Green Mythology: Sun, Wind, Waves & Tides Fail to Deliver the Goods


Perpetual motion machines, turning lead into gold and capturing moonbeams in a jar are just some of the fanciful notions that have attracted human attention over the eons.

The last generation have been obsessed in their attempts to run whole economies on the weather. For those that launched all out efforts to run on sunshine and breezes, the results have been an unmitigated disaster (think notionally wind powered South Australia, now an international laughing stock).

As policymakers seek to quietly retreat from the brink, there are always a few members of the pack who think they can still trade their way out of trouble by building enormous (non-existent) batteries or those who seek quite literally to turn the tide.

Whether its sunshine, wind, waves or tides the ideal is always outstripped by the real – a bit like alchemy, really. Here is a sharp little analysis from Euan Mearns, busting another favoured green energy myth, that mixing it up solves the insoluble intermittency issue.

Green Mythology: adding different types of renewables smooths output
Energy Matters
Euan Mearns
30 January 2017

A favourite assertion of renewables enthusiasts is that intermittent supply can be smoothed by simply adding different types of renewable resource. How often have you heard “If it’s not windy then we can use tidal instead”. I present a simple renewable supply model for the UK that has 20 GW of tidal, 13.6 GW of wind and 8.8 GW of solar for a total of 42.5 GW installed capacity. When everything is on this outputs a maximum of 22.2 GW of power (52.2% load). When everything is off that falls to 0.9 GW (2.1% load). Those contemplating engineering the UK grid along these lines must surely be mad.

The Renewable Energy (RE) Model
I spent a short while reviewing the charts in UK Grid Graphed and selected April 2016 as the base for the model, not because it was representative but because it had a nice pattern of windy spells separated by lulls (Figure 1).

This extreme variance in wind is compensated by solar being mid-range in the Spring. At the end of 2015, the UK had 13.6 GW of installed wind and 8.9 GW of installed solar. Come April 2016 that will have increased but not by much.


Figure 1 UK generation for April 2016 showing wind and solar, data from Gridwatch, chart from UK Grid Graphed

Tide generation data does not exist for the UK and so I somewhat laboriously created a numerical replica of the 1*DoEn model of Borrows et al (2008): Tapping the Tidal Power Potential of the Eastern Irish Sea that was discussed in my post on tides last week week: Green Mythology: Tidal Base-load Power in the UK (Figure 2).


Figure 2 A model of tidal generation from 5 barrages in SW England based on Borrows et al 2008. The Borrows 1*DoEn model has 20 GW installed capacity but has maximum output of 12 GW and produces much less for most of the time.

The 1*DoEn model represents tidal barrages on the Severn, Dee, Mersey and Solway Estuaries plus Morecambe Bay, the latter all located in the E Irish Sea. Combined these have 20 GW of installed tidal capacity. I chose the dual mode model since this is how Tidal Lagoon plc propose to operate their tidal lagoons. This gives a grand total 42.5 GW installed RE capacity.


Figure 3 Stacking the real wind and solar data for the first two weeks of 2015 along with the model data for the Borrows 1*DoEn tide generation provides this picture of renewable output.

Stacking solar on tide on wind provides the picture shown in Figure 3. Adding dual mode tidal to the mix is catastrophic for stability of combined output.

On the first day we get a neap spring tide sitting on top of a wind spike during the day when the sun is up and this combines to produce 22.2 GW.

On the 8th day we get the trough in tidal production of a neap tide coinciding with a lull in the wind when The Sun has set for a total of 0.9 GW. That is an uncontrollable dynamic range factor of 25.

So is the assertion that combining different sorts of renewables smooths output true or false? It is clearly yet another Green Myth that simply refuses to die.

Ramp Rates.
We can take the analysis one stage further and examine what the CCGTs, hydro and pumped storage has to do in order to balance load. Figure 4 shows UK demand for the first two weeks of April and Figure 5 shows this demand profile minus the renewable stack shown in Figure 3. This is what the other dispatchable resources are left to follow and to balance.


Figure 4 UK electricity demand for the first two weeks of April 2016.


Figure 5 UK electricity demand curve (Figure 4) minus the renewable model stack (Figure 3) leaves this rather ragged looking residual that hard pressed CCGTs, hydro and pumped storage would have to follow.

We can make three key observations. 1) The daily demand cycle is still clear to see and has not been obliterated by the intrusion of 42.5 GW of RE, but 2) the residual that needs to be balanced has become significantly more ragged and variable and 3) 42.5 GW of RE has only reduced peak residual demand by about 5 GW (from 45,000 MW (Figure 4) to 40,000 MW (Figure 5)). This latter point is key; 42.5 GW of infrastructure everywhere, all of it working at low load, is doing very little useful work on our behalf.

I am defining ramp rate as the change in electrical demand from one hour to the next. The ramp rate profile for UK demand is shown in Figure 6. The regular spikes represent the sides of the demand peaks where supply must be ramped up in the morning and down in the evening. We see that the UK dispatchable fleet of generators must regularly ramp at +8GW/hr in the morning and -4GW/hr in the evening.


Figure 6 The ramp rates for UK electricity demand as shown in Figure 4.


Figure 7 Ramp rate for electricity demand less renewable residual as shown in Figure 5. Tidal dual mode generation increases the frequency of ramping rather than the amplitude.

