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Renewable Energy: Death of heat pumps

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  1.  
    • CommentAuthorDantenz
    • CommentTimeSep 27th 2011
     
    A couple of years ago or more when I joined this forum heat pump related topics seemed to crop up all over the place to the point where discussion was blocked from the forum because they weren't considered to be green. Why have all the heat pump discussions dried up, does every one suddenly understand the technology or has the novelty of this technology worn off due to bad publicity, experiences etc. Like it or not heat pumps definately have their place in the heating industry for both retro fit and new build although legislation of course will be the main driver for their implementation. Let us not forget the RHI & green deal come in next year and perhaps only nearer the time will heat pumps deservedly get their due consideration. I welcome any other thoughts & opinions on where, why or if heat pumps will feature in the future?
  2.  
    Interesting question!
    Off the top of my head I would say that PV has stolen the lime light somewhat. People are investing in a PV installation because of the grants and feed in tarrifs available, putting heat pumps in the shade as an eco energy investement.

    make sense??
  3.  
    Fads seem to come and go . GSHP , ASHP being fitted more than every perhaps ?
    I think the PV fits cash cow has eclipsed most of the other 'green tech' and is the current vogue to do thing and a popular discussion point. It's the, change your life very little , solve all ills at once and make some money in the process, 'Green' solution ( or may be percieved to be by some)

    Perhaps also people have relised GSHP for one doesn't make sense in areas where mains gas is available.
    GSHP are a viable alternative to oil and biomass in rural locations , but not on a low budget.

    ASHP , well the're ok, but have many negatives, like most other heat producing options.
    Perhaps also there were so many threads anyone looking for info can search and find it, so no need for new questions

    i think thier day will come if this RHI get underway for domestic installs, but I doubt it will

    It would be good if the fabric first approach to energy efficiency was always put first in line when it come to funding incentives.
    • CommentAuthorMegacycles
    • CommentTimeSep 27th 2011
     
    I thought the death of the heat pump would occur 1-2 winters after the introduction of the RHI.

    The number of PV installers has exploded over the last 12months and there's some poor installations now appearing as the 'gold rush' sets in.

    If the RHI supporting heat pumps ever appears, I'm sure the same scenario will occur, there's plenty of scope for expensive mistakes. I understand fossil fuel backups aren't permitted, so I anticipate many vocal unhappy and cold heat pump users appearing on 'watchdog' type programs.
    • CommentAuthorRobinB
    • CommentTimeSep 28th 2011
     
    We have an ASHP and one year on are very happy with it. I think it will be an excellent partner to PV. Perhaps when the people with PV come to renew their boiler they may then consider it a good option, particularly if it is replacing oil or they don't like the idea of "fracked gas" and particularly if the RHI ever comes in. I do't think they are dead or dying.
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 28th 2011
     
    I really want to stop being obliged to burn 100% fossil fuel for heat, and want to put in an ASHP with solar DHW support, so that a diminishing part of our heat demand comes with a CO2 cost.

    But given the poor behaviour of both major parties and the government on the FiTs and especially early adopters, and the lack of progress even on GPDOs for ASHP, I'm hanging back. I'm sure that I'm not alone.

    So I think it's more a case of a short-term focus on PV in the run up to April, and wanting to see the white's of RHI's eyes to avoid being stung again.

    Rgds

    Damon
    •  
      CommentAuthorted
    • CommentTimeSep 28th 2011
     
    Damon, in case you missed it - GPDOs for ASHPs and small wind turbines is coming in (for England and with conditions) from 1st December.

    The Town and Country Planning (General Permitted Development) (Amendment) (England) Order 2011
    http://www.legislation.gov.uk/uksi/2011/2056/made
    • CommentAuthorqeipl
    • CommentTimeSep 28th 2011
     
    GSHPs are expensive to install and only make sense in a limited number of cases.
    ASHPs, as a direct replacement for oil/gas CH, are expensive to run in cold weather.
    Maybe people have read enough and decided to avoid heat pumps in favour of solar, which is a shame because ASHPs can work well in certain circumstances.

    I have an ASHP/DHW cylinder that I also use for UFH and whole house ventilation/heat recovery. It works because my heat demand is low, except for in the depths of winter when I use a solid fuel boiler as an evening-to-morning boost.

