Thursday, 4 February 2016

How much Electricity storage would a wind-powered Britain need?

Short answer: 17,464 GWh, or about 654 times more than we currently have.

How much would that cost?

World experience is that hydro projects cost about US$2,000/kW to US$4,000/kW
-- Pumped-hydro energy storage – cost estimates for a feasible system.

At 2 to 4 $bn/GWh. Total storage costs for UK = £2 × 55 bn to £4 × 55 bn = $110 bn to $220 bn. UK hydro could not store the necessary energy, but could provide the power for a short time. We would need storage for 11643 million m³ of water. 11.643 km³. Let's take a proposed example. This massive scheme drowning a large area at Strathdearn in the Scottish Highlands would manage 4.4 km³ of water with a head of only 300 m. This is similar to the head at Ffestiniog. Scaling 4.4 billion m³ we expect 3365 GWh. This will be 20% of the capacity the UK would need to support wind intermittency.

Britain currently has 4 pumped hydro storage plants providing a total of 26.7 GWh of electrical storage. This pumped hydro isn't used for storage in the sense that renewable advocates want - to buffer intermittent generation. It's used to quickly bring peaking capacity online for quite short periods during late afternoon, early evening 4:30 pm to 7:00 pm.

stationpower (MW)head (m)volume (million m³)energy stored (GWh)
Ffestiniog360320–2951.71.3
Cruachan400365–33411.310
Foyers300178–17213.66.3
Dinorwig1800542–4946.79.1
Proposed:
Balmacaan300-600500-30.0
Coire Glas300-600500-30.0
Sloy60280-20.0
Total:3520 - 412026.7 - 106.7

How much extra would a wind-powered Britain need?

I reckon we'd need enough to cover for days of greatest demand, assuming a very low wind period.

A high demand day fell on 12-December 2012 requiring an average of 47.9 GW. Demand varied from a minimum of 37.1 GW (4am) to a maximum of 56.9 GW (5pm). Britain used 1,149.6 GWh of electricity that day. 23 such days would demand 26,440.8 GWh.

A low wind period happened during the first 23 days of Sept 2014. Back then we had 11,187 MWe of wind generation capacity, but it only produced 587.3 GWh for those 23 days, averaging 9.5% capacity.

That gives us a good idea of what kind of day we need to cover for, and for how long.

In Britain average offshore wind power capacity is 33%, onshore 23%, and the average (of both) is 28%. A wind powered Britain would need 171 GWe of wind (assuming 50:50 offshore:onshore). That's because 171 GWe of wind running at 28% generates 47.9 GWe, which is exactly our average demand on a cold winter day (such as 12-Dec 2012).

How much would have 171 GWe of wind made during that 23-day Sept-2014 low wind period? It would've generated 587.3 × 171 ÷ 11.187 = 8,977 GWh. Yet 23 cold, low-wind, days similar to 12-Dec 2012 would require 23 × 1,149.6 = 26,441. The short fall is 26,441 - 8,977 = 17,464 GWh.

The thin green line on the chart shows the expected (or average) o/p, assuming 28% capacity utilization.



Appendix 1 - British Wind output in Sept 2014
DayGWh
130.0
217.3
319.8
416.1
512.6
625.2
743.5
817.3
96.7
1013.2
1121.2
1218.0
1330.7
1456.5
1527.3
1614.2
1722.2
1824.7
1914.1
2027.9
2162.4
2229.6
2336.9
2493.9
25128.1
26123.2
2759.5
2828.9
2915.1
3072.1
Total days 1 - 23 :587.3
Expected daily average of 11,187 MWe wind plant @ 28%75.2

Source: Gridwatch downloads.
Note: The Gridwatch wind numbers show only metered wind, which is about 2/3 the total, so Gridwatch wind values are multiplied by 1.5 to get those shown above.

Appendix 2 - British Electrical power demand on 12-Dec 2012
TimeDemand, GWe
00:0038.2
00:3038.6
01:0039.0
01:3038.2
02:0038.0
02:3038.4
03:0038.2
03:3037.8
04:0037.3
04:3037.1
05:0037.3
05:3038.6
06:0040.8
06:3044.1
07:0048.6
07:3051.4
08:0051.8
08:3051.8
09:0052.4
09:3052.9
10:0052.9
10:3053.1
11:0053.1
11:3053.1
12:0052.9
12:3052.4
13:0052.2
13:3052.0
14:0052.4
14:3052.4
15:0052.7
15:3054.3
16:0055.5
16:3056.9
17:0056.7
17:3056.5
18:0056.3
18:3055.9
19:0055.1
19:3053.9
20:0052.7
20:3051.4
21:0049.6
21:3047.8
22:0044.9
22:3042.4
23:0040.6
23:3039.0

Source: DECC

References

  1. How much bulk energy storage is needed to decarbonize electricity?, 2015, by Hossein Safaei and David W. Keith

7 comments:

  1. This comment has been removed by the author.

    ReplyDelete
    Replies
    1. Scottish Scientist,

      The fallacy is yours, not this blog owners. He is far more knowledgeable about energy matters than you are.

