ASHP vs Oil in 2022

[MortarThePoint]

I have been planning to use an ASHP so have pipes at the required 150mm centres. Given the energy situation, I am now less sold on an ASHP vs Oil. If you have a tank full of oil you know you can heat the house, not so it there is a risk of blackouts. We'll have log burners as well but that's obviously faff.

 

Environmental:

ASHP: When heating using an ASHP the marginal electricity* will be most likely generated from gas:  0.5kgCO2/kWh electricity / 300% = 167gCO2/kWh of heat

Oil heating: 2.52kgCO2/lire / (10.35kWh/litre * 85%) = 286gCO2/kWh of heat

Winner: ASHP 42% lower*

 

Cost Install:

Hard to say accurately but about the same given the grants available.

Winner: Tie

 

Cost to run:

ASHP: Assuming 300% efficiency again and current electricity price of 45p/kWh -> 45p/kWh / 300% = 15p/kWh of heat

Oil: Assuming 85% efficiency again and current oil prices of 90p/litre -> 90p / (10.35kWh/litre * 85%) = 10p/kWh of heat

Winner: Oil 33% lower

 

Personal Energy Security:

ASHP: heat demand is at a time of year when personal generation not really viable so dependent on supply. Supply could be subject to interruption (blackouts, smart meter bugs). No flexibility on price.

Oil: bar it being stolen, when you have it you have it. Can stock up when price is low.

Winner: Oil

 

[Interestingly, for gas, the environmental is much closer 185gCO2/kwh (so ASHP saves just 10%) but running cost even lower though grid supply so security not so good]

 

* Using marginal generation figure as I am weighing up adding an additional electricity load, rather than the average.

The longest streak without coal is 67 days, so perhaps should use coal for this calculation: 0.8kgCO2/kWh electricity / 300% = 267gCO2/kWh of heat ASHP 7% lower than Oil

That 67 days is unlikely to be over winter. Government plans to ban coal powered generation towards the end of 2024, but that may get pushed back.

 

I doubt these figures include full CO2 emissions from transport, infrastructure, workforce etc.

[jack]

3 minutes ago, MortarThePoint said:

If you have a tank full of oil you know you can heat the house, not so it there is a risk of blackouts.

 

If you don't have some form of battery backup, can you run an oil burner during a blackout given they need power for ignition/control?

[Conor]

The embedded carbod within the oil is also massive, you need to add at least another 25% on top of the actual burner emissions.

 

Also, can you not access off peak tarrifs? We're currently on 15p for economy 7.

[Onoff]

6 minutes ago, jack said:

 

If you don't have some form of battery backup, can you run an oil burner during a blackout given they need power for ignition/control?

 

I've used a small petrol gennie just to keep the lights and central heating on before.

[joth]

Exactly how long a blackout are you expecting? Our house is fine with the heating turned off for 20hours each day, and that was a retrofit. On a new build you should be able to last even longer.

 

If that worries purchase a 3kW backup generator to power the heatpump, this will be cheaper to operate (thanks to the 300% cop of a heatpump) and also allow to run other home comforts like fridge/freezer during the event of an apocalypse 

[MortarThePoint]

9 minutes ago, joth said:

Exactly how long a blackout are you expecting? Our house is fine with the heating turned off for 20hours each day, and that was a retrofit. On a new build you should be able to last even longer.

 

If that worries purchase a 3kW backup generator to power the heatpump, this will be cheaper to operate (thanks to the 300% cop of a heatpump) and also allow to run other home comforts like fridge/freezer during the event of an apocalypse 

 

I'm not too worried about the blackout prospect, but the ability to buy you energy when it's cheaper is a huge plus for Oil.

 

A generator would cost a fortune to run surely.

[joe90]

35 minutes ago, MortarThePoint said:

electricity* will be most likely generated from gas: 

Figures I have seen vary from 40% to 50% currently but surely that figure will be coming down.

 

38 minutes ago, MortarThePoint said:

current oil prices of 90p/litre

Fir how long?, news this morning says opec cutting sales so prices expected to rise again.

[SteamyTea]

43 minutes ago, MortarThePoint said:

0.5kgCO2/kWh electricity

When did you get that figure 2010?

[nod]

Purely from a cost point Oil will be cheaper 

Our neighbors switched from oil to ASHP about 12 months ago Whilst the don’t regret it as the oil boiler was coming to the end of its life 40 years The ASHP noticeably more expensive to run 

Some of the modern oil boilers are very efficient now 

[joth]

1 hour ago, MortarThePoint said:

Cost to run:

ASHP: Assuming 300% efficiency again and current electricity price of 45p/kWh -> 45p/kWh / 300% = 15p/kWh of heat

Oil: Assuming 85% efficiency again and current oil prices of 90p/litre -> 90p / (10.35kWh/litre * 85%) = 10p/kWh of heat

Winner: Oil 33% lower

 

 

If you run the ASHP from octopus Go overnight, it's 7.5p/kWh primary energy so 2.5p/kWh of delivered heat. Giving:

 

Winner: ASHP 75% lower cost than oil.

 

 

(This only works on a highly efficient well insulated build where you can fully satisfy heating demand in 4hours of overnight usage, or with a very large house battery)

Edited October 6, 2022 by joth

[MortarThePoint]

32 minutes ago, SteamyTea said:

When did you get that figure 2010?

 

That's the marginal figure based on natural gas generated electricity. Need to consider the marginal figure for this comparison as all green electricity already being used.

 

[MortarThePoint]

12 minutes ago, joth said:

 

If you run the ASHP from octopus Go overnight, it's 7.5p/kWh primary energy so 2.5p/kWh of delivered heat. Giving:

 

Winner: ASHP 75% lower cost than oil.

