Viaducts with wind turbines, the new renewable energy source

July 2, 2015
Illustration of two identical wind turbines installed in a viaduct. Credit: José Antonio Peñas (Sinc)

Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.

The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this kind of infrastructures can move and produce energy.

The study is based in models and computer simulations, which were carried out by researcher Oscar Soto and his colleagues in Kingston University (London). Researchers have presented the wind turbines as porous discs in order to evaluate the air resistance and test different kind of configurations.

"As natural, the more surface is swiped by the rotor, the more power can be produced; however, it was seen that in small turbines the power rate per square meter is higher", explains Soto, who considers that the configurations with two identical turbines would be the most viable to be installed in viaducts.

If only produced power was evaluated, the best solutions would be the installation of two wind turbines with different sizes - in order to embrace the maximum available space-, or even a matrix of 24 small turbines - due to their power production per surface unit and low weight-, but concerning to viability, the best option is the one which includes two medium sized wind turbines.

Results confirm that each viaduct presents specific energy possibilities and wind potential. In the Juncal Viaduct case, the evaluated power would be about 0,25 MW per wind turbine. So, with two turbines, the total power output would be 0,5 MW, which is classified in the medium- range.

"This would be the equivalent to 450-500 homes average consumption", says Soto, who adds: "This kind of installation would avoid the emission of 140 tons of CO2 per year, an amount that represents the depuration effect of about 7.200 trees".

This research has been promoted by the Canarian company ZECSA. Researchers from Vigo University have taken part to analyze the electrical connections needed to develop the project, along with other researchers from Las Palmas de Gran Canaria University, who were in charge of the integration in the scope of renewable energies ".

In fact, the study has been published in the Renewable and Sustainable Energy Reviews and it is framed in PAINPER, a public infrastructures exploitation plan to boost the use of renewable energies.

"PAINPER is an initiative which emerges from the difficulties seen in the implantation of this kind of energies in heavily built-up territories, as well as protected areas with low available space for new installations", says Aday C. Martín, manager at ZECSA, who considers that renewable energy produced in wind turbines under viaducts could be added to energy from other wind, solar, geothermal and biomass installations.

Explore further: Localized wind power blowing more near homes, farms and factories

More information: Ó. Soto Hernández, K. Volkov, A. C. Martín Mederos, J. F. Medina Padrón, A. E. Feijóo Lorenzo. "Power output of a wind turbine installed in an already existing viaduct". Renewable and Sustainable Energy Reviews 48: 287-299, 2015.

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15 comments

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gkam
3 / 5 (4) Jul 02, 2015
Energy harvesting can reduce the fossil fuel use in the US and elsewhere. Every bit saved is a win.
antialias_physorg
5 / 5 (4) Jul 02, 2015
Couple of issues that need to be resolved:

1) Needs to take into consideration whether the bridge structure will support this (especially during high wind conditions). Bridges aren't built with having effectively high cross sections in mind that cause large transversal forces. So I wouldn't be surprised if the amount of bridges where this is viable is fairly low.
2) Actually here Willie might have a point with his inevitable bird/bat-kill-spam. Bridges are accross valleys - and valleys are natural flight channels for all kinds of avian creatures.
3) The bungee jumping crowd will have to be a bit more selective where they go.

Eikka
3 / 5 (2) Jul 02, 2015
4) the number and size of bridges where one could ideally place these turbines is so small that the benefit of having the turbines is a drop in the ocean. Half a megawatt peak power per bridge means you need 5000 similiar bridges before you get the average output of a single large coal powerplant.

This is really bottom-of-the-barrel stuff. In terms of wind power, there are far easier, far more productive locations to erect turbines.

WillieWard
1 / 5 (3) Jul 02, 2015
Viaducts with wind turbines, it is an innovative way to reduce CO2 emissions by slaughtering millions birds and bats in midair preventing them from breathing out carbon dioxide to the environment.
gkam
3.4 / 5 (5) Jul 02, 2015
Yeah, Eikka, why bother doing anything at all?
WillieWard
3 / 5 (2) Jul 02, 2015
2) Actually here Willie might have a point with his inevitable bird/bat-kill-spam. Bridges are accross valleys - and valleys are natural flight channels for all kinds of avian creatures.
Sorry, it was really inevitable.

antialias_physorg
5 / 5 (4) Jul 02, 2015
the number and size of bridges where one could ideally place these turbines is so small

There's quite a few sea bridges where this could generate a lot of power (e.g. the Florida-Key West overseas highway, and a number of bridges in Denmark or the likes). Basically any sea bridge would be a good fit - alwaays provided the structural force calculations check out.

