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Another cut at US electric vehicle range requirements and usage patterns; fully-charged LEAF could handle 83-95% of all driving days

12 January 2012

Daily
Cumulative distribution curve for daily driven distance by cars that were used on the Travel Day (representing 61% of all cars owned by the participating households). Data source: NHTS 2009. Click to enlarge.

In an effort to calculate what percentage of daily trips in the US could be covered with a fully charged electric vehicle, two Columbia doctoral candidates recently conducted a statistical analysis using the National Household Travel Survey of 2009 on distances driven by the US population. They projected the results on typical range bins seen in the portfolio of electric cars that are available as of 2011.

The second part of their study, Assessment of Electric Cars’ Range Requirements and Usage Patterns based on Driving Behavior recorded in the National Household Travel Survey of 2009, covers car usage patterns on an hourly basis for weekdays and weekends, which are in turn used to assess when cars are connected to the grid and available for charging.

Solar Journey USA project
This study was conducted as part of the Solar Journey USA project, an initiative to educate Americans about electric vehicles, solar energy and the synergy of Sustainable Driving that arises from the two.
In the summer of 2012, Rob van Haaren and Garrett Fitzgerald plan to make a cross-country trip powered strictly by solar energy, generated by a towed PV array. Each day, they will recharge the batteries in their electric car for the next leg of the trip, while giving presentations and workshops about the technologies.

The National Household Travel Survey (NHTS) includes data from 150,147 households gathered between March 2008 and May 2009 on four levels: household, person, vehicle and travel day. The dataset was downloaded from the NHTS website and imported into SPSS 18 for analysis.

Among the top-level findings of the study are:

  • 61% of all participating cars, SUVs, vans and pickup trucks were used on the Travel Day and they drove an average of 40 miles per day.

  • For individual trips (i.e., one-way), 95% are below 30 miles and 99% are below 70 miles. When driven distance is aggregated over the whole day, ~95% are below 120 miles and 99% are below 250 miles.

  • Car commuting distances were found to average 12.6 miles nationally, with 95% below 40 miles and 99% shorter than 60 miles. Assuming the electric car is charged overnight only, a Nissan LEAF with a 62-138 mile range would be able to satisfy 83-95% of all travel days, depending on driving conditions as described before. A 2011 Tesla Roadster would be able to satisfy >98.5% of travel days, assuming a minimum range of 0.85 times the EPA-labeled range.

  • Vehicles owned by households in districts constrained by area—such as Hawaii and District of Columbia—were driven shorter distances than others (~24 miles per day, compared to a national average of 39.5 miles per day). On the other hand, States with primarily rural areas and a large fraction of the population living in single dwellings or small towns (typically in the Midwest) averaged higher driven distances (up to 49 miles per day).

Perhaps the most important conclusion is that the majority of US households have the luxury to simply pick their gasoline car in case they plan on a long trip. 64% of households that own one or more cars have the luxury of owning a gasoline car besides their future EV (assuming the EV replaces a gasoline car). Think of it as owning both a two-seater and a sedan: would you choose the two-seater if you’re picking up three friends to go watch the football game? We’ve seen that 39% of all cars are not even used on the Travel Day. This gives rise to a new research question: “From all cars owned by members of a household, how many vehicles drive beyond a distance of x miles on the Travel Day?”

—Rob van Haaren

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January 12, 2012 in Electric (Battery) | Permalink | Comments (37) | TrackBack (0)

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80% may be a valid statistic, but perception is everything. No one likes limitations, just look at the Carter/Reagan election in 1980. Carter said there were limits and Reagan said there were none. Carter was right, but people liked what Reagan had to say.

Too many mornings when I need to go somewhere I find the needle on my fuel gauge approaching E (and no extra 25 minutes to drive round-trip to fill up the tank at the closest gas station). Definitely inconvenient--there are no gas stations near or on my way to my usual destinations. Can I make my intended trip without running dry? Where is my big gasoline range? With a BEV, I would have a full tank every morning.

I don't know where you live Chris, but in my LA neighborhood there are 4 gasoline stations just blocks from my house.

