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Green Building Bible, Fourth Edition
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    • CommentAuthorbhommels
    • CommentTimeFeb 5th 2021
     

    Seems they are looking at hydrogen production and carbon capture in the north west with the infrastructure to go with it

    Carbon Capture :cry:
    • CommentAuthorEd Davies
    • CommentTimeFeb 5th 2021 edited
     
    Posted By: fostertomUsual confusion over MW vs MWh, comparing solar output with battery storage in same sentence.
    It looks like in this case there isn't confusion; they're talking about the power output capabilities of the two. They don't seem to mention the actual storage capacities much.

    But, yes, the ongoing confusion makes it hard to be really sure.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 6th 2021
     
    Aha - 1200MWh didn't seem like much to me.
  1.  
    = 100,000 home batteries

    = one midsized hydro dam

    = one-thirtieth of UK's electricity consumption yesterday
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 6th 2021 edited
     
    Posted By: fostertom1200MWh
    Posted By: WillInAberdeen= 100,000 home batteries
    = 12kWh per home battery
    = one fan heater for 4hrs
    = still doesn't seem like much to me.
    •  
      CommentAuthordjh
    • CommentTimeFeb 6th 2021
     
    Posted By: fostertom= 12kWh per home battery

    That's a largish battery (Tesla or whatever). I believe there's a rule of thumb that battery in kWh = panels in kWp gives the best bang-for-the-buck. So I might consider a 4 kWh if I did.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 6th 2021
     
    Is that really enough to be significantly useful?
    •  
      CommentAuthordjh
    • CommentTimeFeb 6th 2021
     
    Posted By: fostertomIs that really enough to be significantly useful?

    Well, in summer that's a complete day's grid power usage in our all-electric house. (3 kWh during the day and 1 kWh at E7 night). But the main thing is it's plenty to cover our peak 1630-1930 usage. Which doesn't change much in winter. So I think it would be significant.
    •  
      CommentAuthorfostertom
    • CommentTimeFeb 7th 2021
     
    Sorry Dave I still don't get it. In summer, yes, it would carry you through one whole day that's so dull that there's no solar generation - or more like two poor summer days, as there's always some generation even from heavy overcast. But I'd have thought we'd be looking for more than two days of such endurance, before I guess just one fine day which would fully recharge the battery?

    Covering (with a bit to spare) the 1630-1930 peak, for which there is never(?) concurrent generation - OK - but really a summer-only benefit, enabling zero take from the grid for extended periods (in between heavy overcast periods as above). But surely makes little difference in winter, when generation is just plain inadequate?

    I'm sure anyone will do the sums and decide whether it stacks up, but I'm sceptical!
    •  
      CommentAuthordjh
    • CommentTimeFeb 7th 2021
     
    It depends what you're trying to do, Tom. The evening peak is what drives the need for generation capacity, I think, so every bit scraped off that peak is useful. The infamous kettle at half-time peak and so forth.
    • CommentAuthorphiledge
    • CommentTimeFeb 7th 2021
     
    Our 4kwp system has been producing 3-4kwh/day for the last fairly dull week so a slightly larger system could cover Daves needs, or 4kwp system with a bit of E7 top up
    • CommentAuthorSimonD
    • CommentTimeFeb 7th 2021
     
    To scew back to hydrogen/heatpumps/electic heating someone is clearly tracking my reading of this thread. Youtube threw up the below recent video link for me last night. I know it'll make some people's blood curdle, but nevertheless informative for some. The last part of the video contains quite a bit of waffle. Now I've opened that one up for comments that it's all waffle! ;-)

    I think what drew more of my attention was not the science and academic position behind near term future energy policy and hydrogen v heatpumps but the practicalities of making it happen. Very interesting comments about the most difficult and costly houses to retrofit with heat pumps, for example, are those built in the last 25 year due to contemporary developer build methods.

