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Renewable Energy: GSHP Carbon footprint

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    • CommentAuthorrevor
    • CommentTimeNov 8th 2020
     
    Had a circular this week from a seller of heat pumps extolling the virtues of GSHP. A claim that caught my eye was that they produced 65% less carbon than a gas boiler. Not exactly carbon neutral and how about the embedded energy used in making the HP. Given this is an advert my guess is that there could be a temptation to gild the Lilly a little so it set me wondering perhaps the figure is less than 65% Just how is the figure arrived at . What is the true carbon footprint compared to non green heat sources?
  2.  
    Much depends on the 'green ness' of the electricity that you think you will run it with.

    The UK grid average is jaw droppingly 'greener' than it was only a few years ago, and getting more so, depending on the weather and time of day.

    Last month the average grid intensity was about 170g/kWh so a GSHP with CoP = 4 would be 170/4= 42g/kWh, which is better than a gas boiler (210g/kWh) by 80%

    But if you install a GSHP, they don't automatically build you a new wind turbine for you to power it with. In the short term, they turn up the 'marginal' power station a bit to supply you, which would be a gas power station. Your effective carbon footprint would then be about 500/4 = 125gkWh, which is better than a gas boiler by 40%.

    There are persuasive arguments why either the 40% or 80% figures are 'correct', and if you come back next year or tomorrow evening the numbers will be different again...!

    (Data from Notts energy and Drax insights, many other view points are available!)

    The embodied energy of a GSHP or a gas boiler are probably similar, with the important difference of the refrigerant used. Common refrigerant is R410 which, if it leaks out, is equivalent to a lot of CO2. Newest refrigerants are lower CO2 equivalent.

    There may be carbon footprint in burying the ground loop if you bring in a digger to do it, or not if you were digging that area anyway.

    These days an ASHP has most of the benefits of a GSHP at lower cost, but again there are many valid viewpoints which is better.
    • CommentAuthorEd Davies
    • CommentTimeNov 8th 2020
     
    Reading WiA's reply I kept thinking “yes…but” then he went into it. +1.
    • CommentAuthorSimonD
    • CommentTimeNov 12th 2020
     
    Interesting read this. I was only the other night discussing our heating options for our current build where for now I've chosen to go with gas, in part resulting from discussions I've had with an energy consultant who does work for the likes of Drax etc. He suggested waiting for hydrogen as there is lots of promising work in this area, including the new facility drax are building on the Humber. I've also seen various gas boilers now available to run on hydrogen.

    Both ASHP and GSHP I've eliminated taking into consideration COP and the upfront capital costs of each and how much we have to earn to pay for them even with RHI payments.

    When looking at the electrical energy input into these systems, I was also intrigued that very little data, if any is available to calculate how much 'dirty' grid electricity is consumed in the operation and maintenance of windfarms, thus with some calling them laundering facilities for some of the larger utility companies.

    Does anyone here have any incling on these figures and are they merely a smokescreen?

    I'd certainly be grateful to review my decision to understand what the real world COP figures for current ASHPs and GSHPs together with the total capital costs of installation as it really doesn't seem that straighforwards.
    • CommentAuthorMike1
    • CommentTimeNov 12th 2020
     
  6.  
    Simon, I've been waiting 25years for hydrogen to be available at sufficient scale as a domestic fuel for tens of millions of houses and cars, it's always 'just about' to happen!

    I remain optimistic that it might still happen in my lifetime, though maybe not in a timeframe commensurate with the climate emergency... The amount of hot air around it suggests that somebody maybe using it as a smokescreen, possibly those continuing to market 'hydrogen ready' gas boilers, that will never see hydrogen grid fuel in their useful lifetime...

    Unfortunately, most hydrogen is made from fossil fuels now, as Drax describe, and the conversion is wasteful, so you'd get more heat by just burning the fossil gas directly.

    In the future, if there is ever sufficient renewable electricity left over after charging all the electric cars, some of it might be used to make hydrogen, but again the conversion is wasteful. So if you have a kWh of renewable electricity, you could turn it into hydrogen, burn it, and get less than a kWh of heat in your house. Or you could put the kWh of renewable electricity into a ASHP or GSHP and get four kWh of heat in your house.