    There are several new houses on the island going down the same route as myself because it's a simple, inexpensive installation, and cheap to run, as long as the house is designed to take advantage of solar gain.
  9.  
    I have fitted a GSHP in a rural location away from mains gas. Oil and bulk LPG did not appeal at all long term. I am close to finishing the system and including my 3 bores @ 76mtrs each it will be around the £20,000 mark. I do not feel that is much higher than a good oil system. It is more granted but not drastically more and oil is bound to go up in price long term. I have insulated well and fitted windows with a decent U value. Also good U value external composite doors have been fitted. If the RHI does come in then great but I would have fitted it anyway. I was sick of being held to ransom by the oil companies. Especially in cold weather when demand for oil went up. 70p ltr is not funny.
    I am looking forward to seeing how the system performs,
    Gusty.:bigsmile:
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 28th 2011 edited
     
    ted: thanks, I had missed that!

    Do you think that the prohibition against a turbine affects my non-permanent 'lawn-art' scale off-grid MotorWind (50Wp) job? Or could I just take it down while the ASHP is being installed and put it back up afterwards? B^>

    Rgds

    Damon
    • CommentAuthorDantenz
    • CommentTimeSep 28th 2011
     
    Posted By: bot de pailleInteresting question!
    Off the top of my head I would say that PV has stolen the lime light somewhat. People are investing in a PV installation because of the grants and feed in tarrifs available, putting heat pumps in the shade as an eco energy investement. make sense??

    Certainly, PV has stolen the lime light but for the wrong reasons. Very few have PV installed because of the amount of energy they save/produce but moreover because of the guaranteed revenue stream they get back from it. Also, PV still does't come any where near addressing the largest energy consumption in the home which is for space heating. Perhaps the mindset of some may be that the tariff they receive will help offset or future proof against further fossil fuel price increases so no need to look at replacing boilers with heat pumps?
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 28th 2011
     
    <blockquote><cite>Posted By: Dantenz</cite>Certainly, PV has stolen the lime light but for the wrong reasons. Very few have PV installed because of the amount of energy they save/produce but moreover because of the guaranteed revenue stream they get back from it. Also, PV still does't come any where near addressing the largest energy consumption in the home which is for space heating. Perhaps the mindset of some may be that the tariff they receive will help offset or future proof against further fossil fuel price increases so no need to look at replacing boilers with heat pumps?</blockquote>

    Very true indeed. I'm amazed that we don't pay sufficient heed to the importance of heating, particularly using solar thermal to charge heat stores for space heating, in whatever form.

    The amount of solar thermal energy that impinges on the average house in the UK is in a year significantly exceeds the space heating demand (assuming they are reasonably well insulated). For example, if we assume that the average house has a modest area exposed to the sun of around 30m², and that the average insolation throughout the year is a fairly low value of just 100 W/m² (during daylight hours) then there is potentially around 13,140 kWh of heat impinging on each house through the year. If we could capture this, efficiently store it and use it when required, it would more than meet the space heating and DHW needs of the average home.

    Some are already working towards this, in particular I'm fascinated by the work that Viking House are doing, it shows that building efficient homes with seasonal thermal storage is doable now, it doesn't need special technology to make it work.
    • CommentAuthorGavin_A
    • CommentTimeSep 28th 2011
     
    I think the heat pump guys are just getting on focussing mainly on new builds and oil / electric heating replacement, which is where heat pumps really make sense anyway, and ignoring the majority of existing homes on mains gas as it's not economically viable for those who've recently upgraded to a condensing gas boiler, and offers no tangible benefits (other than for those who've got a renewable supply installed possibly).

    TBH, I don't really see why heatpumps even need much subsidy support as they're already being installed in large numbers in the places where they can make a difference, and are a direct boiler replacement in most situations so someone would already be spending pretty much the same amount of money getting the boiler installer, and new builds are increasingly needing to meet stricter energy standards anyway.

    will see what RHI eventually brings on this one.
    •  
      CommentAuthorSteamyTea
    • CommentTimeSep 28th 2011
     
    Posted By: JSHarrisIf we could capture this, efficiently store it and use it when required


    Looked at this almost every which way I can think off and keep coming back to the same problems of low efficiency and high heat losses. It can help in the 'shoulder periods' but is of little use between April and October. This is largely due to cloud cover that seriously scatters the light around (where PV wins over ST). If we had an Alpine climate (where a lot of the studies are conducted) then it is a different story but we have cloudy, even more so down here in the SW than in the East.
    Weather patterns, keeps us from freezing and stops us from boiling.

