We are told by government, the media and eco-activists that our future energy needs (electricity) should come from "renewable energy", e.g. wind turbines or solar voltaic panels.
Firstly, wind originates from different sources of air masses and is therefore not renewable. The strength of wind is determined by the pressure gradient, which itself is determined by the difference between cold/cool air and hot/warm air. The bigger the temperature differential the stronger the wind speed, which occurs between low pressure and high-pressure systems. Within hot or cold high-pressure systems, the wind is light and often calm.
Solar voltaic is not renewable, photons from the sun cannot be renewed once the energy has been expended. But the sun doesn't shine all the time, water vapour (gas), rain/drizzle (liquid), ice/snow (solid), clouds, and dust, in the atmosphere can change the electromagnetic input. Frost, dew, rain, snow and dust particles can change photon activity at point of contact with photo voltaic panels. Most importantly, between sunset and sunrise there is no sunlight.
How much wind and how much sunshine do we get in the UK?
We all know the wind doesn't blow at times, but how much? A problem with typical wind turbines is, it takes a certain amount of wind speed to get the blades rotating. This is called the cut in speed. At the other end of the scale, when wind turbines have to stop to prevent damage to the gearing mechanism to turn the rotors, this is the cut-out speed.
No wind energy can be produced with wind speeds <10 MPH (Cut-In) and >55 mph (Cut-Out). With this in mind, we conducted analysis of daily wind speeds (48x1/2 hourly observation per day)across the UK for the last 21 years, with the following results.
Fig 1 UK maximum and minimum Daily Wind Speeds Oct1998-Oct2019
Analysis of UK average maximum and minimum wind speeds are shown in the table below.
Table 1 Analysis of UK Wind Speeds Oct1998-Oct2019
Wind Speed in the UK is incredibly variable, as table 1 shows.
Minimum wind speeds - 98.6% of days, at some point during a 24-hour period, wind turbines would be unable to generate electricity
Mean wind speeds - 67.8% of days, at some point during the day, wind turbines would be unable to generate electricity. In effect, only 32.2% of days produced electricity.
Maximum wind speeds - 10.6% of days, at some point during the day, wind turbines would be unable to generate electricity
Using UK averages flattens out the true variability. As such, below is an example of two days (48 observations per day) for one location. We chose Aldergrove airport in Northern Ireland as an example of a relatively windy location.
Table 2 48 half hourly Wind Speed observation on a windy day and a less windy day 2019
On the windiest day so far this year 09Feb2019 the maximum gusts did not exceed cut-off speed of 55 MPH, but 29% of the 24 hours, there was not enough wind to generate electricity.
Every single one of the 48 observations on 23Jan2019 showed there was not enough Wind Speed to generate electricity. Rather than renewable, the word unreliable comes to mind when considering the frequency of the national grid is concerned.
Figure 2 shows UK sunshine hours per day for the last 21 years
Average sunshine over the UK is only 4 hours, just 16.7% per day. Of course, this varies by season, with maximum 17 hours during the peak of summer on a cloudless day and maximum potential of just 6 hours in the north on a cloudless day in winter. But the UK does not very often have cloudless skies. Stating the obvious, at night, there is no sunshine.
National Grid: 18Nov2020
Fig 3 National Grid Averages for the past Year 18Nov2019-18Nov2020
As can be seen in figures 3 "renewable energy" only makes a small contribution, less than 1/3, to our electricity production. The main reasons are; Wind speed is insufficient (average 44.1% of days incapable of generation) and sunshine hours on average can only generate 4 hours per day. There is a third reason, that of grid stability. Due to the intermittency of wind and solar there has to be fast reacting back-up to maintain frequency of 50 Hz. The only fuels capable of fast response (spinning reserve) are gas (CCGT) and coal. Remove these fast response spinning reserves and the grid would collapse, producing no electricity.
Energy companies who claim to provide 100% "renewable energy" are not telling the truth, as can be seen in figures 3 nearly all the electricity produced goes into the Nation Grid which comprises of all types of generators and interconnectors, for distribution purposes.
From this analysis, it is absolutely impossible to have 100% "renewable energy" in the UK. The big question to ask, where is more than 50%, of our electricity going to come from when "Net Zero Carbon" is initiated and removes coal and gas generating operations?
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