Eric,
that's a really shallow analysis. For starters, the food a cyclist consumes is not necessarily any more than what another human would consume-- Most people work out; someone driving a car is likely to go burn a bunch of food calories on a treadmill or playing field elsewhere, so your assumption that cycling inherently means more food consumption is off-base.

Further, food is a renewable resource. Fossil fuel is not.

I also think that when you talk about the "social cost" of driving, you're leaving out a lot of externalities. Fuel consumption and carbon dioxide production are only two of the issues cars bring up. Air and noise pollution, traffic fatalities, roadway building and maintenance costs, obesity (and subsequent healthcare costs), and a myriad of other problems all constitute social costs of driving that everyone has to bear, and that non-drivers bear disproportionately.

Finally, I'm not sure where you get the idea that a bike is only 10 times more efficient than a car. A fit person on a bike (not an enthusiast or racer) generally puts out in the neighborhood of 100 watts, or 1/7th a horsepower. Even with a more underpowered new car car today, let's say 100 horsepower, that's at most 1/700th of the power required to move the car around.

True, it takes longer to ride a bike somewhere than a car, so the power comparison isn't completely straightforward. But ignoring the case of cities (where bikes are often quicker than cars), let's assume the bike takes 3 times as long (i.e. the bike averages 15mph while the car averages 45mpg)-- even then, we're talking about 1/200th the total energy for the bike to get somewhere versus the car.

Are you sure you're not an auto lobbyist?

Count Chocula

Almost every car-bike collision I've seen in my life (and I've seen more than several) has involved bikes riding on the sidewalk and trying to negotiate an intersection. It's an incredibly dangerous way to ride-- Cars don't expect to see you coming, and even if they do, your visibility is often limited by parked cars, pedestrians, greenery, etc.

You're correct; some cities (especially in the south) do provide "bike-specific" or "multi-use" sidewalks for bikes, but these are developments undertaken by officials from the driver's perspective, with little to no understanding of what makes cycling along public roads safe and predictable. As a dedicated and none-to-timid rider (I've been riding in downtown NYC for most of my life, and now live in Pittsburgh), I find myself scared shitless from personal experience at the thought of riding a sidewalk, bike-specific or not. I generally prefer to dismount and walk if there is no way for me to reach a destination other than the sidewalk.

Guys,
All I'm getting at is that using this for serious power generation would be silly-- it would be far more efficient to run a gasoline generator.This technology could be useful for running extremely low-power appliances like traffic signals where the energy required from each passing car is negligible, but anything more would be extremely wasteful; and since the root power source is gas anyway, it's not particularly green.

Tobias,
I understand that human beings ultimately draw their power from the sun-- that was exactly my point. A sidewalk using this technology is essentially a way to harness some solar energy, while the same thing on a road would be harnessing fossil fuel. I also understand that solar panels are more efficient than this; I was just making a point about the "green-ness" of this particular proposition. But that said, this would work in situations without any sun, and seems like it might be cheaper.

Regardless of friction, any surface that harnesses energy from cars is going to require more energy from those cars. With a piezoelectric system like this, the energy comes from "squishing" the crystals-- essentially making the road a little softer. softer surfaces require more energy to traverse.

This idea makes much more sense with pedestrians and bikes, because at least then the root energy source isn't burning fossil fuels.

A large issue is actually size-- many CFLs are too large to fit into older light fixtures, especially at higher outputs. If they've really managed to make the bulb smaller, this actually would let me use them in my bathroom and kitchen, for example, where I've got permanent fixtures in the ceiling.

Granted, they don't say what wattage this one is.

Tyler,
Learn your history. Horses actually did just fine on unpaved roads because they could step around potholes and other road damage. Although cobblestones and other surface treatments were popular in cities where the sheer volume of traffic could destroy the road surface, continuously asphalt or gravel-paved roads were first systematically pursued by cyclist groups. Of course, during the thirties the efforts to pave roads shifted to automobile use as the car became ubiquitous (there were five US residents per privately owned auto by 1930). I'm not saying that all of today's roads are designed for cyclists; any idiot can see that that's not true by looking at the boneheaded design when it comes to bike accommodations on most roads. I'm saying that the first groups to actively pursue a network of continuously paved roads (I.e. paved along the entire length, from city-to-city) were cyclist groups.

Remember, the bike was the first mode of personal transportation after the unhitched horse to be able to maintain 15 miles per hour easily. Although that speed seems a little pokie now, it was sufficiently faster than wagons and pedestrians to generate a vision for a paved highspeed network of highways.

Actually, a lot of the roads in the US were first paved by or under pressure from bike lobbyist groups, especially the League of American Wheelmen. A lot of people don't realize that bikes actually drove a lot of the infrastructural development that made cars possible...

Hate to go all smug-cyclist on you, but there are plenty of other selfish and community-centered reasons to ride a bike:

Selfish/personal benefits:
-Riding's more fun.
-Riding's cheaper.
-Riding (can be) less stressful than driving.
-Bikes are fun to play with.
-Garages are better with toys in them.

Selfless/collective benefits:
-Less traffic congestion
-Less traffic noise
-Less risk of killing people (When was the last time a cyclist lost control, ran into a house, and killed four people?)
-Less need for public parking facilities
-Less wear on roads/need for high-capacity roadways

...Just saying. Listen, there are plenty of assholes on both sides of the driver-cyclist divide. We need to quit acting like everyone is the on either side is the same, or blameless, or that everyone rides/drives for the same reasons.

I see what you're saying, and you may be right, but transmission lines do add an inefficiency to the power station equations that isn't present in the vehicle-to-grid idea.
Also, as the article mentions, the cost of doing the car-generator thing is constant while market prices for electricity fluctuate, so what may be economically unfeasible at times of low demand may be viable at times of peak demand. Also, it would be interesting if widespread use of this could provide a sort of "back-up" to the grid in the case of a blackout.