Why is the Electric car not more popular? Many attribute this to some conspiracy by the oil companies. The simple fact is that physics killed the electric car, not any conspiracy, because the ability of batteries to store energy is about one thousandth that of gasoline.

Energy Density is often measured in Watt Hours per Kilogram. This means that a battery which can store 100 Watt Hours per Kilogram can run a 100 watt light bulb for about an hour for every kilogram of battery weight. The Watt Hours measurement is simply the product of the two, if it can run a 100 watt bulb for one hour, it can run a 200 watt bulb for half an hour, or a 50 watt bulb for 2 hours, etc.

The best batteries store a mere 300 Watt Hours per kilogram - and those are aerospace grade batteries used in satellites. Common rechargeable Lithium Ion batteries store about 100 Wh/Kg while lead Acid batteries (the ones in your car) store less than half that. Gasoline, for comparison, stores almost 30,000 Wh/kg. This is the main reason why electric vehicles are so rare and consumer demand is so low, when it comes to range, they have about 1/10th that of gasoline powered vehicle and need to be re-powered 10 times as often.

Many small motorcycle manufacturers are pushing electrics now not because they have vast performance potential but because they don’t need to go through the 10 - 20 million dollar EPA Engine approval process to get a vehicle on the road. This has led to results like the Providence based Vectrix motorcycles, producing an Electric Scooter that retailed for about 10,000 dollars, it managed a paltry 40 miles on a charge. This was after a reported 70 million dollars spent on R&D.

For the record though, Electric Motors generally have many advantages over internal combustion engines, the problem of electric cars is not the motors but how to power those motors. The performance advantages of electric motors in terms of power output and instant torque are commendable, and Electric motors are rated in constant power output (what they can produce continually without over heating) while Gas motors are rated in Peak power output (the maximum they can produce in a short period of time, but would destroy them if continous). A 10 Horse Power (HP) electric motor can sometimes produce for short periods of time 20 - 30 HP, while a 30 HP gas motor usually runs at 10 HP. If you have a compact car, that 100 HP engine in your car is usually running at about 20 - 30 HP. These admirable performance qualities of electric motors however simply do not make up for the pathetic range that batteries produce.

Electric vehicles may be simpler, not requiring air and fuel injection systems, transmissions, and exhaust systems, but the fact that you need to recharge them about ten times as often as a gas powered vehicles need to be refueled does not make up for that in any feasible mass marketable vehicle. No conspiracy killed the electric vehicle, pure and simple physics did.

While there are common news reports of advances in battery technology, these incremental advances are little compensation for battery energy density when it is a full two orders of magnitude off from gasoline.

Usually when celebrating electric vehicles, people are touting the advantages of electric *motors* not batteries, while apologizing for the batteries. But if gasoline far exceeds the capacity of batteries and electric motors have significant performance and complexity advantages over Internal Combustion gas engines, then serial hybrids are the best solution, or some form of liquid based fuel cells, not electric vehicles powered by batteries. A serial hybrid is not the configuration of today’s modern hybrids but something simpler. The serial hybrid exploits the advantages of gas as a storage system and electric motors as the motor power of the system. In it a gas tank fuels a small simple gas engine that is optimally tuned to run at one single speed (gas engines are super efficient at one and only one speed, at every other speed they waste tremendously more power) This gas engine does nothing but turn a generator and recharge a small temporary energy storage system made up of capacitors, which are like batteries in that they store energy, but are unlike batteries in that they can release almost all of their energy nearly instantly. Those capacitors power the electric motors which turn the wheel. Although this sounds like a somewhat complex system, it’s actually much simpler than the parallel hybrids found in most cars today, and could potentially get twice the mileage.

Tech news is often flooded with claims of amazing advancements in battery technologies, or amazing ultra-capacitors. From a recent article of that type we find

“We recently reported on new research that makes a Lithium Ion battery perform more like a supercapacitor, now we can report on research on a supercapacitor that performs more like a battery”

While super and ultra-capacitors provide high power density, but they are still low energy density. This means that while that can release alot of energy in a short amount of time (think flooring your gas pedal) they contain very little energy overall - so you might get one single rapid acceleration out of a capacitor bank, but then they will be dead and will need a recharge. In physics power and energy mean to very distinct specific and different things. Power is the rate at which energy is used, and energy is merely the capacity to do work.

In terms of energy density, super-capacitors are an order of magnitude lower than even batteries, and in terms of power density, batteries are an order of magnitude lower than capacitors. A new Lithium Ion battery, as celebrated in that article, that performs as well as a capacitor simply means you don’t need to use capacitors in your EV design, but you still have 1/1000th the energy density of gasoline.

Besides all that, these are merely claims, and until I see a product on the market which I can buy that gets these kinds of performance numbers then it is just speculation. Equally impressive claims can be made on the future efficiency of gasoline based power systems as well, one type of gasoline engine, the HCCI engines, for instance, could double or quadruple the efficiency.

But I don’t value something based on what some people say it *might* be capable of someday, but what it is proven capable of now. Unfortunately the industry incentives now are toward making outrageous claims then getting government funding to research them, ultimately finding out that they were merely outrageous in the first place. When a university comes out with an unabotanium-ion super battery claim they are looking for grants to do the research to find out if the idea is practical - they are not on the verge of mass production.

The current popularity of EVs is not driven by massive consumer demand but by a bias in research grant awards and the fact that you don’t need to spend 10 – 20 million dollars getting government approval to make an EV bike and engine. Unlike gas engines which require years of testing by various government branches to even get approval to manufacture and sell.

Lets do a quick example, imagine you want an electric car that performs as well as your 100 HP gas engine powered car. You get about 300 miles out of a full gas tank. Cruising on the highway your car probably uses about 20 HP, and one HP is the equivalent of 740 Watts. That makes your car require, cruising at highway speeds, 14,800 watts, or 14.8 kW (20 HP * 640 watts / hp) So if you need 14.8 kW for 5 hours (300 miles at 60 miles per hour) you need 74 kW hours (14.8 kW times 5 hours). If your car is powered by lead acid batteries you get about 40 Wh/kg (40 Watt Hours per Kilogram) Now, at 40 Wh/kg for lead acid batteries, that means you need … wait for it … 1,850 KG worth of batteries. That’s over 4,000 pounds, or 2 tons worth of batteries, yet right now your entire car weighs 2,000 pounds. With expensive Lithium Ion batteries, which get twice the energy density but cost four times as much, you would need a mere 925 kg of batteries. Compare this to the 40 kg your 15 gallons of gasoline weighs and it becomes clear why electric vehicles are not more popular. Remember, Gasoline has an energy density of almost 30,000 Wh/kg, while Lead Acid batteries are 40 Wh/kg.

Ultimately then, it’s physics that killed the electric vehicle, not an oil conspiracy or government cover-up. To put it simply, batteries just suck. You need 20 - 50 times the weight in batteries that you do in gasoline to get the same performance, and this does not take into account the potential significant advances in gasoline performance in the future. Unless some revolutionary battery technology arises whose basis is currently at the frontiers of physics, It’s highly doubtful that any time soon batteries will replace gas as the most convenient and useful energy storage mechanism.