    There were also some interesting figures quoted in terms of relative costs given; that the gas network currently has a public value of around £40bn; that upgrading the grid to supply electricity for heating/cooking/transport etc. is estimated to be in the region of £400bn whereas upgrading the gas network to supply hydrogen using blue technology is estimated to be about £150bn.

    https://youtu.be/4uNKPDREa-Q
  2.  
    For maximum green-ness, someone should export PV during the day when grid carbon intensity is usually worse. Then import electricity at 2am when carbon intensity is lowest, charge up their battery. Then use the battery for their own consumption the following day (or at least for the following evening peak).

    The time of use tariffs we discussed recently should make this the most economic strategy too.

    Someone could even do this without needing to install PV, they could import at 2am to greenly charge the battery, then export the following day whatever charge they don't use themselves.

    Though I dunno if these schemes would pay for installing a battery now or if it's better to wait for V2G.

    Edit: I also don't know enough about the efficiency and energy losses of home batteries, they waste some of the 'green' electricity into heat along the way which would need to be reckoned into a decision.
  3.  
    Simon, isn't that the same video that was quoted way back in the very first post of this thread? By the marketing director of a well-known manufacturer of gas boilers, who are quite keen to sell some more gas boilers.

    To be fair, that company are also selling heat pumps, so they are backing both horses, which seems a prudent approach for us all.
    • CommentAuthorphiledge
    • CommentTimeFeb 7th 2021
     
    Posted By: WillInAberdeen

    Someone could even do this without needing to install PV, they could import at 2am to greenly charge the battery, then export the following day whatever charge they don't use themselves.


    I assume someone has crunched the figures, but if theres a big uptake in EVs, heat pumps and battery storage will there actually be surplus green energy to power this night time load?
  4.  
    AIUI, by far the most of the renewable generation in UK is wind, hydro, and biomass and nuclear if you include them. They work fine all night when there's less demand anyway. Solar is much less in UK, though big in Australia.

    The problem is the evening peak time when demand is much greater. If there is enough generation to get through the evening peak, then there will be plenty for the early hours. They really need to shift some demand out of the evening peak and into the early hours.
    • CommentAuthorLF
    • CommentTimeFeb 7th 2021 edited
     
    Not read this fully yet but linked report seems well balanced.

    Hydrogen and decarbonisation of gas: false dawn or silver bullet? March 2020 Martin Lambert Senior Research Fellow, OIES Recommend start at Page 21 is discussions and conclusion. Page 11 deals with domestic uses.

    https://www.oxfordenergy.org/wpcms/wp-content/uploads/2020/03/Insight-66-Hydrogen-and-Decarbonisation-of-Gas.pdf

    Pragmatist in me feels even post 2050 a smaller mostly decarbonised gas grid with up to 20% hydrogen, some biomethane and other low carbon developments will help serve peak energy use and may we will need natural gas on cold windless winter days to help it out. Energy price will be a lot lot higher than current gas prices!

    Not had massive amount to do with industrial pure hydrogen but it is a pig to work with, extremely leaky and burns with invisible flame that's really hard to spot. It is so much easier to ignite than natural gas too.
    So more dangerous to handle but then who would like to write a risk assessment for a petrol tank on a car ?
    • CommentAuthorRobL
    • CommentTimeFeb 7th 2021
     
    We've had V2G on our 30kWh leaf for 7 months now. The company (OVO/Kaluza) charge & discharge whenever they like, so long as we remembered to leave the cable plugged in. In that 7 months it's charged up by 2701kWh generally at night, and discharged 1964kWh into the grid. You can't tell efficiency from those figures, as the car has been driven a bit here and there - although I think it's about 80% round trip. It wastes a lot of power being ready-to-go all the time - fan on (low), contactors etc. If I was organised I would have made an odometer reading at the start :-( That's an average of 9.3kWh discharged into the grid at peak times 5-10pm generally.
    We have PV too - I haven't noticed them using it to charge the car. I think the charger is generally charge/neutral/discharge - it does it sometimes over short periods (minutes), sometimes power slops back and forth repeatedly quite quickly, but I don't think it throttles back, generally charge 3kW or 5kW / off / discharge at 3kW.
    With this V2G there's no incentive to use all available PV, as we get paid a flat rate for all exports. I think it's early days though and that will change - more sensible is a time of day tariff in & out. Ovo haven't got around to such sophistication, so it's just one tariff in (16p), one out - the out is high (26p), as they have control over it, and it's their trial.
      V2G.PNG
    • CommentAuthorSimonD
    • CommentTimeFeb 7th 2021
     
    Posted By: WillInAberdeenSimon, isn't that the same video that was quoted way back in the very first post of this thread? By the marketing director of a well-known manufacturer of gas boilers, who are quite keen to sell some more gas boilers.