 

 

(This only works on a highly efficient well insulated build where you can fully satisfy heating demand in 4hours of overnight usage, or with a very large house battery)

 

Are Octopus allowing new customers on that tariff?

[ReedRichards]

1 hour ago, MortarThePoint said:

current electricity price of 45p/kWh

 

I'm on the SVT tariff for single rate electricity and I am paying approximately 34 p per kWh (including VAT but excluding the Government discount scheme).

[MortarThePoint]

52 minutes ago, ReedRichards said:

I'm on the SVT tariff for single rate electricity and I am paying approximately 34 p per kWh (including VAT but excluding the Government discount scheme).

 

I'm not on a tariff yet so it will be whatever is available as a new customer which doesn't look great

[JohnMo]

2 hours ago, joth said:

purchase a 3kW backup generator to power the heatpump

Will this be big enough to start it?

[Dillsue]

1 hour ago, MortarThePoint said:

 

I'm not on a tariff yet so it will be whatever is available as a new customer which doesn't look great

British Gas standard variable tariff is price capped at 36p unit and around 50p a day standing charge. Fairly sure those sort of rates will be available from lots of suppliers 

[joe90]

However people like @ProDave run their ASHP during daylight hours most likely to gain from PV panels providing some contribution (which is what I plan).

[joth]

Just now, joe90 said:

However people like @ProDave run their ASHP during daylight hours most likely to gain from PV panels providing some contribution (which is what I plan).

Ironically right now I'm selling my PV to the grid for twice what I buy it for overnight (15p Vs 7.5p) so it's better value for me to export as much as I can during the day and buy it back overnight to run the ASHP. This calculus will obviously vary as the tariffs change in future.

 

I technically could make profit by discharging and refilling the battery each night too. 75p for an entire fill of the 10kWh battery probably not worth it for the degradation on the battery. (And definitely not from a needless configuration hassle point of view)

[SteamyTea]

10 minutes ago, joth said:

I technically could make profit by discharging and refilling the battery each night too.

Interesting concept.  Probably cost more than just the maximum energy storage of 10 kWh, probably nearer 12 kWh needed overall, so £0.9.

Assuming you can export the full 10 kWh back for £1.50, that is £0.60/day.

So the truer value is 6p/kWh.

 

 

[MortarThePoint]

I don't know how mass adoption of ASHP will come about until the running cost is comparable to oil/gas heating. The grants address the increased capital expense, but not the increased running cost. Electric cars may limit the lifetime of E7, I don't know, but that isn't a solution for existing building stock anyway. It will be very unpopular to tax oil/gas heating out of existence. I also find it hard to imagine a running cost grant for ASHP or disproportionately lower electricity prices.

[joe90]

42 minutes ago, MortarThePoint said:

I don't know how mass adoption of ASHP will come about until the running cost is comparable to oil/gas

Does not the COP of an ASHP bring it in line with gas? (Well it did before Putins war 🤔)

[Onoff]

"They" want "you" hooked into a commodity. Whether it be electricity or whatever. 

 

The way the whole eco friendly thing is promoted is complete b@ll@cks. It should be on a fabric first basis. Putting an ASHP into an unsuitable setting shouldn't be allowed to happen. 

 

I'd liken it to vegan products. Promote vegetarianism and you can grow a lot of your own food at home. Promote veganism and the whole industrial, socioeconomic status quo is maintained. Factories that now produce chicken nuggets produce vegan chicken nuggets. The infrastructure barely changes, profits remain the same or higher.

 

The population becomes reliant and thus controllable. 

 

Soylent Green / Red.

[billt]

37 minutes ago, Onoff said:

I'd liken it to vegan products. Promote vegetarianism and you can grow a lot of your own food at home. Promote veganism and the whole industrial, socioeconomic status quo is maintained.

 

Sorry, but vegan merely means that you don't eat eggs and dairy products as well as not eating meat/fish. It is perfectly possible to prepare vegan food without buying ultra-processed rubbish. It predates the modern bandwagon by several decades. (Consults Wikipedia - in fact it dates back to 3300-1300 B.C.)

[SteamyTea]

The thing about electricity is it is very flexible, not only for the end user, but also in the methods it can be generated. Non gas powered generation can be solar, wind, nuclear, biomass, oil, land fill gas, hydro, wave (one day, maybe), tidal (will take longer than nuclear), and the easy one, importing.

Wind power now has a strike price of £37.35/MWh.

For the last year, wholesale natural gas has had a day ahead price of around £65/MWh (quite hard to get an exact figure).

That is up from £16/MWh back in February 2021.

Now I doubt in the near future (next 3 years) we are going to see gas prices much less than £30/MWh, so going to be a similar price to new build renewables.

Also, at the moment, if we really want gas, we are going to have to outbid others.

 

Going to be much easier to reduce waste, which is not the same as improving efficiency.  Hopefully the current high prices will solve this, but people can be twats and feel entitled to waste their own money.

Thing is, they are also waste everyone else's money as we are all now chipping in.  I am not sure how we are going to get that message across without having a similar attitude that the nation has taken to smokers (but oddly enough not drinkers who cause a lot more problems).

So who is going to go around a fully lit up house and ask them to turn some of the lights off?

[SteamyTea]

3 minutes ago, billt said:

It is perfectly possible to prepare vegan food without buying ultra-processed rubbish.

Perfectly possible to prepare any food in that manner.

Generally cheaper to buy semi prepared food though.

 

To make an un processed vegan mean, first buy a field, then leave alone for 3 years, then plant your choice of fruit and veg, then wait till harvest time, then harvest and throw most away as it is diseased and maggot eaten.

Then boil or roast.

Then throw away and get a donner kebab.