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ORNL researcher suggests that most consumers better off with <100-mile EV range until battery costs drop to $100/kWh

18 August 2014

Until battery cost is cut down to $100/kWh, the majority of US consumers for battery electric vehicles (BEV) will be better off by choosing an electric vehicle with a range below 100 miles, according to a new study by Oak Ridge National Laboratory (ORNL) researcher Zhenhong Lin.

The research, published in Transportation Science, a journal of the Institute for Operations Research and the Management Sciences (INFORMS), suggests reconsideration of the R&D goal that battery electric vehicles should have a driving range similar to that of conventional vehicles. It also implies that the focus of policy and R&D should be on continued reduction of battery costs to make short-range BEVs more price-competitive.

The focus should also remain on deployment of charging infrastructure to improve usability of short-range BEVs that attract more potential buyers.

In the study, Lin proposed a framework for optimizing the driving range by minimizing the sum of battery price, electricity cost, and range limitation cost—referred to as the “range-related cost”—as a measurement of range anxiety.

The objective function was linked to policy-relevant parameters, including battery cost and price markup; battery utilization; charging infrastructure availability; vehicle efficiency; electricity and gasoline prices; household vehicle ownership; daily driving patterns; discount rate; and perceived vehicle lifetime.

The electric driving range of a BEV was optimized separately for each of 36,664 sample drivers representing US new car drivers. Key results were the distribution of optimized BEV range among US consumers and the change of such a distribution in response to battery cost reduction and charging infrastructure improvement.

The quantitative results strongly suggest that ranges of less than 100 miles are likely to be more popular in the BEV market for a long period of time. The average optimal range among US drivers is found to be largely inelastic. Still, battery cost reduction significantly drives BEV demand toward longer ranges, whereas improvement in the charging infrastructure is found to significantly drive BEV demand toward shorter ranges. The bias of a single-range assumption and the effects of range optimization and diversification in reducing such biases are both found to be significant.

—Zhenhong Lin

The results of the study explain the dominance in the BEV market of products with an electric range below 100 miles, the author said.

Before the introduction of the Nissan Leaf (certified with a 73-mile electric range) in December 2010, BEV ranges were often assumed to be between 150 and 200 miles. Now, eight out of the ten BEV products on the US market are equipped with an electric range below 100 miles, Lin said.

The paper further discusses the policy and R&D implications of the found distributions of optimal BEV range, providing insights for BEV-related policies and market strategies. The paper also includes sensitivity analysis and quantifies the significance of the optimization approach.

Resources

  • Zhenhong Lin (2014) “Optimizing and Diversifying Electric Vehicle Driving Range for US Drivers” Transportation Science doi: 10.1287/trsc.2013.0516

August 18, 2014 in Batteries, Electric (Battery), Policy | Permalink | Comments (23) | TrackBack (0)

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That 100 mile range needs to be all-conditions, all-seasons. Which means that it will likely need to be EPA rated at 135 miles. Beyond that, we'll need to see vehicles equipped with fast-charge solutions, as well as fast-charge stations pop up that can provide a 25 mile charge in 5-10 minutes (enough for people to finish their day).

How many households can afford a second car with limited range? How many households that can afford only a single car could make do with a limited-range electric car? How many households which might support a limited-range EV have garages or other access to home charging?

Mass adoption of EVs is going to take some time. We would love to switch to an EV, but our situation (small town, lots of mid-distance highway driving) makes any pure EV except the (unaffordable for us) Tesla Model S a non-starter from any practical perspective.

@Anthony - Today's < 100 mi EVs that can QC, can pick up 25 miles of range when QCd from a low state of charge on a 40-50kW QC station in 10 minutes. So with sufficient QC infrastructure situated so that one knows that they can rely on charging if they get low, current EVs are OK. With even a bit more battery, EVs will be able to even better take advantage of 40-50kW QC stations.

@Nick - availability of street charging especially in residential areas is definitely an issue for wide-spread adoption. Ultimately more workplace charging and larger battery packs will be required for wider adoption once it gets to that point.

For a lot of reasons, it's pretty reasonable to expect a mix of hybrids, PHEVs and EVs for the forseeable future. It will take 200+ mile affordable EVs along with 100 kW+ charging infrastructure, to really see widespread EV adoption.

@nick, Dave R already summed it up well, but I'll add that innovative options, like Fiat's 12 per year voucher system for Enterprise rentals helps address those long distance travel days. I'm not speculating, we have a 500e in the household. Add car share and other options (the occasional train ride or carpooling) and 80 mile BEVs become even more practical. Not everyone will be flexible and innovative and use car share or low cost rentals to fill those edge cases. But those who do in California and several other states can drive a brand new car for less than $200 mo including fuel, and get an HOV sticker to boot.