      Unfortunately, as usual, you ignore or don't understand the significance of what you've been told by various people in comments on your thread; people who clearly do know what they are talking about. You can calculate energy storage capacity in either have a little over 300 m head and full storage capacity or on about 10 m less than full head and active storage which is just the top 10 me of the reservoir or there abouts. Read the comments I've posted, try to understand them and read the Reviewers comment on the Tantangara-Blowering conceptual pumped hydro project. Also read the comments on that post and you might start to understand why even small pumped hydro is seldom viable if powered by intermittent renewable energy sources. However, conventional hydro and intermittent renewables are a good match.

      Why you ignore the elephant in the room - i.e. nuclear is a much cheaper, and more flexible option - sends signals that you are more interested in advocacy and promoting green fallacies, than in objective analysis.

      Delete
    2. Mark,

      I've deleted my first comment, posted in haste last night, because on closer examination, it seems the exceptionally low wind conditions over Britain during September 2014 have proved to be more challenging than any I had previously modelled.

      Your expectation of “3365 GWh” for the energy storage capacity for the Strathdearn pumped-storage hydro scheme is an underestimate, arrived at most likely because you have erroneously assumed the head always to be “of only 300 m”, whereas 300 metres would be lowest operation head that only applies when the upper reservoir has drained to almost empty.

      As the reservoir fills up the head rises, to a maximum of 650 metres in the super-sized version of the Strathdearn scheme. Then the average head of the 4.4 km3 of water is 570m.

      Also your calculations that arrive at a necessary energy storage for the UK of “17,464 GWh” are an overestimate. You have assumed –
      “A wind powered Britain would need 171 GWe of wind”
      – whereas my scientific computer modelling has previously recommended

      annual maximum wind power = 5.5 x peak demand power

      which for a UK peak demand of 52.5 GW would be 290GW, which is 119GW more wind power than the mere “171GW” which you have assumed.

      This graph, again from my modelling, based on wind and demand data from April 2015, suggests that 1,400GWh would be all the energy storage capacity needed to serve British April 2015 power needs from a simple wind power and pumped-storage hydro system.

      Line graph of power grid and energy store timeline – April, UK
      https://scottishscientist.files.wordpress.com/2015/04/windpumpedstorage_april_1_26_2015.jpg

      I have today applied my computer spreadsheet model to the wind and demand data from Mark’s selected time period – September 2014 – and was confounded to discover that my (up until now) recommendations of

      store energy = 1.11 days x peak demand power
      annual maximum wind power = 5.5 x peak demand power

      would not work well, the reservoir would run dry and a power deficiency would require the import of power into the system to meet demand.

      Wind Pumped-storage September 2014
      https://scottishscientist.files.wordpress.com/2016/09/windpumpedstorage_september_2014.jpg


      I intend to investigate further and report back with my detailed findings and a new recommendation.

      Delete
    3. After further research today, I found that with my new recommended -

      • store energy capacity = 1.5 days x peak demand power
      • annual maximum wind power = 7 x peak demand power

      the system now has enough wind power and energy storage to cope with the very low wind conditions of September 2014.

      https://scottishscientist.files.wordpress.com/2016/09/windpumpedstorage_september_2014_7_1-5.jpg
      Wind & Pumped-storage September 2014 UK 370GW 1,900GWh

      Thanks again Mark for presenting a successful challenge to my previous recommendation!

      Delete
    4. Further updates and comments welcomed on my Scottish Scientist blog post -
      Modelling of wind and pumped-storage power

      "Such modelling can predict how much wind power and pumped-storage energy capacity should be installed for satisfactory renewables-only generation."

      Delete
  2. Mark4asp,

    Thank you for posting a comment on ScottishScientist's crazy pumped hydro project. He won't state his name or background and appears to do work for Greenpeace or similar.

    Did you see my several comments on that thread? He was rather dismissive of the first, so I gave more info.

    Also thanks for linking to my post on pumped hydro. BTW, the title of the blog post was not mine. I do not claim it is a feasible system - it isn't for both technical and economic reasons. The technical is the 53 km of headrace tunnels each holding some 10 million tonnes of water that has to be accelerated to 2.5 m/s in a minute or so and decelerated even faster.

    BTW, DECC gives estimates of the cost of hydro in UK. Pumped hydro is more expensive and manages about 20% capacity factor if charged using power from reliable baseload sources at night, every night. I doubt Scottish Scientist's concept could achieve anywhere near this capacity factor.

    You said "US$2,000/kW to US$4,000/kW" then said "At 2 to 4 $bn/GWh". These are the same figures for generating capacity and energy storage capacity. Is that intentional?

    ReplyDelete
  3. Mark4asp asks:

    "How much extra would a wind-powered Britain need?"

    Figure 10 in this excellent report shows GB would need about 8 TWh of storage if most electricity was generated by wind ans solar (based on 2012 electricity consumption and scaled up wind and solar power capacity): http://erpuk.org/project/managing-flexibility-of-the-electricity-sytem/

    ReplyDelete