Idea for electricity generation

[MotCO]

Mods - I wasn't sure whether to post in Speculative Discussion or General Discussion - please feel free to move.

Whilst driving along a motorway recently, my mind wandered on to how all the passing traffic could be harnessed to make electricity. If waves and wind can produce electricity, why not passing traffic.

My solution was to install turbines with magnets under the carriageways. As a vehicle passed overhead, the magnets would be attracted by the metal in the vehicles overhead, and would turn the turbine; when they had passed, it would revert to a neutral position, thereby producing a movement to turn the turbine. Clearly it would only work on busy motorways, and possibly not in all lanes (although the fast lane is often occupied!)

The question is, would it work? (If so, I'll submit my patent application tout de suite!) Are there any downsides - e.g. would there be a drag on the vehicles passing overhead, either slowing them down momentarily or increasing fuel consumption?

 

[The Lad]

You would increase fuel consumption due to increased drag.

 

[zwk500]

If you wanted to generate power from vehicles on the road surely linear induction would be more efficient than a giant magnetic brake on every car?

(Also, in traditional generators a turbine spins a magnet in a coil of wire to generate electricity, so here you have cars spinning a magnet to turn a turbine that would then ... spin a magnet?)

 

[MotCO]

If you wanted to generate power from vehicles on the road surely linear induction would be more efficient than a giant magnetic brake on every car?

(Also, in traditional generators a turbine spins a magnet in a coil of wire to generate electricity, so here you have cars spinning a magnet to turn a turbine that would then ... spin a magnet?)

Ok, maybe my physics is not up to scratch, but I'm thinking of the concept. How would linear induction work?

 

[AM9]

Ok, maybe my physics is not up to scratch, but I'm thinking of the concept. How would linear induction work?

None of it would work because there are losses in the process meaning that there would be a net loss. Why burn even more hydrocarbons in a vehicle that has a thermal efficiency of under 35%?

 

[NoRoute]

As already covered, the problem is that the energy produced is extracted from the vehicle, so it simply adds drag to the car, making its efficiency worse.

I recall some years back a similar proposal but that was to fit an energy generating road surface near road junctions, it was still taking energy from the vehicle but in this case the vehicles would be slowing or coming to a stop away and the energy being extracted would be wasted by the vehicle brakes, so a form of regeneration. Today with hybrids and EVs, which have regenerative braking built in to recover the kinetic energy into a battery, the technology is kind of obsolete for energy generation purposes, might be interesting for self-powered traffic signalling applications.

The best road-related electricity generation ideas I've seen to date are solar carports and canopies, using the space above car parks to install solar panels, and an interesting idea that hasn't taken off, of solar roadways, putting solar panels under a heavy layer of toughened glass to use them as a paving material for paths, pavements and even roads.

 

[edwin_m]

It's remotely possible some form of energy harvesting could be employed on the approaches to junctions where everyone will be slowing down anyway, so much of the energy would be lost in the brakes. Although EVs should regenerate this anyway, unless braking hard...

Edit: NoRoute got there first!

 

[Arkeeos]

The cars need that energy to move!

 

[Lucan]

maybe my physics is not up to scratch, but I'm thinking of the concept. How would linear induction work?

With respect, if you don't know how linear induction works, your knowledge of physics is not up to your proposing new methods of electricity generation.

As for the specific proposal, it would be taking energy from the cars, increasing their fuel consumption. It would be ironic if they were electric cars - adding to the drain on their batteries in order to re-charge others elsewhere. Theft, in a nutshell.

an interesting idea that hasn't taken off, of solar roadways, putting solar panels under a heavy layer of toughened glass to use them as a paving material for paths, pavements and even roads.

It was only interesting in that it was barmy. Some short trial lengths were actually built (at great cost) but soon fell to bits, even with only foot traffic. I think most some schemes were just kick-starter scams, promoted with the usual "Changing the World!" hype.

 

[markymark2000]

It's not the same as your idea but one company has developed turbines which work using the wind produced by passing traffic. They are called Alpha 311. They were first installed on the o2 Arena in London last year.

The company says (https://alpha-311.com/news/turbines-installed-spinning-at-london-o2-arena/)

Collectively, the 10 turbines could produce up to an estimated 87,600 kWhs a year, which is equivalent to the total electricity used annually by 23 British homes, providing locally-generated renewable energy to the restaurants and shops at The O2. While this is overall a small portion of the venue’s energy needs, it’s an exciting new step into the future of local and distributed 100% carbon-free electricity generation.

In another part of their website, they claim (https://alpha-311.com/case-studies/government/)

One Alpha 311 turbine, placed on a road and harvesting the untapped air from moving vehicles, can generate as much energy as 30 solar panels.

Some interesting stats there.

Greater Manchester are due to get 2,000 of these turbines
Telford has some and could have upto 181.

 

[WAO]

In thinking about energy, we come up against the natural limits of the laws of thermodynamics; no perpetual motion machines and the less concentrated energy is the less useful it is potentially. A petrol engine with a work efficiency of c25% does reject the other 75% to the surrounding atmosphere in many ways. This is however at very low concentrations (such as temperature or wind speed excess) so cannot be effectively harvested.

The best energy source we have is the Sun but it is fixing and storing it economically that is the challenge.

That's why we use (excessively) natural energy stores like biomass, coal, oil and gas!

Arts graduates please note.

WAO

 

[InTheEastMids]

It's not the same as your idea but one company has developed turbines which work using the wind produced by passing traffic. They are called Alpha 311. They were first installed on the o2 Arena in London last year.

The company says (https://alpha-311.com/news/turbines-installed-spinning-at-london-o2-arena/)


In another part of their website, they claim (https://alpha-311.com/case-studies/government/)


Some interesting stats there.

Greater Manchester are due to get 2,000 of these turbines
Telford has some and could have upto 181.

Can't comment on this specific product, and their website is decidedly cagey about the technical characteristics, but these sorts of tech come with quite a few issues.

Small wind turbines are typically not cost-effective generators (in general) so suitable for "behind the meter" applications like in windy locations (e.g. farming).
There's a reason utility-scale turbines are >2 MW onshore and now >8 MW for offshore. Bigger is better.
Wind turbines are not suited to highly turbulent locations - this is what basically killed the residential wind turbine market about 10 years ago.

Typically roadside tech such as lighting and CCTV is unmetered, so either a meter is needed, or it needs be compliant with the standards set by UMSUG
There also needs to be agreement about who pays, and what they pay for the generation

From the O2 arena publicity, it infers these turbines are 1 kW rated output and so its theoretical maximum output is 8760 kWh a year. Practically, the wind doesn't blow the whole time so a utility scale 2MW onshore turbine in GB might get 25% of this ("capacity factor"). This product will almost certainly be lower, so I'm going to guess 15%. This means the output per year is going to be something like 1,314 kWh per year. For context, if you generated that off solar panels on your roof and exported it, with the smart energy guarantee, your supplier would pay you 4.5p / kWh, meaning £57.11 per year (this is why O2 have them on the building).

Traffic management on busy highways is expensive and carries with it significant risks to workers. i.e. there's a high chance it simply won't be cost-effective to maintain them, and the saline spray you get by busy roads in winter is really not nice to electrical products.

So provided they have something that is *very cheap* to make and install, has utterly bomb-proof reliability, high performance in turbulent airflow and a way of metering and settling the power generated, then there may be something in this...

 

[D365]

This photo, rather aptly, appeared again recently on one of my social media feeds...


[Photo shows a Chevrolet car with a makeshift dynamo attached to the rear wheel]