PV solar design example

Hmm, interesting. Say, what's the frequency limit of a superconductor, anyway -- the plasma frequency? Is this something you could use with that IR resonator stuff you've talked about? I don't recall seeing pictures of e.g. YBCO suddenly becoming shiny below Tc, for example.

Tim

-- Deep Fryer: A very philosophical monk. Website @

run

Smile when you say that, pardna.

Did I mention that's insane?

That's common back East, a combined central-heating furnace and water heater, run off heating oil. Also insane.

John

The superconducting energy gap (the energy required to break a Cooper pair) is a few times kTc, where Tc is the critical temperature (where the material becomes superconducting at zero magnetic field). How big 'a few' is depends on the material. You can't do anything very superconductor-ish at frequencies comparable to or above kTc/h, which is in the far-infrared.

Some superconductors do show large changes in infrared reflectivity at the critical temperature.

I'm actually just learning a lot of this stuff myself, so I can't give the kind of crisp answers that I like to get from other people.

The collaboration involves using antenna-coupled tunnel junctions to couple small amounts of microwave energy into superconducting resonators. Until all the IP is nailed down, I can't say a great deal more than that--sorry to be all cloak-and-daggerish about it.

Cheers,

Phil Hobbs

I did the helium level/temperature measurement gear for CEBAF, now Jlabs, and did the microstepper drivers they they use to mechanically tune the cavities. The e-fields here are just below what it takes to rip electrons out of the metal.

These things have incredible unloaded Q's and field levels...

John

run

Anything John dislikes is forthwith defined as "insane", not an unusual stance for a Californicator ;-)

...Jim Thompson

run

A power plant turns fuel into electricity at maybe 50% efficiency. Lose maybe 5-10% of that in distribution. An electric water heater has a thermodynamic efficiency of roughly 10% [1], so we get overall about

We have gas space and water heating, no a/c, and we still pay about the same for electricity as for gas. If we were "all electric" our net costs would probably triple.

John

Nuke??

I seriously doubt your numbers... my electric water heater is well insulated, and doesn't lose heat up the "stack" like natural gas.

Plus the safety issues of natural gas worry me... having seen a whole commercial corner near me, when I lived in North Scottsdale, MELT due to a natural gas leak under the street.

There isn't any natural gas available here due to the extremely rocky soil... cost per mile to install is horrific.

...Jim Thompson

So how close to ideal are the heat pumps on gas water heaters?

A gas water heater isn't a heat pump.

Since the flame temperature is close to 2000C, and we trying to heat the water to 50C, there's a huge inefficiency, not to mention the heat lost in the exhaust. It's basically an impedance mismatch issue.

But it's still a lot more economical than electric heating.

Ideally, one would use the gas to boil water, spin a turbine, recover a bunch of electricity, and get the same amount of hot water in the end. Or use the turbine output to run a heat pump cycle, to move a lot more heat than the flame does directly.

I designed a bunch of controllers for a natural-gas microcogen unit that used a piston engine and an induction generator to supply hot water to restaurants and recover the electricity "for free." They worked, but weren't economical for such small-scale applications.

John

The question was tongue in cheek. If you are comparing electric heat to gas heat, it seems you should not criticize one for not doing something the other does not do.

I doubt the thermodynamic efficiency isn't so different. But it is a real carbon footprint embarrassment that almost every water heater of any type is not fed from a solar pre-heater. It costs very little to cut the fuel consumption in half.

But gas water heaters just heat water (and air). Electric water heaters heat less air.

Or an inlet/wastewater heat exchanger. I've considered building one of those. Our cold water comes in off the street mostly frigid.

If you ignore the power plant and the transformers and stuff.

Hey, look, Craig and the boys,

the guys I did the controllers for. Craig's innovation was to put the

John

The Q is pretty amazing.

Cheers,

Phil Hobbs

Now really, what point is there to that? At 10^9 Hz we're talking two minutes to make the damn thing ring up! I mean, the least thing you do to it completely ruins the Q. The bandwidth is so narrow, you'll have a hard time tuning a real oscillator to it! You'll end up in the sidebands, or something...

Tim

-- Deep Fryer: A very philosophical monk. Website @

Keeping the Q high means that the main energy sink is in accelerating the particles--i.e. you can make a powerful accelerator without wasting several megagores of fossil fuel energy. Also , phase noise in the accelerating field translates into energy uncertainty in the particle bunches. From both points of view, having really high Q is goodness.

Cheers,

Phil Hobbs

But that appliance also heats cold water, so it is not a "hot water heater". ;-)

OTOH, a Dewar keeps hot things hot and cold things cold. How does it know? ;-)

We tried that. Ever hear of a small company called Enron? ;-)

...no matter what it costs?

Ok, ow do you put a price on it. More importantly *WHO*?

Of course you wouldn't be just a tad simplistic and over-general here... Of course not. Weenies would never do such a thing!

LLP

Hardly a "free" market.

;-) Doing some furniture shopping in the Amish area around here a few months ago, I was given the cook's tour of one of the shops. This particular family didn't believe in being attached to the power grid, but certainly did believe in business. They had four pretty good sized Cumins diesel generators in the back yard providing power for their woodworking tools (and lights in the show room). I don't recall them using the waste heat though.

I've always wondered why there wasn't more cogeneration. Perhaps there just isn't a big enough (constant enough) user of heat to pay for the infrastructure. ...no one wants that power plant in their back yard and pipes cost real money.

Which doubles the generation infrastructure costs. Seems like a waste, no?

Of course. That doesn't change the fact that $$ is important.

run

It's not that rare at all. Electricity is cheaper than oil in many areas; cheaper than gas in some too. My apartment is all electric. I was pleasantly surprised how little we paid this past winter. Less than gas the previous season (but we no longer live in VT ;-).

run

They exist standalone.

That's what both of my houses were; domestic hot water coil in the furnace. I switched the one in VT from oil to gas in '97ish. They made me an offer I couldn't refuse. ;-)