George Osborne demands massive cuts to windfarm subsidies

[Dave2002]

http://www.google.co.uk/search?q=tel...vnPSZx5gEdgjM: ??

[An_Inspector_Calls]

If one had the luxury of building ones own house from scratch then best-practice would appear to be massively thick external walls with insulation on the outside, triple glazed windows, airlock external doors (in other words, two doors so that the minimum of heat is lost when going in/out of the house) and a heat-exchanger/cleaner for recirculating hot air from the top of the house to the lower floor(s). If anyone is interested, I can put them in touch with an architect who has focussed on these type of houses for most of his working life. He lives in one and his heating bill was IIRC £12 last year.

Your previous post: yes GSHP can be had with a cooling cycle. They're usually just slight variants of normal GSHPs and cost slightly more. The Danfoss range shows this. I don't see why radiators can't be used as cooling elements, esp. the finned/low water content type. You then dump heat from the house back into your winter store! As for radiator leaks, if you convert the house to a pressurised central heating system then usually the very most you can 'leak' in a rush is the water stored in the water/air accumulator - perhaps 5 litres. It's perhaps worth thinking about; the other virtue of that system is that you can monitor the system pressure and the slightest leak will be visible immediately. It gets rid os a storage tank in the loft complete with dodgy overflow pipes. (And while you're at it, convert to a pressurised domestic water system as per modern building regs).

Sounds like you're (Edit soryy, I mean RM) thinking of PassivHaus (as I think is AHinton). I wouldn't triple glaze; yes the U value is better than double but you also block insolation heating. Many consider it to be a poor system compared to double glazing. Go for a low value window with a U value of 1.1. We can't, economically achieve PassivHaus, but we are insulating the outside walls. That achieves several things in addition to heat saving: removes need to paint the rendering, repairs/removes poor rendering, replaces facias with plastic.

[Resurrection Man]

http://www.google.co.uk/search?q=tel...vnPSZx5gEdgjM: ??

LOL! I too scoffed when he first told me about it. Then he sent me a photo...looks just like a normal house!

[Resurrection Man]

..... (And while you're at it, convert to a pressurised domestic water system as per modern building regs).

....

Not true. The Regs only specify a condensing boiler etc...but some makes of combis can be run on a vented system.

[An_Inspector_Calls]

Condensing boilers have nothing to do with the type of domestic water system you install! I'm talking about your hot and cold water supply to your basins, baths, showers, etc. I think you'll find the building regs mandate pressurised systems nowadays. If you have an old cistern type you can usually retain them (it depends on local edict) but you have to modify them with some protection against Legionella. And I think you'll see that many domestic appliances, like taps, are now designed in such a way that they favour pressurised working (try getting a replacement 22mm bore tap).

Meanwhile . . .

Have I ever mentioned my admiration for the sandwich tern - beautiful bird, glorious in flight. And now the reason why Docking Shoal won't be an offshore wind farm. saved a few quid there then!

[Resurrection Man]

Condensing boilers have nothing to do with the type of domestic water system you install! I'm talking about your hot and cold water supply to your basins, baths, showers, etc. I think you'll find the building regs mandate pressurised systems nowadays. .....

Not the last time I looked.

[Dave2002]

Pressurised systems are, in themselves, not necessarily good news. There are probably various types, but we have a Megaflo tank which is supposed to provide hot water at pressure. Apart from one valve failure, there are interactions between this and the mains. Perhaps if we could get a similar pressurised tank for the cold supply all might be well, but at present the supply pressure from the mains is problematic. The static pressure is OK, but one plumber said that we have a problem with what he called dynamic pressure. Essentially the flow rate is not high enough. This causes problems with devices which work directly off the mains, such as the washing machine and an electric shower. This is probably due to old narrow bore pipe work into the house. A possible solution is to install a pump (possibly noisy, and maybe would incur a moderate cost to run if the pump wasn't controlled effectively) and another tank for the cold supply, while another, though not guaranteed to work, is to replace the pipe work into our house with modern plastic pipework. The mains pressure is also affected by external events, such as neighbours running hosepipes (not during the ban, now lifted, hiopefully) and nearby building work.

Re water damage, even a few litres of water, if dirty and not detected quickly enough, can do a lot of damage. After our experience with a radiator which was almost new (just over 2 years old), but which failed just ouside its guarantee period, ruining a carpet and causing damage to some expensive bookcases, I am now much more wary about systems based on fluids, such as conventional radiators or water based underfloor heating. This is why I have now specified electric underfloor heating for the heating for our replacement construction, as well as an air source ac/heating unit.

Re the wind farms, good for the birds that one wind farm was refused, but OTOH two others were authorised which could provide power for close on a million households . One good thing about wind farms is that unlike PV systems they may still be able to deliver significant power during the winter, which could, if necessary, be used for heating, and thus avoid the burning of fossil fuels with consequences for sustainability and climate change.