    The primary role for hydrogen will be to fuel airliners and HGVs, and it will be a valuable fuel once the fossil alternatives are withdrawn. So don't expect hydrogen to be a cheap way to heat your house!

    I could be wrong but I don't think RHI is available for newbuilds. ASHPs, and particularly GSHPs, are indeed very expensive. If you can meet your TER target with a fossil gas boiler and the gas connection isn't too expensive then it could be cheaper to fit one before they are banned, and plan to convert to a heat pump when it wears out. We all have to make cost-vs-greenness tradeoffs in our builds.
    • CommentAuthorMike1
    • CommentTimeNov 12th 2020 edited
     
    Posted By: SimonDHe suggested waiting for hydrogen
    How long do you want to wait? It's not likely to become mainstream until some time after 2030.

    Posted By: SimonDBoth ASHP and GSHP I've eliminated taking into consideration COP
    Why, when that's how they work? Would you multiply the cost of running a fridge by 5 (roughly the COP of a fridge - it's a heat pump in reverse) to work out your future energy bills, or just believe that it will use roughly what it says on the label?

    Of course a heat pump's COP will vary according to the season and the temperature you run it at, and other factors, but so will a fridge.

    Posted By: SimonDhow much 'dirty' grid electricity is consumed in the operation and maintenance of windfarms
    Wind farms use grid energy which, as mentioned above, is becoming dramatically less carbon intensive wind and solar displace fossil fuels. They clearly use much less electricity than they produce, or the carbon intensity of the grid wouldn't be falling so fast.
    •  
      CommentAuthorfostertom
    • CommentTimeNov 12th 2020 edited
     
    The new Drax Humber plant producing hydrogen by hydrolysis from air instead of chemically from fossil, AFAIK is still just a large-scale pilot or research project which initially will supply 25% of the hydrogen that the chemical works itself consumes i.e. none of it, for a long time, intended to contribute to supply outside the site.
  9.  
    Posted By: WillInAberdeenI could be wrong but I don't think RHI is available for newbuilds.


    I just checked this and it is eligible for "Custom Builds" which are defined here:
    https://www.ofgem.gov.uk/key-term-explained/custom-builds

    Good job as I have just paid for the Heat Pump for the Barn Conversion and spent the whole of my week off work last week in a digger installing ground loops!
    •  
      CommentAuthordjh
    • CommentTimeNov 12th 2020
     
    Posted By: SimonDHe suggested waiting for hydrogen ... I've also seen various gas boilers now available to run on hydrogen.

    Hmm, what others have said. Plus, there are two obstacles, I believe. One is an economical clean source of hydrogen as mentioned. The other obstacle is that existing gas mains are not designed to contain hydrogen, and don't. So before it can be distributed as a mains fuel, all the gas infrastructure needs a major upgrade. If that's true, you'll be waiting a long time.

    Both ASHP and GSHP I've eliminated taking into consideration COP and the upfront capital costs of each and how much we have to earn to pay for them even with RHI payments.

    I did that too, on the basis of my low demand and how much that increases payback times. Things are slowly improving both on the performance and the cost front. Air-air in particular ('splits') are now fairly cheap but air-water are more expensive. GSHP I wouldn't look at except in special conditions. What I did was fit a very simple and cheap direct electric system - post heater in the MVHR, radiant heater in the hall and immersion heaters in the thermal store. My PV production nearly matches my total consumption - I may buy a few more panels.

    What I would do differently if I had been building with benefit of hindsight is to consider where I would mount both an air-air HP system and an air-water HP system and make some provision for them. As it is, there'll be some disruption if I do ever decide to buy one or the other.

    Posted By: Dominic CooneyI just checked this and it is eligible for "Custom Builds"

    That's interesting. Has it always been like that, or has it changed, I wonder? I don't remember it being the case.
  11.  
    Thanks Dominic! Interesting you can buy a new developer-built house with a gas boiler, and then get RHI to immediately convert it to a heat pump. But if the developer installed the heat pump at your request, then no RHI.

