water vapor, not liquid water.
          DaveMart
          • 2 Years Ago
          @Dave
          EZEE: Here you go, rocket scientist! Here is the real engineering skinny! http://www1.eere.energy.gov/hydrogenandfuelcells/tech_validation/pdfs/fcm01r0.pdf http://www.zsw-bw.de/fileadmin/ZSW_files/Infoportal/Vorlesungen/Universitaet_Ulm/docs/ESTIII-WS11-12/FCFormulary.pdf Its pretty clear that there is massive confusion surrounding the use of LHV and HHV, with in the case of hydrogen an 18% difference between the two, which is the latent heat of liquifying the steam. Which it is appropriate to use really depends on whether you can use at least some of that energy, as for instance a condensing boiler does, or not, as seems to be the usual case in a fuel cell, at least in a car. Its all above my head, and I suspect above enough other people's heads to result in said confusion.
          Dave
          • 2 Years Ago
          @Dave
          Bottom line: Prius = $2.82 / 50 mpg = 5.64 cents per mile FCVR = $4.15 / 70 miles per kg = 5.93 cents per mile (I just paid $3.23 per US gallon including 41.9 cents per gallon gas tax)
        Jesse Gurr
        • 2 Years Ago
        @EZEE
        While the two Daves' talk about efficiency, I will directly answer your questions. "Okay, but electrolysis uses, by nature, a lot of electricity. Did the study mention where that came from?" -"Wind turbines are the first significant component of the Audi e-gas project. During the project’s first phase, four large power plants at an offshore wind park in the North Sea are being financed by Audi and a regional power-supply company. Rated at 3.6 MW each, these four turbines are to supply some 53 GWh of electricity annually." http://www.greencarcongress.com/2011/05/egas-20110513.html "but how much energy are they using , to create energy (the e gas)?" -Apparently about 6MW for the whole process start to finish. "The Audi e-gas plant, which can convert six megawatts of input power, will utilize renewable electricity for electrolysis, producing oxygen and hydrogen, the latter which could one day power fuel-cell vehicles." http://www.greencarcongress.com/2012/12/egas-20121213.html " Also, where is the CO2 coming from that they are using?" -It comes as a byproduct of a bio-gas plant. Bio-gas is burned to produce electricity, then the resultant CO2 is used for this eGas project. "The CO2 used in Audi’s e-gas plant is a waste product from a nearby biogas plant, operated by energy provider EWE." http://www.greencarcongress.com/2012/12/egas-20121213.html Greencarcongress.com already did a story on this as well as the audi A3 TCNG. The info I got was from 2 articles they did. They have a lot more info about it than this article does. Interesting thing they are doing though. They basically make their own natural gas, then if people move towards hydrogen, they got that too.
      • 1 Year Ago
      Ok I am an old woman Living on S.S. and I have not saw anything about what it will cost us for a gallon for this fancy new E-gas , This is the problem , Not what we use in our cars, It is the price that we need help on , Lower fuel prices mean more money going back into the economy , Any ideas would be helpful , It will probably be something we can't afford , Not worried about more mileage as much as the price, Thanks from Indiana
      DaveMart
      • 2 Years Ago
      I don't understand how fuel cell cars are so efficient. One question is how much energy it takes to make a kilogram of hydrogen, then you have the separate question of how the FCEV uses it. If you are using electrolysis producing a kilogram of hydrogen, whether you describe that kilogram and its efficiency of production in terms of HHV or LHV takes something like 55-60kwh of electricity. We also have a solid point of reference in that we know for a fact that the pretty big and heavy Toyota FCEV gets 68 miles per kilowatt hour from that kilogram. The efficiency of fuel cells depends on which type you are talking about, and solid oxide can hit 60%. For the PEM cells used in cars which are similar to this Panasonic home fuel cell though: 'The 2011 model of Panasonic's household fuel cell (ENE FARM) released in April 2011 features high environmental performance including the world's highest(*1) rated electricity generation efficiency of 40% (LHV)(*2) and heat recovery efficiency of 50% (LHV), i.e., an 90% (LHV) total efficiency.' http://panasonic.co.jp/ap/FC/e... Using the LHV of hydrogen at 33.3kwh, then 40% is 13.33kwh. That comes to 5.1 miles per kwh, or 196Wh/mile. How the heck it gets that I don't know, although of course it doesn't need to use electricity for heating etc. Ignoring charging losses the much smaller and lighter Leaf gets 4.3 miles/kwh, which is 232Wh/mile: http://www.plugincars.com/economy-efficiency-nissan-leaf-my-experience-after-3-months.html All I can imagine is that in some way the waste heat is utilised