The biggest limitation is not the vehicle, it's awareness and education.

Range anxiety mostly disappears with PHEVs.  If the goal is petroleum replacement, replacing 4 ICEVs with PHEVs with 25-mile AERs is superior to building 1 100-mile EV.

PHEVs benefit from widespread charging opportunities even more than EVs.  Even Level 1 charging is quite beneficial (personal experience); if existing circuits were re-wired from 120 V to 240 V to permit charging at 240 V 12 A, the benefit would be increased without any costly pulling of new wire.  That would be sufficient to displace at least 50% of current petroleum consumption (my experience is more than 3/4).

Nick,

re: "How many households", the answer in the US is "most."
The majority of US households own more than one car.

@electric-car-insider.com:

The biggest limitation is not the vehicle, it's awareness and education.

This may apply in some urban areas, but it is certainly not true for us where we live.

What would work for us would be the Voltec platform in a more practical vehicle--better outward visibility and rear seats usable by tall-ish adults.

How many families can afford a second car with limited range?
In April I chose to lease a Nissan Leaf for $250 per month. My lease payment for the Elantra I turned in was also $250 per month. The Elantra had a rated fuel economy of 28 mpg City/38 mpg highway. And I was spending $160 a month in gas.

I charge at home and my average monthly electric demand for the Leaf is about 300 kWh, or about $30 worth of electricity. So my monthly transportation cost has declined by over $120 per month. And my employer is installing a Level 2 charging station so I can "gas up" for free.

If I need to take a long trip I borrow my wife's car.

We will soon replace my wife's car with a Chevy Volt. Our lease payment will be $360. Based on her driving pattern we estimate that we'll need one tank of gas a month or less vs. the 4+ tanks that she normally requires - so it's a break-even proposition.

To elaborate: "long-distance travel days" are not the problem for us. It's the mid-distance: I drive 75-100 miles round trip on a regular basis--once or twice a week--just to get around. I really need 150 miles of actual range, including going over 1700' elevation hills at times. 150 miles would cover our everyday, regional travel. There is no car share available here, no rental car agency closer than 35 miles distant. EVs are city cars (save Tesla).

As I said, a more practical PHEV or REEV is what we need here (or winning at Lotto).

@Dave R: The problem with the current EV fast-charging infrastructure is that its not numerous enough and its not well maintained, as a recent Op-Ed at InsideEVs recently discussed. I'm confident that if we have a robust charging infrastructure using 90kW CCS here in the states, then people would feel more comfortable with ~100 mile range vehicles.

Nick - driving 75 - 100 miles 50 to 100 times a year makes you an outlier.

Only 10% of all US driving days are greater than 75 miles. People who drive a lot, many days a week are likely responsible for a lot of that total. A limited range EV won't work for them, and seemingly for you.

But look back to Raymond's $120 per month savings. For someone who takes a few long trips a year they are way ahead to rent a car for the long trips.

@Bob Wallace: Maybe. Back when I lived in the Bay Area and commuted to work by car--35 miles one way--a Nissan Leaf *might* have worked for me--but I get the impression that distance is right at the limit of what's realistic. With workplace charging it would have worked fine, and then we'd have a city car.

But then my wife, home raising the kids, would be driving our minivan around the city during the week, getting 18MPG on a good day. Alternatively, she could drive the Leaf and I commute with the minivan and get maybe 22MPG on the freeway. Since both of us needed cars (our house was up in the Berkeley hills--not walkable for everyday chores), and both cars were used every day, we would really need two 'green' cars to really cut down our carbon footprint/reduce petrol usage. Now I suppose with two short-range cars we could rent for those 500-mile weekend jaunts, etc.

Now if we had lived in a more walkable neighborhood and we had lived closer to my work (things that can be hard to accomplish once you get established somewhere), then maybe we could have driven a lot less and having a short-range EV would have made a lot of sense. Nowadays, retired away from the city with solar panels on the roof, I would love to refuel our car in our garage by plugging in. Given that Tesla is not an option, there really isn't anything out there yet that works for us (Volt comes closest). I'm hoping for workable options coming down the road.

@Electric car insider, I am really pleased that Fiat have the car rental voucher system - it seems like an obvious thing to me if you don't have a second car.

[ I have been saying this since 2011].

A problem is the ICE pickup - you drive to the rental place and need to be able to park your EV there while you use the ICE, or you need them to drop off the EV and take your ICE with them.

