Electric Cars in their Time and Place

(originally published in Facebook, 2009-12-01)

Grid-powered electric cars are a short-sighted idea for general motorised personal transport. The concept doesn’t scale to fit a significant proportion of the motoring public.

It’s a simple matter of energy storage and transport. And the viability of such a scheme can be tested with a few simple calculations. Energy is energy.

Limits in Battery Technology

The energy density of safe, roadworthy batteries is simply too low with existing and foreseeable technologies. Electrochemical limits are the barrier. Physical limits of the real world. The energy needs for transport are too high when the vehicles have to meet the same standards for safety and comfort as “normal” cars.

The result is that electric cars will be city-bound; as the range is limited to about 100 km in practice; and will probably have no more than 2 seats. With such a short range, they will need frequent recharging and/or battery swaps if used for another purpose.

Battery Exchange

Battery exchange facilities would be getting between 3 to 5 times as many customer visits per day as a fuel filling station because of shorter vehicle range. For a busy exchange centre, that would mean around 10,000 exchanges per day. That takes a great deal of space because recharging a battery pack takes 50 times longer than refuelling a conventional car. The electricity supply grid isn’t capable of charging that many large batteries at a filling station. Each station would consume as much electricity as a suburb.

The “exchange fee” would have to be of the order of $10 to $20. With less than $5 in electricity stored in a “fully charged” one. Batteries will “wear” as they are discharged and again recharged; able to recover less and less of the initial energy put into the battery. The range of the vehicle becomes unpredictable as the battery is “suddenly empty”; with little warning possible.

Home Recharge

Charging at home also doesn’t scale. If one overlooks that garages are far from universal and a secure charging point is imagined viable, then it’s still a matter of putting the necessary energy into the car. And that amount of energy is 2 to 10 times the normal household’s electricity consumption for a daily commute.

Most commuter vehicles will need to be recharged during what are now off-peak hours for electricity; typically after 10 p.m. and before 5 a.m.. Off-peak electricity rates will shift to normal business hours as electricity providers will need to provide 3 times as much electricity in the dead of night, all night, as they do during the business day. That’s assuming that the electricity generation and distribution grid are upgraded substantially to match the demand for “domestic” traction power.

Viable Electric Cars

With battery technology having hit physical limits, we need to look elsewhere for ways of fueling electric vehicles. If you can’t get over the hurdle, sneak underneath or walk around it.

One option is to seek to produce chemical bonds in materials to produce a stable, synthetic compound; i.e. efficiently put the energy into a compound from a convenient, high-density energy source (e.g. nuclear). Then put that compound into the vehicle and collect the energy as the chemical bonds are released in a catalytically controlled reaction, as needed by the vehicle’s electrics.

The first part, that of producing a liquid electro-fuel, needs to do backwards what a fuel cell does forwards. Hydrogen is a small stepping stone, albeit in the wrong direction. It’s quite volatile with great expenses in distribution and storage; and is very energy-intensive to synthesize.

BMW announced early in December 2009, that the current fleet of hydrogen-fuelled vehicles would be the last in the foreseeable future. That followed VW’s earlier announcement that fuel cells were unsuited for volume deployment. (Article in the German Autogazette)

One of the “gotchas” with fuel cells that is not immediately obvious is that they develop a lot of “waste” heat. That heat must be rejected into the environment; which becomes more difficult in warmer climates and at higher altitudes. The amount of heat rejection is about the same as for a diesel-engined vehicle with similar engine output; so an active cooling system of about the same dimensions is essential.

Developing a liquid fuel with handling and storage characteristics like those of diesel fuel or gasoline would be a lucrative, commercial research field.

Finding CO₂ not-guilty as accused of making the sky fall is probably a breakthrough as it makes carbon available for a heavily bonded synthetic fuel, which when run through a fuel cell, would produce nothing but harmless CO₂, N₂ and H₂O.

The rest of the technology already exists to some degree. We “know” how to go about it.

Essential Internal Combustion

We can’t un-invent the internal combustion engine.

It’s gotten us where we are, and it’s doing so more efficiently and cleanly every year. The motor car provides unprecedented freedom of mobility, providing a large scope for choice of where we live, work and enjoy ourselves.

Remember those guilt-free Sunday drives?

Let’s not forget that internal combustion engines also move the raw material and products that we need to live. The even get us to a hospital in an emergency.

And we still need the internal combustion engine to provide a certain future. The necessary technologies for sustainable electic cars simply don’t all exist. Those technologies can be wished, but they also need to be invented before substantial money can be invested into making them commercially viable.

---

Footnote 2013-02-05:

Breitbart:

Hybrid car pioneer and “father of the Prius” Takeshi Uchiyamada says the billions poured into developing battery electric vehicles have ultimately been in vain. ”Because of its shortcomings–driving range, cost and recharging time–the electric vehicle is not a viable replacement for most conventional cars,” said Uchiyamada. “We need something entirely new.”