    To be fair, that company are also selling heat pumps, so they are backing both horses, which seems a prudent approach for us all.


    Thanks for the heads up! Duh, it may very well be. I hadn't actually watched the video at the start of the thread! (Much of my info on the future of hydrogen and renewables comes from elsewhere, from people working within the field and research). Maybe I should watch these things next time :shamed: :bigsmile:
  5.  
    Posted By: RobLWe've had V2G on our 30kWh leaf for 7 months now. The company (OVO/Kaluza) charge & discharge whenever they like, so long as we remembered to leave the cable plugged in.

    My understanding of batteries is that their life is governed (amongst other things) by the number of charge / discharge cycles. Will V2G shorten the expected battery life
    • CommentAuthorEd Davies
    • CommentTimeFeb 7th 2021
     
    Posted By: Peter_in_Hungary: “My understanding of batteries is that their life is governed (amongst other things) by the number of charge / discharge cycles. Will V2G shorten the expected battery life”

    That's my understanding, too, but there's some research which shows use like this actually increases the life slightly. I'm very confused as to why. A quick search found this. I've only read the abstract but:

    https://www.sciencedirect.com/science/article/pii/S0360544217306825?via%3Dihub#!
    •  
      CommentAuthordjh
    • CommentTimeFeb 7th 2021
     
    Posted By: philedgeOur 4kwp system has been producing 3-4kwh/day for the last fairly dull week

    It's been doing a lot better than ours then :bigsmile: A couple of days of zero and an odd day of 5 kWh+
    • CommentAuthorRobL
    • CommentTimeFeb 7th 2021
     
    Will V2G shorten the expected battery life?

    Well, it might. I think it depends what it's compared to - V2G is sophisticated and ours charges 25%-80%. In contrast if you charge with a granny cable it goes to 100% - and that's definitely worse. The leaf battery guarantee allows V2G, but doesn't allow leaving the granny cable in continuously.
  6.  
    Battery life: Is that one of the things that the V2G trials are hoping to find out? The vehicle leasing company presumably takes the hit if the battery life is shortened, so they need to settle up with the V2G operator, if they're not the same company?

    RobL thanks very much for posting the data!
    As you have both a solar inverter and a V2G export, did you have to get a G99 for more than 3.6kW total installed capacity?

    Do you know why only 9.3kWh of the 30kWh battery was discharged on average - was it because the V2G (dis)charger power was limited to 3kW?

    Interested that the charging/discharging happened in shorter bursts than the half-hour slots which could be recorded by the smart meter.

    LF: thanks, that's an informative paper
    Posted by LF:https://www.oxfordenergy.org/wpcms/wp-content/uploads/2020/03/Insight-66-Hydrogen-and-Decarbonisation-of-Gas.pdf

    "Beyond industrial applications, the next most promising is the use of hydrogen in transport for those, typically heavy duty, long distance, situations..
    it may prove more appropriate for
    most existing gas networks to continue to carry methane, albeit either biomethane or other non-fossil
    synthetic methane, and probably at lower volumes than is currently the case...
    While there is not yet any clear pathway for decarbonisation of residential space heating in countries
    with high winter heating demand, it is likely to prove particularly challenging to convert a large number
    of small domestic consumers to hydrogen...
    ‘green’ hydrogen will necessarily be significantly
    more expensive than electricity (€30/MWh electricity leading to a hydrogen cost in the range of €50-€60/MWh)"
    • CommentAuthorRobL
    • CommentTimeFeb 8th 2021
     
