Electric Highways and Byways

President Obama recently announced new fuel efficiency standards for cars and light trucks. By 2025 the Corporate Average Fuel Economy of these vehicles will be 55 miles per gallon of gasoline or its equivalent from other energy sources. It is unlikely that this standard can be met by sticking with the internal combustion engine. In fact the standard has encouragements built in which favor alternatives.

Foremost will be gas/electric hybrids, but plug-in hybrids and pure electric vehicles will contribute to the mix. Gas/electric hybrids such as the Prius gain efficiency and therefore higher mileage because they have batteries and electric motors to boost power when needed. The batteries are recharged from the gasoline engine when less power is required. Plug in hybrids and pure electric vehicles get some or all of their power from batteries charged from the electrical grid.

The greater simplicity and efficiency of electric motors mean that their mileage is much better than cars powered by internal combustion engines. Another advantage of electric cars is that the energy used to charge the batteries can be produced at locations remote from urban areas. This will have the effect of lowering pollution where people live and work. Overall less energy is needed to power an electric fleet of vehicles, regardless of how the energy is produced.

The significant advantage of gasoline powered cars is one of energy density and refuel time. A simple comparison is illustrious. A gasoline powered car can travel several hundred miles before refueling is necessary, and then the refueling time is only a matter of a few minutes. Currently available pure electric vehicles have a range of less that one hundred miles and recharging the batteries takes hours, not minutes. Research is ongoing to improve both the energy density and recharge times for batteries, but an alternative would be to charge the batteries on the fly.

This is the way a gas/hybrid electric works but it requires hauling a gasoline engine around with you. Ideally if you could charge the batteries as you go without a gasoline engine then the issue of battery life and recharge times becomes immaterial. We need a technological leap to get there but it should not be that difficult.

Enter microwave power transmission. Imagine a highway system with microwave broadcast antennas imbedded in the pavement. As electric cars drive over a segment of an antenna, computer controls on board would turn on the broadcast antenna, and a receiving antenna in the car would use the received power to charge batteries, essentially continuously. No power would be wasted as the broadcast antennas only function when a car is overhead and signaling to receive power. The system could begin in urban areas, extend to the interstate highways, and finally to the byways.

In all but the most remote areas, cars could still operate on batteries big enough to get them “off-grid” for reasonable distances, say a one hundred mile range. To minimize transmission losses, power could be provided from solar panels lining the highways. Or how about decking over the highways with panels? Both protect the highways and drivers from the weather and power the vehicles at the same time! I won’t go so far as to say the possibilities are endless, but there are a lot of novel ideas out there to be exploited.

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