        Jesse Gurr
        • 2 Years Ago
        @DaveMart
        @Davemart, Dave, i'm sorry but i gotta call BS on that. I think you are looking at that wrong. I'm pretty sure they are talking about the efficiency of the system being 40%. That's because it uses natgas for hydrogen generation in turn used for electricity. It isn't the efficiency of the hydrogen to electricity. They don't really give a whole lot of details though. According to this page: http://panasonic.co.jp/ap/FC/en_doc02_03.html It gives some numbers for usage. Let me try to decipher it. Annual gas usage:10,624 kWh worth of natgas used per year. Generated about 3505 kWh in electricity for about 33% efficiency. per day that is 29kWh/day worth of natgas. and 9.6kWh of electricity. Interestingly enough, 1 therm of natgas is about 29kWh. Unfortunately, it doesn't say how much hydrogen is produced in the process. If we assume 1 kg/day then the efficiency is (9.6/33.3 = 28.8 %) If we assume .5kg/day then efficiency is (9.6/16.65 = 57.6%) what I am saying is that we don't have enough information. Usually though, most hydrogen fuel cells I've seen are around 60% efficient. So that would be 33.3 * 0.6 = 19.98 kWh. That would be about 3.4 mi/kWh or 294 Wh/mi.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          We got there. I forgot about the energy losses in reforming for a while. Doh! That puts the cat amongst the pigeons for those who like to claim that it is much more efficient to run a BEV than a FCEV, with numbers of 2-3 times often bandied about. I reckon that the Toyota FCEV including compression for the hydrogen will use around 700Wh of NG per mile including reformation. At the typical efficiencies of the US grid including transmission losses of 7% (!) then the ~300Wh/mile of the Leaf becomes 900Wh per mile. Dedicated combined gas turbines, solar panels or so on can alter that, but if you are just sticking a plug in the wall to charge your BEV then you are going to be using somewhat more energy gross than if you run an FCEV.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          I am not sure who you are saying is BS'ing, as I clearly said that the figures do not make sense to me. Solid oxide fuel cells get up to 60% efficiency, but not PEM, which top out at around 40%. What I can't understand is how the Toyota FCEV moves such a big, heavy car so fast on 1kg of hydrogen, which at its LHV is only 33.3kwh of energy. Move it the Toyota certainly does though: http://www.nrel.gov/hydrogen/pdfs/toyota_fchv-adv_range_verification.pdf At 40% efficiency that is only 13.3 kwh, although this link does give it at up to 50%: http://americanhistory.si.edu/fuelcells/basics.htm Still, at 50% that is only 16.65 kwh, for an energy use per mile of 245Wh/kg, not a lot for such a big, heavy vehicle driven in normal road conditions. Something is screwy with the figures, and I don't understand them at all, but we do know how far 1 kg of hydrogen will take you, even if they trash what we think we know of how the efficiency figures work.
          Dave
          • 2 Years Ago
          @Jesse Gurr
          ".... PEM, which top out at around 40%." Where are you getting 40% for PEM fuel cells? This chart gives a maximum efficiency of 60% for PEMs used in transportation: http://en.wikipedia.org/wiki/Fuel_cell#Efficiency_of_leading_fuel_cell_types There may be a design tradeoff between efficency and lifespan that limits the efficiency of stationary fuel cells. Stationary fuel cells need to last for 10s or 100s of thousands of hours, while the fuel cell in a car would only have to last ~3000 or so hours.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          If you have a link which shows that the efficiency of the fuel cell includes reforming, fine. I can't see anything there to show that, but it would explain the lower efficiency. I was trying to reconcile fuel cell mileage with that for BEVs, which is difficult enough, without worrying about the very different comparisons with petrol cars, which will have its own pitfalls. Your contribution would have been taken rather better had you not started shouting BS about other's attempts to clarify a difficult and murky subject. Presentation and manners also count.
