Pocster Posted March 4, 2022 Share Posted March 4, 2022 Given we need to reduce our dependancy on gas due to climate change and war - what do we think of electric combi's? Regardless of government initiative millions of households won't ( or can't ) be updated sufficiently to benefit from ASHP for example. With gas prices set to rocket does replacing a gas combi boiler with an electric one start to make sense??? Link to comment Share on other sites More sharing options...
JohnMo Posted March 4, 2022 Share Posted March 4, 2022 (edited) Possibly the worst of all things as far a cost to run and performance. 3 to 4 times the cost to run compared to a heat pump or gas. Low flow compared to gas combi. Would it be better to use E7 to heat a unvented cylinder for DHW, or a combined cylinder heat pump, basically the same price as gas or a third the cost if run on E7. Space heating with an all in one aircon/heat pump (no outside unit, just inlet outlet through wall), if you have UFH Willis heater's run on E7. Summer heating of DHW with solar either PV or/and thermal solar. That's my thoughts. If knew how our house performance a year before moving into it and wanted all electric. UFH with Willis heated on E7, combined cylinder (stainless or duplex) and heat pump, immersion diverter and solar thermal for shoulder months when PV performance is low for DHW. Edited March 4, 2022 by JohnMo Changed spelling of unvented 2 Link to comment Share on other sites More sharing options...
ProDave Posted March 4, 2022 Share Posted March 4, 2022 I would love someone to work out the round circuit efficiency of burning gas in a gas powered power station to generate electricity to heat your house with an electric boiler. My instinct says it will burn MORE gas as well as costing you a lot more. People seem to make such suggestions thinking somehow we can get any amount of clean electricity we want. While I agree we have to reduce fossil fuel usage, energy security is a more urgent issue. Do we still have any coal powered stations still in a state they could be re started? As unpalatable as that may be to the environmentalists, as a short term alternative to Russian gas, it has to be considered? 2 Link to comment Share on other sites More sharing options...
saveasteading Posted March 4, 2022 Share Posted March 4, 2022 20 minutes ago, ProDave said: burning gas in a gas powered power station to generate electricity That has all been done , and a web search should find it. Do I recall 25% combustion inefficiency and up in smoke*, then 25% as friction/ cooling, 25% gets lost along the line, and 25% reaches end user? * That perhaps includes energy used to get it to destination). Re line losses, apparently that is why Denmark has multiple small power stations as well as wind turbines all over, as they feed into the grid close to end use. On cooling: I was privileged to have a nearly full tour of Dungeness. From 12 stories up there was a view out to sea, and the cooling water created a maelstrom perhaps 200m diameter. The amount of water and energy was unsated. Likewise a tour of a coal power station many years ago, that included going into a cooling tower. Opening the pedestrian door required a huge heave and apparently cost ££/second in lost efficiency. All that heat being thrown away and nobody had a better solution. Link to comment Share on other sites More sharing options...
Temp Posted March 4, 2022 Share Posted March 4, 2022 The figures here are out of date but give the general idea. https://nottenergy.com/resources/energy-cost-comparison/ The key column is the cost per kWh after taking into account boiler efficiency. 1 Link to comment Share on other sites More sharing options...
ProDave Posted March 4, 2022 Share Posted March 4, 2022 5 minutes ago, Temp said: The figures here are out of date but give the general idea. https://nottenergy.com/resources/energy-cost-comparison/ The key column is the cost per kWh after taking into account boiler efficiency. That wasn't what I was asking. Say you burned 1000kWh of gas in a year. You replace your gas boiler with an electric combi, and use the same amount of heat. The electricity you use gets generated by a gas powered power station (all the greener / cheaper alternatives are already at capacity) How many extra kWh of gas will the gas powered station consume to supply your electric combi boiler? Link to comment Share on other sites More sharing options...
JohnMo Posted March 4, 2022 Share Posted March 4, 2022 You can generate electricity from gas at around 60% efficiency, using a combined cycle system. Where the gas turbine drives a generator, the exhaust gas is used to generate steam and drive a steam turbine; which also drives the generator. But once generated, you get system losses to get to the end user. Which brings down efficiency. The beauty of a gas boiler is it converts to heat in the high 90% efficiency, if set up correctly and no distribution losses at the point of generation. 11 minutes ago, saveasteading said: All that heat being thrown away and nobody had a better solution. Yes other countries, use the heat distributed to heat homes, water etc. Our power stations are well away from residential areas, so does not work. Link to comment Share on other sites More sharing options...
ProDave Posted March 4, 2022 Share Posted March 4, 2022 9 minutes ago, JohnMo said: You can generate electricity from gas at around 60% efficiency, using a combined cycle system. Where the gas turbine drives a generator, the exhaust gas is used to generate steam and drive a steam turbine; which also drives the generator. But once generated, you get system losses to get to the end user. Which brings down efficiency. The beauty of a gas boiler is it converts to heat in the high 90% efficiency, if set up correctly and no distribution losses at the point of generation. So I rest my case, switching to an electric combi will definitely increase the amount of gas being burned. Link to comment Share on other sites More sharing options...
