Solar Panels - verifying the numbers

[NT]

Possible yes, desirable no way. The greens will have us back in the medieval era if they ever get their way.

NT

[The Natural Philosopher]

I wouldn't mind a population of 2M as long as I was one of them.

Of course at that level, we could burn coal and oil with no real effect on anything.

[news10paul]

Money is merely a cultural artefact, and can be made in any desired quantity. Clearly, it far surpasses 1kW/m2 on the earth's disk in its intrinsic value.

#Paul

[Andy Dingley]

Geothermal can have serious problems with acid rain. Many of the sites which offer enough geothermal to generate power, as opposed to merely space heating, have groundwater full of sulphides. This means either venting it, with emission problems, or a horrible expensive system of down-hole plumbing with a secondary circuit.

It can work, but it's not the free lunch that was hope for.

[Andy Dingley]

The problem is that nuclear power reactors that compact and that simple are _horrendously_ expensive, such that only a military budget can afford them. They traded engineering complexity for fuel enrichment - the enrichment levels in a sub reactor are extremely high, which makes the rest of the design smaller and simpler in comparison. However manufacturing this fuel is orders of magnitude more difficult than fuel for a typical commercial power nuke. There's also a real proliferation risk. You can't make much that goes bang out of PWR fuel from a power reactor, but you certainly can from a submarine PWR.

One of the sad aspects of the current British purchase of nukes is that we're inevitably going to buy old inefficient PWR designs from the USA or France. Far better designs would be the high-temperature gas reactors that Europe was working on in the '70s, and have since been developed by the Chinese.

[The Natural Philosopher]

Fairly sure our sub reactors are made by rolls royce actually.

[Andy Dingley]

Yes, but as pointed out, they bear little relation to the sort of reactors used for power generation.

[NT]

The value of money is what counts, ie what it can purchase. Printing it just gives more units worth less per unit.

NT

[The Natural Philosopher]

You would be surprised, but anyway, that was not the point: the point is they are not foreign made.

[The Natural Philosopher]

Ultimately money as a cost relates simply to the man hours needed to arrive at the product, times the standard of living of those men.

Low standard of living (china) or low man hours (hi tech investment) reduces the costs.

fuel is free, at the point of mining/drilling etc .. If it lasts anyway. Then you cant get it at any price at all..

[tim....]

For me it's the (apparent) completely open ended costs of disposal. If the private sector is going to be allowed to build nuclear power stations they have to factor in the total cost of decommissioning into their kWh price, but they can't.

tim

[tim....]

I think I do (BICBW)

No, because you can run the fridge down to -5 by putting more power in.

The idea of an "efficient" heat pump is that you use less power to "extract" the heat from somewhere else that you would use to heat up the place instead.

tim

[The Natural Philosopher]

Fraid you still dont get the point.

A heat pump will pump in a single stage about 40 degrees C at about 4:1 uplift in power in to power out of the hot end. It will do about 50C at about 3:1. You can do more with multiple stages.

So it doesn't matter what the outside temperature is, as long as the working fluid doesn't freeze, it works.

What matters is that below about -10C, its barely able to get the output up to 30C. You need a two stage pump, or simply add top up resistive heating.

[dennis]

Normally any power you put in also arrives at the heating side (excluding the fan on ASHP). So even if you put in more power they still work and still give out more heat than the input. Or at least they do until they have a complete covering of ice which acts as an insulator to some extent. I wonder why they don't have a flat plate with a scraper/de-icing boot to remove the ice?

[NT]

In summer you can do it simpler and with less energy by just running under-house cool air through a fanned heat exchanger.

NT

[Dave Liquorice]

'cause users would get fed up going out every hour or so to scrape the ice off. Easier for the control system to monitor the thing and run the heat pump in the other direction to thaw the ice build up.

[Andy Dingley]

Do the numbers - Kelvin did a century ago, and that ought to be within your timescale.

[Andy Dingley]

Countries that use heat pumps, and have cold enough winters that they care about this stuff, generally also have dry winters and so this form of icing isn't a big problem.

It's also a further encouragement to use ground source pumps, rather than air source.

[dennis]

Why would they need to go and do it?

Mechanically removing the ice means you have extracted the latent heat.

[Andy Champ]

I don't think there are any energy sources that are adequate for our civilisation and are factoring in the true costs. Nuclear is closer than most.

No fossil fuel system is factoring in the costs of the environmental damage that most people accept is being caused by uncontrolled release of carbon dioxide and other pollutants.

Andy