          Jesse Gurr
          • 2 Years Ago
          @Jesse Gurr
          Davemart, You know what? I did some calcs for a natgas based hydrogen generator a while back. And your last post reminded me of it a little. http://www.nuvera.com/pdf/PowerTap_Hydrogen_Generator.pdf not one of the most efficient but efficient enough for what I'm doing I think. Now I calculated that per kg of H2 it would use about 4.32 kWh of electricity and 51 kWh worth of NG. With the Toyota getting 68 mi/kg. Now what if we put the energy used to get 1 kg H2 from NG into a combined cycle plant to generate power? Did your grid calc assume something like 36% power generation * 93% grid efficiency to get that number for the leaf? Lets use that then, even though natgas is usally better than that, that is about the efficiency of a coal plant though. The 51 kWh of NG would then generate about 17 + 4 kWh of electricity to the plug in your house. At 4 mi/kWh thats about 84 miles. If say the generation is more like 50% for natgas, then it would be 23 + 4 kWh. Which would be about 108 miles. It is getting closer. I think using natgas is more energy efficient than using hydrolysis to get H2, but it seems that its still more efficient to use it to power the grid, for now, it may change in the future. Not by a wide margin, just a little better though. Also depends on where you live and other factors.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          Ah! Many thanks! I had not known that there was a difference in the efficiencies in the two applications! This is confirmed here: 'If the fuel cell is powered with pure hydrogen, it has the potential to be up to 80-percent efficient. That is, it converts 80 percent of the energy content of the hydrogen into electrical energy. However, we still need to convert the electrical energy into mechanical work. This is accomplished by the electric motor and inverter. A reasonable number for the efficiency of the motor/inverter is about 80 percent. So we have 80-percent efficiency in generating electricity, and 80-percent efficiency converting it to mechanical power. That gives an overall efficiency of about 64 percent. Honda's FCX concept vehicle reportedly has 60-percent energy efficiency.' http://auto.howstuffworks.com/fuel-efficiency/alternative-fuels/fuel-cell3.htm So we are at a more reasonable 33.3*0.6 = 20kwh. That comes out to 3.4 miles/kwh, or exactly the same as the Leaf gets from the wall. Arguably though the better comparison is with the Leaf minus charging losses, where the Leaf gets 4.3 miles/kwh, so covering the bigger, heavier Toyota vehicle. That sort of efficiency also gives hope that as the technology improves, likely through investment in fuel cells due to wanting to use them in cars, that home fuel cells may improve enough to be able to cover all of a home's needs, instead of some of them. Here it is indicated that a fuel cell of about 54% efficiency would be needed to do that, as against the current 33%: http://panasonic.co.jp/ap/FC/en_doc02_03.html
          Jesse Gurr
          • 2 Years Ago
          @Jesse Gurr
          But the point i was trying to make before is that the panasonic fuel cell you link to says 40% electricity efficiency. That doesn't mean its 40% efficient in turning hydrogen into electricity, that's how efficient it is in turning natural gas into electricity. Since it is sourced with natural gas to turn into hydrogen then to electricity. It looks like you assume it is a straight hydrogen fuel cell without the step that converts natgas into hydrogen. I was just trying to inform you of the confusion. That fuel cell is also only rated for 750 Watts which is apparently enough for the average japanese home. --"What I can't understand is how the Toyota FCEV moves such a big, heavy car so fast on 1kg of hydrogen, which at its LHV is only 33.3kwh of energy." By that logic then I don't know how they can move a Highlander, which the FCEV is based, so far with one gallon of gas. Engine is 25% efficient and Highlander rated 23 combined, then we have: 33.7 kWh * .25 = 8.425 kWh to go 23 miles, that makes it 2.7 mi/kWh or 366 Wh/mi Or a 35 mpg car will get 4.15 mi/kWh(240 Wh/mi) which makes it more efficient than the fuel cell car. It all depends on how you look at it.
