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PostPosted: Jun 24, 2014 9:23 am 
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alexterrell wrote:
(2nd attempt to write this - don't know where the first went).

On France:
France could reduce it's nuclear power by reducing electricity consumption. I get the impression they waste a lot.


Agree with the second part, disagree with the first.

There is no technical, economical, or environmental reason to reduce nuclear power even if energy efficiency is more succesful. That's just misguided ideology.

If France can reduce resistive electric heating by use of heat pumps and/or better insulation, they should keep the exisiting nuclear capacity and export the excess electricity generated to other countries that already have the misguided and utterly failing energy policy that the recent French leaders aspire. In other words, plenty of neighboring fool countries that crave for reliable, dependable power.

Quote:
We went skiing in France last year. We had a brand new apartment, with fairly standard insulation - no triple glazing. At night it was -10C outside (it can go to -20). And yet, all the heating was resistance heating. We needed about 8KW on - almost continuously - to keep a 50 square metre apartment warm.


Yes, either heat pumps or better insulation would help a lot. I'd prefer air source heat pumps because you reduce annual electricity consumption by a factor of 4 without extensive custom (expensive) insulation work (which often isn't feasible especially in older buildings, without major construction expense). Probably both heat pumps and insulation in the same building will not be cost effective.


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PostPosted: Jun 24, 2014 10:20 am 
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It is worth noting that ASHPs will only reach COPs of 4 when the temperature outside is above freezing.

If its -10C or -20C outside then they will not do that much better than a resistive heater while having significant maintenance requirements.


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PostPosted: Jun 24, 2014 2:23 pm 
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E Ireland wrote:

Surely the objective is to drive electricity prices so low that heat pumps are not worth it anywhere?
The reason that heat pumps are becoming more common in Germany but not in France is that retail electricity rates in Germany are essentially double those in France.
So per kWh of delivered heat a h eat pump in Germany will cost about as much as a resistive heater in France without considering the collosal capital costs of the heat pump compared to a simple fan heater.



It would be nice to have low electricity prices - from a clean source - so you don't have to care about efficiency. But they're not building LFTRs near me, so that's not going to happen.

If the EPRs deliver at 90p/KWh to the grid, that's still 15-20p to the consumer, or about 3 times the price gas, which is why heat pumps are slightly cheaper to run than gas, but not enough to make the investment worthwhile unless you're off gas grid.

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The problem with significant property densities and ground source heat pumps is they can freeze the ground solid during a cold winter which has some major implications for both local plant life and for underground utilities (you start to get frost heave and similar problems)


If they're badly sized. Like nuclear plants get flooded or blow up - if they're badly designed or operated.

My case was a ski resort. Freezing the ground could have been designed in to help extend the ski season - but that's an exceptional case.
Quote:

alexterrell wrote:
I'm not sure why you think solar + storage will never be competitive with retail electricity. People said the same thing about solar even 5 years ago, and now it's cheaper than retail in Italy, Spain, Germany (and even the UK at a 3% discount rate). With falling battery prices solar + storage will be cheaper than retail prices by 2020 in the above countries.


If it were cheaper than retail why does it still rely on huge subsidies for new installations?


Good question. Solar is cheaper than retail electricity, but you have to export some of it where it's not worth much at all. So the current business case without subsidy would be slightly positive in Spain or Italy but negative in the UK.

Add in storage and the amount you have to export goes down, and you can export it when demand is high - it's worth a lot more.

But it is interesting (say the Economist in me - boring says the Engineer) why there are so many south facing roofs with no solar panels, despite the current subsidy regime making it a very attractive investment.

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Solar+Storage is especially worthless in northern latitudes because it will produce almost no power for several months of the year.

No - the consumer doesn't necessarily care about the winter. Being able to export when the price is high and not import, for 8 months of the year, makes the business case. In winter, the consumer can still import electricity at night and sell it at a higher price in the day.

That does create a capacity utilisation issue for the CCGT operators, who have to idle their plants for 8 months. If I care about that, then I'll get myself a fuel cell module to provide heat and electricity in the winter.

