Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Re:Saving energy? (Score 1) 168

Why either / or? I suspect we'll need both.

In southern CA, you'll see plenty of warehouses with white roofs and PV mounted on top. With an air gap, the PV provides further shading.

PV is relatively low on the net-payback list, but the experience curve marches on- the more we install now, the closer we get to grid-parity economics.

Comment Re:Uh? (Score 1) 327

The following paragraph is vague, but it looks like homeowners get a cut of the value of electricity generated.

I know that for my Freewatt system, I paid for the system, but I get credit for the electricity generated under net metering laws (or at least I would if I had the generator part; so far I only installed the boiler and am saving funds for the generator piece). I pay for the gas, too, but I'm using that gas very efficiently, so I make a profit on the electricity.

The economics aren't great, in terms of ROI (the capital costs yield energy savings), but they're not bad, either.

Comment Re:Uh? (Score 1) 327

1) These peaks are significant (at least in the U.S.), in terms of the size of the peak, but the duration isn't all that long (assuming that these things are used as the peakiest of the peakers). And I presume they have a mode that sheds the heat outside- this loses the CHP part of the equation, but this should be a small part of the work cycle (these things should run most of the winter and a few 10's of hours in the summer). You could even do trigeneration (where you generate electricity plus cooling), but I suspect the thermodynamics won't work for these units.

2) It's burning natural gas, so it's easy to be clean. The cost-competitive part comes from CHP: traditional electricity generation wastes 2/3 of the input energy as "waste" heat; these don't (as long as they put in 80+% of their hours during heating season).

I have a system in my basement that's 1/2 way to CHP now (it's an integrated engine plus boiler; I just have the boiler part so far). See Freewatt. The pure economics of adding the generator are kind of blah, but it is more energy efficient, and that has value to me.

Slashdot Top Deals

Too many people are thinking of security instead of opportunity. They seem more afraid of life than death. -- James F. Byrnes