[An_Inspector_Calls]

The problem with vented, unpressurised water systems is that they require water storage in the loft. In my view, such storage is a disaster waitng to happen. I got fed up with that game after suffering failures separately due to (a) sinking ball-cocks/inadequate, small-bore, overflow pipework and (b) overflow from dripping ball-cock into aged, cracked overflow pipework.

Wind farms won't produce any power during a pan UK (or even European) high pressure. This situation seems to occur every winter. During the last winter, esp. in January, there was a period of little wind power generation (I think it lasted nearly two weeks). And various studies in the USA (by Bentek), Denmark (Sharman) and Ireland have shown that because wind power requires fossil fuel generation to compensate for its variability and intermittancy the CO2 emission savings are close to negligible.

[Dave2002]

The problem with vented, unpressurised water systems is that they require water storage in the loft. In my view, such storage is a disaster waitng to happen. I got fed up with that game after suffering failures separately due to (a) sinking ball-cocks/inadequate, small-bore, overflow pipework and (b) overflow from dripping ball-cock into aged, cracked overflow pipework.

Been there, done that. However our replacement pressurised tank is still in the loft area, and the valve which I mentioned which failed dripped into the garage, though fortunately I don't think it damaged anything significant.

Wind farms won't produce any power during a pan UK (or even European) high pressure. This situation seems to occur every winter. During the last winter, esp. in January, there was a period of little wind power generation (I think it lasted nearly two weeks). And various studies in the USA (by Bentek), Denmark (Sharman) and Ireland have shown that because wind power requires fossil fuel generation to compensate for its variability and intermittancy the CO2 emission savings are close to negligible.

I wouldn't disagree that periods of calm will result in very little output from a wind farm, but I'm surprised that the studies show that the savings are "close to negligible". There is work on short term electricity storage. It might not work well in the UK, though for example, water could be pumped back up to reservoirs using energy produced by wind turbines - which is a technique which has been used for many years, though perhaps not on the scale really needed. Some tidal energy schemes also pump additional water up if there's energy going spare, but of course the UK has not gone in for tidal power in any significant way I think. Some storage systems pressurise air underground, and there are other techniques, but it's possible that none of them are really viable. Maybe if electric cars come into greater use, the storage from the car batteries could be used - I have heard this put forward as a serious suggestion. Obviously would only work if the generating companies agreed to "borrow" the energy from a car, and then put it back later, and hopefully before the vehicle is needed.

I still dispute your assertion that wind power does not save on CO2, but I will look into this further.

[Resurrection Man]

.....
I still dispute your assertion that wind power does not save on CO2, but I will look into this further.

It is going to depend on the type of wind turbine and whether or not it needs to keep the blades and gear-trains moving to prevent seizure if they stop rotating for any length of time and also the amount of power needed.

Not had time to read this article but it looks interesting. http://www.guardian.co.uk/environmen...rbon-emissions

And the report that says windfarms are pretty poor at saving CO2 is here http://www.clepair.net/europhysics201203.html

[An_Inspector_Calls]

The Bentek report covers wind generation over the entire USA for a period of 10 years; it is an analysis of a huge amount of data for six different grids (there is no whole-USA grid) containing different supply mixes. The study is, unfortunately, pay-walled. However, these quotes are from the concluding sections:

The results of this study suggest that wind energy constitutes a significant paradox: Generation of power from wind, per se, yields no emissions. However, integration of wind power into a number of complex utility systems has led to little or no emissions reductions on those systems, and has significantly increased costs to power producers, grid operators and electricity consumers.Several specific conclusions can be drawn from this research.
1. Utilities are forced to cycle coal and natural gas-fired generation capacity in order to accommodate intermittent wind generation. Cycling significantly decreases efficiency at the facilities, thereby increasing the emissions rates.
2. Emissions savings due to wind generation vary by territory and are heavily dependent on what type of fuel is being offset by wind generation. In the case of BPA, hydro generation is offset by wind generation. As there are no associated emissions with hydro, very little emissions are saved through wind generation in this area. An operating area where coal fuels a higher proportion of its generation base, such as MISO, achieves more emissions savings benefits by using more wind.
. . .
4. The same CO2 benefits that wind generation currently achieves also can be met by re-firing coal facilities with natural gas. The difference in the CO2 emissions rate between coal- and gas-fired facilities is the same as the actual emissions savings from currently installed wind power across the nation, or about 0.6 tons/MWh CO2. The economics and reliability of natural gasfired generation suggest that achieving CO2 emissions reductions through re-firing coal plants with natural gas is more favorable than using wind generation. Switching to gas avoids many of the costs associated with wind, including transmission, billions of dollars in tax credits, maintenance costs due to cycling and other variables mentioned above.
5. As natural gas market share continues to eat away at coal-fired generation, the potential emissions savings due to increased wind generation will decline. The convergence of low, stable natural gas prices, increasing coal costs and impending EPA environmental legislation that will tighten SO2, NOX, mercury and other emissions will increase the market share of natural gas-fired generation across the U.S. As this happens, total power generation-related emissions rates will decline. As the generation share associated with gas increases, the CO2 savings associated with an incremental MWh of wind will decline and the cost of using wind to achieve the savings will increase. Wind will become an increasingly expensive way to reduce emissions.