Performing the same exercise on the demand minus renewables profile (Figure 5) produces the picture shown in Figure 7. The key observations: 1) the amplitude of the positive ramp rate is not materially changed although there is one spike of almost 10 GW / hour; 2) the negative ramp rate is materially changed with an increase from -4 GW/hr to a range of -6 to -8 GW/hr and 3) during the period of high springs in the first 7 days (Figure 2) we see the need to ramp from extremes of 3 to 8 GW/hr four times per day.

Concluding Comments
As discussed in my earlier post, the high frequency ramping that tidal demands can only be sensibly balanced using bespoke pumped hydro storage. The vendors of tidal energy should be required to provide this load-balancing service.

Two Hinkleys with combined capacity of 6.4 GW will do a far superior job to the 42.5 GW of renewable infrastructure everywhere.
Energy Matters


Endless CO2 free power is no fantasy, it’s a real thing.

About stopthesethings

We are a group of citizens concerned about the rapid spread of industrial wind power generation installations across Australia.


  1. drgenenelson says:

    CGNP dot org is fighting a similar fight in California, USA. For a variety of reasons, the utility Pacific Gas & Electric wants to shut down in 2025 a highly functional nuclear power plant called Diablo Canyon, which produces about 18,000 gigaWatt-hours of electricity annually.(About five Hoover Dam’s worth of electricity.)

    In 2025, Diablo Canyon will still have about 60 years of useful life. Solar and wind are being promoted as partial replacements. CGNP understands that there are a number of fossil-fuel interests that will benefit financially if this horrible plan is implemented. Please visit CGNP’s website for additional details. The parallels to south Australia are alarming. .

    • drgenenelson says:

      CGNP has also discovered that PG&E’s Helms Pumped Storage (HPS,) a mature, 32-year-old facility has been used only modestly, per the U.S. Energy Information Administration. Between 2003-2016, the HPS capacity factor ranged between 0.84% (an average of about 12 minutes/day) and 4.69% (about 1.13 hours/day.) When CGNP inquired as to the reasons for this modest HPS usage, PG&E recently declined to answer CGNP’s questions in California Public Utilities Commission (CPUC) proceeding A.16-08-006.

  2. Jackie Rovensky says:

    I find it alarming that the SA Government is rushing ahead with large scale battery storage just as they did with Wind before ensuring it is safe, cost effective and suitable to our needs. Taking no notice of calls for caution or valid information that they will only provide enough power for a very very sort time and then will need to be recharged – from what it seems they are ignorant and don’t care to become informed as their ideological push is more important.
    They have fallen again for the quick fix and spin of spin doctors who only want to sell their product.
    Yes there may be a roll for battery’s at people homes for home energy storage but for industry you have to question the intelligence of our ‘leaders’.
    When they talk of energy production that relird on natures forces taking over it’s just not possible – but these idiots who would have us believe in fairy tales are wantonly deluded.
    They consider they will be able to get industry and us to change how we use energy and only use it when there is enough being produced.
    For example it would require industry to operate with a permanent standby staff day and night to jump in and switch on the machinery to produce what ever they are producing and switch off again when energy supplies peter out even when at mid production. Office workers will have to be ready to rush into work when there is enough energy to do their jobs and return home or stay on standby when energy production falls off. People at home will have to be ready to cook dinner do their washing and the multitude of other day to day chores only when the power is on, which could be in the middle of the night. Multiply these cases by all the jobs undertaken by us in today’s society – Chaos would become the way of life.
    Of course these deluded, ignorant and stupid people believe its the way of the future. You have to wonder what caused them to be such daydreamers with the ability to influence a modern democratic country in the way they have.
    Is it a case of long term indoctrination or is it simply a case of personal ambition by some of our politicians and so called ‘intellectuals’.
    In SA we have had Political leaders who have constantly portrayed and spouted we are leaders in the world for one thing or another, but in pursuing this personal ambition and push to be seen to be the ‘best in the world’, they forgot, to be the best you have to do the best.
    Our politicians should stop wanting to be world beaters and concentrate on making the best of what we have for the betterment of Australia not themselves.

  3. Crispin Trist says:

    On a recent trip to Mount Gambier, across the border in South Australia. I had a conversation with a local shop keeper about the SA Statewide power blackout. I asked how long the power had been out for. At first I thought they said 2 hours. “No”, she said. “2 days!”

    They went on to declare however that they were the lucky ones as other parts of the state had been out for a week or more.

    This is the 21st Century in South Australia?

    As we headed out of Mount Gambier for home, I caught a quick glimpse of 2 hired in shipping container size power generators at the rear of a well known supermarket. Has there been a war on, I thought to myself, that nobody else has told us about? This is despicable. How could such a once wonderful state be governed so badly?

    How did we get here?

    And Victoria is now on the same path to self destruction.

    Words fail me.

    • Felicity says:

      Words don’t fail Jay Weatherill- but like the wind industry misinformation and ‘achievements’ he and Koutsantonis promote, they pour out like the lies of a criminal under pressure.

      The question remains whether the media and/ or what is called ‘the opposition’ in South Australia will ever have the courage and integrity to interrogate the charade that is pretending to be a Government ‘for the people and planet’. Meanwhile the Weatherill Labor government continues to facilitate the channelling of ‘renewable’ profits to its mates in the Union super funds at the expense of the citizens well-being.

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