On-grid domestic battery storage

12357232

Replies

  • I've just been skimming the thread and saw a few posts about the tidal lagoons and energy storage. I'm not sure about using batteries for storage (their ecological impact and short life-cycle puts me off) but I can see a use for compressed air energy storage.

    As these lagoons are obviously on the coast, large bags can be fixed to the sea bed and filled with compressed air using excess energy from the barrage. When the energy is required, the air is released to drive turbines and generate electricity. This technology is used in Germany, where they use former salt caverns for the compressed air. However, there is an issue with pressure loss as the caverns empty. With bags under the sea, the weight of the sea on top will keep the pressure constant, right up until the bag is completely empty of air.
  • edited 14 February 2017 at 3:05PM
    zeupaterzeupater Forumite
    5.1K Posts
    Tenth Anniversary 1,000 Posts Name Dropper Combo Breaker
    ✭✭✭✭
    edited 14 February 2017 at 3:05PM
    Alan_Brown wrote: »
    I've just been skimming the thread and saw a few posts about the tidal lagoons and energy storage. I'm not sure about using batteries for storage (their ecological impact and short life-cycle puts me off) but I can see a use for compressed air energy storage.

    As these lagoons are obviously on the coast, large bags can be fixed to the sea bed and filled with compressed air using excess energy from the barrage. When the energy is required, the air is released to drive turbines and generate electricity. This technology is used in Germany, where they use former salt caverns for the compressed air. However, there is an issue with pressure loss as the caverns empty. With bags under the sea, the weight of the sea on top will keep the pressure constant, right up until the bag is completely empty of air.
    Hi

    The issue you'd come across is the necessary water depth ... the seas around the UK are mainly very shallow and to get anywhere near the level of compression mentioned for the schemes/technology used above you'd need around ~2000 feet of water, which is only available as the continental shelf starts to slope away to the west of the UK, so normally somewhere between 100-300miles from the coast depending on location .... possibly not the best place to site compressors and turbines or run HV cables to .... ;)

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    For coastal and inland areas I think LAES rather than CAES is probably best, like the Highview scheme in Slough, which can be scaled up to 200MW/1,200MWh plants.

    But, lagoons can provide some balancing/storage for a brief time, as they can be emptied slightly early or late to better match peaks, though this will reduce the maximum amount of energy in that cycle. Basically, they supply leccy for 3.5hrs on each in tide and out tide, so 14hrs per day, and you wait for the optimum time (and head of water differential) to let the water flow from one side to the other, but this can be varied as mentioned.

    I've also wondered if they themselves could be used for pumped storage during the brief window when the lagoon is full and the tide is high. At that point you are pumping in at very low head, say from 5m tide outside, to 5m + 'a bit' inside. But that pumped water energy input of 'a bit of a metre' then 'magically' becomes 5 and a bit metres high when the tide goes out giving a multiplayer on the pumped energy.

    I suspect my idea is relatively stupid as the opportunity window is quite small, and the cost of the extra kit and complexity, not worth it ...... just a thought.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    This article is about EV's but is relevant in that it talks about the cost of battery cells falling faster than expected.

    As always my optimistic thoughts on batts (like PV) seem to be wrong, and I'm more than pleased. :)

    Electric Vehicle Battery Prices Are Falling Faster Than Expected
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    I think this one is important, well it is to me:
    So yesterday was the first really good day in Feb with 7.6kWh of generation - and I managed to get 5.33kWh in and out of the battery as a result :)
    I'm really quite impressed - especially as it's nominally "only" 4kWh of battery capacity - just shows that it'll contribute during the day and if there's enough hours of generation, can still re-charge and catch up again for later on.

    I've provisionally estimated that I need 4kWh of useable storage based on:
    Summer months useage capped by average 2.5kWh import.
    Winter months useage capped by average 1-3kWh of export.
    Spring/Autumn months import less than export and around 4-5kWh.

