Energy Harvested From Evaporation Could Power 70% Of The U.S.

Are you suggesting that thermal efficiency is the problem in using solar energy to power the grid?

It's one of the roadblocks. I see you didn't say how you can get round it with technology.

NT

That has to be one of the more moronic responses posted here.

Nobody is in the least interested in the "thermal efficiency" of solar cells. Sunlight is free (though there isn't enough of it) and "thermal efficiency" simply isn't a useful measure of anything remotely interesting.

NT is in the running with Cursitor Doom, krw and Jamie for posting the least useful response ever.

D-subs (1952) are still great connectors. Ditto BNCs (1945.)

But 1800s?

Isn't much of the world powered, in part, by evaporation? Isn't that how hydro works? HUGE free collector, AKA ocean. Free delivery to many parts of the world, AKA rain. If you have a place with significant river drop, the energy conversion is easily handled by current technology. One problem is that the tree-huggers don't want more dams, they want the existing ones removed. Wonder how they'd vote if the grid got disconnected from those who voted to remove a dam? It's easy to protest if someone else takes the hit. Remind me again how many mansions Al Gore has?

Good news is that places with no rain often have a lot of sun and/or wind.

rote:

's a lot of resistance to charging a realistic price for the damaging effec ts of emitting CO2 into the atmosphere. Hydro can be cheap, but there's not a lot of it about.

ll the time, so you need back-up generators (gas turbines or pumped storage ) to provide dispatchable power when you need it.

y burning fossil carbon, even if you don't charge for the damage done by th e CO2 emitted when you burn fossil carbon.

her

ut?

can become trivial.

Some of the dams, not all of them, and they'd probably be happy with lots o f small up-river dams collecting the water when it has still got lots poten tial energy.

They aren't against dams as such, merely against dams that mess unnecessari ly large chunks of the natural environment and consequently discourage tour ism.

many

I only know of one, and Snopes is inclined to forgive him - he and Tipper b oth work from home, so it's office space as well as residential space.

Not so good news in that hydropower that is generated from water stored in big dams is eminently dispatchable, and wind and solar aren't. Pumped or ba ttery storage can much up for this, but it isn't cheap. Thermal solar can f ill big tanks with molten salts (at 570C) and insulated them well enough to keep generating steam overnight, but it isn't all that cheap, and you need big tanks to get long thermal time constants.

You need to explain why thermal efficiency is an issue with a solar energy. Are you referring to any particular technology or just solar energy in general?

Hopeless uneconomic by the looks of it.

Sylvia.

Or you end up with insane capital investment that will never recoup the energy used to make the hugely inefficient "energy harvester".

Most of them are to take money off gullible green investors.

The green innovation I think is least appreciated and ought to be more widely known is the new generation of very luminous glow in the dark compounds based on strontium aluminate. Tape with this stuff on should be mandatory in any household where natural disasters could take them off grid. A piece about 10x1cm will provide enough light to see with once dark adapted and it will recharge in sunlight and last all night (starting fairly bright and getting dimmer all the while)

I have one of the original torches. They sometimes come up on eBay.

Wireless piezoelectric tire pressure monitors are pretty great!

Banana plug?

George H.

SM0KE

Well the Krypton bulb is a non-starter. If someone painted an LED flashlight with the stuff.

But thanks for the strontium aluminate hint. I found this,

and this

George H.

An even more efficient phosphor (is that possible?) would be great for remote villages; leave a panel out in the daytime, take it in at night.

But for emergency lighting, for hurricanes or whatever, batteries and LEDs work fine. We have some LED lanterns that have small leds that flash about every 10 seconds, to find them in the dark. It takes under a microamp average power to do that.

You can hang a beta light on things to find them in the dark, too. Once you locate one light, it's easy to find the rest. A cell phone makes a good optical bootstrap, too.

Use them to power the car!

When it was first on sale a Krypton filament bulb was about as good as you could get. LEDs were still dim panel indicators back then. LED torches were something of a joke until comparatively recently.

If it bothers you you can swap the bulb for a pin compatible LED and 3v to current driver. Mine still has its original bulb in.

On a simple white LED torch bridging the on/off switch with 2M or so makes it glow dimly without really affecting battery life.

It is surprisingly good stuff. I prefer the variant mixed with dayglo yellow which to my eyes is the brightest of the available phosphors. The pale green is supposed to be brighter but not to my eyes. YMMV

It is very handy when you are out in the wilds since it provides some light to see by even in the pitch dark (without switching it on).

Huh, that's a fun question. (Knowing nothing about phosphorescence.)

We could guess it's a surface area effect. (Only the surface atoms can emit and not have the photon reabsorbed.) So maybe a wavelength deep ~1um, then how many atoms in a square cm. (to keep the numbers easy say an atomic spacing of 0.1 nm.) So I've got 10^8 * 10^8 * 10^4 = 10^20 atoms, we'd like it to last for several hours... Say 3 =~10^4 seconds So a photon flux of 10^16/s (per cm^2) I have no idea if that's a reasonable number.

(I hate lumens...this says a lumen is about 10^15/s)

-is-one-lumen

The spec is 190 mcd/lux/sq.m I don't know what the unit means.... cue Phil Hobbs (Have I mentioned I hate optical units.)

George H.

would be great for

The lumen is a measure of the total light emitted by a source. In light bulbs to calculate efficiency you need to know the lumens. This is effectively the photons/s.

Candela is a brightness at a point, so it would be lumens divided by the area, or more accurately the limit as the area shrinks to zero.

Lux is similar to lumens, but is the light falling on a given surface divided by that surface. Lux is what photographers care about.

So think of lumens as the power emitted by an antenna, candela the field strength and lux as the power density at a receiving antenna.

Nah, that's backwards thinking. It's not that the power generated is too small, it's that people are too big. Need to develop a way to shrink people

I think it's a bulk crystal effect. Strontium aluminate is vastly better than the old zinc sulphate types. Get some and play with it; it's amazing.