Juice
In one hand you’re holding a gallon of gasoline weighing six pounds, in the other a three pound battery, now imagine them containing equal energy. Spoiler alert: they already can. The most exciting and far-reaching scientific advance is the dramatic increase in electric battery density allowing it to displace gasoline, and solving the problems of night electricity, vehicle range, and becalmed windmills.
Electric car range extends about 9 percent every year and has reached a point where one can imagine round trips that don’t involve a flatbed. But the public was startled in 2011 when a seven figure prize was claimed from Green Flight Challenge who offered it to an aircraft that could fly 200 miles under two hours with a passenger using less than one gallon of fuel. Three planes competed—two electric and one a hybrid—with only the electric planes finishing under two hours. The winner averaged 114 mph on a plug-in electric plane sans a gas engine; this was a Tom Swift fantasy five years earlier as the weight of the batteries couldn’t be lifted by the plane even if they could be crammed into fuselage. The weight and size of the battery shrunk while its energy storage increased.
Presently, our battery density peaks at about 250 watts-hours per kilogram, up dramatically from the 150 Wh/Kg a few years ago, but still far inferior to petroleum, which is 12,000 Wh/Kg or about 30x. One company is about to release a 400 Wh/Kg, up 60 percent over the previous best, but batteries under development could pass the energy density of fossil fuels within a few years.
The most exciting and counterintuitive battery invented is the lithium-air that inhales air for the oxygen needed for its chemical reaction and exhales the air when finished. This should ring a bell given the similarity to gas engines: they inhale air, add a gas mist and the expanding air creates power, but then expels an atmospheric sewer. The lithium air battery is solid-state and exhales clean air. MIT has already demonstrated a Lithium-air battery with densities of over 10,000 Wh/kg.
Batteries need not have the energy density of gasoline in order to replace it as the physics of harnessing gasoline power are lame, only 15 percent of the energy in one’s tank motors the car down the highway. The rest is lost to heat, engine and transmission weight, friction, and idling. As a practical matter, batteries in the labs are already beyond useable energy density of fossil fuels, an energy density that results in a 500 mile range for an electric car with a modest battery, probably more for a small plane.
The second dramatic change happening now is that increased battery density has lowered both the size and cost of electrical storage, creating the bridge between intermittent wind, daytime photovoltaic energy, and the round-the-clock current demands of the consumer.
Windmills produce prodigious electricity during a good blow but bupkis when becalmed, hence the batteries provide steady current until a breeze appears. A new battery installation at Elkins, West Virginia windfarm allows the 98 megawatt turbines to be a constant part of the overall grid supply, with pollutant free electricity and the reliability of a conventional fossil fuel plant.
Also fossil fuel plants run at higher capacity than needed in case of a spike in demand, not needed with a battery backup: a new megawatt battery installation in Atacama Desert, Chile brought stability to their grid and a reduction in fuel usage.
The green revolution that has been hoped for is suddenly here, improbably due to the humble battery. A century ago there were more electric cars on the road than gasoline cars, very soon we will be back to the future.
