Dual Fuel Boilers (Electric + NG) to solve heating and curtailment

zeupater

michaels wrote: »

I don't think people who are talking about local distribution issues understand the idea.

If local demand is high then (winter evening etc) then it unlikely that there will be a curtailment situation from excess wind until we have a much larger wind build out. Thus curtailment will arise when demand is low and thus switching on electric heaters at this time will not put pressure on the grid.

WE have an iboost solar diverter, in the summer it sends excess solar generation to the hot water tank. We set the tank temperature on the gas boiler down to 50 and the electric thermostat to 70 thus we always have hot water but there is 'room' in the tank for solar storage. If the iboost was controlled via a remote signal so that it switched on to avoid wind generation curtailment then it would be win-win, the energy gets used and the curtailment fees are saved, I am sure that the energy could be sold to us for a price that was cost competitive with gas.

[note the iboost on a standard immersion is able to 'modulate' to match the amount of solar that would otherwise be exported so not even just an on/off solution.]

We could do the same with our EV, if it was cheaper per unit we would be happy to opt for charging when it suits the grid (obviously subject to a minimum amount of charge every morning and an override)

Our house is 170m2 and our boiler modulates between 5kw and 18kw and is plenty enough to heat and hot water.

Hi

However, Winter curtailment is far less pressing than Summer as that's where spot energy supply is more likely to far exceed spot demand, so where does all of the huge heating-dump demand come from then? ... that's why it makes far more sense to look to improve energy use efficiency and smooth temporary demand to supply imbalance through the creation of strategic storage facilities, whatever the technical solution ....

HTH
Z

zeupater

Reed_Richards wrote: »

Yes, that's useful to know. But a lot of under-sink heaters cannot cope with a hot water input whereas i want something that will heat water briefly but cut-out when the water from the boiler comes through. Is that what your friend had?

The water in my old house was very hard and I ended-up fitting a water softener because my wife decided she wanted to replace the bathroom because of the limescale left by years of hard water. Then we moved house instead. £100 a year for salt seems about right.

Hi

Hot water input wasn't the issue, it's the length of the pipe runs and both the water & heat energy loss involved in delivering DHW to the taps in a total renovation project ... running a single 15mm copper tube a long distance as opposed to two (H&C) goes a long way towards paying for the undersink unit before even considering the resource based running cost!

Regarding your DHW 'top-up' heating .... doesn't that mean that whenever you run the hot water the undersink unit heats it up, but hot water from your cylinder enters the pipe run but hardly ever reaches the tap? ... I would tend to see this as an unnecessary energy waste unless there's an additional underlying reason.

HTH
Z

zeupater

Hexane wrote: »

This is approximately what I'm involved in a trial of. Actually, the inverse too. The grid asks for my immersion heater to be turned on (or up) when there is surplus power that needs using up to avoid curtailment, and the grid asks for my immersion heater to be turned down (or off) when there is a shortage of power such that fossil fuel power stations might have to be used instead of my solar panels.

Fortunately, I live in an area with extremely soft water.

Hi

This is pretty standard in quite a few areas around the world .... our heat pump already has a similar level of control designed in, it's just that the UK energy supply infrastructure doesn't! ....

HTH
Z

Reed_Richards

zeupater wrote: »

Regarding your DHW 'top-up' heating .... doesn't that mean that whenever you run the hot water the undersink unit heats it up, but hot water from your cylinder enters the pipe run but hardly ever reaches the tap? ... I would tend to see this as an unnecessary energy waste unless there's an additional underlying reason.

Whenever I wash my hands I turn on the hot tap and the water comes out cold. As I run-off the water, the combi boiler turns on (I don't have a cylinder) and heats the water flowing through the pipe but I have finished washing before the heated water reaches the tap so this is 100% wastage of energy. The alternative is to run the tap long enough that the water runs hot which wastes a lot of water and even then I don't need a lot of hot water to wash my hands and face so the energy wastage is still say 80% because 80% of the heated water remains in the pipes.

Now an instantaneous water heater connected to the hot pipe might use more energy but it would not be wasted because it would actually give me the hot water I want. It might even use less energy than my alternative scenario of waiting for the water to run hot.

zeupater

Reed_Richards wrote: »

Whenever I wash my hands I turn on the hot tap and the water comes out cold. As I run-off the water, the combi boiler turns on (I don't have a cylinder) and heats the water flowing through the pipe but I have finished washing before the heated water reaches the tap so this is 100% wastage of energy. The alternative is to run the tap long enough that the water runs hot which wastes a lot of water and even then I don't need a lot of hot water to wash my hands and face so the energy wastage is still say 80% because 80% of the heated water remains in the pipes.

Now an instantaneous water heater connected to the hot pipe might use more energy but it would not be wasted because it would actually give me the hot water I want. It might even use less energy than my alternative scenario of waiting for the water to run hot.

Hi

The issue is that if you're looking to connect the under-sink heater to the DHW supply pipe then whenever you run the hot tap you're still drawing water through the combi boiler which flows towards the tap until you turn it off, so although you're not wasting as much water or energy through running the tap until the hot water gets to it, you're still heating the water in two places, ie the boiler and the under sink heater unit ....

