Alternative Energy Forums

My idea is to harness the lost energy created by the millions of tons of traffic traveling along our countries highways systems. The method would involve placing compression devices under the substrate of the asphalt highways which through hydraulics or vibration the energy which would be normally lost, could be harnessed and converted using generators. These generators would transfer power to the existing power lines, which follow along the same highway systems, through out the United States. I would be interested in hearing from others who may have knowledge of devices, which might currently exist, which could be incorporated into my idea. I feel the amount of energy available would be immense. Tell me your thoughts.

JohnK Ormond Beach, Florida

John,

It’s a great idea, but It sounds extremely expensive. I don’t think it would produce much power considering the cost.

In order for it to produce a good amount of power the system would have to be designed so that the highway would have some "give" to it. As the amount of "give" in the pavement was increased, the amount of energy lost by the cars would increase. In other words, I think that a system like this would just rob power from the cars driving over it, decreasing their fuel mileage. Imagine a car driving through sand, the sand gives a bit as the car goes through it, and the car will get reduced fuel milage vs rigid pavement. There would probably also be some safety issues with this highway.

Another factor to consider is that this system would have some vehicles weighing 50 tons and some weighing only one ton driving over it. That’s a big variation to accommodate.

I’m speaking more on the compression idea. I’m not familiar with gaining electricity through vibration. Perhaps someone else that is familiar with power generation through vibration can comment.

Keep up the great ideas!

Grant M

Hello Johnk,

I trust to be of some help, the idea you propose is quite logical an in fact easy to do, however I can only quote my experiences and trust others have had better luck, with Queensland Government Au. opposition to generation of power from other than their coal fired power stations.

A small air line laid partial subsurface in a road produces a pulse of compressed air each time a wheel crosses it. Each pulse goes toward a collective compressed air container. The accumulated high pressure then goes to drive a piston or turbine attached to a generator.

My working model went one step further in that it employed the 90% efficient fully recycling hydro turbine in place of the 40% efficient gas turbine.

This device uses gas pressure to pressurize the water flowing through the hydro turbine.

Another version of this very simple gas to water pressure device uses recycling hydrogen using the road as a heat sink for longer operation.

Good luck,

Peter

Thank you both for your comments. The idea of compressing air to generate energy is kind of what I had in mind. I was thinking of thin bladders containing fluid which would be only slightly compressed with the passing of each vehicle. It would be spread over a very large surface area and would not require a great deal of actual movement up or down. Maybe only centimeters. The idea would be every slight compression would press large quantities through tubing directed through a turbine which would turn a generator. Let’s say one section of highway would be let’s say 1000 ft. long when the same vehicle (s) move on to the next section. Another system would force the fluid back to the bladder previously exited. etc. etc. I realize there would be a trade off of lost vs gained energy, but I am convinced the loss would be minimal compared to the gain. I think with the right design. There would be no appreciable effect on vehicle performance or mileage. I admit, I am not an expert and must submit to others who are more knowledgeable.

John K, Ormond Beach

Hello John,

The water bladder you speak of needs to be limited to no wider than a tyres road contact as a greater width would not create a further displacement of water, only movement of water within the bladder.

So long as your hydro turbine is in a raised position its discharge water could gravity refill the bladder, thereby doing away with the need of return pumping

DaS Energy

The energy that would be harnessed is not really free or wasted energy. Rather, it would be taking a very small amount of energy from each car that passes over the device - if the car depressed something and moves a distance down, it must return to it’s original height thus expending energy. This would essentially lower the fuel mileage, as Grant mentioned, though it would probably be quite small.