    Here's a pitch for a project to convert sections of the gas grid to hydrogen. They propose the first section could be completed by 2034 and the final section by 2050.

    https://www.northerngasnetworks.co.uk/wp-content/uploads/2018/11/H21-Meeting-UK-Climate-Change-Obligations.pdf
  12.  
    Posted By: djha very simple and cheap direct electric system


    I think we will follow this approach on the next one, there is more room for insulation.
    •  
      CommentAuthorfostertom
    • CommentTimeNov 13th 2020
     
    Posted By: Dominic Cooneyand it is eligible for "Custom Builds" ...

    Good job as I have just paid for the Heat Pump for the Barn Conversion
    Surely you can't get grant on a retrospective scheme (i.e. if you've already done it, or paid for (part of) it)?
  14.  
    Posted By: djhHas it always been like that, or has it changed, I wonder?


    I had a quick look on the Ofgem website but it's not clear if it has changed over time. I just searched for "RHI Barn Conversion" and that was one of the search results. I must admit there was a few moments of anxiety...!
  15.  
    Posted By: fostertomgrant


    It's not an upfront grant its a regular payment over 7 years.
    An upfront grant used to be an option, I know someone that had that about 3 or 4 years ago.
  16.  
    Eligibility for the RHI (and so making sure that we use MCS certified installers) was the deciding factor in using GSHP technology for this Barn Conversion. There is no gas here. Oil or or biomass are the only other options.
    The cost is not insubstantial. It will end up being about 20% of our budget but we also thought it was the right choice, we shouldn't really be burning stuff.

    I would love to switch the farmhouse from oil over to GSHP but it needs a bigger heat pump and more trenches, and bigger radiators, so would cost even more. Arguably that money may be better spent on retrofit IWI.
    • CommentAuthorSimonD
    • CommentTimeNov 13th 2020 edited
     
    Posted By: WillInAberdeenSimon, I've been waiting 25years for hydrogen to be available at sufficient scale as a domestic fuel for tens of millions of houses and cars, it's always 'just about' to happen!

    I remain optimistic that it might still happen in my lifetime, though maybe not in a timeframe commensurate with the climate emergency... The amount of hot air around it suggests that somebody maybe using it as a smokescreen, possibly those continuing to market 'hydrogen ready' gas boilers, that will never see hydrogen grid fuel in their useful lifetime...

    In the future, if there is ever sufficient renewable electricity left over after charging all the electric cars, some of it might be used to make hydrogen, but again the conversion is wasteful. So if you have a kWh of renewable electricity, you could turn it into hydrogen, burn it, and get less than a kWh of heat in your house. Or you could put the kWh of renewable electricity into a ASHP or GSHP and get four kWh of heat in your house.


    I'd agree that there probably is a lot of smokescreen and it's difficult to seperate the wheat from the chaff. However there do seem to be many more seriously rumblings and the industry insiders I've spoken to seem pretty optimistic given recent technological advances.

    My take on the conversion of renewable energy into hydrogen is slightly different. I think that, regardless of the losses in conversion, it may have its use in storage of excess harvesting. If anything has hampered, and still hampers the growth of renewables it's energy storage. And we all know batteries are not good for long-term storage. Hydro would be a better and more efficient means of storage than hydrogern, but we're limited in the reservoirs available to benefit from this, hence there must be a potential benefit here with hydrogen. This of course may not help my gas boiler!

    Posted By: WillInAberdeen
    I could be wrong but I don't think RHI is available for newbuilds. ASHPs, and particularly GSHPs, are indeed very expensive. If you can meet your TER target with a fossil gas boiler and the gas connection isn't too expensive then it could be cheaper to fit one before they are banned, and plan to convert to a heat pump when it wears out. We all have to make cost-vs-greenness tradeoffs in our builds.


    It is indeed that cost-vs-greenness tradeoff I'm struggling with right now. I've made some before that everyone told me I was crazy to do because of upfront costs and then worked out amazingly well in the long run - a simple example was converting a previous car to run on lpg. I also decided recently to buy an electric moped which I use around our city and which has been an incredibly positive purchase so far and I've since found we hardly use the van or family car now - even the boys prefer coming on the back as we never get stuck in traffic. The moped app tells me I've already saved about 590kg on co2 emissions since buying it in August.

