Electric cars are part of the vision of a clean energy society, in which Americans would use few fossil fuels, emit limited greenhouse gases and depend less on foreign sources of energy. Will that vision be realized – and are electric cars even necessarily part of that vision? Are electric cars environmentally friendly? Are they an economical means of transportation now? How likely are they to capture the market in the coming years?
The answers to these questions are maybe, yes, no and not very.
What exactly is an electric car?
An electric car is any car that is powered by electricity. It could be powered by an on-board battery or an on-board fuel cell – which itself could be powered by on-board hydrogen. I’ll ignore the fuel cell for now and consider the different types of battery-powered vehicles.
A battery-driven electric vehicle could be a hybrid-electric vehicle (HEV), a plug-in hybrid-electric vehicle (PHEV) or a pure battery-powered electric vehicle (BEV).
A HEV, like the Toyota Prius, has only a small battery, which is recharged by the vehicle’s internal combustion engine running a generator. The Prius’ battery only stores enough electricity to run the car for about five miles. But because of the Prius’ ingenious design, it uses less gasoline per mile than a similar gas-powered vehicle. That is largely because it can shut itself off when idling and can recover energy when the car brakes.
A PHEV is a HEV that can also be plugged into an electric socket to have its battery charged. For that capability to be of much use, the PHEV must have a larger battery than the HEV so that it can run more than five miles on the charge.
A pure battery electric vehicle, BEV, unlike the HEV and PHEV, has no other source of energy than its battery.
The electric vehicle scenario
Electric cars are part of the environmental vision because that vision includes an economy that is not powered by fossil fuels.
The idealized scenario runs like this. In the future, because of the dwindling supply of fossil fuels and climate change concerns caused by their emissions, electricity would be generated from non-carbon-emitting sources. In the usual vision, these sources would be renewable – chiefly wind, solar, hydroelectric and biomass – though they could include nuclear. Because most of the renewable sources generate power intermittently and randomly, some means must be found to store the energy or to manipulate demand so it matches the power generated.
The only economical means of large-scale electricity storage is what is known as pumped hydro. Excess electricity is used to pump water uphill, where it is stored behind a hydroelectric power dam. When more electricity is needed, the water is released through turbines at that dam.
The smart grid is envisioned for large-scale matching of demand to power generation. A smart grid is a region-wide interconnected electricity transmission and distribution network. It is rigged with an enormous number of sensors and controllers, in every household, commercial building and industrial operation. The grid’s sensors and programming can tell when an end use – a water heater, for example, or a refrigerator – can be temporarily shut off without impeding its function, and the grid is able to shut off those appliances when necessary.
This scenario ideally takes care of electric energy use. It doesn’t do anything about oil, however – which is now the principal energy source for transportation and the fossil fuel considered the most limited and geopolitically precarious. Oil is also the second-most carbon-emitting energy source, after coal.
In the idealized low-carbon future, transportation would be powered by biofuels or electrification. We tried biofuels in the U.S. with corn ethanol, but it finally proved to be uneconomical. The way corn is grown in the U.S. is highly petroleum-intensive, so using corn ethanol doesn’t save that much oil. (The ethanol derived from sugar cane in Brazil, where ethanol is a primary transport fuel, is less petroleum-intensive.) Additionally, corn ethanol diverts corn that could otherwise be used for food and animal feed, driving up the worldwide price of food.
Hence, electrification of transportation is the preferred option. An electric car in every garage would mesh perfectly with the smart grid strategy for taming the variable energy sources. The smart grid could use the cars’ batteries as energy storage. Whenever supply from renewable sources exceeded demand, whatever electric vehicles were plugged into the sockets in their garages would be charged from the grid. Whenever supply fell short of demand, the smart grid would have the option of temporarily deferring some uses or temporarily drawing down the batteries of electric vehicles that were parked in their garages.
Obviously, only PHEVs and BEVs could fit into the smart grid scenario in which the electric vehicle acts as storage for excess electricity when total power generated exceeds demand.
Electric cars also produce no emissions in the places where they are likely to spend the most time: urban areas. These areas are most in need of emissions reduction, especially in developing countries.
Are electric vehicles environmentally friendly and economical now?
Let’s take this question in its two parts. Are EVs environmentally friendly now? In general, yes, but it depends. If environmental friendliness is measured by public health outcomes and exposure to atmospheric pollutants, they are more environmentally friendly than internal combustion engine (ICE) vehicles. Their use in urban areas would drastically reduce the unhealthful particulates and nitrogen oxides to which urban-dwellers are exposed.
When it comes to carbon dioxide emissions, which can drive atmospheric warming and climate change, the answer is a little less clear. With an ICE vehicle, CO2 emissions occur when the fuel is burned. With an electric vehicle, the emissions occur at the power plant where the electricity is generated. If the electricity is generated in a manner that emits no CO2 – as from nuclear, wind, solar, hydro or geothermal sources – then the EV causes no CO2 emissions. But if the electricity is generated from coal, the race is much closer.