Likewise, according to a recent study, less than half of all Californians have off-street parking. Thus, for the majority in the Golden state charging is definitely the inconvenience.

Moreover, just because an EV provides generally acceptable range doesn't mean Americans find value in them. They're still significantly more expensive compared to conventional cars without tax incentives -- both to consumers and automakers/suppliers. Finally, for now automakers can subsidize EV costs through PR, etc. If they were suddenly forced to survive off EV profits, I bet EV prices would have to rise significantly.

Think about American automakers, for instance, and the massive percentage of profit driven by the pickup truck segment. Having to replace that profit with EV profit would be extremely difficult. Why do think the President essentially gave pickup trucks a pass in new CAFE requirements through the next decade? Because if we got tough on trucks today we'd crush the Big 3.

In theory, EVs make a ton of sense, in the real world; however, they still have massive obstacles to overcome.

Chad, the only reason you see as many gas stations around as you do is because the network grew up alongside the automobile fleet. That took time and it will take time to build up a BEV fleet - time which can be used to put in the charging network alongside it.

The first time we did this it took 100 years because we did it guided only by short term thinking, this time around we could do it faster and better because we know better.

Electricity is already everywhere that people frequent so all we really need is to give EV drivers access to the wires. Take your Californians with their on-street parking as an example: Are there parking meters on those streets? Parking meters run on electricity, they are already wired into the cables under the ground so all we have to do is wire an outlet into the parking meter. The city will gladly do this because they can get the EV driver to pay extra as he charges.

Additionally, I think there is a bit of a flaw in this study.

In particular, the Nissan Leaf is not representative of the average vehicle in the US. Consequently, its range capabilities are therefore questionable.

For instance, typically around 50 percent or more of US sales are light duty trucks. Saying Nissan Leaf range meets the capabilities of a Ford F150 or a Chevy Silverado seems hardly accurate. The extra weight of the vehicles, aerodynamics and payloads would require a massive upgrade to the size of the Leaf's battery pack, otherwise, potential range would decrease significantly.

Why do proponents of electric vehicles always talk about HOW MANY TRIPS can be electric instead of HOW MANY MILES?

The fact that they even bother to tell you high percentage values for single trips below 73 miles should be a huge RED FLAG! Why not count all the zero mile trips? Count all the trips I thought about using my EV, but went to the frig instead! This would be a very high percentage after all. Report it!

What gets me is on the same day there are plenty of short trips that occur after the long ones have been taken. The 5 miles trip taken after you drove for 80 miles will not be electric!! If we want to trade gasoline miles for electricity, then we need to see how many miles can be driven electrically! And using a sound method.

I am doing my own study using the NHTS data on BEVs (I was the chair of the SAE committee that developed “utility factors” for PHEVs). And I got news for everybody, things don’t look good for BEVs. When a round trip away and back to home is beyond the range, then 100% of those miles of that round trip have to be gasoline. For PHEVs, the beginning miles are always electric. Turns out, the Volt is as electric as the Leaf. Take that "100% Electric" Nissan Leaf. Yes, 100% of the miles that I am able to use the car without being stranded on the highway, I am running on electricity. But for 46% of the miles, I have to drive the minivan.

I will show some of the results at SAE Hybrid Symposium in Feb in San Diego. And I may include it in an EVS26 paper due out in May.

Current e-range BEVs limitation will fade away as batteries energy density will improve by 2X to 3X by 2020 or shortly thereafter.

Limited 100 miles range will be past history. Buyers will have the choice to purchase enough battery modules for 100, 200, 300 or 400 miles to suit their needs and/or pocket book.

Excellent observations.

It does make a difference when the short trips take place. Someday the electric BEV might prove practical. But for the forseeable future, the PHEV or EREV is the technology that preserves mobility, and civilization, while substantially increasing the fuel economy and or displacing petroleum. We are not condemned to return to the caves.

If the USA had to depend only on its own domestic production at todays production levels, the VOLT makes that entirely possible.