          Dave
          • 2 Years Ago
          @Jesse Gurr
          "Presentation and manners also count." It's very easy for these discussions to get heated. Most importantly, however, both of you are thinking critically and making honest efforts to wrap your heads around all of these numbers (which sometimes seem to contradict each other) Keep up the good work. Merry Christmas.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          Hi Jesse. I was interested in the meme trotted out around here that battery cars are several times as efficient as fuel cells using hydrogen. I can come out with a figure of around twice as efficient if I really push it, by assuming that the hydrogen is produced by present methods of electrolysis rather than using a thermochemical system which would utilise otherwise waste heat, by assuming that the electricity for batteries is generated by solar at home so that there are no grid losses and doing the usual of ignoring the fact that solar would not actually be available when you need it to charge your car most of the time, but in reality hydrogen use is in the same ball park for efficiency as batteries at the moment, and likely to remain so in the future, even using low carbon energy sources. The precise figure though is open to all sorts of alternative calculations. I simply used the best figures I could back up for a particular point in time. For instance, I used 33% for the US grid which included 7% transmission losses. The actual figure varies from year to year, depending on the relative price of gas and coal. Gas has been very, very cheap lately, so gas burn which is normally more efficient has been substituted for coal. That is normally more efficient with the equipment in the US, so the grid efficiency rises. This is limited however, as for instance you have around 20% of the US grid powered by nuclear, which with the present generation of station is only around 32% efficient due to their running at lower temperature than coal or gas. The pebble bed reactor being built in China for completion in 2016 is high temperature however, and designs like that might manage 42% efficiency. Arguably for nuclear and hydro, wind and solar the efficiency does not really matter, as only small amounts of CO2 would be emitted. This though takes us into a very different type of calculation, and so I have stuck with gross energy as that is what the claims of many times fuel cell efficiency are made for. There is nothing fundamental about coal plants running at the relatively low efficiency they do in the US either, as they can be built with up to 65% efficiency. This is a reflection of the reality that it is not all about efficiency, or we would all be riding bicycles much of the time, but about convenience and economics. Sure the whole of the US grid could be upgraded, as could the transmission system. That would make the supposed unsupportable costs of installing hydrogen infrastructure look trivial. The conclusions that I reached are however robust. If an efficiency of 38% for the grid and transmission losses are assumed, then the ~300wh/mile for the Leaf from the wall becomes around 790Wh/mile total energy. This compares with around 700Wh/mile for the Toyota.
          Jesse Gurr
          • 2 Years Ago
          @Jesse Gurr
          Davemart, Sorry about that. I don't mean to sound mean or anything. I apologize. It is a little hard to convey speech in text. Like you, I was just trying to make sense of the numbers. I try to keep an open mind about things so i'm not putting down any type of fuel because i think they all have advantages/disadvantages. As far as the panasonic home fuel cell goes, on the specs sheet: http://panasonic.co.jp/ap/FC/en_doc03_00.html The first item on the table is "fuel type", and lists city gas as fuel type, which is methane/CNG. Then there is this page where they talk about steam reformation of methane: http://panasonic.co.jp/ap/FC/en_doc02_02.html I just wish that they would have given more info like how much city gas is used per day and how much hydrogen is produce. That would have been nice Here is a wiki article about home fuel cells: http://en.wikipedia.org/wiki/Home_fuel_cell Then an american fuel cell distributor: http://www.clearedgepower.com
          Jesse Gurr
          • 2 Years Ago
          @Jesse Gurr
          Yes! Merry Christmas dave and davemart.
