Naked Science Forum
Non Life Sciences => Technology => Topic started by: thedoc on 16/01/2014 17:30:01
-
Antonie van der Lingen asked the Naked Scientists:
You will find my train of thought in the end. I will start with storage of energy.
Statment:
1) The big problem with all renewable electric energy currently is the storing of the energy. Standard Battery systems are to expensive and have a very limited lifespan. In most instances the renewable energy is not availible when we need to use it so we have to store it for later use.
2) The hydrogen fuel cell could solve it.
3) Hydrogen is currently produced from fossil fuel. However it can be produced by braking the H2O bonds of water by applying electricity to two electrodes in water. The electricity generated by wind, sun or other renewable energy could thus generate the hydrogen that we then use in our fuel sell when we actually want to use the energy.
Note:
If this work I think all energy used in homes will change to Direct Current over time. I believe one of the reasons for Alternating Current is due to the way we have been generating our main power in power station.
My thoughts and questions:
1) Lightning is cased by static electricity build up. If there is lightning within a cloud, does the electricity that flow, also, brake up H2O into Hydrogen and Oxsigen?
2) We all know that various people has tried to use the energy from lightning but it seams that there is to much energy to store at once, in batteries or any other forms.
I think the focus is wrong we need to harness the energy as it is created in the cloud and not at the peak when the energy is so high that it can ionize the air and cause a lightning strike.
So I am thinking of creating a mix of two or three ideas.
Idea 1 (I read this up) having a wind farm flying or rather gliding in the yet stream whear the winds are more constant.(they have problems with static electricity and lightning in the line or cable coming down, brining the power down from the wind turbines.)
Idea 2 having the wind farm glider harnessing potential difference between clouds and the earth via connecting cable generating hydrogen on the ground. So the electric wiring will be cloud and mother earth is the battery - and . A wire run from the glider to a base station on the ground bringing the one polarity. Now you connect one electrode to that wire and another electrode with earth, both electrodes in the same bole of water to generate hydrogen and Oxsigen.
3) I know that it is important to earth aeroplanes when they land before the get fuel to prevent sparks from static build up. How does planes collect static and how does it connect to my idea of harnessing lightning before the stick?
4) If I have a glider that I want to collect static electricity in the air how would it look to collect efficiently? (A ball with wings maybe? With the wings isolated electrically from the ball?)
5) What will be the ideal condition for collecting static electricity? Wet or dry conditions?
6) Would there be a way to control the flow of energy once you start collecting or would the device just turn into a lightning but if it can not discharge quick enough.
Thank you I think I will cut it hear for now. I do not listen to the radio often so please reply by email or send me the podcast link. If you can not respond thank you any way for making me think and dream.
Best Regards
Antonie
What do you think?
-
Idea 1: There are already some research & development projects to extract wind energy using large tethered kites (http://www.youtube.com/watch?v=4CH7qmMid5g). Modern computer controls aim to keep the kites stable under changing wind conditions. Most of these projects aim to extract energy from the wind using the pull of the kite, or lifting a turbine to higher altitude where the wind is stronger.
Idea 2: One of the goals of an electricity generator is to provide electricity with a low source impedance, so that little energy is lost in the generator, and then transfer it at high voltage so that little energy is lost in the transmission lines.
While static electricity is certainly generated at a high voltage, it also has a very high source impedance, which means that if you try to attach an electrical load to the kite, the voltage will drop severely, limiting the generated power.
A turbine can extract up to about 45% (http://en.wikipedia.org/wiki/Wind_turbine#Efficiency) of the kinetic energy of the wind passing through the sweep of its blades. I fear that the efficiency of converting moving air into static electricity will be a lot lower; for one thing, only a small amount of air comes into contact with the wing surface.
I am also concerned about flying a kite in thunderclouds, where the winds are very violent, with strong updrafts and downdrafts. I think the kite would be easier to control, and survive longer if it is flown in a steady stream of air with a fairly constant speed and direction.
3) Planes build up static by continually rubbing on the air. They try to discharge this static buildup in a controlled way by having high-resistance spines along the trailing edge (http://en.wikipedia.org/wiki/Static_discharger) of the wings. This is mainly to prevent uncontrolled sparking causing interference with radios and other onboard electronics (and perhaps causing problems near flammable fuels?).
4) A kite needs to have an aerodynamic shape to provide lift (usually with a curve under a wing). Some of the research projects prefer to use a cloth wing, as these are cheaper to manufacture, more flexible to survive sudden wind gusts, and safer for the people on the ground in the unfortunate event that the rope breaks and the kite crashes to the ground. Some of them have inflatable segments to provide some rigidity while adding minimal weight.
The kite should also be fairly streamlined, or the rope would need to be much stronger, and it will be much harder to launch.
6) I expect that the kite would charge up to some very high voltage which depends on the kite material and the wind speed. If the electricity is not used, the voltage will stay high. If the voltage is used, the voltage will drop. The challenge here is that our best techniques for converting a high DC voltage into a stable lower voltage output use semiconductor switches, which with today's technology are cheap and work well at hundreds of volts. Arrays of them can be made to work at 800,000 Volts - but are only economical where there is huge amounts of power being transferred over long distances (eg see the photo here (http://en.wikipedia.org/wiki/High-voltage_direct_current#Line-commutated_converters)). With present technology, I doubt that they would be affordable for a low-power source like one (or a few) kites, operating at many millions of volts.