When David pointed out that plug-in electric hybrids (PHEVs) can reduce carbon emissions in all possible futures, two main arguments were raised in opposition — practicality, and the possibility that they will provide too low a reduction, while blocking the path to something better.


The way commercial plug-ins look to be implemented within the next five years is that normal hybrids will be built with large batteries and the ability to plug into a socket in your dedicated parking space. They will travel the first twenty miles or so on electricity and then turn on their gasoline engine around the 21st mile or so. Even with our current grid, they will emit less CO2 per mile than when they switch to their gasoline engine.

Like hobbyists, who manually convert existing hybrids, these will have to be more expensive than a normal hybrid, because they have every expense a normal car has plus the extra battery cost. If gasoline prices rise high enough, I suppose they may pay for themselves in fuel savings, but mostly they will sell on the “cool” factor.

However, there is another way to implement plug-ins, one we could begin now with a large enough investment, which produces savings comparable to a full electric car — and which, if run on wind, or sun, or other ultra-low-carbon electricity sources, could actually provide a 98 percent emissions reduction.

The idea of the HypercarTM has been around longer than the name. Build an ultralight car that is reasonably aerodynamic. (No, it does not have be a tear drop; you have a choice of a lot of shapes.) Drive it with electricity — even if the electricity is generated from an on-board gasoline-powered generator. You still end up with better efficiency than using straight gasoline to power light normal internal combustion cars. Alternatively, you can make an all-electric HypercarTM, like the prototype Sunrise that Solectria demonstrated back in 1997, which ran off a 30-kWh battery pack and had a 216-mile range (a bit more than the Tesla with its 56-kWh pack). Let’s look at the economics of a PHEV and an EV car with today’s technology.

Tesla chose to use thousands of commodity laptop LiON batteries combined in special packs that provide cooling, safety, and battery management. These packs cost around $20,000 for 56 kWh, or $280 per kWh, and are expected to last about 600 cycles (in the Sunrise, around 130,000 miles). So if we were pricing the Sunrise today, its battery pack would cost about $11,400. A carbon-fiber body would run around $6,400 at current prices, according to an article highly critical of lightweighting. Add the rest of the cost of a car, including O&M, marketing, and profit, and you would end up with an all-electric HypercarTM today for a cost of $25,000 to $30,000. That range is above that of the Prius. It would NOT pay for itself in energy savings, even if gasoline rises to $5 per gallon.

However, it is also not that far from the median price of today’s automobile. I suspect that it would have a nice niche market — people who bought it for the cool factor, to be environmentally conscious. Even with our current grid it would get the equivalent of about 90 mpg. (It would actually get more, because the Sunrise runs on NiMH batteries; LiON are much lighter.) With a low-carbon grid, the emissions would be about 98-99 percent less than a conventional gasoline-powered car. (This combines a grid that produces power with 5 percent of the emissions of our current grid with cars that use that energy three to five times more efficiently than our current “average” car uses gasoline.)

Note that the cost difference between an all-electric HypercarTM and a normal hybrid is real, but small. That is because the cost effects of driving a car by electricity are not all one way. An all-electric car needs no engine; since much of the speed control comes from the amount of electricity fed to the motor, it can either do without gears or (as with the Tesla) use a much more limited gearing system than a normal car. In general, the combination of a unibody and less mass to move saves really large costs.

Note that the largest cost here is the battery pack. You can reduce the cost of this electric HypercarTM to that of a Prius or below by reducing the size of the battery pack and adding a small, variable-speed, gasoline-powered generator to send electricity to the motor when the battery pack is low. Note that, unlike normal hybrids, this would basically remain an electric car. You are not running a battery in parallel with a gasoline engine. The car is always driven by electricity. It is just that that electricity is produced by gasoline or diesel fuel when the battery is low. Full electric drive, regardless of how the electricity was generated, was the original intention behind the HypercarTM concept.

So what would the economics look like? If you decided on a 18-kWh pack (140-mile range) instead of a 30-kWh pack, this would cut about 4,600 off your battery costs. You are adding back $2,000 for motor and generator, so your net savings is $2,650. Instead of a $25,000-$30,000 price range, you now have a $23,000 to $28,000 price range, around the cost of a Prius. And you could make cars at this price in large niche-market quantities — volume 10,000 per year.

There is one problem; the same 600 cycles that could last 130,000 miles with a 216-mile range would only last 80,000 miles with a 140-mile range. So you have to change your battery pack after eight years. LiON costs are dropping about 7 percent a year, and we do have major technical innovations in the works that may lower costs as well. So the cost of a replacement battery pack will probably run about $4,000 with labor and tax, in eight years. By that time, the replacement pack should be good for a thousand or more cycles.

What about the emissions cut? Well, such a car would have a range of about 130 electric miles using the NiMH batteries of the original Sunrise, probably at least 140 miles with the new LiON packs. Most estimates suggest that about 85 percent of miles are driven on trips under 60 miles. A 140-mile range ought to allow 95 percent of miles on such cars to be driven from the battery. It should get about 75 mpg when the gasoline engine comes on.

With a low-carbon grid (and we are not going to solve the climate chaos crisis without a low-carbon grid), this means you can drive 95 percent at a 99 percent reduction, and drive the other 5 percent at a 66 percent reduction; this averages out to better than a 98 percent reduction in both carbon emissions and oil use. That means that the PHEV HypercarTM is not just a transitional technology. Ninety-eight percent per capita exceeds both the emission reductions Monbiot proposes to avoid frying the planet and the reductions most peak-oil theorists suggest.

The cost difference compared to a $18,000 conventional car is small enough to pay for itself with $5-per-gallon gasoline, or a feebate comparable to current hybrid tax rebate.

It is another example of something where we have the means, we just don’t have the will. Yes, technology breakthroughs would be wonderful — cheaper batteries and cheaper carbon fiber. But we just need to make the decision, as a society, to buy this.

I’ve seen some commenters who suggest they are going to wait for PHEV before they buy a new car. The problem with that is: we don’t know then they will be available. If we as a society wanted them to be, they would be here soon. But as it stands, they are going to take a while to get here, and the first ones may come from companies who have trouble building anything too different from a standard IC engine. The GM Volt, if it ever really arrives, won’t have a very long electric range, won’t run much more efficiently than a hybrid on electricity, and will probably run less efficiently than a hybrid on gasoline.

In short, if you are driving a really inefficient car now, better to get the most efficient cars available today than wait for breakthroughs Detroit won’t deliver in the near future. Note that there are a fair number of both non-hybrid and hybrid cars that get over 30 mpg you can buy today.