          DaveMart
          • 2 Years Ago
          @Jesse Gurr
          OK, here is a link breaking down the reformer and total system efficiency for the Panasonic home fuel cells. http://juwel.fz-juelich.de:8080/dspace/bitstream/2128/4236/1/ST2_7_korr1_Kusumura.pdf Depending on load reforming is 69-77% efficient. Total system efficiency is 38-39% That puts the fuel cells hydrogen conversion efficiency at 50-55%, which is reasonable considering that they are looking for a life of 40,000 hours and 4,000 stop/start events compared to the much lower lifetime they would need for car fuel cells.
      DaveMart
      • 2 Years Ago
      I do wish ABG writers could use google. 'Since compressed natural gas fueling stations are hard to find, the A3 also makes use of a 13-gallon gasoline tank to help give the car an effective range of around 745 miles.' They aren't hard to find in Germany: 'In order to reasonably extend the existing network of nearly 900 natural gas filling stations the initiators have updated the Germany-wide network planning of natural gas filling stations.' http://www.erdgasmobilitaet.info/en/aims-and-content/filling-station-expansion-and-fuel-marketing.html Of course petrol stations are even more numerous, so that a petrol tank is handy if you happen to go somewhere where it is not very convenient to go to an NG pump, but for a country the size of Germany 900 is a good number.
      Dave
      • 2 Years Ago
      Unfortunately, the rest of the steps (combining with CO2 to produce methane, compressing the methane, burning the methane in an ICE) also detract from the efficiency. This seems like Audi is building hydrogen infrastructure that will temporarily be used as CNG infrastructure.
      Dave
      • 2 Years Ago
      "That's the conversion efficiency of the water. The energy efficiency is different." Yup....I caught my mistake just before you did. Oops. "This is a rather old report (2004) and things have moved on a bit, mainly in compression efficiencies." No doubt it is outdated. But it is a pretty comprehensive study that includes a full economic analysis. Most probably, the improved efficiency cancels out the inflation, so we end up with approximately the same retail hydrogen prices.
      • 10 Months Ago
      So when is the USA going to make natural gas widely available for internal combustion engines? With all the fricking fracking going on, there should be plenty of gas available!
      DaveMart
      • 2 Years Ago
      That's the conversion efficiency of the water. The energy efficiency is different. (ibid) 'Energy efficiency is defined as the higher heating value (HHV) of hydrogen divided by the energy consumed by the electrolysis system per kilogram of hydrogen produced. The justification for using HHV can be seen in Appendix B. The energy efficiency of the electrolysis process is shown in Table 4. The energy efficiency ranges from 56-73%. Proton’s PEM process has the lowest efficiency at 56% and both Stuart’s and Norsk Hydro’s bipolar alkaline efficiencies are the highest at 73%. An efficiency goal for electrolyzers in the future has been reported to be in the 50 kWh/kg range, or a system efficiency of 78%. However, this 78% includes compression of the hydrogen gas to 6000 psi. Currently, these electrolyzers, other then Avalence’s, reach a pressure ranging from 60-435 psig for the power requirements presented. These efficiencies would decrease if additional compression up to 6000 psig were included. Only Avalence’s energy requirement of 60.5 kWh/kg includes reaching hydrogen pressures in the 6000 psig range. Note that in this study the energy requirement of the entire electrolysis system is used to calculate the efficiency, not just the efficiency of the electrolyzer. As an example, the electrolyzer alone for the Stuart IMET 1000 requires 46.8 kWh/kg (4.2 kWh/Nm3), which corresponds to 83% efficiency when you divide the HHV of hydrogen by the electrolyzer power requirement. However, when you include the rectifier and auxiliaries the energy requirement becomes 53.5 kWh/kg or 73% efficient. As a result, when referring to the “System Energy Required” in this study, the value refers to the entire electrolysis system, not just the electrolyzer itself.' This is a rather old report (2004) and things have moved on a bit, mainly in compression efficiencies. See the link I gave below for more up to date electrolysing efficiency. compression (to 12,000psi) is in the 5-10% range. Note that with the use of waste heat in this German system, we are talking somewhere north of 80%, ball park similar to wall to wheels efficiency of batteries, although of course this is only attained by roping in the otherwise waste heat energy for other uses. 'Good enough' is the broader answer.
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