    The issue here is that 5kWh is more than 4kWh, but I've always assumed that some of that import will be from variable weather and generation in those months, particularly from clouds, and that storage would allow for lots of small battery cycles as demand and supply vary through the day. My friends e-mail seems to confirm this, which helps guide me on the capacity of battery needed.


    Also, thought I'd add this thread on from Navitron, for anyone interested. It's far more complicated and I'd suggest reading nowty's autosig first to get an idea of what he's been up to, and where his experiments are taking him.

    Growatt SP2000 Storage System
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    I found this interesting background reading, but otherwise not too important, except for this bit:
    The analysis assumes an average selling price of battery storage starting at $US250/KWh, deflating 5 per cent per year to $US150/KWh by 2027.

    -5% pa is very promising, and hopefully understated.

    Tesla & LG Chem Set To Dominate Massive US Battery Storage Market
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Staggering savings from the first Powerwall in Australia after 1yr. This is the smaller 7kWh model, not the new 13.5kWh model.

    He also has a system that can sell battery leccy to the grid (at a premium) when demand is very high.

    Rather jealous!

    Living with the Tesla Powerwall for a year: the first Australian case study
    Powering the home with electricity in 2015 cost him $2289. But just over a year ago, he invested in a solar power system that has since significantly cut costs.

    Nick, a self-confessed Tesla fanboy, was the first person in Australia to buy the company's Powerwall. He bought a 7kW battery, a 5kWp solar array, a SolarEdge inverter and a Reposit monitoring system for $16,790 in January 2015.

    A year on and Nick's annual electricity bill has dropped to $178.71 – that's a 92% saving of $2110.
    "The aim is to try and export about three times of what I import because my electricity cost is about three times [as much]."

    The going rate is 8 cents per kilowatt-hour, but Nick installed a Reposit monitoring system – an $800 extra – that'll push the price up to $1 per kilowatt-hour at certain times.

    "So when we had that really hot weather last week, what happened is, there's a peak event on the network and [electricity companies] asked batteries to start dispatching power, so it's kind of like a little power station if you like."

    Obviously UK PV generation and seasonality mean we are unlikely to see such savings, but the better these systems do in Australia (and elsewhere) the faster they'll be deployed, and the faster we'll see prices drop. At least that's what I tell myself, with my fingers crossed!
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • CardewCardew Forumite
    28.7K Posts
    Part of the Furniture 10,000 Posts Name Dropper Rampant Recycler
    ✭✭✭✭✭
    Selling electricity back to to the grid at up to $1 per kWh helps the figures!!
  • Martyn1981Martyn1981 Forumite
    12.4K Posts
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    ✭✭✭✭✭
    Cardew wrote: »
    Selling electricity back to to the grid at up to $1 per kWh helps the figures!!

    Absolutely and helps to bring down the wholesale price during these peak times. Perfect.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW)

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • NigeWickNigeWick Forumite
    2.6K Posts
    Part of the Furniture 1,000 Posts Name Dropper Debt-free and Proud!
    ✭✭✭✭
    Martyn1981 wrote: »
    Obviously UK PV generation and seasonality mean we are unlikely to see such savings, but the better these systems do in Australia (and elsewhere) the faster they'll be deployed, and the faster we'll see prices drop. At least that's what I tell myself, with my fingers crossed!
    I think it's just a matter of time before enough people get on at the government and they start favouring renewables with storage and ditching fossil and nuclear.

    I have started e-mailing (bombarding) my MP with renewables and EV stuff. John Hayes MP is Minister at the Department of Transport. Before the election he was canvassing in my road. He looked tired so I dragged him in for a single malt and put the world to rights for half an hour. In private he's actually quite sensible and he does work hard for his constituency (well his researchers do).
    The mind of the bigot is like the pupil of the eye; the more light you pour upon it, the more it will contract.
    Oliver Wendell Holmes
Sign In or Register to comment.
Latest MSE News and Guides