    If it is just space heating you are after and costs are not so much of an issue then PV with storage heaters/HPs (if you can get the starting load down) may be a solution. 30m² of PV could give me up to 1050 kWh/month in December, 1200 kWh/month in January and 1800 kWh/month in February.
    At that time of year I am using around 25 kWh a day or 750 kWh a month. So very possible to just use resistance heating as I do now.
    As the worst month is January at 1050 kWh I could possibly get away with 20 m², but would have no 'spare'.

    What would 20 m² of PV and associated inverters cost (though could go for charge controllers and some battery storage, about 150 kWh, to feed custom made elements)?
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 29th 2011
     
    I think we just need to think about seasonal heat storage in more innovative ways. Whichever way you look at it, more than enough heat energy impinges on most homes throughout the year. The snag is we get too much solar heat in summer and too little in winter.

    If we could develop something like an affordable chemical phase change heat store, where a substance is converted from one form to another using excess summer heat, then converted back, releasing the stored heat, during the winter, it might make for a good solution. Although I started life as a chemist, I'm a bit rusty now, but I do know that such compounds exist, as you can get them as gels in novelty heat packs.

    I'll also be interested to see how Viking House' project with the large solar thermal collectors and wall-embedded heating works. I suspect there may be enough solar radiation, even in cold weather, to make this sort of system alleviate some of the space heating needs.
    •  
      CommentAuthorted
    • CommentTimeSep 29th 2011 edited
     
    Steamy, I think your rough figures are out by an order of magnitude. 20m2 of PV (Sanyo HIT at 190 W/m2) would only give you around 3000 kWh in a whole year - split monthly like this.

    Jan 72
    Feb 120
    Mar 220
    Apr 334
    May 453
    Jun 459
    Jul 466
    Aug 386
    Sep 262
    Oct 154
    Nov 86
    Dec 57

    Either you got a decimal point in the wrong place or forgot to account for the PV efficiency of max 20% from the total solar insolation figure and then maybe deduct another 20% for system losses.

    To get 1050kWh in January you would need around 300 m2 of PV = 238 Sanyo HIT 240W panels = a 57 kW system.
    •  
      CommentAuthorDamonHD
    • CommentTimeSep 29th 2011
     
    There is barely enough insolation on every square inch/cm of my property in winter, collected with 100% efficiency, to cover peak heating demand, so PV-driven from the subset of space on my roof clearly can't cut it.

    More numerically, I estimate ~0.5kWh/d/m^2 incident energy of my roof space mid-winter, and about 40m^2 of that, so ~20kWh/d if collected at 100% efficiency, but my peak heating demand is nudging 40kWh/d currently. (And of course that will be on days with less insolation by and large.)

    Rgds

    Damon
  18.  
    Why doesn't the EU fund the construction of massive PV factories in each member state? EU citizens would then have access to very cheap PV, could cover every roof surface with low cost electricity generation, feeding into the European super grid.

    Instead we fight foreign wars for oil supplies and build nuclear reactors.
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 29th 2011
     
    <blockquote><cite>Posted By: DamonHD</cite>There is barely enough insolation on every square inch/cm of my property in winter, collected with 100% efficiency, to cover peak heating demand, so PV-driven from the subset of space on my roof clearly can't cut it.

    More numerically, I estimate ~0.5kWh/d/m^2 incident energy of my roof space mid-winter, and about 40m^2 of that, so ~20kWh/d if collected at 100% efficiency, but my peak heating demand is nudging 40kWh/d currently. (And of course that will be on days with less insolation by and large.)

    Rgds

    Damon</blockquote>

    This will be the case for a lot of houses, hence the point I was making about insolation through the year being far more than was required; the problem being it occurs mostly when we don't need it. A means of storing heat in an easily accessible way for long periods would mean that excess heat captured during the warmer months of the year could be used during the colder ones.

