Nature takes its revenge ;-)

I doubt that turbines or solar panels or solar plants will actually work for the lifetimes that are used to calculate return. I sure wouldn't want a mess of solar panels, with their associated wiring/controls/inverters, on my houses.

There are older wind turbines on the hills near my house that have been there for at least 15 years. (With other, newer, bigger ones nearby.) I'm guessing that the repair and maintenance costs/ schedules for them is pretty well known.

The one meeting I went to, I heard that the energy cost pay back time for the wind mills is ~6 months, with total investment return in 3 years. I think this was for the big ones. (Google Sheldon Wind Farm for pictures.)

George H.

Fell in the forest? Was there a sound?

I'm sure it is, if you use a bunch of unrealistic assumptions & figures. Never might be closer the truth.

NT

Never for what? Here's a link for the energy pay back time.

I'm not sure about total capital investment. But this looks like a reasonable site.

George H.

LOL, I thought you woke up this morning with your home's water pipes wrozen :P

Bye Jack

Probably had a locked rotor, and the ideal wind direction. They can't spin too fast either with out the same results.

Cheers

Do an image search for

wrecked wind turbines

or

destroyed wind turbines

or

damaged wind turbines

or

burning wind turbines

and get stuff like

Cool pics! Tide-powered things are even worse, but at least they seldom catch fire.

At least a wind turbine falling over is relatively harmless.

heres a particulary violent failure

Cheers

Provided it is installed somewhere with a mean windspeed above 6m/s then there is every chance that the wind turbine will achieve a very handsome lifetime payback of the energy invested in building it.

The same cannot be said of photovoltaic arrays which have a lifetime payback even on very optimistic assumptions of at most 7x.

McKays book "Sustainable energy without the hot air" is a reasonable assessment of the science and engineering reality from a UK perspective.

Problems arise when the kit is installed to farm the grants and various renewable subsidies that governments offer as inducements. Particularly dodgy is paying them by installed capacity rather than power delivered.

This just in:

So who cares?

Wind turbines - like every other work of man - are fallible. For one reason or other the high-wind protection mechanisms occasionally fail, and the wind turbine falls down, with photogenic results.

Conventional electricity generating systems have their own problems, but they mostly take place behind closed doors, out of reach of photographers.

Hydroelectric dams are the obvious exception - the one that failed in China killed 170,000 people, and even the Chinese government couldn't keep that under wraps.

Hi John, I was going to respond, but I was thinking how great SED has been lately mostly electronics, or instruments.

So I'll ask the instrument type question instead.

Too much insulation? I've got this Rb cell heater I made years ago. The cell is a 1 cubic inch cylinder. (diam. = length = 25mm) It's inside a 4" diameter plexiglas cylinder. There's a 1" diam. optical path through the middle. with windows one the ends, And about 1/2 inch of insulation. There's a ~50 ohm heater of bifilar wound wire on a glass cylinder.

It works fine, but it's got an awful time constant. (I'll have to measure the voltage at max. temperature.)

I was thinking maybe some holes in the insulation, more heater power, but faster.

George H.

What? Annoying us with electronics?

Is the heater wound directly on the glass cylinder? What's the desired temperature?

Faster heating needs more power, which implies a temperature sensor to limit the max temp. A wire won't transfer heat very well to a glass cylinder, and one way to cut glass is with a hot wire.

I'd consider using a Kapton heater/sensor thing wrapped around the cylinder, which would be less glass-cuttery than just wires. If you're talking roughly 110C, a Kapton+adhesive thing would work, with maybe something else, like a couple of tie-wraps or o-rings, to keep it from unwinding over time. Lots of people will make you Kapton flex heaters. Take a look at Minco, then buy something cheaper.

You might be able to use just a long skinny copper trace as both the heater and the sensor. Maybe a long narrow Kapton strip with a field-canceling copper trace or so, wrapped around the cylinder.

Yeah the heater wire is wound on the outside of the glass cylinder. (Wire concentrated at each end.) But then the inside of the cylinder is exposed to the open space between the window(s) and the cell. So it's far from optimum. (The experiment totally hates anything magnetic. and there are some exterior RF coils so metal is not great either.)

Temperature is 25 C to ~120 C or so.

Oh sure there's a sensor too. A copper /constantin TC. The constantin is magnetic, but it's a thin piece.

Yeah we make our own bifilar heaters with kapton tape to hold 'em in place.

Good stuff kapton tape.

Thanks for the nice reply. (I hate all the political crap. Why is everything so divided? I like both wind mills and hydro-fracking.

George H.

Windmills sure look fragile to me. The blade/generator assembly explodes or catches file, or the gears strip, or the pylon breaks near the ground, or an insufficient concrete base tips over.

There are a lot of pics and vids online, but I can't estimate what fraction of wind turbines fail.

How is the time constant "awful"? If you get a single pole response to a ch ange in heat input, you are generally better off if the time constant is lo ng - external changes are kept well away from the area you are controlling.

If you've got a two pole response - which usually means that your temperatu re sensor is appreciably separated from your heating element, life get more complicated. If you are using a PID algorithm to control the temperature, the proportional gain then has to be kept pretty low to prevent oscillation , and you rely on the integral term to get decent regulation.

Or putting the sensor closer to the heater.

Or use more instantaneous thermometry.

non-contact does not suffer the "distance from source" issue as you describe.