As people have said, if you live in the country or have longish drives, an EV isn't for you at present.

The idea that BEVs with a range below 100 miles could be popular is nothing new to me. This article talks about "BEV products on the US market" [cars that are made by car companies and sold to the public], but for many years before the companies saw the need for electric cars people who wanted a BEV have had to go the DIY route.

Of course these people could not apply the same high level of resources to building their cars as a car company could so their DIY cars almost always had sub-100 mile ranges.

If these cars weren't popular/useful to these people they wouldn't keep on making them. Oh sure, these people are as much outliers as Nick is but still... have a look at how many of them are willing to go to such measures to own a BEV; http://www.evalbum.com/

@Nick, you're right, there are still big gaps in the EV lineup. Mitsubishi Oulander PHEVS and Chrysler minivan will help.

Ford Fusion Energi is a four door that seats 5. It only gets 21 miles all-electric range but with workplace or destination charging that's ~1,000 all-electric miles a month. I would not have thought much about Ford 15 years ago, but they came a long way under Mulally and the Focus Electric I leased about a year and a half ago has been a great car. Far better appointed and equipped than I had remembered the Focus. Good performance. The people I know who have the Fusion Energi are also happy with their cars, which probably explains Ford's recent good sales performance with the Energi line. Despite zero ad budget, it's becoming a top seller. Word's getting out.

I've managed 32 miles electric in my Fusion Energi, with 3 miles remaining on the meter at the end.  Of course, that was hypermiling to the max.

If you drive 55+ MPH on a course with hills, I can see 21 miles AER.  On flat ground with no wind, 25 is about the least you should see in warm weather (no A/C use).

I'm confident that if we have a robust charging infrastructure using 90kW CCS here in the states, then people would feel more comfortable with ~100 mile range vehicles.

Call it 100kW baseline, with a 33kWh usable battery for 100mi of range. Which battery chemistry can be charged at 3C regularly and be economically warranted for 8 years and 100000 miles with no more than 20% capacity loss?

Plus, that infrastructure would need multiple chargepoints at no more than 50mi apart to be practical.

There's so many good things you get with bigger batteries, and which scale with size: energy, power, charge rate. They all go together.

Im sure that there is other studies that say exactly the opposite, everybody like longer range even if it cost a little bit more. This report is silly.

Limited range EVs make sense only UNTIL batteries price drop to $100/kWh. Beyond that point, extended range BEVs will probably reach 500+ miles.

Limited range EVs make sense only UNTIL batteries price drop to $100/kWh. - HarveyD


JB Straubel, CTO at Tesla, has stated, and it's on Youtube now that I remember, that the absolute lowest cost with an acceptable profit margin looks to be $120/Kwh.
But he hastens to add that you don't even need to wait until then since it is believed that by the $150/Kwh price point you will already be seeing the death of the ICE passenger vehicle.

Which battery chemistry can be charged at 3C regularly and be economically warranted for 8 years and 100000 miles with no more than 20% capacity loss ? - Otis

Good question. I also have raised concern over Mr Musk's assertion - at a press conference in England recently - that Tesla users should use Superchargers all they want. Trouble is I brought it up on Tesla's Forum. This was in rebuttal to comments from new owners, made on the "potential buyers" thread for Model S where they immediately called me a troll. I was asked to provide a valid source for my assertion. Well my experience is with the DIY crowd using Pb-acid batteries. We made sure our members were informed of the care and feeding of Pb_acid battery packs from our monthly newsletter. Apparently this was not good enough for the moderators (admin). They said Li-Ion was not the same as Pb-acid in other words I was making an orange to lemons comparison. At which point I challenged them. I said that since they were the ones making the claims they should be the ones providing the proof and not the anecdotal proof that some members came up with. Anyway their response was to move my subsequent posts to the OFF TOPIC section.

Why did Musk make the assertion ? I'll apologise for him. He is very much an engineer and you can often see him choosing his words slowly and wisely unless he has opportunity for a canned reply in which case he reels off a professional delivery. In this case I think he was tired and the journalists caught him off guard.

Three things you need to consider. The Supercharger option is free to those with the Model S equipped with the 85Kw pack which is a high proportion of the approximately 40,000 cars made. Most of the vehicles are still less than two years old. Any data collected by the more than 2600 Roadsters now approaching four years old is non applicable since their internal circuitry will not allow them to accept the 120Kw DC charging from the Supercharger. Bottom line is that supercharger use should be judiciously taken until we have more data.

