Colour

[richardw]

John wanted some non-trading info, so here goes. If this is a stupid topic, add your own below!

I've been interested in solar cooking the last few weeks, essentially after wondering if there's a way for poor people to reduce costs/impact on environment. There seem to be various methods, like parabolic dishes, box cookers, etc, each of which has various pros and cons. I bought three box types the other day and am testing for effectiveness. Winter is a bit iffy, but it can still get pretty darn hot in there. I've also been looking at fresnel lenses, which originally were used on lighthouses but can now be bought as flat plastic panels for a couple dollars from Chinese factories. The bigger ones can melt coins from sunlight. One paper in the last year used a fresnel lens focusing sunlight onto optical fibres which you could use to direct the light & heat into a house.

[jack12]

I spend most of my time designing wind generators, the biggest problem is the time it takes to get effective result, as you need all weather conditions. In winter it gets to -35 so icing becomes a major problem on the blades. Working on the blades is difficult as they are 15m off the ground and are 3m long. If antone has expearience or usefull info it would be most welcome.

[richardw]

That's interesting. Howcome designing - aren't the designs stable by now?

[john_1]

Colour..this is a *****img Rainbow... Well done. It also happens to be one of my favourite pet projects... I am interested in wind farming. My one concern with the current designs is they are great for the Roaring 40's but are barley effectual in the temperate zones in which most of us choose to live.. what are your views.

[#5]

jack, you could fit solar panels on the blades that charges a cell in the blade wich then runs a series of heating element veins across the blade, that can keep the frost away. Or mix 1L antifreeze with 2L plascon wall and all, and give two coats..lol

[john_1]

or you simply could redirect a little energy from the turbine down a defroster much like on the wings of a plane. Same problem and I believe its a real ***** clearing the ice at -60 and at 33 000 feet.

[jack12]

Yip, there are some good designs, but each has it own inherent weakness. most are installed in temperate regions. the -35 is one problem no one has looked at. I am using a Darrieus design with elements of Savonius to create a low wind start up. Then due to the high wind speeds need a brake. Wind is cool cause increase the current to induce heating and brake electrically. Summer is +30 so need a mechanical brake. Each takes up space and is complicating the others. When it freezes -35 icing on the blade causes vibrations. So most are designed for specific regions and temperature ranges.

[john_1]

Here is my big thing with eskom... alow anybody who can generate electricity to sell it onto the grid at a market related price..that way you do not need to store the power generated, as there is always going to be a need somewere at some time.. so if I can cover my roof in sollar pannels currently I also have to store the power( which makes it econmically unatractive. If I can sell it when I am at work it makes me money and when I come home I use less than I use it actually will pay for itself, or become an earner..its a great way to empower the poor also. Not to mention aleaving the current supply issues... just a thought.

[richardw]

Agreed, and it's done in many places so why not here?

[john_1]

Just a thought..and its only been in my brain for 5 seconds....what about a retractable reverse set of blades..... so at low speed they are tucked away and at high wind speed they are doing the same thing as the mane blades but are set in reverseand to a lesses extent (5 feet vs 30) so that they naturally slow down the machine and prehaps in some way that increase the electricla yields.

[john_1]

it works so well that in Northan Germany many have solor pannels but on the high veld you hardly see them...go figure.

[jack12]

I presume there is no one to challange the SA/ Eskom law about power generation monopoly. I was stopped from building a test wave generator because it would produce more than 50kW.

[MichaelR]

Yes. only my opinion.

[john_1]

Another question ... why can't you use the resistance of the generator itself as the break.. increase winds = increase output..it seems silly to me that the purpose of the thing is to go fast in the wind and when it does you slow it down in a way that waist that addtional energy. Pleasae educate me as to why this can't be done.

[#15]

Understanding 3 phase the electricity distrubusion network is quite tricky. Eskom deals with the capacitance and inductance properties of your appliances. tons of energy isnt lost due to poor demand.

[john_1]

I trully believe that this is what SA should be doing...we have wind, wave, light, heat, currents and the most econmically alternitive energy company in the world (just for drama) SASOL yes its coal but it was 40 years ahead of its time...

[#17]

jack, did you stop your vodka testing, for wind turbine design?

[jack12]

one of the reasons SA has problems with koberg, the cannot ballance the output as there are to few factories requiring capacitive loading of the generators, so are inefficient. loose money and until someone build a mine or 2 will always cost us money

[jack12]

one of the reasons SA has problems with koberg, the cannot balance the output as there are to few factories requiring capacitive loading of the generators, so are inefficient. loose money and until someone build a mine or 2 will always cost us money

[jack12]

Nah, this is what I do on weekends