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Washington DC
PhD Transportation Systems
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Good points by EP. I have heard the RRB process will also produce naphtha, which improve the numbers a bit.
Wondering if this is related to Uber's choice of the XC90 as it's autonomous vehicle platform.
So EVs can do everything we need to get to deep decarbonization? Hmmm... haven't seen an analysis to show that yet.
Is anyone else surprised/amazed at the -300 carbon intensity of bio-CNG? Wow. Time to start investing in dairy farms in California. I guess it's all about avoided emissions. The figure shows negative carbon intensity values for some H2 pathways but I can't find documentation on the CARB website. Is that biogas to H2 that's negative? Will be interesting to see how the fuel mix changes in the state as the LCFS gets more stringent next year and into the future.
Good study! I think the results are as expected but it's good to confirm with real data. Next question: what are the indirect effects of lightweighting vehicles? e.g., market-mediated price effects of increasing demand for carbon fiber, decreasing demand for gasoline, etc.
The bullet point on driving range is odd -- people who drive farther are more interested in HEV and PEVs? That seems opposite to the marketing strategy from OEMs (i.e. to focus HEV and PEV sales on short range, start-stop drivers). But I suppose people who driver farther also have greater access to at-home charging... I would like to get my hands on the data.
I think its misleading when they report electrification of TRIPS rather than electrification of MILES. 90% seems like a large number but the vast majority of trips are very short distances. In reality what we care about is % of electrified miles. Also, Henrik - this is the 2nd gen volt. The article you shared is the 1st gen Volt with 35 mile AER.
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Jul 18, 2015
Very interesting to finally quantify the impact of right-sizing vehicles. I wonder, though, if people shift to paying for travel on a per-trip basis with autonomous taxis (as opposed to purchasing a vehicle) how that will impact their travel behavior, likelihood of carpooling, and annual miles traveled. Seems like we should expect VMT reductions and greater carpooling in addition to the benefits enumerated in this study. The real wild cards with autonomous vehicles are their impact on travel behavior and residential location choices. Maybe DOE can study that in the future as well.
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Jul 4, 2015
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Jul 3, 2015
nice paper and useful set of scenarios. here are 3 comments: 1) carbon intensity assumption around cellulosic biofuel is still highly disputed. authors use 20% of reference GHG but there are plenty of folks who would disagree. 2) if we're talking about "economy-wide" reductions in GHGs, then our limited biomass resources might be best used in other sectors with few/no alternatives like aviation, marine, heavy duty vehicles. the single focus on LDVs could result in misallocation of resources. 3) more consideration should be given to h2 fuel cells. they are expensive right now, but like anything else, costs come down quick in initial years of roll-out. five major OEMs are commercializing FCEVs. You can't just write them off because of "techno-economic limitations." cellulosic biofuels are also suffering techno-economic limitations (see Biofuel Digest article from July 1st -- 'Where are all the gallons?')
@ DaveD - the 30-40% of drivers able to adopt a PEV is my own estimate. Here's my rationale... Pearre et al. (citation below) used GPS units to track ~500 cars in Atlanta, GA for 1-3 years. Of these vehicles, only 21% never exceeded 150 miles in a single day of driving (see Fig. 4). Admittedly, other authors suggest higher max daily mileage, but most of these do not use GPS units or are only a few days worth of data. The 93% you suggest is higher than any number I've seen for a 100 miles of range. Of course, multi-vehicle households have the ability to swap to a ICE on a higher mileage days. Also, drivers might accept a certain number of "inconvenience" days in which they rent a car or borrow from a friend or fast charge if available. On the other hand, if only ~50% of vehicles currently have access to a level 1 charger within 25 ft (see my comment above), then the fraction of PEV-adopters decreases. As ECI points out, installing more at home chargers is not impossible, but I haven't seen this as a major strategy so far. Thus, my estimate of 30-40%. I think a mix of PEVs and FCEVs in the LDV fleet plus FCEVs for medium and heavy duty trucks is the way to go. We use our limited biofuels in aviation and marine and voila.... we've got 80% reduction in GHGs. Pearre, N.S. et al. (2011) Electric vehicles: how much range is required for a days worth of driving. Transportation Research C.
There are some arguments that haven't been made yet on H2: 1. what are we doing about medium and heavy duty vehicles that use ~50 billion gal/diesel a year and are responsible for a considerable amount of air quality problems (in addition to GHGs)? You can electrify some, improve efficiency, and try to use as much low GHG biofuels but... (a) you can't electrify everything (b) biofuel carbon intensities are increasingly contentious and won't be settled any time soon and (c) efficiency+electrification won't get us to an 80% reduction in GHGs like the IPCC says we need to stave off a 2 deg C temp change. 2. Even a high range 200-mile Bolt (with an effective range of ~150 miles) will not satisfy range needs of something like 30-40% of drivers if you assume people are willing to charge once per day and are willing to be "inconvenienced" by lack of range a couple times a year. Battery swapping and inductive roadway charging are all nice options but show me they work and are cheaper than a H2 infrastructure (estimated at ~$40-50 billion net present value in the 2013 NAS transitions study). What to do? I don't like building a whole new infrastructure either, but seems our only choice.
@ Bernard (and backing up Dave M)....One paper showing ~50% of US can plug in a PEV says: "study 1 estimates that about half of new car-buying US households park at least one vehicle within 25 ft of a Level 1 (110/120 V) electrical outlet at home" Axsen, J. and K.S. Kurani (2012). Who can recharge a plug-in electric vehicle at home? Transportation Research Part D, 17(5), 349-353. Available at:
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