    The problem I have is that everytime I sit down and plug the figures on ASHP or gas boiler, my gut still concludes for me to go for gas in this instance, hydrogen potential aside ;-)


    Posted By: Mike1
    Posted By: SimonDBoth ASHP and GSHP I've eliminated taking into consideration COP
    Why, when that's how they work? Would you multiply the cost of running a fridge by 5 (roughly the COP of a fridge - it's a heat pump in reverse) to work out your future energy bills, or just believe that it will use roughly what it says on the label?

    Of course a heat pump's COP will vary according to the season and the temperature you run it at, and other factors, but so will a fridge.



    Yes, COP will vary, but there must be figures taking annual average COP in the field? Given the uptake of these systems surely there must be lots of current real world studies? I have some older studies from about 2010 showing an averaged COP of about 2.8 over the year. If this is indeed the kind of COP I can expect, then it really doesn't make any sense financially given that at present my electricity costs just over 20p/Kwh (full green electricity supply) versus 4.68p/Kwh for gas (apparently green gas whatever that might mean :-)). I have to take the COP into consideration for this calculation. Looking at some of the basic estimates for RHI, it's questionable it would make sense then either.

    Posted By: Mike1
    Posted By: SimonDhow much 'dirty' grid electricity is consumed in the operation and maintenance of windfarms
    Wind farms use grid energy which, as mentioned above, is becoming dramatically less carbon intensive wind and solar displace fossil fuels. They clearly use much less electricity than they produce, or the carbon intensity of the grid wouldn't be falling so fast.


    Perhaps, but being the nerd that I am I'd like to know what these figures are :bigsmile:

    Posted By: fostertomThe new Drax Humber plant producing hydrogen by hydrolysis from air instead of chemically from fossil, AFAIK is still just a large-scale pilot or research project which initially will supply 25% of the hydrogen that the chemical works itself consumes i.e. none of it, for a long time, intended to contribute to supply outside the site.


    I think it is a proof of concept experiement but there is also the study at Keele where they're using 20% hydrogen within the gas supply. Don't know of the outcome of this though.

    Posted By: Dominic Cooney
    Posted By: WillInAberdeenI could be wrong but I don't think RHI is available for newbuilds.


    I just checked this and it is eligible for "Custom Builds" which are defined here:
    https://www.ofgem.gov.uk/key-term-explained/custom-builds

    Good job as I have just paid for the Heat Pump for the Barn Conversion and spent the whole of my week off work last week in a digger installing ground loops!


    Brilliant thanks for this Dominic. I'll have a look at it.


    Posted By: djh
    Posted By: SimonDHe suggested waiting for hydrogen ... I've also seen various gas boilers now available to run on hydrogen.

    Hmm, what others have said. Plus, there are two obstacles, I believe. One is an economical clean source of hydrogen as mentioned. The other obstacle is that existing gas mains are not designed to contain hydrogen, and don't. So before it can be distributed as a mains fuel, all the gas infrastructure needs a major upgrade. If that's true, you'll be waiting a long time.

    Yes, perhaps, but apparently tests have shown it is less problematic than originally thought to pipe the hydrogen through existing distribution channels, again just from my discussions with an industry insider.

    Posted By: djh

    What I would do differently if I had been building with benefit of hindsight is to consider where I would mount both an air-air HP system and an air-water HP system and make some provision for them. As it is, there'll be some disruption if I do ever decide to buy one or the other.


    That's what I'm seriously considering doing as I'm currently completing the the calcs for my heating and hot water systems. I have been looking at some air-to-air pumps but also high temperature air-to-water pumps.


    Posted By: Dominic CooneyEligibility for the RHI (and so making sure that we use MCS certified installers) was the deciding factor in using GSHP technology for this Barn Conversion. There is no gas here. Oil or or biomass are the only other options.
    The cost is not insubstantial. It will end up being about 20% of our budget but we also thought it was the right choice, we shouldn't really be burning stuff.

