Thursday, 26 May 2011

The growth cycle of a technology.

Where are we in the development cycle of the electric car? Can we look at other technologies and decide how mature the electric car is? A model for technology development might be:

1) Initial work by dedicated visionaries. Building and improvising many parts.

2) High cost, early models. Rich mans toy stage. Techniques and components are borrowed from existing technologies. Profits are starting to be made.

3) Volume, mass production. Huge industrial base. Ongoing development is cross fertilised from helper technologies. The technology is so significant that the base product inspires developments that enhance other technologies.



The combustion engined car and commercial passenger aviation are at stage 3. Cars are now universal and mass air travel is trivially cheap. By comparison, personal flight technology, today only available in owner flown helicopters, is still a largely impractical, expensive way for millionaires to kill themselves.  This technology is still at stage 2, the rich man's toy stage.

Universal communication, cellphones etc is well into stage 3. It too had a rich mans toy stage. Back in the 1960s it was possible to have a car telephone installed, if you were rich enough. Even thought the technology was little different to a police radio, with a telephone operator to dial through your connection to a landline phone, the basic need, for continuous, on demand communications was being realised.

When an existing solution is already in use a new technology has to be very good indeed before it can replace it. In the 1930s a couple of visionaries, one in Germany and one in England, developed the gas turbine jet engine. They came up with a technological step change so great that it was eventually worth while designing brand new aircraft and much new infrastructure to best exploit it.

With the electric car, production vehicles are derived from existing combustion powered designs. The energy storage systems are still largely improvised from those designed from vastly different, much lower power applications. The Tesla high performance electric sports car, for example, is based on ancestor technology. The frame and chassis are developed from a combustion powered Lotus Elise, and the energy storage system is derived from some 6,831 cells of the battery type found in laptop computers. These characteristics, and the high cost, lodge what is possibly the best example of the electric car, the Tesla firmly in stage 2.

Battery technology has improved greatly in the last thirty years. Energy density, the amount of power that can be stored in a certain weight of storage, has increased greatly, although it is still well below that of petrol. Additionally, combustion fuels have the advantage of reducing weight as they are depleted, a discharged battery weighs as much as a charged one. But, none of the battery improvements thus far have been as part of a development for electric vehicles, they were mainly developed to improve the performance of mobile phones and portable computers.

Recent years have brought improvements in electric motors. Werner Von Siemens invented the DC, direct current, electric motor in the late 1800s. The AC, alternating current, induction motor was invented by Nicolas Tesla in 1924. An AC motor is much more efficient than a DC motor. AC motors lack the mechanical brushes that must continuously break-reverse-make the circuit within a DC motor. (the things you see sparking away inside cheap electric toys) For an AC motor some form of alternating current power supply, not just a battery, is necessary. Miniature AC induction motors were used in some of the first airborne analogue computers devised in the 1940s. The aircraft that used them had to carry around their own source of AC power.

But, by the early 1990s, the development of microprocessors meant that small battery powered systems could use brushless AC motors. Power switching and control was then localised to individual motors. This makes for much more efficiency.

But that's not the end of it. Combustion engines have their own disadvantages that we just don't notice anymore. They work best at a particular speed, around 3000 revolution per min. As a result of this combustion cars have to carry around gearboxes in order that the most efficient engine speed be matched to the road speed. Piston engined aircraft do something similar by varying the pitch of the propeller as the airspeed changes. But, the electric motor inherently generates high torque at low speed. The Tesla sports car has no gear selection box, or clutch, it has a single speed transmission, and a forward, reverse and off switch. Although the energy density of gasoline is still much higher than batteries electric drive offers some sure savings. But the development stage 2 practice of borrowing technology does not yet allow full exploitation of these advantages.

A blank sheet electric car design would have a specifically designed automotive energy storage, using the latest battery chemistry. It would have a specifically designed drive system, probably all wheel drive with one motor, direct drive per wheel. A control system would be needed to keep it all working within safe limits and to precisely control the motors. Arguably, the most difficult part of the job would be that one, developing the safety critical software to get the best out of it. The fact that it hasn't happened yet isn't because the Tesla designer are idiots, they are working pragmatically to a budget. This requires employing as much existing technology as possible,while in stage 2 of the (electric car) technology development cycle.

An all out effort in electric car design could yield a much more effective technology quite quickly but in order to do that the initiative probably has to be taken out of the hands of private industry. Despite the broad claims of the free market fundamentalists private industry rarely pioneers brand new technology. The early history of the jet engine is a good example. Whittle, the British jet pioneer, tried and failed to interest the engine companies who would, post war, make massive sales, and profits from the jet engine. Even the Royal Air Force gave Whittle more help than the British aero engine industry and, but for the wartime opportunity of near limitless, taxpayer funded development, the technology might have languished in the doldrums for years. (or been developed elsewhere)

The electric car is also disadvantaged by the highly developed state of combustion engined cars. The newest developments in energy storage and motors are, not yet, enough to dislodge the combustion car. Petrol is a great means of storing energy in a very compact form, it has a very high energy density. Even the best new batteries still fall short of this. Energy density of a lead acid battery, 0.14 Mj/kg. A Lithium Ion battery 2.5 Mj/kg. -- Gasoline, 46.4 Mj/kg.

There is, perhaps, one other factor which is inhibiting electric car development, the fact that there are competing, energy storage systems that might turn out to be be more effective than batteries. The hydrogen fuel cell, or flywheel technology might turn out to be more practical than batteries.

The primary problem is one of improving energy storage. Out of this will eventually come new technologies that will find other applications. Amongst these, perhaps, local storage of renewable energy. At the moment homes with rooftop photovoltaic cells get financial benefits by selling surplus power back to the grid. It could be more efficient if it were stored and used locally, at night time.

However, it will be ironic, after the motor car has burned up most of  the hydrocarbons, if the next big technology breakthrough for renewable energy comes as a result of car development.

4 comments:

  1. # By comparison personal flight technology [is]
    # still a largely impractical, expensive way for
    # millionaires to kill themselves.

    You're so right, if only society had sufficient vision and commitment back in the 80's, then by now it could be a practical, cheap way for millionaires to kill themselves!

    Colum

    ReplyDelete
  2. # You're so right, if only society had sufficient
    # vision and commitment back in the 80's, then by now
    #it could be a practical, cheap way for millionaires
    # to kill themselves

    Oh, hang on, I just realised, we've already got those. They're called cars.

    Colum

    ReplyDelete
  3. I don't mind if they do it on the cheap. ..just so long as they keep killing themselves.

    ReplyDelete
  4. We need clean energy and we need it NOW!! It only took 2 years to develop and build the first atomic bombs, the Manhattan project.They went all-out on it 24/7, and got it done fast. Why does it take so damn long, for something that is actually good for humanity, but deadly weapons and things that are not necessary are developed very fast. We need clean energy or we will all be gone soon.

    ReplyDelete