But the good news, dispite the all too prevalent doomsday blarney, is that the North American oil production will make the area once again petroleum independent within the decade thanks to the advance of technology extraction methods. Together with the enormously growing reserves that can be commercially extracted with that technology, are making the day of reckoning from petroleum exhaustion, recede into the next Millenium.

PHEV technology is still a car/battery generation or two from equality with ICEs prices, but that gap is not anywhere as large as it once was, and shrinking.

I am always baffled when people takes sides on the electric vs. gasoline debate, when in fact it isn't either/or. Is it really a debate about whether BEVs can replace ICE vehicles?! Whether BEVs can duplicate gasoline car performance and range? BEVs are different animals than traditional ICE cars; I don't see why people should want them to be the same, or to fill the same transportation niche, or be used in the same way. It's not one size fits all. There is room for both (it's not a contest).

People who can charge at home and need a car for mostly shorter trips and who appreciate the esthetics (quiet, simplicity, seamless power, reliability) of electric vehicles can buy a BEV. Maybe they have a second car for long trips. Maybe they will rent. BEVs are practical NOW for those people, and that choice will likely not come down to cost. I hear too often that BEVs cost more than traditional ICE vehicles, so therefore somehow they are not now ready for prime time. Well, how many people buy cars/trucks based solely on how economical they are? Horsepower, status, entertainment systems, exhaust sound, magic seats, style, image, the latest thing . . . Why buy a Mercedes when you can get by just as well with a Camry?

For too many years I spent three hours a day commuting into Washington in rush hour traffic. I also regularly drove up and down the east coast in 600 mile lumps. I would not do that now; it's a matter of priorities.

But people who think nothing of routinely driving distances should buy a gasoline car. People who like trucks should have an ICE. People who don't need long range, and could charge at home, but who are nevertheless more comfortable with traditional cars should buy the ICE vehicle that makes them feel good. People who prefer gasoline vehicles will be in the majority for a long time to come.

I thought the point of the study was not that people who drive shorter distances should buy BEVs, but rather that for many people, a BEV would meet their mileage requirements. But that's not news. The real purpose of the study was to fulfill the academic requirements of two doctoral candidates by generating quantitative data (and not to challenge the psyche of ICE fans).

Nevertheless, technology evolves, and some people don't like change. So I suppose the debate will continue.


This debate would not exist were it a settled question. I can't even imagine buying a BEV. I have bought two new hybrids and as soon as they build a hybrid with AWD, I'll likely buy another one.

I doubt that a PHEV is worth the cost.

Car commuting distances were found to average 12.6 miles nationally, with 95% below 40 miles and 99% shorter than 60 miles.

This is THE most important finding here. And all worth discussion re: actual needs of commuters. But range anxiety is a fear-ploy used by oil and ICE companies unwilling to transition quickly to EV. Thus the wisdom of the Chevy VOLT which addresses the fear factor and deliver EV range equivalent to 95% of commutes.

Slow adoption is in part because the old industries do not want to give up the gravy train. Which is why when ultra low cost electricity arrives - the decision will leave their hands. Just as it left the hands of horse and buggy business.

as soon as they build a hybrid with AWD...

Ford has had the Escape hybrid 4wd for years.

http://autos.yahoo.com/ford/escape/2012/hybrid-4wd/

Last year, every travel day I made could have been done in a Leaf. In fact, now that I think about it, I would have to go back 15 years to find a day I would have needed the range in a Tesla.

Last year, every travel day I made could have been done in a Leaf

Lucky you,

Mike D:
Obviously the reason for breaking downt the trips into single journeys and others is that as charging points become more common a lot of people will have the opportunity to charge at work and so on, so the range will effectively double.
The same rationale applies to short post work journeys etc.

As for the truck argument, clearly you are not comparing like for like due to the load carrying capabilities of the truck.
However it is also true that for most of the journeys most truck drivers take they do not actually use the load carrying capabilities, so a BEV would do just as well on that particular trip.

The article says that 64% of all households in the US have more than one car.
This is not the best metric to use at this stage of the game, as car makers are not interested in the general population, but in the new car buying demographic.
Since they are considerable richer than the general population the percentage having access to more than one car is going to be higher, perhaps around 80%.