This is really bottom-of-the-barrel stuff. In terms of wind power

Every bit counts. Renewables (any) isn't a race for big singular installations. Many, decentralized ones are far better for any risk crtiterium you care to name.
Edenlegaia
1 / 5 (1) Jul 02, 2015
Yeah, Eikka, why bother doing anything at all?


It may be a bad idea to do it, it do not means Wind Turbines shouldn't be used because it's a waste of time, ressources and "damn, we have better things to do, like staring at dying trees and Oreo Towers". It means we need more efforts to make it possible AND efficient.
There's some difference between avoiding doing something that may not be as useful as it should and redirect efforts in improving ways to do what we want, and not doing anything because "it doesn't matter anyway, it won't work". Ideas and efforts. On a rush, we erected Nuclear Plants because "we had to hurry". We must hurry again, yes, but we know now how reckless acts can be dangerous.
antialias_physorg
5 / 5 (4) Jul 03, 2015
It means we need more efforts to make it possible AND efficient.

What do you mean 'more efficient'? Wind is already the cheapest power source if you take cradle to grave costs (i.e. taking into account all needed cleanup costs and costs to the society due to pollution)...with the possible exception of hydro - and that is limited in its availability. What level of efficiency should we be waiting for?

Also there's the issue that you will _never_ get more better unless you try out stuff in real world settings and at real world scales.

We must hurry again, yes, but we know now how reckless acts can be dangerous.

I'm pretty sure wind power can't go boom.
Eikka
5 / 5 (1) Jul 03, 2015
Every bit counts.


Yeah. Like tossing a glass of water in a burning house.

You do that - I prefer to fetch the firehose.

Wind is already the cheapest power source if you take cradle to grave costs


You can't make a sweeping generalization like that. Wind power in some locations is very cheap, and in other locations such as the one proposed here, it's very expensive because it produces so little energy per unit.

Besides, how about the integration cost?

Remember the old adage:
"A byrd in hand - is worth ten flye at large."
-John Heywood
16th century
Eikka
5 / 5 (1) Jul 03, 2015

I'm pretty sure wind power can't go boom.


But it's making our grids "go boom", and the energy prices "go boom", and the demand/price for rare earth metals "go boom"... etc. because of the uncoordinated rush to build more and more.

Also there's the issue that you will _never_ get more better unless you try out stuff in real world settings and at real world scales.


The scale required for testing in the real world is vastly smaller than the scale where we're at with wind energy right now, because you can extrapolate from data.

Like in product testing; suppose you're trying to test the strength of a plastic spoon. You don't need to break every single spoon in the box to get a good estimate. In fact you need surprisingly few. Similiarily, you only need a couple large wind farms to test the concept and try out different designs.
Eikka
5 / 5 (1) Jul 03, 2015
On the technical point of turbine size: wind along a valley and around bridges in particular, is often gusty and turbulent, which precludes the use of large diameter low unit cost turbines because they're too slow to react to changes in wind conditions and cannot extract energy efficiently out of a non-uniform flow, so they have to use smaller high unit cost turbines.

The turbines cannot be made arbitrarily small, because the fill factor gets worse and worse as the structure starts to resemble the holes of a colinder. There has to be some rigid material between the holes or the whole thing would just flap in the wind.

A large turbine would cover the same surface area more efficiently than many small ones, but as it is less efficient to do so, a compromise has to be made.

There's another type of wind energy extractor that might be very cost effective here, and it's a vibrating ribbon strung across the pillars.
Eikka
not rated yet Jul 03, 2015
The basic idea is that you take a flat ribbon and stretch it across an opening, and as you blow against it the ribbon starts to buffet in the wind. Piezoelectric or magnetic transducers at the ends of the ribbon absorb and dampen the vibration and essentially turn it into electricity.

It's basically a stretched out microphone that the wind is blowing into.

Creating a fence of such ribbons and suspending it with taut cables below the bridge might collect a significant amount of energy very cheaply. For very strong winds, it could be loosened or ever rolled away like a curtain.
antigoracle
3 / 5 (2) Jul 03, 2015
The AGW Cult:
We've only just started to scratch the surface of stupid.
Save_energy
1 / 5 (1) Jul 16, 2015
It was proposed 4 yrs ago in Italy…..then they found …
You cannot add these to an existing bridge or viaduct because-
1) Increased lateral forces will make the bridge unstable
2) Harmonic vibrations will demolish the foundations

You could design a bridge or viaduct to incorporate them BUT the limited intermittent output of the turbines will never equal the increased cost in cash, materials, CO2 emissions & energy.
Guess how I know !!

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