If you want evidence of the severity of wind intermittancy in the UK then look at the Stuart Young report:

http://www.jmt.org/assets/pdf/wind-report.pdf

This is based on data captured from the settlement system NETA reports. Quoting from that:

At each of the four highest peak demands of 2010 wind output was low being respectively 4.72%, 5.51%, 2.59% and 2.51% of capacity at peak demand.

. . .
10MW Events
At each of the four highest peak demands of 2010 wind output was low being respectively 4.72%, 5.51%, 2.59% and 2.51% of capacity at peak demand.
Between 1st November 2008 and 31st December 2010, a period of 791 days, there were 51 days on which generation fell below 10MW for at least one five minute period. The shortest time was five minutes and the longest was seventeen hours and fifteen minutes. The total number of five minute periods below 10MW was 2662. The average frequency and duration of low wind events below 10MW over the period in question can be calculated thus;
Frequency: 791 days divided by 51 = 15.51 days
Duration: 2662 five minute periods divided by 51 = 52.2 periods = 4.35 hours
20MW Events
Between 1st November 2008 and 31st December 2010, a period of 791 days, there were 124 days on which generation fell below 20MW for at least one five minute period. The shortest time was five minutes and the longest was thirty-three hours. The total number of five minute periods below 20MW was 7330.
The average frequency and duration of low wind events below 20MW over the period in question can be calculated thus.
Frequency: 791 days divided by 124 = 6.38 days
Duration: 7330 five minute periods divided by 124 = 59.11 periods = 4.93 hours
ANALYSIS OF UK WIND POWER GENERATION NOVEMBER 2008 TO DECEMBER 2010• Between November 2008 and December 2010 inclusive, a less than 20MW event occurred on average once every six and a half days and lasted for almost five hours. This included 10MW events occurring on average once every fifteen and a half days
and lasting for just under four and a half hours.
• Very low wind events are frequent and not confined to isolated high pressure events in winter.

[Dave2002]

Interesting, though perhaps showing difficulties which should be managed/overcome, rather than simply discarding wind power as a renewable resource. The Bentek report shows that there is little CO2 emissions reduction in areas where hydro electricity is used, though possibly hydro and wind might make a good combination. If the hydro power is abundant there might be little point, but if hydro energy is not so abundant, then the wind power could be used to push water back uphill to a storage reservoir. In areas where coal fired stations are used the CO2 emissions reductions are significant.

The experiences of the grid in Denmark are also of interest, though there there is considerable interaction with the grid systems in Norway and Sweden, which have significant hydro generation. Also the Danish situation shows that wind can be managed if there is a relatively small scale generation feeding into a larger grid, but unfortunately this does not seem to be such a good thing for the UK.

[An_Inspector_Calls]

I am quite sure that these difficulties of wind can be managed. Pumped storage, interconnectors, etc. But how much does this management cost?

The Denmark emissions savings also show that wind has a negligible impact on emissions. The experience there is similar to Ireland where they have a significant amount of wind and CHP and in rural communities. Sharman's studies point up that the concept of using CHPin an eonomy with little large-scale industry is rather silly .

The reason why Denmark copes with all its wind is because it's not an isolated grid: it's connected to the massive European grid and to the Norsk grid. Denmark manages to export a lot of its surplus wind generation to Norway, thus exporting the subsidy benefit out of the country into Norway's economy - neat! And then they buy back Norwegian hydro when the wind doesn't blow at a price set by the Norwegians.

There's always someone worse off than you.

[Resurrection Man]

.....
The reason why Denmark copes with all its wind is because it's not an isolated grid: it's connected to the massive European grid and to the Norsk grid.....

So are we. We regularly import electricity from those nice nuclear reactors in France !

[An_Inspector_Calls]

So are we. We regularly import electricity from those nice nuclear reactors in France !

Yes, but it's a matter of degree. Our connection to the European grid is very weak such that the UK is considered to be an island grid. Ireland is about to get an interconnector to the UK, but it will still have all the characteristics of an island grid.

The most direct manifestation of an island grid is frequency stability in the event of disturbances to supply and load. On the continent if you lose 2 GW of supply, the frequency will hardly shift; in the UK a disturbance of 1.5 GW can cause widespread power cuts as happened in 2010 when there was a cascade of problems starting with Longannet, then Sizewell, and topped off by automatic shedding by the wind fleet. That's why the UK has to operate about 1.5 GW of generation (0.9 GW in winter because the grid is stiffer) all the time in spining reserve, ready to compensate for any unpredicted supply/load swings. That's why Dinorwig was built by the CEGB; to remove the need to part load coal plant and make the provision of reserve cheaper and to reduce emissions.

Our connection to France (2 GW) is barely sufficicient to balance out the present level of variability of the wind fleet.

(And just for completeness, Iberia, Italy and Greece are considered to be peninsular grids)