Yeti

Thanks again for your replies. I should add that my idea would use some kind of viscus fluid and would work on a hydraulic basis. My idea is that the passing of vehicles over one section would compress the bladder, sending the fluid through a narrow tube which would increase the pressure via compression. The same vehicles would then pass over another section which would compress the same fluids back into the bladder system from which it came. Does that make sense. As to the previous persons comment about the loss of energy by the passing vehicles thereby the energy not being exactly free, I would agree. My belief is that the energy gained would be great compared to the energy lost. The massive weight of these vehicles creates a huge amount of lost energy. If properly designed, I feel the loss in fuel would be minimal if any. I am thinking the amount of movement necessary to make the system work, would only require movement of fractions of an inch. I feel the impact on fuel economy of the passing vehicles would be minimal. I have no proof, just my instincts.

johnk

You are taking energy away from the car. I can’t see a way of doing this without doing so. Even if it is a very small amount, it is still gasoline that is being converted to kinetic energy at ~25% efficiency and then to electricity at another efficiency. This would be similar to telling everyone to "donate" 1 ML of gas to be used to provide electricity.

Yeti

The vehicle is already traveling, no energy is taken from the car other than already being expedited, and no further fuel is used up by its bumping across flexible hose.

Peter

Thanks again for your comments. Here is an additional point to consider. Several of you have mentioned that the idea lacks merit because the system I suggested would create additional friction on the tires of passing vehicles thereby costing the vehicle a loss of fuel as a result of such friction on the tires. Do I have it right?. My point is this. The vehicle has mass and momentum which in my mind represents a great deal of potential and actual energy. Taken to the nth degree, in order to cancel the benefits of this salvaged energy, the friction on the wheels would have to be so great as to completely stop the forward motion of the vehicle. If one could imagine the vehicle entering a stretch of highway paved with hot tar which would cause the vehicle to bog down and eventually stop. That would represent a 100% cancellation of any benefits of my idea. Am I wrong?

Johnk, Ormond Florida

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subodhgarud

To summarize:

We are talking about cars transferring kinetic energy to these "speed bladders" to perpetually generate electricity. The amount is questionable, and definitely negligible per car. This strategy, at the core, is to look at our existing habits as consumers and take advantage of the opportunities that these habits create to capture energy that exists as a by-product of our habits, vs. adopting new habits. Adopting new habits will take a long time, and will be forced. It would be asking a lot of consumers. Both strategies have their place.

To make this work, someone has to "own the incentive." What I mean is that this has to benefit someone enough that the cost isn't outweighed by the gain.

3 different types of speed bladders might benefit 3 different markets:
1) high-speed bladder for highways for cars traveling between, say 55-80 mph
2) speed bladder that acts as a speed bump for cars slowing down to take exit ramps off the highway and/or into small towns
3) city speed-bladders that help regulate traffic and collect energy in a design optimized to capture energy at lower-speeds/higher-frequencies.

The idea has merit -looking for the "nickel and dime" energy out there that takes advantage of the habits we have now, instead of changing the habits we have now and conserving energy that way. Both are sound strategies and are appropriate in their own contexts.

Muskrat

Hi everyone;

I'm brand new to this forum. I just found it the other day. I'll try not to be too opinionated. I'll always try to back up what I say with accurate and reliable information.

I have worked in mechanical and electrical engineering most of my working career. I have a sound technical background in energy, mechanics, electronics and physics.

I have designed and lived in a successful passive home for 20 years. I have designed a solar heated workshop and solar water heater. I'm now involved in building a solar heating/cooling system for my home. I have recently become much more interested in "green" technologies, conservation, energy independence, climate problems, etc.

I believe I can comment meaningfully on some of the topics in these forums.

Your idea of using the up/down motion of the highway surface due to the passing weight of vehicles is interesting. But, any such scheme, whether using air, fluid, electro-dynamic devices,etc, WILL rob the vehicle of more power than is generated. It will be a net loss scenario - - as others have already mentioned. The reason is as follows. It is a phenomenon well know in the trucking and road building industry. That is, when a moving loaded wheel presses down on a paved or any other surface, a moving depression in the surface is formed. Because of friction in the subsoils and the mass (and thus the inertia) of the pavement and subsoils, the center (lowest point) of this depression lags slightly behind the centerline of the wheel (the lowest part of the wheel). The traveling depression is traveling along at the same speed as the vehicle, but is slightly retarded in position compared to the wheel. Thus, the wheel is constantly trying to "climb" the up-sloping front of the depression. It's like the vehicle is going "uphill" all the time to varying degrees. The heavier the load on the wheel, the more pronounced this effect is, because the depression is deeper. This "climbing" translates to drag, and drag times speed is power. This occurs naturally, and highway engineers use this phenomenon to determine how strong to make the sub-surface systems to withstand the expected loads, considering speeds, weights, climate, number of wheels/weight, and other things.