About ten years ago Sean O'Keefe, chief administrator at NASA, in a televised address, mostly to Nasa employees regarding the transformation that NASA would be making to avoid another Columbia disaster, made a particularly honest appraisal of the situation. Apparently when it was first noticed that lumps of ice were breaking away from the upper part of the LOX tank and striking the re-entry heat tiles on the undersurface of the SST as it lifted off the pad, the reaction from observers was subdued. No one would blow the whistle on it - most could make the case that it wasn't in their job anyway - and subsequent successful launches gradually dispersed those who had been accused of unwarranted paranoia. As the shuttles began to be reused any broken tiles that appeared on the heat shield were replaced as a matter of course. Ice falling on to the heat shield was no longer considered a problem. Everthing was fine for many years. Then 2003 happened. Later on, investigators were able to pull down lots of video with sheets of ice raining down onto the shuttle's shield. Perhaps the risk being assessed as being marginal was in fact not the case. How about that any statement inferring minimal ice damage to the orbiter was less than true in fact could it be a big fat lie ? Mr O'Keefe continued.

You have a developing situation at Tesla where a $100K car can be leased with little investment from the driver. Then you set up a situation where high power chargers are free to use as often as needed. If the battery pack is degraded by this practice it will be the shareholders - that's where I come in - who will carry the can for the warranty replacements. Nissan's battery warranty protects the company by specifying 1100miles/month + 25c /mile overage or something like that.
Finally Proof of Life is not set out for when these vehicles become CPOs in the automobile market. The battery is a big part of an EV. How accurately can the state of the battery be measured for a future buyer ? Owners report that even on-board range estimation still leaves a lot to be desired.

To be fair, Model S Supercharging looks like it currently ranges between 1.5 and 2C. I guess the jury is still out, but my prediction is that apart from some extreme outliers (long distance drivers and/or cheapskates) Tesla can keep Supercharging percentages down thanks to placement out-of-the-way in between cities, at least in the US.

And if 2C is considered high, then companies that think they can scrimp on battery to achieve a range figure will end up getting stuck in the slow-charging lane. It's science: 100kW is the _minimum_ for practical intercity charging, 250kW is a pivot-point. To achieve those power levels, you need batteries that can accept them. Those batteries can do so either via power-tolerant chemistry that's TBD or by scaling up their size. The latter is much less of a technology risk than the former, so if you really mean to sell a practical, normal-livable EV-as-only-vehicle you really need to do the latter.

Otis, from your previous two comments I see that you are pushing for larger batteries until battery tech catches up. Here's the problem I see with that. When is enough enough ? I think even at $150/Kwh the 24Kwh Nissan Leaf would have a $3600 pricetag. Not surprisingly there are many out there who are demanding double that for what they consider to be a viable car. However the case for future transport should be that "the purpose of cars is to primarily transport people and not the carriage of tons of chemical material through the streets". A single occupancy Model S weighing over 4000lbs is not the answer when some are purchased to gain unbridled access to the HOV lanes.

My deal is with the Superchargers which permit range extension for any size battery and the way in which they are being introduced to the market. In particular the free use aspect. When free use is permitted on anything, like supercharging in this case, then most people are going to want to capitalise on it.

Again human nature being what it is, a better strategy may be to impose a minor fee per use. Overtly this stategy might discourage bunching up around supercharger sites which is very likely to occur as the population of Tesla vehicles escalates, while achieving the underlying purpose of serving to avoid or mitigate any possible, but as of yet unproven, acceleration in the deterioration of battery capacity. A condition vehemently denied by Tesla supporters and something I hope will turn out not to be the case when more data is available.

However you have to be aware that a negative outcome carries the risk of additional financial implications to Tesla since the company has pledged to support the resale price to the original owner. The idea is that providing a backstop on the residual price will enhance the value of the brand and encourage future sales.

Meanwhile at Tesla, software designers may be taking advantage of the vehicle knowing - through the touch screen - when the vehicle is about to be visiting a SC site and will use the intervailing time by supercooling the battery enclosure in anticipation of the event. This proaction should ameliorate the effect of heat which will eminate from those 8000 individual cells during the subsequent sustained recharge at an ~2C rate.

Marketing at Tesla has taken the stance of saving on cost and to rely on word of mouth advertising, in which case they might try an assurance to remind consumers that " Whenever you leave home you start off with a FULL TANK". A sentiment that costs nothing but may dispel thoughts of range anxiety.

Is it also too much to ask that marketing will better connect consumers to the effect of speed on range ? I find it somewhat circumspect to benchmark range at 55mph in order to enhance vehicle capability on paper. Is it safe to say that no one who has paid out close to $100k for a Tesla is going to be satisfied by driving it at that speed unless, of course, they happen to be in a 40mph zone ?

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