    I would love to switch the farmhouse from oil over to GSHP but it needs a bigger heat pump and more trenches, and bigger radiators, so would cost even more. Arguably that money may be better spent on retrofit IWI.


    I certainly decided to spend more on insulation and detailing on this projects as it's often easier not to burn it that to make up for the burning. I still wonder whether it's enough and I shouldn't have gone for more, but I'll have to leave that for the next project :bigsmile:
    • CommentAuthorrevor
    • CommentTimeNov 13th 2020
     
    I had a bit of ulterior motive in posting the post in the first place as I went with bottled LPG based on the cost of the newer modes of heating even including any RHI. On a cost basis I believe the decision was sound but somehow felt somewhat guilty from not being totally green despite all the other green stuff we have done. I have done a calculation based on using the 8 bottles of 46 kg /84 l over a 13 month period from August 2019 to now and calculated the CO2 produced as being between 4.6 tonnes and 5 tonnes depending on who's information is used. I reckon 25% of this was used in Aug /Sept 2019 conditioning the floors before tiling. I have no idea how good this is against renewables particularly HP. We chose to stuff the place with insulation and build in solar gain along with the fabric first approach. The other heat input which we use in winter is a 5 kw wood stove using wood from windblown trees in our grounds. As an aside we spent as much on wild bird food as we did on buying LPG. I wonder what the carbon footprint of producing this is?. Has anyone got a link to a decent C footprint calculator ones I have looked at don't seem very good either oversimplified or overly complicated.
    • CommentAuthorrevor
    • CommentTimeNov 13th 2020
     
    edit my last post have entered my kwh figure not carbon figure this should read 1.0 to 1.1 tonnes.
    • CommentAuthorEd Davies
    • CommentTimeNov 13th 2020 edited
     
    Posted By: SimonDMy take on the conversion of renewable energy into hydrogen is slightly different. I think that, regardless of the losses in conversion, it may have its use in storage of excess harvesting. If anything has hampered, and still hampers the growth of renewables it's energy storage. And we all know batteries are not good for long-term storage.
    Yep, agree with all that.

    Also, there may well be niche uses for hydrogen like heavy transport (trucks, ships, trains (airships????)).

    But, I don't see the point for personal applications for fuel-cell cars or domestic use (space heating, DHW, cooking). For those uses electricity is just as good, or if a heat pump is used then better, apart from the very marginal advantage of hydrogen for fast refuelling.

    If we're producing substantially all of our energy (not just electricity) from renewables with a certain amount of storage as hydro, hydrogen, whatever, then most of the time anything electrically powered will be getting its energy directly with just grid losses (quite small) to worry about. Only in lulls in the renewable generation will some portion of the electricity have come via the relatively inefficient electrolysis then burning-or-fuel-cell route. Even then it's unlikely to be all of the electricity that's come that way.

    On the other hand, anything directly hydrogen powered takes the efficiency hit all the time. There needs to be a compelling reason to do that. The only one I can think of is energy density which implies the use of liquefied or otherwise compressed hydrogen which has its own energy inefficiencies.
  21.  
    wot Ed said +1

    If people heat their house with a heat pump and use less than a quarter of the electricity that would have been needed to make the equivalent heat from hydrogen, then that's quarter of the demand on the grid during shortage periods. Even better, if people run their heat pump during plentiful generation periods, and store the heat in their hot water tanks, they are actively helping the grid. Market forces would suggest that should end up cheaper for them.

    But if it takes till the 2040s until grid hydrogen is available (which I'll be happy to believe when I see it!) then any gas boiler installed today will have been retired long before any hydrogen arrives at its burners, so this debate is all a bit of a diversion, probably as the gas boiler manufacturers have intended. Just buy the best heating you can afford and be happy with it!

    Revor, LPG has similar CO2 to mains gas, so a heat pump would have saved about 40-80% of your CO2, as per the numbers at the top of the thread.