Now, if we ADD to this deflection using any such method previously suggested, we extract even more power from the vehicle because the depression is deeper and the wheel is constantly "climbing" a steeper slope. The combined energy conversions involved will necessarily be well less than 100% efficient. This ADDS even more to the power penalty experienced by the passing vehicle. The vehicle will require ADDED power to drive along. The power GENERATED by these "bouncing" device will be MUCH LESS THAN what is extracted from the vehicle because of the "climbing" effect AND the inefficiencies in the energy conversion process - - a double whammy.

Though it hasn't been mentioned here, a similar argument would apply against such schemes as lining the highways margins with some kind of wind turbines to extract power from the induced wind created by the passing vehicles. These wind turbines would interfere with the air that tries to move out and around the passing vehicles. The airflow gradient around and near the vehicle would increase and would then result in more aerodynamic drag. The amount of increased drag and the associated energy penalty would necessarily be greater than any energy generated by the turbines - - again, basically the same kinds of arguments as with the "bouncing" devices. In other words, you can't get something for nothing - - or more appropriately, you never even get out what you put in.

It isn't my intention to discourage anyone, but I feel it is important to move on to other more fruitful ideas when the old ones become untenable.

ecoconvert62

Hey everyone;

I've continued to seriously consider the "bouncy" or better yet a "resilient" highway method of producing useful power. There actually is a situation where it could provide a net gain (to society). It could be installed only on deceleration lanes and off-ramps from expressways, where everyone needs to bleed off energy anyway. Why burn-up your brakes when a compliant energy generating highway surface could do this for you. Others have mentioned this also.

The actual mechanism to accomplish this has to be optimized for efficiency, longevity, reliability, ease of installation, cost, etc. But, in principle this could work. It would require a serious study as to whether there could be a reasonable pay-back scenario though.

ecoconvert62

Thank you ecoconvert, for re-thinking the lost energy idea. There will be no lost energy if the vehicle is already trying to decelerate for say a toll booth, and that would be the perfect time to utilize this device, when vehicle speeds are already slow. Remember, we are trying to use vehicle weight, not means of propulsion, to capture this energy. Very few passenger cars weigh less than 3000 lbs, most are substatially higher. Passenger cars and light trucks already are routed to different lanes in toll booth highways, than heavy, over the road trucks which could provide even more pressure than cars/light trucks. Entrances to truck weigh stations would also be perfect candidates. We are talking about a substantial amount of weight to take advantage of here. I had already responded to a poster under "Recapturing Lost Energy" regarding this same idea, as I have been considering this concept for quite some time. Just an inch or two of deflection can pressurize hydraulic piston pumps, which can power hydraulic motors to turn turbines creating electric power. I am not an engineer, I do purchasing for a hydraulic manufacturer/distributor, and have seen many applications for hydraulics that seem more complex than the ideas we are considering. I also am not suggesting this is inexpensive, but after the initial expense this looks to me like nearly free energy. After all, we are dicussing alternatives to fossil fuels, so investing in infrastructure to help us get there seems worthy of discussion. One more point, this produces electricity in the urban areas that need it most, at peak usage times, unlike wind turbine energy, which needs to be stored or transferred great distances in most cases. Hydraulic pressure can also be stored to a certain degree, fairly inexpensively. I also suggest placing turbines underground, no one would even know they are there!

Let me know what you think.
Thanks.

Rkonrad