    We've already discussed giant thermal stores, using water, soil etc, but these are always going to suffer from constant heat loss to some degree. If we can find a nice chemical reaction, one that is non-toxic and readily bidirectional (endothermic one way, exothermic the other) then it opens up the possibility of long term heat storage and control over when heat is delivered.
    •  
      CommentAuthorSteamyTea
    • CommentTimeSep 29th 2011 edited
     
    Posted By: tedSteamy, I think your rough figures are out by an order of magnitude

    Could be right, doing sums when tired is never a good thing. Shall look when I have some time.

    Edit:
    Yes, looks like I just did the sunlight, so realistically I could get 10% of that to a resistance heater.

    Even ST would not be enough allowing for a minimum temperature of 40C in the store and 50% system efficiency.
  21.  
    Like my father I try to not let facts interfere with a good discussion.
    Anyway my uninformed take on the heat pump situation is based on observation & hearsay.
    (o) Snake oil salespeople got on board early
    Therefore
    (i) Overoptimistic/unrealistic COP,s were quoted
    (ii) systems undersized/oversized/inappropriately sized due to poor knowledge
    (ii) inadequate/skimped/bodged installations
    (iii) not properly understood/therefore not correctly commissioned (if at all)
    All resulting in the "back-up/top-up" electric immersion heaters taking the load.
    Which resulted in unexpected humengeous electric bills.
    Perhaps in part because users were too ready to enjoy the "free heat" & kept the thermostat set higher?
    **********************
    I do, however, know of one apparently successful installation, fitted in a new build by a very competent electrical engineer.
    The calculations were all rigerously done, then the Ground loops were deliberately oversized, the heat pump feeding underfloor heating, with a wood burning stove providing easy & fast control of temperature within the living area.
    I have not spoken to him in about 10 years ( a friend of the brothers)
    Perhaps the other technologies are more transparent in their outputs
    cheers
    Marcus
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 29th 2011
     
    <blockquote><cite>Posted By: orangemannot</cite>Like my father I try to not let facts interfere with a good discussion.
    Anyway my uninformed take on the heat pump situation is based on observation & hearsay.
    (o) Snake oil salespeople got on board early
    Therefore
    (i) Overoptimistic/unrealistic COP,s were quoted
    (ii) systems undersized/oversized/inappropriately sized due to poor knowledge
    (ii) inadequate/skimped/bodged installations
    (iii) not properly understood/therefore not correctly commissioned (if at all)
    All resulting in the "back-up/top-up" electric immersion heaters taking the load.
    Which resulted in unexpected humengeous electric bills.
    Perhaps in part because users were too ready to enjoy the "free heat" & kept the thermostat set higher?
    </blockquote>

    Pretty much seems to sum up the situation. The EST have a report somewhere that shows typical COP for a few installed systems. The general conclusion was that it was lower than predicted pretty much across the board, with ASHP being a bit worse than GSHP, IIRC. There was (maybe still is) a lot of duff information around about heat pump performance and probably a fair few installer who don't appreciate the benefit from over-sizing the input, in terms of better COP. I think there are still some who see heat pumps as being a universal heating method, when in reality there are a lot of property types where other forms of space heating/DHW might be better.
    • CommentAuthoringleside
    • CommentTimeSep 29th 2011
     
    "If we can find a nice chemical reaction, one that is non-toxic and readily bidirectional (endothermic one way, exothermic the other) then it opens up the possibility of long term heat storage and control over when heat is delivered."

    In the nineteenth century, railway carriage heating was done by heating solutions of sodium acetate in metal containers, and putting them in the carriage. As they cooled, the sodium acetate came out of solution. When they were cold, a vigorous shake redissolved the sodium acetate, and more heat was available.

    Just a thought.
    • CommentAuthorgcar90
    • CommentTimeSep 29th 2011
     
    Modified carbon nanotubes can store solar energy indefinitely, then be recharged by exposure to the sun.

    http://nextbigfuture.com/2011/07/modified-carbon-nanotubes-can-store.html
    •  
      CommentAuthorJSHarris
    • CommentTimeSep 30th 2011
     
    As this idea was going a bit off topic in this thread, I've started a new topic on phase change heat storage to bounce around some ideas.

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