• May 20, 2011
2012 Honda Civic Natural Gas – Click above for high-res image gallery

In a paper published in the journal Biofuels, Bioproducts and Biorefining, Joshua Gifford, a Master's student in mechanical engineering at Iowa State University (ISU), along with Robert C. Brown, director of ISU's center for sustainable environmental technologies, propose the evaluation of four metrics in well-to-wheels (WTW) analysis of automotive vehicles – primary energy consumption, greenhouse gas (GHG) emissions, water usage and cost of vehicle operation. As Gifford and Brown explain:

Life cycle analysis for automotive transportation, commonly known as well-to-wheels analysis, has traditionally focused on GHG emissions and primary energy consumption. Clearly, economizing on the use of primary energy sources and the amount of GHG emissions associated with automotive transportation are important sustainability metrics. Other important metrics are water usage and cost of vehicle operation.

No scenario is likely to simultaneously minimize all four metrics, suggesting the identification of a single figure of merit that encompasses all four economies of transportation fuels. We employed a normalization scheme that allowed calculation of a single composite score for each scenario called the CWEG (Cost-Water-Energy-GHG) score. Automotive transportation scenarios evaluated in this paper include a variety of fossil and renewable primary energy sources; several energy carriers as transportation fuels; and three distinct vehicle platforms including internal combustion engines, battery electric vehicles, and fuel cell electric vehicles.
Okay, with that complex explanation out of the way, here's what Gifford and Brown discovered: compressed natural gas vehicles dominated the eco-standings, with CWEG scores ranging from 71 to 74 out of a possible 100. Diesel-electric vehicles (aka hybrids) scored 45 out of 100. Meanwhile, fuel cell vehicles, running on hydrogen generated by using power from the U.S.' electric grid, had the lowest CWEG scores, ranging from 13 to 15. The article costs money to access, and the abstract doesn't tell us what the score for BEVs was. Kudos to Gifford and Brown for including water – a vital substance if there ever was one – in their analysis.



Live Photos Copyright ©2011 Drew Phillips / AOL

[Source: Green Car Congress]