A presentation by the MIT Electric Vehicle Team depicts the so-called “well-to-wheels” (WTW) efficiency of ICEs and EVs. In the ICE energy chain, only about 13% of the energy in the fuel actually goes to power the ICE vehicle’s motion.
With the EV, energy is lost in generation and transmission of electricity, even within the vehicle itself. The MIT presentation estimates that 23% of the energy in the fuel at the well goes to power the EV’s motion.
From this, it would seem that the EV produces lower emissions than the ICE, even if electricity generation is entirely fueled by fossil fuels. But the analysis omits two things. First, coal is more likely to fuel power generation than is oil, and coal emits about 30% more carbon. Second, the analysis doesn’t account for the fact that in a fossil fuel world, manufacturing the EV battery produces CO2 emissions initially and when the battery is replaced. How often the battery will be replaced is the subject of controversy. The lithium-ion batteries in new PHEVs and BEVs have not been in widespread use long enough to produce adequate data on their longevity.
Hence, the environmental friendliness of EVs is unclear. They are clearly friendlier than ICEs to the atmospheric quality in the neighborhoods in which they operate. They probably account for fewer CO2 emissions than ICEs, but the difference between the two depends on how the electricity that powers them was fueled.
Are electric vehicles economical now? The answer to this seems to be a clear no, but again, it depends on how they are used. Golf carts are electric-powered for good reason, since an ICE would not do the same job as well. In some situations and for some households, an EV with a small battery as a second car might be useful. But neither BEVs nor PHEVs, based on current retail prices, are economically competitive with ICEVs now, even with a large subsidy.
HEVs, on the other hand, are close – as sales of a million Toyota Prius hybrids worldwide (generally with subsidies) suggest. Furthermore, according to an MIT analysis, the HEV’s well-to-wheel efficiency is as good as the PHEV’s and better than the BEV’s. The HEV is as good as any vehicle on CO2 emissions, and it is much better than pure ICEs on local pollutants.
The devil is in the battery
EVs have not been selling well. The Nissan Leaf, the bestseller, has sold half as many as Nissan projected. EVs’ problem in the marketplace is often identified as “range anxiety:” They won’t take drivers far enough before they have to recharge the battery, and with current infrastructure, recharging is a major nuisance. Given current battery technology, batteries sufficient to take cars long distances are very expensive and heavy. The company Better Place is trying to improve the infrastructure by providing battery-exchange stations in which depleted batteries are exchanged for charged ones quickly, but the process is costly.
The hope for electric vehicles lies in improved battery technology. However, Energy for Future Presidents author Richard A. Muller points out that the effective energy density of batteries is only about 4% that of gasoline. That is, a kilogram of batteries can deliver to the wheels only 4% as much energy as a kilogram of gasoline. “Most of the work of the past few years has been to address the messy technical details of rechargeability and safety,” Muller writes. “This is the kind of engineering development that is linear, not exponential. So expect batteries to improve, but not at the pace that we’ve seen in the recent past.”
The potential scourge of electric vehicles: other kinds of vehicles
There is a good chance that other transportation technologies will outcompete electric vehicles, at least in the near- to mid-term. Prices in the United States for natural gas have come down and may stay low if shale gas hydraulic fracturing continues to produce the boom in natural gas supply that many believe it will. If fracking technology moves to China, gas supplies may grow apace there too, where much of the growth in automotive vehicle sales is predicted to occur.
The fracking successes are so recent that auto companies haven’t had time to plan and tool up for the change in relative fuel prospects. As they do, a shift of emphasis toward compressed gas-powered vehicles and compressed-gas hybrids is likely. Compressed natural gas (CNG) vehicles will produce significantly fewer CO2 emissions, particulates and nitrogen oxides than gasoline-powered vehicles do. Their economics may compete even with ICEs, let alone EVs – unless some tremendous breakthrough occurs in battery technology.
In an intriguing development, The Economist reports that Volkswagen’s Audi division is about to try to combine hydrogen, made from water using wind power, with carbon dioxide emitted from power plants to make methane, which can then be used in CNG vehicles. If this proves possible and economical, the CNG vehicles get credit not only for lower emissions but for recycling CO2.
It is far too soon to know what the transportation scenario of the future may look like. It may include electric bubble cars just narrow enough for commuters to scoot through traffic, or cars that drive themselves in a Borg-like alliance with other cars on the road. But it may not necessarily be as heavily reliant on EVs as some imagine, or at least not soon. One suspects that the affinity many have for electric vehicles as the Holy Grail of transportation derived from that love-at-first-sight moment when many assumed that EVs actually created no emissions at all, overlooking the power-generation systems that give them their energy.
Michael Edesess is an accomplished mathematician and economist with experience in the investment, energy, environment and sustainable development fields. He is a senior research fellow with the Centre for Systems Informatics Engineering at City University of Hong Kong and a project consultant at the Fung Global Institute, as well as a partner and chief investment officer of Denver-basedFair Advisors. In 2007, he authored a book about the investment services industry titledThe Big Investment Lie, published by Berrett-Koehler.
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