    V2G answers:
    - we own the car, it's a 2nd hand 2016 one. No "missing bars" indicating battery degradation yet - and as I say, if there was loads (<66% life within 8years or 100k miles) Nissan would swap it out - and I'm sure they don't want to do that! We're being rewarded for the risk of battery degradation, by being paid to export - there's nobody else involved. I think the jury is out as to whether V2G knackers the battery - eg here's a paper from Warwick(Uni) that says it actually extends life :shocked:
    https://www.sciencedirect.com/science/article/pii/S0360544217306825?via%3Dihub#!

    The trial could detect the battery state of health - so they could datamine for battery loss due to V2G, if they have enough users, and they have different use profiles. Some users will hardly plug it in maybe, or perhaps they can get data from somewhere else to compare - I'm sure when it's serviced Nissan take odometer & battery SOC readings. Not that ours went for a service... didn't want the journey in lockdown, so just took it for a local MOT (batt guarantee doesn't require the service, which is not electrical).

    We do have a G99 now - I don't know what the max export is though. The company organised it. The charger has a current sensor on the main house live, so it can see if it should throttle back.

    I think it only discharges 9.3kWh/day on average for many reasons: its not always plugged in at the relevant time. The battery is probably 26kWh now being almost 5 years old (I understand when we loose a "bar" on the dash SOC it means 85% SOC so ~25kWh). It only uses 55% of the battery anyway (25% to 80% SOC). The 9.3kWh is AC out - there's a conversion loss and a "standing" loss from the contactors etc being "ready to go". We use some of the battery actually driving the car - not much in lockdown land though, so all their data is a bit unusual I expect. :cry:
    • CommentAuthorjms452
    • CommentTime4 days ago
     
    Posted By: RobLWill V2G shorten the expected battery life?

    Well, it might. I think it depends what it's compared to - V2G is sophisticated and ours charges 25%-80%. In contrast if you charge with a granny cable it goes to 100% - and that's definitely worse. The leaf battery guarantee allows V2G, but doesn't allow leaving the granny cable in continuously.


    For modern EV batteries leaving fully charged and deep discharging are pretty bad for battery life.

    everything else is 'it depends' :bigsmile:
  7.  
    Hi everyone,

    i am a final year Building Surveying student at UWE and am currently carrying out some research regarding Energy Performance Certificates for my dissertation. I'm looking for home owners who are interested in energy efficiency within their homes to take part in a quick survey. I would greatly appreciate anyone who can spare a few minutes to take part!

    You can find the link for the survey on the consent form here:

    https://www.dropbox.com/s/ogiiny8pymsgqkr/Dissertation%20Consent%20Form%20-%20LR.pdf?dl=0

    The following links are a privacy notice for anyone concerned about the safety of their data, as well as a participation information sheet providing more information about the research.

    Privacy notice - https://www.dropbox.com/s/7pg7ok26f7896gn/Dissertation%20Privacy%20notice%20for%20research%20participants%20-%20LR.pdf?dl=0

    Participant info sheet - https://www.dropbox.com/s/xcp6hm442cl2iz2/Dissertation%20participant%20information%20sheet%20-%20LR.pdf?dl=0

    Thank you!
    •  
      CommentAuthordjh
    • CommentTime51 minutes ago
     
    Posted By: lloydroutleyYou can find the link for the survey on the consent form here:

    Unfortunately not a working link. Just a picture of a link. :cry:
  8.  
    <blockquote><cite>Posted By: djh</cite><blockquote><cite>Posted By: lloydroutley</cite>You can find the link for the survey on the consent form here:</blockquote>
    Unfortunately not a working link. Just a picture of a link.<img src="/newforum/extensions/Vanillacons/smilies/standard/cry.gif" alt=":cry:" title=":cry:"></img></blockquote>

    https://uwe.eu.qualtrics.com/jfe/form/SV_73eV3Q5sJ6gu6CG

    Hopefully this link works for you!:bigsmile:
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