Discussion on:

California highways may soon produce their own power

This was looked at in the 1980s and discarded as impractical to install and maintain.

Besides, you also have a problem with one statement in the article. - captures the ambient energy generated by moving cars - This is California traffic we are talking about. During rush hour top speeds are close to 10 mph. How much energy will you get?

It is just another way Californias are trying to ease the guilt of living an unsustainable life style.

The energy comes from the motion of the cars which comes from the fuel used to power the cars. There is nothing 'free' here. The drivers pay for the electricity in reduced mileage although it may be only a fraction of a cent per mile it is still a tax on the driver.

The public gets taxed twice with this plan. First we pay for the project then we supply the energy out of our own gas tanks and batteries. There is nothing renewable about this plan. We still have to burn coal or gasoline to get the energy in the first place.

This is one of those idiot projects that Lobbyists sell to politicians because the politicians are gullible.

Tell a politician that something is free and they will always agree to pay an exorbitant shipping and handling charge.

The power generated is free in the sense that cars are and will be
driving on California roads. Currently this energy is just wasted.

jvierra doesn't understand the tech. The piezoelectric tech converts vibrations into electricity that would otherwise flow into the ground as a waste heat. There's no additional drain on the energy generated by auto engines, no decrease in fuel economy. Nor should we dismiss the proposal as being not cost effective as Hates Idiots does without seeing what the manufacturing, installation & maintenance numbers would be now as opposed to what they would have been years ago.

Thanks for clarifying the information about piezoelectric tech. When I started reading the article I was thinking they could use electromagnetic power to generate electricity; this would add drag to vehicles. Piezoelecticity works by pressure and would not add any drag to the vehicles.

Because there would be a drag imposed on the vehicle (Simple physics at work)
I wonder if this technology would be accepted by the motorist if he got reimbursed for supplying the primary source of energy.. Sometimes "money talks" ???

Well it's about time someone got the right idea

@hoodedswan: It's not necessarily true that only vibrations that were there before are converted to energy. It depends on the construction of the sensors, which will change the elasticity of the roadway. If they don't match the elasticity that was there before, they could actually take more out of cars passing than was lost before.

Think of it as walking on a trampoline. The stiffer the trampoline the less work it takes to walk. If the trampoline is very elastic, it's as though you are always walking uphill. Just as you can vary the tightness of the trampoline to change the effect, so could the roadway sensors be made to take more energy out of passing cars than they were losing before to heat.

Unfortunately this still sounds a LOT like fantasy. The article states that a 30-ft strip produced 2kwh of electricity. My current elctric rate is $0.15 per kwh. So... when you consider labor rates to "plant" the piezo cells and then the cost of producing the piezo-electric unit I cannot fathom how can this plan be ecconomically feasible. Just consider minimum wage at $7.25/hr/person vs. a gain of $0.30 for the 200 watt-hours. What am I missing here ???

It tells you the strip produced 2kWH of energy. But not how long it took to do it. They need to tell you what the average power output is (Watts not watt-hours.)

Using your trampoline example, will you simply pass the cost of producing the energy onto the drivers of the cars with lower gas mileage?

Going back to our trampoline, it takes more energy to walk across a trampoline than it does to walk on solid level ground. Your body is constantly climbing out of holes.

If you do not match the rolling resistance of the energy producing road with that of a solid roadway will you risk increasing the rolling resistance of the roadway to get the additional energy zackers mentioned?

Does tire wear also increase with increased rolling resistance?

On another point, friction between the tires and the roadway make the heat mentioned by zackers.

Either the road material needs to convert that heat into energy or the heat is still lost energy in the process of moving a vehicle. The only other way to reduce the heat is to reduce the friction that keeps the cars on the roads. A good analogy is driving on bald tires or on an oily road after a big multi-car accident. Eliminate the friction between the tires and the road and you eliminate the heat, but you also slid all over the place.

These are just a few of the issues that killed the same free energy proposal made in California in the 1980s.

Where are the sensors embedded in the roadbed? In the base? or subbase? In the first layer of pavement?

Given the average size of most piezoelectric sensors, I don't expect they would significantly change the rolling resistance at the surface.

Hmm... seems like schools do a louzy job in educating students about what energy is and IS and about what energy is NOT.

There is ONE simple law for you to memorize:

You CANNOT, ever, in ANY WAY, TAKE ANY FORM and ANY AMOUNT of energy by ANY MEANS, from ANY SOURCE, without actually SUBTRACTING that exact amount of energy from that source! (the rest is just details that confuse your brain).


There. You con't have to go back to school now.

You also don't have to pay for such ridiculous mediaeval projects.

If they can't even keep the asphalt in a state of repair, how will they
ever maintain anything this complicated?

I wish they would do that here in Manitoba, most of our roads are 40-60 years old, have more pot holes then pavement, and create plenty of vibrations. Driving down Main street, a car could produce enough power for half the planet.

Only downside is, when these sensors wear out and break, it will take 60 years to replace them...

Why not install sensors in skyscrapers to harness the energy generated when these buildings sway back and forth?
Also, I believe there are companies doing this with athletic shoes.
Imagine sensors in your shoes and shirtsleeves that could generate enough electricity to power cellphones and/or MP3 players, etc.
I am envisioning a device that mounts on your cheeks and generates electricity from windpower... I am picturing certain Senators and Congresspeople...

I think that solar roadways.com has a better, longer lasting, more profitable answer to making money with roads in the whole USA while reducing pollution, lengthening the life of the roadbed, adding jobs, etc, etc.

That is even dafter than this one, as an EE I just got to throw up my hands when non EEs start talking about energy.

situation more than a battery scenario to me.

Anything imbedded into the roadway will prove to be expensive for whatever little energy it can generate, plus the cost of transmitting such small amounts of energy over distances. As an illustration, many streetlights don't work because thieves stole the copper wires.