This means that there is no effective limits on the potential market for BEV cars in the US for the foreseeable future.
Should previous spring petrol price rises repeat this year petrol would be over $5/gallon, and even a much more modest rise to over $4/gallon would likely cause demand for BEVs to soar.

@ChrisL

Excellent points! Unfortunately an electric vs ICE debate has broken out instead of a more constructive electric and ICE debate, as to how different types of vehicles fill different niche roles.

The problem with "averages", as in average commuting mileages is that they mask a huge range of extremes. Some people will commute 1 mile whilst others will commute 70 miles or more. But then cars are for much more than commuting. They're used for road trips for holidays and to see families and this is when their full potential is realised - good range, space for passengers and luggage or camping gear and so on.

Hence electric cars = short journeys round town.
ICEs = longer road trips / longer commutes.

Of course this could well change as EV technologies develop with better range batteries. By the same token ICE vehicles will continiue to improve in effiency, whilst fuel will come from a wider variety of sources - petro fuels, synthetic fuels and bio-fuels. Also don't forget the potential of hydrogen as a source for ICE and fuel celled vehicles.

Whilst its easy now to criticise the environmental credentials of bio-fuels or question the costs of syntheic liquid fuels, everything will change as techology develops, that's what human inventiveness does. It overcomes barriers. If progress results in a wide diversity of vehicle choice - electric, ICE and fuel cell, this would be a good thing. Relying on just one route could be disastrous if it turns out to be a cul-de-sac.

Has anyone else noticed how some people on the ICE side of the argument (ICE vs. BEV) are extremely hostile and skeptical about BEV's?
They take great pleasure in pointing out any limitations of BEV's.
I don't understand this hostility.
-
There will come a tipping point when batteries will store enough energy to eliminate the range advantage of the ICE. At that point the auto co's will favor the BEV, because of simplicity, reliability, etc.

Davemart,
I will accept the argument that we only care about trips if there were a way to fully charge in just a few minutes everywhere you park.

In the meantime I will use assumptions like slow charging at home and maybe at work. I am investigating several of these scenarios.

My overarching point is that to do ‘good’ we are not interested in happy customers. We are interested in happy EV miles (reduced fuel consumption). If we satisfy a high percentage of low-mileage drivers, what does that accomplish? Not as much as other alternative fuel vehicles.

Also, the 2008-2009 data may not be worth much. This survey occurred at exactly during the economic meltdown. It doesn’t seem to match 2001 very well. Still looking into it.

Our local CarSharing Org. (1100 ICEVs and 50 Leafs) has post-phoned addition of more Leafs due to (1) shorter e-range during cold winter months (two Leafs had to be towed and/or recharged with the mobile unit last week). (2) Current lack of enough quick charge stations.

Our Hydro e-energy supplier and 10+ large retail chain stores, drug stores and restaurants etc have agreed to install 2,000 (Level II, 240 Volts) charging stations in priority parking places in 2012. A few 440 Volts charging station will be installed and tested. That will solve no. 2 above.

I also don't understand why this is a debate. The market will move as people see benefits.

Personally, I could drive 100% of my trips in a Leaf, but would not buy one because I too have range anxiety. Until charging points are ubiquitous, I would prefer a range-extended PHEV -- one that is cheaper with small battery capacity would do just fine for my average 20 mile commute. The range extender will get me further those two days a month that I need it.

JM...very quick charge 440/660 DC Volts stations at every shopping, eating, school, working places and roadway (Ex) gas stations etc will become common place in the next 5 years or so. Coupled with improved (2x or better) batteries, EV range anxiety will become past history before 2020.

Harvey .... I think you are right, and I am looking forward to that future.

What about winter driving in canada. Today there is a storm and driving are longer because traffic is heavy, also someone driving a bev in these conditions need more heating. I never read an analysis of these car in winter. Please make a study on this. Measure the difference in soutern california compare to montreal canada, is it clear now ?

Also it's more difficult to recharge the bev with solar panels , non-polluting and free electricity in winter

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