Quote:
It is worth noting that ASHPs will only reach COPs of 4 when the temperature outside is above freezing.

If its -10C or -20C outside then they will not do that much better than a resistive heater while having significant maintenance requirements.

Which is why they make sense in most of England (if you don't have gas), Spain and Italy, but not in Germany or Scandinavia. Plus the fact they're easy to retrofit and some modules can be reversed for air-con in the summer, which would be useful in England for about 4 days in the year.

Air to water heat pumps are more useful still as they can use night time electricity to heat the thermal mass of water.

(My one reaches a COP of 5.5. But it's only for heating a pool in the summer.)


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PostPosted: Jun 24, 2014 3:32 pm 
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alexterrell wrote:

Which is why they make sense in most of England (if you don't have gas), Spain and Italy, but not in Germany or Scandinavia. Plus the fact they're easy to retrofit and some modules can be reversed for air-con in the summer, which would be useful in England for about 4 days in the year.

Air to water heat pumps are more useful still as they can use night time electricity to heat the thermal mass of water.

(My one reaches a COP of 5.5. But it's only for heating a pool in the summer.)


Although ASHPs may not make sense to you in Scandinavia, Sweden is a leader in the use of heat pumps: 46 % of detached homes in Sweden had a heat pump installed in 2010 (17% GSHP and 29% ASHP), according to 2011 figures from the Swedish Energy Department. So you are right, just think what heat pumps could do in countries with more moderate climates, like the UK or France.


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PostPosted: Jun 24, 2014 4:45 pm 
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In the UK, price of offpeak electricity per kWh is comparable to the price of gas per kWh-thermal.

Which sort of destroys the case of solar panels when you can just draw off peak electricity, every night, and then export it during the day.

IN other words, the storage might be economic but the panels certainly won't be.


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PostPosted: Jun 24, 2014 11:52 pm 
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I'm not sure where you guys get your info on heat pumps. The COP is always substantially above 1, right up to the limit of operation, even with ASHPs. New near supercritical CO2 heat pumps are available for really cold climates as well, these get better low temp efficiency.

Perhaps very obvious but most people don't live in ski resorts, they live in low elevation cities, the countryside, and the coast of France. Temperatures there are mostly mild and rarely get below freezing.

So bottom line you always get a huge savings over resistive heating. It's the average COP that really matters since the capacity is already there (in terms of peaking) - basically the currently installed resistive heating has a COP of 1. France on the whole could probably get an average annual COP of 3 even if some ski resorts keep the resistive heating.

Thinking about energy savings some more, there probably won't be any net savings for France. All the saved electricity from replacing resistive heating with heat pumps will have to go to the 7 million electric cars the new French plan calls for. In fact add in economic growth (French economy is still growing substantially) and the only way for electric demand is up. Which just makes the French plan even more stupid.


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PostPosted: Jun 25, 2014 7:09 am 
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camiel wrote:
Although ASHPs may not make sense to you in Scandinavia, Sweden is a leader in the use of heat pumps: 46 % of detached homes in Sweden had a heat pump installed in 2010 (17% GSHP and 29% ASHP), according to 2011 figures from the Swedish Energy Department. So you are right, just think what heat pumps could do in countries with more moderate climates, like the UK or France.


Thanks - surprising number of ASHPs - maybe more effective in coastal areas like Malmo?

E Ireland wrote:
Which sort of destroys the case of solar panels when you can just draw off peak electricity, every night, and then export it during the day.

IN other words, the storage might be economic but the panels certainly won't be.


In Germany, night time electricity rates are no longer available, thanks to solar. The same will happen eventually in the UK.

In the short term, with night time top-up, you can export in the morning peak and with solar top-up in the evening peak.

Cyril R wrote:
In fact add in economic growth (French economy is still growing substantially)


Is it? Long term growth prospects for the French economy are pretty poor.

I concur on heat pumps, I thought they'd have a COP of about 2 at really cold temperatures.