The systems that I've seen simply use a Tee connector on the 15mm cold water pipe to divert some of the flow to the heater, then the heater is connected to the hot water tap, that way there's no unnecessary load on the combi boiler to provide DHW when all it will do on most occasions is sit in a supply pipe and cool down ...

HTH
Z

1961Nick

Reed_Richards wrote: »

Whenever I wash my hands I turn on the hot tap and the water comes out cold. As I run-off the water, the combi boiler turns on (I don't have a cylinder) and heats the water flowing through the pipe but I have finished washing before the heated water reaches the tap so this is 100% wastage of energy. The alternative is to run the tap long enough that the water runs hot which wastes a lot of water and even then I don't need a lot of hot water to wash my hands and face so the energy wastage is still say 80% because 80% of the heated water remains in the pipes.

Now an instantaneous water heater connected to the hot pipe might use more energy but it would not be wasted because it would actually give me the hot water I want. It might even use less energy than my alternative scenario of waiting for the water to run hot.

There are quite a few triple faucet monobloc mixer taps on the market. The 3rd faucet is usually for filtered drinking water, but there's no reason why it couldn't be used with an electric water heater fed from the cold.

zeupater

1961Nick wrote: »

There are quite a few triple faucet monobloc mixer taps on the market. The 3rd faucet is usually for filtered drinking water, but there's no reason why it couldn't be used with an electric water heater fed from the cold.

Hi

Odd, other than occasional reference on TV, I don't think I've ever seen or heard a tap referred to as a 'faucet' this side of the Atlantic, we'll probably be changing the way we spell colour and calling a bonnet a hood next ...

.... anyway, I'm aware of these being available as high format units for kitchen sinks, but I don't think I've ever seen one in a low format presentation for a cloakroom/bathroom basin ... are they available at Screwf1x ?

Z

GreatApe

zeupater wrote: »

Hi

However, Winter curtailment is far less pressing than Summer as that's where spot energy supply is more likely to far exceed spot demand

Offshore wind power produces some 60-70% more output in the winter months than the summer months. So a future UK grid that is wind heavy will produce a lot more output in the winter months than in the summer months

And with your statement you are more or less saying boilers have little to no use in the summer months so there is not much NG curtailment to be had in the summer. This is not true there is significant NG used in boilers in Q2 and Q3 in less efficient homes and in water heating. For instance I have been using 10-25 KWh of gas per day this month. That is more gas than I use in electricity!

so where does all of the huge heating-dump demand come from then?

Summer space and water heating is in the ballpark of 15 TWh per month which is a huge number works out to about 20GW average power demand.

that's why it makes far more sense to look to improve energy use efficiency and smooth temporary demand to supply imbalance through the creation of strategic storage facilities, whatever the technical solution ....

No one is saying dont improve building energy efficient where economical to do so

But you still need to heat water and heat homes and the three solutions are

1: Natural gas boilers: What we do today. 300TWh in NG
2: Heat pumps: Might work but Norway and Sweden dont use them instead they use direct eletrical heating. Why? Estimated 100TWh in electric
3: Hybrid gas/electric boilers: One possible path. Estimated 200TWh in electric

Assuming #1 is off limits due to high FF usage
What works better #2 or #3

The real question will be, is it cheaper to produce 100 TWh of additional offshore wind power and do direct electrical heating or is it cheaper to install 40 million heat pumps?

My guess is it will be easier to install 30GW of additional offshore wind capacity than it would be to install 40 + million heat pumps. But if regulation does not allow differential tariffs then it will have to be heat pumps lets hope it works

michaels

zeupater wrote: »

Hi

However, Winter curtailment is far less pressing than Summer as that's where spot energy supply is more likely to far exceed spot demand, so where does all of the huge heating-dump demand come from then? ... that's why it makes far more sense to look to improve energy use efficiency and smooth temporary demand to supply imbalance through the creation of strategic storage facilities, whatever the technical solution ....

HTH
Z

Fair point although for those of us with hot water tanks can store energy there as noted in my post

GreatApe

4 ways to heat buildings

1: Natural gas (most uk homes today)
2: Direct Electrical heating (Norway/Sweden and millions of French and even UK homes)
3: Heat Pumps (nowhere in EU does it have significant market share today, why??)
4: Hybrid gas electric (easy to produce and implement)

#1 is out due to using !!!!!!
#2 is possible but will be expensive for larger inefficient homes
#3 is probably un-affordable (40+ million heat pumps installed at a cost to the government of £5-8k each = £200-£300 billion)
#4 is basically #2 in slow motion in a more affordable and more green way

I think it will actually be a mix of #2 #3 & #4

#2 for new builds and smaller flats
#3 for large inefficient homes where the large capital cost of a heat pump can be spread among many more heat units
#4 for those homes in between the two described above where heat pumps are too expensive for the amount of heating needed

I would guess
#2 Direct electrical heating will have about 1/3th market share so about 10 million homes
#3 Heat pumps will have 1/6th market share so about 5 million homes
#4 hybrid boilers will have 1/2th market share so about 15 million homes