Temp Posted March 4, 2022 Share Posted March 4, 2022 13 minutes ago, ProDave said: That wasn't what I was asking. Say you burned 1000kWh of gas in a year. You replace your gas boiler with an electric combi, and use the same amount of heat. The electricity you use gets generated by a gas powered power station (all the greener / cheaper alternatives are already at capacity) How many extra kWh of gas will the gas powered station consume to supply your electric combi boiler? Yeah sorry. Google says.. Gas fired power stations are 56 to 60% efficient. Transmission losses are perhaps 6 to 9% so let's say the grid is 95% efficient. Domestic boilers claim over 90%. So a kW delivered by your gas boiler consumes 100/90 = 1.1kW of gas. The gas power station consumes around 100/60 * 100/95 = 1.75kW of gas. Link to comment Share on other sites More sharing options...
saveasteading Posted March 4, 2022 Share Posted March 4, 2022 35 minutes ago, JohnMo said: heat distributed to heat homes, Grangemouth oil refinery's waste heat goes to the town. Not so convenient with power stations, esp nuclear ones. They really should build the next nuclear PS in London or Surrey, as that would allow for heating the city. Link to comment Share on other sites More sharing options...
JohnMo Posted March 4, 2022 Share Posted March 4, 2022 Wouldn't want one on my doorstep. Polluting the sea is one thing, polluting many thousands of homes not that good. Link to comment Share on other sites More sharing options...
SteamyTea Posted March 5, 2022 Share Posted March 5, 2022 We loose ~5% of the natural gas due to distribution. And then there is the processing losses, which are less for large users than domestic users. Electricity is also more useful than gas. If we still had gas lighting in our homes, airtightness would have to be above 10 ACH, not below it. I also doubt that many gas boiler actually get close to 90% efficiency in reality. 1 Link to comment Share on other sites More sharing options...
ReedRichards Posted March 5, 2022 Share Posted March 5, 2022 Given that the questioner merely wants people to express an opinion, perhaps this statement is the one that we should be challenging? On 04/03/2022 at 16:17, pocster said: Regardless of government initiative millions of households won't ( or can't ) be updated sufficiently to benefit from ASHP for example. 1 Link to comment Share on other sites More sharing options...
ProDave Posted March 6, 2022 Share Posted March 6, 2022 10 hours ago, ReedRichards said: Given that the questioner merely wants people to express an opinion, perhaps this statement is the one that we should be challenging? That is the question nobody wants to answer. If a house is so poor in it's insulation that you can't heat it with an ASHP and there will come a time when you have to stop using fossil fuels, then the answer is NOT an electric combi boiler. The question yet to be answered is just what do you do with such a house to make it to an acceptable energy usage, and who is going to pay for that probably quite major work to be done? 2 Link to comment Share on other sites More sharing options...
SteamyTea Posted March 6, 2022 Share Posted March 6, 2022 (edited) 50 minutes ago, ProDave said: who is going to pay That is easy, the property owner. I am a bit miffed that the daily rental on the electricity meter has gone up, in part to pay the debt on the failled suppliers. No one, who save on their bills through these bad businesses, offered to but me a coffee even, let one pay part of my bill. Edited March 6, 2022 by SteamyTea 1 Link to comment Share on other sites More sharing options...
ProDave Posted March 6, 2022 Share Posted March 6, 2022 7 minutes ago, SteamyTea said: That is easy, the property owner. Then in most cases it won't get done. I still see threads about people who have just moved into a new (to them) house and are shocked at the energy usage. Buyers in general ignore the EPC rating then wonder why their EPC G house costs a fortune. I guess one day, we will reach a point where a house with a poor EPC is worth less than a good one, to factor in the cost of the work needed to improve it. I don't want to be the owner of a poor EPC house while we go through that transition. 1 1 Link to comment Share on other sites More sharing options...
MikeSharp01 Posted March 6, 2022 Share Posted March 6, 2022 6 minutes ago, SteamyTea said: I am a bit miffed that the daily rental on the electricity meter has gone up Plus one to that - although our supplier here 'BULB' is one of the failures, perhaps rightly given the problems we have had with our smart meter, cannot be read remotely can't display our dual tariff and they seem not to be bothered (They are prorating our bill based on our 2019 split - which is outrageous given we might have an EV charging over night now and not then) AND worse of all we cannot switch! Link to comment Share on other sites More sharing options...
SteamyTea Posted March 6, 2022 Share Posted March 6, 2022 4 minutes ago, ProDave said: 11 minutes ago, SteamyTea said: That is easy, the property owner. Then in most cases it won't get done As they say, "Can't help stupid". It will highlight that bewildering mentality that when property prices rise significantly above inflation (as they have done in many places for 25 years), people think they are better off. Not as if you can pay the gas bill with a brick from your mansion wall. Link to comment Share on other sites More sharing options...
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