Future of UK generated power

[Raditechman]

I had air condition installed last year and it works for heating or cooling, ie .set the temperature you want and it will supply what is needed to maintain that temperature. I have been told it is fairly economic for heating. There are two units outside the house connected by pipes to internal units. I still have a gas boiler and hot water central heating but would much would prefer to be all electric, so when my boiler fails I may just not get a new one.
I think gas is being phased out on new buildings from 2025.

John

[Nick]

Worth mentioning the heat pumps run most efficiently when producing water at around 50-55C and when run continuously, i.e. not cycled. Also, no maintenance costs - the system is effectively sealed for life - just top up with a litre or two of water every year due to losses in the coils through osmosis.

This is ideal for underfloor and domestic hot water - the first thing that most folk do when running a hot tap is to run the cold as well so they don't get burnt. With a HP, that is not normally necessary (there are exceptions - every few days the hot water is raised to 70C to kill any legionella bacteria in the supply).

We reckon that the HP install paid for itself in about 40 months. Previously we had an oil-fired boiler, but it's difficult to compare as we didn't just replace the boiler - we demolished the house and built a green one twice the size  The GSHP was installed when we had diggers on-site, so was cheap, though the main lawn was shagged for about 2 years...

Whilst underfloor is best for HPs, you can use standard emitters (radiators), but they have to be oversized due to the lower operating temperature compared to a conventional boiler. This generally doesn't matter as modern radiators are more efficient than older ones, so in many cases the "oversized" radiators are physically smaller than those they replace.

We only have the HP - no backup system (except a wood burner!). In 15 years it's not missed a beat.

[ppppenguin]

Not only heatpumps. Condensing boilers are more efficient when the flow temperature is 55 to 60C. If your radiators are sized for 70C flow as is traditional then a condensing boiler will be less efficient. Still better than a non-condensing type but not as good as it might be.

Nick is in the fortunate position of having built from scratch. Was your house to Passivhaus standards? A house like this barely needs a central heating system at all though of course it still needs hot water. In a Passivhaus you can probably make a case for using direct electric heating for the small amount that's needed. The extra cost of a heatpump etc may not be worth it. Solar hot water (often only pre-heat in the UK) and PV would be standard on a Passivhaus.

[ppppenguin]

Saw this article today: https://www.theguardian.com/business/201...p-power-uk
The idea of demand side management is hardly new. This paper (behind paywall) is from 1999: https://www.researchgate.net/publication...tic_sector

Calling it a "virtual battery" is a bit excessive as it can't generate on to the grid. Unlike V2G: https://en.wikipedia.org/wiki/Vehicle-to-grid The paper edition has a different and worse headline: "Supermarket fridges 'can act as batteries to boost energy grid' "

Demand side management is a good way of reducing peak demand on the grid. https://en.wikipedia.org/wiki/Load_management "Interruptible tariffs" have been used with some industrial customers: https://www.sciencedirect.com/topics/eng...ble-tariff In general, a willingness to accept short term power outages has a value that can be traded. Usually a lower unit cost of power in return for a willingness to be disconnected at peak load times. This is harder for smaller customers, right down to domestic level. Though Economy 7 is often supplied as guaranteed 7 hours of low cost electicity in the night but not necessarily the same 7 hours or continuously every night. No problem for heating but a nuisance if you run your washing machine overnight to keep down cost.

The idea of a domestic fridge reducing its power usage in response to a drop in grid frequency has been proposed and may even be available. Though in general you're not being rewarded for this sort of DSM. But this approach to demand side management could affect grid stability if widely used: https://arxiv.org/pdf/1703.01195.pdf

[`FRANK.C]

Regarding the domestic Fridge.
It could be done by using forced air Fridge freezers where all the cooling is done in the freezer and a fan is used to blow the cold air from the freezer into the fridge to cool it when needed.
Keeping the freezer cooler than normal could be used as a cold accumulator. During peak demand only the fan would be needed to cool the fridge .

Customers might find this objectionable. With Ice cream being hard and frozen food taken longer to cook than it should.

I was once out to a new oven where the customer was complaining that it was not heating properly, it was taking over twice as long to cook as it should.
After carrying  out extensive  test on the temperature it was reaching and finding no fault. I asked what were they cooking in it. "Frozen pizzas"  they said.
A quick look at there Freezer revealed that the fast freeze button was on. A check on the freezer temperature showed it was down to -32C. Mystery solved!

Frank

[Terry]

Regarding the domestic Fridge.
It could be done by using forced air Fridge freezers where all the cooling is done in the freezer and a fan is used to blow the cold air from the freezer into the fridge to cool it when needed.

How is this more efficient than the conventional fridge/freezer configuration where the freezer compartment (only) at the top of the unit is cooled and cold air from the freezer drops down and cools the fridge section - no fan required using additional power.

[ppppenguin]

All frost-free freezers have the freezing elements outside the main compartment and blow the cold air into the food compartment. Every so often the fan is turned off and the freezing elements heated slightly to stop ice accumulating. I though that all fridge frezers with a single compressor (in other words almost all FFs though not my old Bosch which has 2 completely separate compressors) had some means of ducting cold air from the freezer into the fridge. Not sure how the relative temperatures are controlled.

[`FRANK.C]

Hi Terry
That indeed would be more efficient.
That type appears to have gone out of favour. I haven't seen a large fridge of that type in years or maybe decades.
The last ones of that type that I have seen were small under counter ones.
Of late I haven't seen any of them either.

I think what was disliked about them was that they required defrosting relatively often.
The later type that has two evaporators requires less defrosting. Because the fridge evaporator self defrosts and the freezers evaporator sees fresh humid air only when the freezer door is opened. We have a fridge freezer of this type it was over 10 years old when it needed its first defrost due to not opening the freezer very often. This type of fridge freezer usually gives less trouble than frost free types.

Hi Jeffrey
In forced air fridge freezers the temperature of the fridge is usually controlled by a door in the duct that supplies the cold air to the fridge. This allows just one fan to cool both fridge and freezer. With the door shut the freezer can be cooled without reducing the temperature of the fridge. When the fridge needs cooling the fan turns on and the door opens. On some fridge freezers the compressor don't kick in immediately but waits until the freezer temperature rises above a cretin level.

Not all frost free fridge freezers use forced air in both fridge and freezer. Some use forced air in the freezer and a self defrosting evaporator in the fridge.

Frank