    The old house we bought has oil heating, so more CO2 than gas or electric. At some point we will replace it with a heat pump, so reducing our CO2 by more than 80% in one go. We could spend a vast amount on insulation and still wouldn't get an improvement like that. So despite the upfront cost, actually a heat pump is probably the most cost effective way for many people to reduce major CO2, certainly more cost effective than EWI or floor insulation or replacement windows or PV panels. (Better still, do all of these as well!).
    • CommentAuthorphiledge
    • CommentTimeNov 13th 2020
     
    Posted By: WillInAberdeen

    If people heat their house with a heat pump and use less than a quarter of the electricity that would have been needed to make the equivalent heat from hydrogen, then that's quarter of the demand on the grid during shortage periods. Even better, if people run their heat pump during plentiful generation periods, and store the heat in their hot water tanks, they are actively helping the grid.


    Thats true for a limited heat pump install base but if the majority of households move to heat pumps and EVs, will there ever be plentiful generation periods? Idont know the figures but I suspect not without colossal additional infrastructure. It may be better that for the time being we prioritise insulation/draughtproofing over heat pump install
    • CommentAuthorEd Davies
    • CommentTimeNov 13th 2020
     
    • CommentAuthorSimonD
    • CommentTimeNov 13th 2020
     
    To provide an addition to the RHI/grant side of this discussion, I've just dug out information on the recently launched Green Homes Grant which does provide upfront grants for Air source heats pumps amongst other things. It's then possible to apply for RHI too. The guidance does, however, state that the Green Home Grant award is taken into consideration in the RHI calculation so I presume that it gets reduced in proportion to the grant.

    The website also confirmed that RHI is available for self-build.

    For me, this could be a game changer so I'm going to go off and get some quotations for an air-source heat pump!
    • CommentAuthorEd Davies
    • CommentTimeNov 13th 2020
     
    Posted By: philedge: “Idont know the figures but I suspect not without colossal additional infrastructure.”

    My back-of-the-envelope calculations say large but far from impossibly so:

    https://edavies.me.uk/2017/05/pv-enough/
    https://edavies.me.uk/2018/01/primary-final/
    • CommentAuthorEd Davies
    • CommentTimeNov 13th 2020
     
    All these grants and initiatives need to be balanced against the cost of just buying a heat pump and having a plumber and an electrician install it without the MCS stuff. It certainly works for those who can do a self install so it can't be far off if you have to include a couple of days for tradesmen. For a new build the extra costs must be very marginal, I'd think.
    • CommentAuthorphiledge
    • CommentTimeNov 13th 2020
     
    Posted By: Ed DaviesSome potentially relevant numbers:https://www.carboncommentary.com/blog/2020/11/13/bp-and-synthetic-fuels-at-the-lingen-refinery" rel="nofollow" >https://www.carboncommentary.com/blog/2020/11/13/bp-and-synthetic-fuels-at-the-lingen-refinery


    I think these figures are whats needed just to operate refineries, not what the UK needs.

    On a separate page its stated that current electric supply isnt remotely adequate to meet our needs. To what extent the shortfall is or what needs to be done to meet future electric demand I dont know but I guess its fairly scary in terms of cost, land loss, construction emissions etc.
    • CommentAuthorEd Davies
    • CommentTimeNov 13th 2020
     
    Posted By: philedgeI think these figures are whats needed just to operate refineries, not what the UK needs.
    Of course, but maybe there's some useful info in there relevant to the trade-offs of using hydrogen.
    •  
      CommentAuthordjh
    • CommentTimeNov 13th 2020
     
    Posted By: Ed Daviesthere may well be niche uses for hydrogen like heavy transport (trucks, ships, trains (airships????)).

    Agreed it's a possibility, but I keep seeing a lot of stories about things like the Tesla semi, and electric ferries in Scandanavia etc so I don't think it's a foregone conclusion. It'll all depend on the technology, cost and efficiency for producing zero-carbon hydrogen. Or methane for example - that makes a lot more sense for distribution through the mains.
    •  
      CommentAuthordjh
    • CommentTimeNov 13th 2020
     
    Posted By: SimonDapparently tests have shown it is less problematic than originally thought to pipe the hydrogen through existing distribution channels, again just from my discussions with an industry insider.

    Difficult to confirm or deny any such claim.

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