An Expensive day in April.

The 30th April 2017 was a Bank Holiday Sunday in the UK and consequently the use of electricity was very low.

By chance it is also a Goldilocks day for wind and solar. Not too much wind but windy enough to provide a high output. The icing on the cake was that the wind speed was pretty constant across the day. Solar meanwhile has a nice day too with cloudless skies.

The day has been lauded far and wide as the day the UK was supplied with more power by renewables than by all other sources combined. When averaged over the day, the subsidised renewables (wind, solar and biomass) contributed 41% of the total energy used.

I wondered how much this Goldilocks day cost the UK taxpayer in subsidies.

The Electric insights website (Here) gives us a lot of information.

Here is a snapshot of the full day of generation from 30th April.

Knowing a few of the details of the subsidy regimes and the average generation per technology over the day we can get a rough idea of how much this golidlocks day cost, both for actual electricity generated and for wind, solar and biomass subsidies.

All of existing RE generation (bar the shouting) is subsidised by the Renewables Obligation (RO) or for smaller generators by the Feed In Tariff (FiT). CfD's (contracts for difference) are yet to apply to operational generators, but they are unlikely to reduce the total cost by much (if anything).

Bear in mind  RO and FiT subsidies are NOT the full price. The fullprice is (subsidy + selling price).

Currently one ROC is worth £45.58

Interestingly the RO for ground level solar (1.2 ROC/MWh) is almost the same as the latest total FiT price (generation + export) for small arrays.  Which means I will assume all solar gets the same subsidy of 1.2 ROCs/MWh (actually this is an significant underestimate of the subsidy due to a number of reasons - but I'll use this to err on the side of caution with this rough calculation)

Large scale wind has two separate ROC subsidies - one for onshore (0.9 ROCs/MWh) and one for offshore(1.8 ROCs/MWh). Offshore is far more productive per turbine than onshore while there are more onshore turbines than offshore. So a happy medium is to place the average ROC subsidy at 1.35 per MWh( (onshore + offshore)/2)

There is also some embedded wind which is subject to the FiT scheme. But per MWh this works out at approximately the same level of subsidy as our average for on-shore and off-shore.

Roughly working out the subsidy per technology for this single Goldilocks day:

Wind. 
The average power output over the day for wind was 8.8GW So the total energy generated was (8.8 x 24) just over 210GWh. Our subsidy  per MWh is (1.35 x £45.58) or £61.53 per MWh. So the subsidy on 210GWH amounts to £12,921930.

That is (as near as dammit) £13 million for the day

Solar.
Obviously solar only works during daylight so although there was a glut at midday of around 5GW, when averaged over the day the output was a more modest 1.5GW or 36GWh. The subsidy cost is 1.2 ROCs per MWh.

That comes out roughly £2 million for the day.

Biomass
Biomass power averaged 1.4GW over the day producing 33GWh of energy. Biomass gets one ROC per MWh.

The subsidy for this single day was just over £1.5 million.

So the total subsidy was £16.5 million.

How does this compare with the total generation cost?

Now the average payment (ex-subsidy) for all generators over the day was £32.43 per MWh and the average total power was 28.4GW.  So the total cost (ex subsidy) for all the electricity generated (28.4 x 24 x 32.43) was about £22 million

Bear in mind that my back-of-a-fag-packet subsidy calculation of £16.5 million uses the latest (and smallest) FiT rates.

It is pretty clear that when you include the hidden ROC and FiT subsidies this single day of 41% penetration by Wind, Solar and Biomass came close to doubling the wholesale price of electricity.

Yet on this sunny, windy, and expensive day in April, there was also an elephant in the room.

It is an elephant whose name environmentalists dare not speak. An elephant that is shunned, ignored or pilloried.

That elephant is the UK's existing nuclear power fleet.

One that April day it continuously provided about 25% of our power or 7.3GW. It does this day in day out 24/7. Not just when there is a Goldilocks day.

There were no emissions and for existing nuclear, there are no subsidies.