Naked Science Forum
Non Life Sciences => Technology => Topic started by: katieHaylor on 17/08/2017 15:58:52
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Roland says:
I would like to know if it would be economically viable/possible to get a longer range from the battery of an electrical vehicle using the energy of the air being pushed away in front of the vehicle while travelling at speed?
In theory I'm thinking that, when the electrical vehicle is travelling at speeds of (let's say) 60km p.h or more, it pushes air ''out of its way'' in order to sustain momentum. If one could catch that air with a large scoop and funnel it towards the rear of the car through an ever decreasing channel, could one then not generate enough (air) force to drive a turbine which could generate current to charge the battery?
I am not an engineer. I once visited a farm in a mountainous terrain in South Africa. The farmer diverted water from a stream into a concrete canal. The canal was running down hill for a short distance. At the end, the farmer had a turbine which was driven by the force of the water. Once the water has gone past the turbine, the canal joined the main stream again.
Back to the electrical vehicle - I realize that scoop, turbo/turbine and other parts would add weight to the vehicle. But perhaps this method could generate enough energy to replace the additional energy usage and still be able to provide some amount of charge to the battery which could lead to the electrical vehicle getting some additional mileage from the battery on a given charge.
What do you think?
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There is no way that you can end up with more energy using a method like this (or any method). We could imagine putting a huge windmill on top of the car, and doing away with the battery altogether, give the car a push, expecting the motion of the car to push wind across the blades, which would turn and drive the car. But this would never work, because there is no way to generate energy from nothing. Windmills merely extract energy from the wind (slowing down the wind to speed up the blades), but if the air is still and the car is moving, then the windmill extracts the energy from the car (slowing down the car to speed up the blades).
There might be some ways to recapture a very small portion of the energy that gets transferred to the air by turbulence, but it would be far more effective to make the car more aerodynamic and prevent the most of the drag in the first place.
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A large part of the design of an electric vehicle is to make it more streamlined, so it has less wind resistance, and consumes less electricity while it is driving. Wind resistance is a major loss of efficiency for a petrol vehicle above about 50 mph (80 km/h); electric vehicles are far more efficient, so wind resistance becomes dominant at much lower speeds.
Putting a scoop or windmill increases the wind resistance of the vehicle, so you don't want to do that!
One place where I have seen an idea like this is as a "last ditch" emergency scenario on commercial airliners. If you lose:
- all the jet engines
- the auxilliary power unit (a small jet in the tail)
- and the battery backup
...then some planes drop a small propeller into the windstream, using some of the jet's considerable kinetic and potential energy to power emergency controls.
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Years ago it occurred to me that a vehicle could use electromagnetic suspension dampers (commonly misnamed shock absorbers) which could convert the movement of the suspension into electrical energy, partially recharging the battery in an electric vehicle, at the same time providing the damping effect currently provided by hydraulics. I read somewhere not long ago that some development is taking place now. Does anyone think this might be useful?
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Years ago it occurred to me that a vehicle could use electromagnetic suspension dampers (commonly misnamed shock absorbers) which could convert the movement of the suspension into electrical energy, partially recharging the battery in an electric vehicle, at the same time providing the damping effect currently provided by hydraulics. I read somewhere not long ago that some development is taking place now. Does anyone think this might be useful?
It might work, given that regenerative braking also works on the principle of "turn some waste energy back into useful energy".
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Years ago it occurred to me that a vehicle could use electromagnetic suspension dampers (commonly misnamed shock absorbers) which could convert the movement of the suspension into electrical energy, partially recharging the battery in an electric vehicle, at the same time providing the damping effect currently provided by hydraulics. I read somewhere not long ago that some development is taking place now. Does anyone think this might be useful?
It might work, given that regenerative braking also works on the principle of "turn some waste energy back into useful energy".
Once a technology like this even on a small-scale charging system has been developed, more concept will follow.
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At the moment, it is very unlikely...
Why hasn't it been used in other places till now ?