Until we have enough PV that electricity production from gas (or maybe coal) goes to zero at any time it doesn't matter and producing the largest amount of energy is best.

Posted By: tonyWest facing panels produce more energy during the peak period, indeed for this reason alone it could be argued that they all should face west!

Or that long distance east-west interconnects make sense as well as long distance north-south interconnects.

You get more W/m^2 out of solar than wind. Not a problem when wind is at low density, but if you are looking at replacing the existing power generation then solar and storage will supply more, and more reliably. The economics of it are not viable at the moment, so wind seems to be a better bet at present. This will change, but not sure when.
I think one of the misconception about wind turbines is that they only take up the land they are sited on, truth is they need a huge ellipse (an egg shaped one really) to produce power. So a 200 kW turbine may look small (and it is small), but needs more land than a similar yielding solar farm.
You do get to use the land below the turbine though.

But realistically we we need wind, solar, hydro, gas (from existing national reserves and non-conventional sources) and a lot of nuclear if we wish to make the country self sufficient in energy.
The alternative is to reduce our usage by about 60-70%, easy enough at the domestic level, but not very viable for industry and transport with existing technology.

If you want to maximise PV yield throughout the year and reduce some of the 'peaking', then start building with flat roofs and have horizontal PV.
Alternatively let some of the PV be controlled so that it can be turned off when there is too much (it does this at the extreme level already, but we could lower that level).
In time, some sort of central control is going to have to happen as you run the risk of the tail wagging the dog, but we are a long way off that with PV.

Swish swish swish

Posted By: SteamyTea

Posted By: djhin what sense do the wind turbines take up the land?

It is to do with the area around a turbine.

I understand that turbines have to be separated in order to work effectively. But I don't see how they make any use of the space that separates them. I don't understand what the 'misconception' is.

I have a preference for small solar over small wind. We already have a significant number of wind farms and individual turbines in our area. It's hard to say the landscape hasn't been significantly affected when a study shows that half the county will have a wind turbine that is "prominent" or "conspicuous" in the landscape.

Posted By: djhI don't understand what the 'misconception' is.

The misconception is that turbines take up less land area to deliver the same amount of power as a PV system.

The space between turbines is, for want of a better term, the wind resource, bit like the space above a solar farm. If you interfere with the area around and above them you reduce yield. Not sure if that answers your question though.

The problem is, as Chris Vernon points out, not a simple one. Changes in land use, economies and overall energy usage change the formula. But you have to start somewhere and when you look at a state in isolation, the simplest metric is land area.

According to Wikipedia, in 1212 the UK used 2,187 TWh of primary energy, the land area is 246,610 km^2. So the one metric of power per area, our energy usage is 886.8 kWh/m^2 or 101 W/m^2 (just my house alone uses 16W/m^2, car uses 432W/m^2, but that is a bad example). Other metrics are available i.e. energy use per capita, energy use per GDP,
I think the reason for using the surface area metric is that it is a constant, we are not making any more land.

Posted By: CWattersIt's hard to say the landscape hasn't been significantly affected when a study shows that half the county will have a wind turbine that is "prominent" or "conspicuous" in the landscape.

That is the problem with a diffuse energy source. A year or two back I looked up how many micro turbines had been put into Cornwall, I think I looked at sub 50 kW ones, added up the total capacity and worked out it was less than 1 MW. It would have been cheaper and easier to just club together and buy just one 1 MW turbine. Large turbines are more efficient than small one for a couple of reasons at least.

Posted By: CWattersSay you had a large farm house that needs heating and you don't have access to mains gas.

How much energy does the farm need and what is the split between thermal and electrical? How much free land does the farm have to convert to energy production? Do they need a reliable supply? (most dairy farms have back up generators).

Back to Tony's question.

Posted By: tonyWest facing panels produce more energy during the peak period, indeed for this reason alone it could be argued that they all should face west!

There is a consistent peak in the afternoon/early evening, and if there was enough West facing PV installed this would reduce conventional generation at that time for some of the year. But it is just supply time shifting, overall you would still use more conventional generation.
It all comes down to the storage problem. It is easy to store conventional fossil fuels (though gas is relatively costly) that can be converted to electricity later. It is hard to store electricity from renewable sources. Knowing this you just then work out the best usage times if your aim is to reduce overall conventional generation.

Posted By: CWattersI have a preference for small solar over small wind. We already have a significant number of wind farms and individual turbines in our area. It's hard to say the landscape hasn't been significantly affected when a study shows that half the county will have a wind turbine that is "prominent" or "conspicuous" in the landscape.

You don't like 'small' wind because large turbines are conspicuous! By the same token you prefer 'small' solar even though large solar farms are hideous, land-sterilising naffness compared to the elegance of large wind farms?

It's tilting at windmills (!) to require wind farms to coexist with forests, valleys or cities. Where wind farms can go, it's already grass and sheep, and can continue to be so.

Posted By: SteamyTeaSo what should be the best metric to define energy generation for a nation state?

For a start, how little (20%) is still needed after determined demand reduction (by 80%). That makes such desperate-necessity energy-density type metrics quite non-critical, so choice can the be governed by more humane criteria.

You could always flood the Thames valley that would get you demand reduction and more renewables all in one shot! But possibly not a good enough head for hydro and would eliminate the wind resource in Westminster.

Good stuff ST but I don't understand your drift, how it follows from

Posted By: SteamyTea

It's tilting at windmills

That is just comparing different technologies

No it''s not, tilting at windmills means putting your energy into red herrings (and other coloquial beings).

It is all straying from the point, so if you want to carry on, start another thread. I think Ed has made a valid point about value or amount (though should be price and amount ).

<blockquote>You don't like 'small' wind because large turbines are conspicuous! By the same token you prefer 'small' solar even though large solar farms are hideous, land-sterilising naffness compared to the elegance of large wind farms?</blockquote>

It's a relatively flat rural area where I live. Even small turbines are visible for quite some distances, where as small solar installations aren't. I didn't say anything about large scale solar but we have a few airfields that are coming up for sale and I'd far rather they put large solar on them than more wind farms.

The elegance of a wind farm wears off when you have one to the south, one to the west, one under construction to the east and two more in planning.

Posted By: CWattersThe elegance of a wind farm wears off when you have

How about street lights (never dark), TV dishes, paved-over front gardens, cars roaring by, noise, toxins, RF noise and all the other ugly modern things that put windmills in the shade?

Does it really need spelling out? Really?

Our current carbon emissions will very likely result, directly and indirectly, in a lot of deaths in the 3rd world over the next few centuries mostly via climate change. We need to replace them as quickly and economically as possible.