Sept 16, 2011
My friend and colleague John Petersen has it in for the electric car. Recently he wrote a summary of his anti-electric car views, entitled "It's Time to Kill the Electric Car, Drive a Stake Through its Heart and Burn the Corpse." Did I mention he also has a flair for the dramatic?
Many electric vehicle (EV) advocates, or "EVangelists," as he calls them, have tried to refute his arguments. One of the more coherent attempts was "Tesla and the Future of the Electric Car," which I recently reprinted as a guest article on AltEnergyStocks.
Innovation
I personally find both arguments incomplete. Petersen has a strong libertarian streak, and the thought of wasteful subsidies drives him to distraction. EV subsidies top his list of pet peeves, although he's curiously a fan of government meddling in the transportation market when it comes to CAFE standards. The EVangelists often correctly point out that Petersen is overly pessimistic about innovation, but they focus too much on the potential of innovation to reduce the price and increase the durability of vehicle battery packs. Yet even the true battery experts are skeptical of the rapid advances in batteries EVangelists predict. I find both sides to be too focused on "winning" the argument when what we all should be doing is trying to overcome the very real economic barriers to EV adoption.
Like the EVangelists, I believe in the power of innovation. But it is the nature of innovation to appear where it is least expected. Battery technology will advance, but the innovations which reduce our dependence on fossil fuels for transportation need not be innovations in battery technology. Innovations to our mobility system have the potential to reduce the use of oil far more quickly than than improvements in batteries, even while battery innovation will continues. Such innovations are likely to include potential better battery chemistries and manufacturing, as well as improvements in the rest of the battery, such as better separators, or other changes most of us have not yet thought of.
Systems Thinking
Those battery innovations we can foresee will only bring marginal improvements to battery performance. As energy efficiency professionals know, giant qualitative improvements come not from replacing a building's components with more efficient ones, but by redesigning the whole system with energy use in mind. The same is likely to be true in our transportation system: just replacing internal combustion engines (ICE) with electric motors leaves all the potential gains from system improvement on the table.
To get some idea what sorts of system changes may be effective, it helps to understand the costs of our current car paradigm, and why simply replacing the ICE with electric drive alone is unlikely to lead to the widespread adoption of EVs.
Most of the objections to electric cars, and certainly Petersen's, focus on the up-front cost of the car, and the difficulty of paying this back based on the lower operating costs of an electric car. The key to understanding EV economics (or "EVconomics") is that compared to the cost of the fuel a gas tank holds over its lifetime, it is practically free, while the cost of a rechargeable battery is comparable or even greater than to the cost of all the electricity/fuel it will hold over its useful life. While ICEconomics is all about the cost of fuel, EVconomics is about getting the most out of the expensive battery, while the cost of the electricity to charge it is relatively unimportant.
EVconomics
A car battery which is only recharged at night will be fully cycled no more than once daily, and probably much less if the car is not driven to its full range every day and may stay in the garage some days. Because of this, it seems unreasonable to expect an electric car battery to go through more than 300 full charge cycles a year, while 200 full cycles per year is probably closer to the real world average for cars charged only at night. Since EVs get between 2 and 6 miles per kWh, while gasoline vehicles (not counting hybrids) get between 15 and 40 mpg, I will use as an approximation that 1 gallon of gas can be displaced by about 8 kWh. That means that each kWh of a battery pack will displace approximately 25 gallons of gas with 200 kWh, and at most 38 gallons of gas with 300 kWh in a year's use. The following chart shows the number of annual savings expected for each kWh of an electric car's battery for different driving/battery recharging intensities.
If electric cars are to become truly mass market, they will need to accommodate drivers who normally only use half of their potential range a day, and don't drive some days (for about 100 full charge cycles per year, represented by the yellow line) as well as the most intensive users with 300 or more full charge cycles per year. The yellow line only reaches breakeven over five years with the most optimistic (many would say unrealistic) battery improvement scenario, and then only with gasoline prices doubling to $9 a gallon, meaning that EVs will not make sense for casual drivers any time in the foreseeable future.
EVconomics of the Urban Commuter
Yet even EVangelists do not consider causal drivers to be ideal electric car users. They tend to focus on the urban commuters. Such urban commuters have regular commutes that allow them to use most of their battery range on a near daily basis (300 full charge cycles per year, represented by the middle green line on the chart.) For this group, a five year payback can be achieved if we assume battery prices falling to a more believable $750 per kWh and gas prices rising to a not-incredible $4.80 per gallon.
Yet such intensive usage might reasonably be expected to shorten battery life, meaning that a shorter three year payback might be needed to make the electric car economic. (Note that a battery's life depends not only on the number of times it is cycled, but the depth of those cycles, and how long it is kept at full charge. Keeping a Lithuim-ion battery at full charge or fully depleted can be particularly damaging.) A three year break-even would require either a battery cost breakthrough and gas at $5.20, or significant battery improvement and gas at $7.50 per gallon, which seems possible, but is not likely in the next few years.
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