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    • 1 Second Ago
  • 21 Comments
      harlanx6
      • 3 Years Ago
      Statistics= Tools used to support previously conceived ideas. Statistics can be skillfully used to support any side of any issue. I think this should be the last nail in the HFCV coffin., but there is no way anyone can be sure because of the misinformation and lies we are being overwhelmed with.
      letstakeawalk
      • 3 Years Ago
      Fair enough regarding Hydrogen via electrolysis from the grid. But what about SMR hydrogen?
        Joeviocoe
        • 3 Years Ago
        @letstakeawalk
        LTAW, doesn't suck when they do that. The compare the best of one technology, to the worst of another. BEVs have been getting this bad rap for decades now. It is not fair to calculate this way. And I would like to see SMR numbers as well.
      Nick
      • 3 Years Ago
      I read an article in the German magazine 'Der Spiegel', where it says that natural gas extraction and combustion are way more polluting than advertised. In some cases, it's worse than gasoline.....
      paulwesterberg
      • 3 Years Ago
      Only looking at CO2 emissions hides the fact that oil & natural gas drilling, pipelines & refineries leak a lot of natural gas, which is mostly methane which is a 20x worse greenhouse gas.
      paulwesterberg
      • 3 Years Ago
      Well to wheel efficiency of natural gas, fuel cells and battery electric vehicles: http://i272.photobucket.com/albums/jj169/KarenRei/WellToWheel.jpg
        letstakeawalk
        • 3 Years Ago
        @paulwesterberg
        US Dept of Energy WTH greenhouse gases and WTW petroleum energy use : http://www.hydrogen.energy.gov/pdfs/10001_well_to_wheels_gge_petroleum_use.pdf The metric used (efficiency, GHG emissions, petroleum use, cost, water use, whatever, etc.) obviously makes a big difference in terms of deciding which vehicle performs best. This is why a variety of options - including alternative ICEs, BEVS, and FCVs - are being developed. Simply put, different people have different goals, and depending on their personal goals, different vehicles may appeal to them.
        paulwesterberg
        • 3 Years Ago
        @paulwesterberg
        Source article(unfortunately costs $35): http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V2S-4M04DW9-1&_user=440026&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000020939&_version=1&_urlVersion=0&_userid=440026&md5=e7b3b8bfb288aaed28ee38d247e49a24
      lne937s
      • 3 Years Ago
      So here is the real question, what about CNG fuel cell vehicles. Hydrogen reformation requires energy to reduce the potential energy of natural gas to create a hydrogen that is harder to store. Remember that CNG (primarily CH4)will provide twice the amount of hydrogen and even more potential energy than pure hydrogen at the same pressure... and it is easer to move and store. In other words, in order to store 2kg of hydrogen, you could do so with half the pressure or or half size of vessel using CNG, with a narrower ignition range, and less likelihood of leaks, which is far superior, even though it to would add 6kg to the vehicle. Creating hydrogen from natural gas is a counterproductive waste of energy. So how would a bloom-box CNG fuel cell vehicle fare in comparison to a natural gas ICE?
        Joeviocoe
        • 3 Years Ago
        @lne937s
        The energy stored in Hydrogen gas is MUCH easier to extract using a fuel cell. Right now, fuel cells that can use natural gas are VERY low power (for their size and weight), and won't work well in vehicles. To move a mid-sized vehicle at highway speeds, you need a constant 20Kw or so.... no problem for a decent sized H2 fuel cell stack... but a similarly sized NG fuel cell stack, currently would only produce about 2 KW. The energy conversion per surface area is just too low with current technology. Also, the impurities in Natural Gas (everything except the Methane)... degrade the catalyst material. I think eventually, we will see them.... but the technology for that is not yet ready. From what I have seen with the prototype methanol fuel cells... they are designing them for low power portable electronics. On the order of a 50 watts or less.
          lne937s
          • 3 Years Ago
          @Joeviocoe
          But realistically, a better use in the near term is to use natural gas fuel cells to generate electricity to power a BEV
          • 3 Years Ago
          @Joeviocoe
          Fair enough with current fuel cells. However, a lot of progress is being made in methanol fuel cells: http://www.greencarcongress.com/2011/03/wang-20110322.html#more
          lne937s
          • 3 Years Ago
          @Joeviocoe
          Actually, the majority of Natural Gas fuel cells are 400kW and larger, being used for such things as industrial server centers, running for much longer duty cycles than what is required for a car. http://bloomenergy.com/customers/ Realistically, neither hydrogen fuel cells or natural gas fuel cells are ready for production vehicles. However, Natural Gas has far more potential.
          Joeviocoe
          • 3 Years Ago
          @Joeviocoe
          yeah... my point exactly. those 400Kw fuel cells, even if scaled down to 20 KW would be way too big to fit in a car. Duty cycle was never my concern. But Power density. If it requires an entire 12' x 12' room to make 20 Kw... this is NOT viable for transportation. And I agree, NG to electricity to BEV would be a good idea. We just need to make the cost per kwh competitive with the alternatives. The technology is there, the economics tend to kill it though. :(
        letstakeawalk
        • 3 Years Ago
        @lne937s
        Easy. An automatic doubling or tripling of efficiency. But that efficiency comes at a price. However, the metric he's developed has four factors: Cost, Water, Energy, GHG. The cost of a FCV is where it currently suffers most significantly in comparison to CNG ICE. Indeed, due to the low-cost of CNG and CNG vehicles, I feel that one single metric may play a significant role in the overall results. As prices drop on both BEVs and FCVs, their ranking will significantly improve under that sort of ranking.
      Doug
      • 3 Years Ago
      Comparing CNG ICE with HFCV, I've suspected similar CO2 and efficiency while blowing HFCV out of the water wrt cost. This is part of the reason I'd prefer not to see money spent on a hydrogen fueling infrastructure. Makes no sense to move around something with such a low energy density (by volume) with the available alternatives. I would like to see work on NG and liquid fuel FCVs.
      Dave
      • 3 Years Ago
      None of the other options is as clean as fuel cells supplied with hydrogen produced in a nuclear reactor. (not by electrolysis, btw)
      Doug
      • 3 Years Ago
      Yay for free access to papers from a Stanford IP address. Unfortunately, that doesn't seem to extend to the ISU paper without some digging around.
      paulwesterberg
      • 3 Years Ago
      Well its a good thing that fracking for natural gas only uses secret poisonous chemicals and helpfully mixes methane into the groundwater aquifer. Most H2 comes from reformed natural gas so it seems that hydrogen was unfairly handicapped compared to cng. The only time it might make sense to make H2 from electricity is in the pacific northwest this time of year when the dams have too much water and the grid cannot take any more electricity.
        letstakeawalk
        • 3 Years Ago
        @paulwesterberg
        Great point paulwesterberg. I agree that grid based electrolysis isn't really a good option, but considering how they're shutting down wind turbines, why not just converted that excess capacity into a usable resource? The wind turbine owners are suffering financially by not being able to sell their electricity, they'll eventually realize they have another valuable product they can produce as well. http://greeneconomypost.com/wind-turbines-shut-pacific-northwest-15566.htm
      Doug
      • 3 Years Ago
      Would be great to get more info the the actual break down of these numbers. Perhaps autobloggreen could do some actual, you know, reporting and call up the authors of the study for a phone interview. I lament the fact that ABG has become mostly Eric Loveday style posts which simply paraphrase what's typically already a secondary source, often losing accuracy in the process. Where's the old ABG I used to love??
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