(What I couldn't find was the COP for the pool heat pump with a pool at 20C and air at 25C :) )

My observation on a single French apartment block in a single ski resort was simply an anecdotal observation about energy efficiency. The same with UK shops with doors open on to the street and hot air blasting down on the open doorway.


Last edited by alexterrell on Jun 25, 2014 4:31 pm, edited 1 time in total.

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PostPosted: Jun 25, 2014 10:08 am 
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Yes, all mainstream official predictions are for a substantial increase by 2020 (500-600 something TWh range). The only scenarios that keep demand more or less constant are those provided by naive, unprofessional and ideologically misguided organisations such as Greenpeace. These scenarios all forget things like they want electric cars and electric heat pumps replacing gas heaters. If memory serves something like 10% of the electricity goes to resistance heating, so replacing with heat pumps puts that down to 3%, a 7% savings. Electric vehicles alone will need more than that. France still has a lot of fossil fired space heating (in fact I recall this being more than the resistance heating). So replacing that with heat pumps offsets a lot of that 7% savings even without electric vehicles.

There is just no way that French electric demand is going down if the goal is to get rid of fossil fuels since transport, industry fossil fuel etc. will have to be electrified, these demands total a far larger demand than all households electric demand combined. Negawatts are useful for France to increase exports of electricity at best and will prevent further buildouts of nuclear plants at worst.


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PostPosted: Jun 25, 2014 10:26 am 
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alexterrell wrote:
Cyril R wrote:
In fact add in economic growth (French economy is still growing substantially)


Is it? Long term growth prospects for the French economy are pretty poor.


It is true that the French economy is a laggard right now, but in the long run the economic prospects may be better in France than in other European countries, because of demographics. Countries like Germany, Italy and Spain will suffer from a declining population in the future, unlike France, which may well surpass Germany as western Europe's largest country in terms of population in 30 to 40 years. So, France would do well to plan ahead and add new nuclear power plants, because of ongoing electrification of space heating (increased use of heat pumps) and transportation (battery-powered light vehicles) will simply require more electricity, in addition to supplying a growing population with more electricity.


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PostPosted: Jun 25, 2014 11:04 am 
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Cyril R wrote:
France still has a lot of fossil fired space heating (in fact I recall this being more than the resistance heating). So replacing that with heat pumps offsets a lot of that 7% savings even without electric vehicles.

There is just no way that French electric demand is going down if the goal is to get rid of fossil fuels since transport, industry fossil fuel etc. will have to be electrified, these demands total a far larger demand than all households electric demand combined. Negawatts are useful for France to increase exports of electricity at best and will prevent further buildouts of nuclear plants at worst.


Yes, that is correct: if I recall correctly, only about a third of French households use electric heating, mosty resistance heating (the use of heat pumps is increasing thanks to tax credits). But most French households still use fossil fired space heating. In my opinion, the electrifcation of space heating is very important and the situation in other European countries is more perilous: Britain and The Netherlands have a very gas-centric infrastructure, but their domestic gas reserves will be depleted in less than 20 years and they will be relying on importing natural gas, being at the mercy of the Russians, Algerians and the Qatari's. I'd rather have an infrastructure in place with heat pumps and more nuclear power plants by then.


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PostPosted: Jun 25, 2014 1:53 pm 
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Even if space heating goes to heat pumps it seems unlikely that hot water can be so engineered.

ASHP for hot water have COPs of about 1.8 at best and cost large sums of money.
A night time immersion heater with a hot water cylinder is likely to come out ahead in terms of life cycle cost.


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PostPosted: Jun 26, 2014 2:18 am 
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http://jes.ecsdl.org/content/161/9/A1371.full.pdf+html
If the battery introduced or some equally good storage such as
http://www.gizmag.com/iron-air-battery/23646/
gets into production, there will be a definite niche of distributed generation from wind or air. While Germany's dependence on it as main power source may not be feasible, the niche considered by the French may be workable.


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