STEM update - The Rise (and Rise) of Renewables, 2nd March 2021

This is the second update of last year's Bingham u3a STEM Group presentations relating to climate change and in particular renewable energy.

Which renewable energies are best?

There is a wide range of renewable energy technologies and a method has to be found to determine which is worth building.  This is determined commercially using the strike price which is a price for wholesale electricity reflecting the cost of investing in a particular low carbon technology and is used to determine which generating plant are likely to be built in the future. Recent (2020) estimates put large scale solar and wind ahead of other technolgies, for example ...

  • large scale solar - £44 per MWh  (4.4p per kWh)
  • onshore wind - £46
  • offshore wind - £58
  • tidal - £93 (with subsidy) to £150
  • wave - no figures available
  • combined cycle gas turbines - £85
  • nuclear -  £95

... so it is no surprise that wind and solar dominate the market for new plant.  Many new sites are combined with battery storage which enables them to receive additional support for providing network resilience services such as backup and frequency control.

Capacity factor is a large factor in determining price

Capacity factor is the ratio of the actual annual electrical output in MWh compared to that which would be produced if the plant operates 365/24/7 and the strike prices take this into account.  So solar power is cheap despite its very low capacity factor of 11% - a plant with a  nameplate output of say 50 MW will produce only 5.5 MW on average.  This low value is determined mainly by seasonal and daily variations in sunshine and cannot be improved upon.

The average offshore wind capacity factor in 2019 was 38.9% but this has been steadily increasing with projections of 58% for new-build as technology improves and turbine sizes increase.  Some very interesting live data for Eurpope can be found here.  A comparable average figure of onshore wind is 26.6% and we can expect similar improvement if and when more onshore turbines are built.

Wind power generation in 2020

In the UK, wind was the second most dominant source of energy, providing 24.8 per cent of the grid mix

Wind also set a new record for highest share in the energy mix on 26 August, when it contributed 59.9% of the nation’s electricity

The 1.2 GW third phase of the 3.6 GW Dogger Bank wind farm owned by Equinor and SSE will become the world’s largest offshore wind farm when complete in 2026
. It uses the 248m high 14MW Haliade-X wind turbines
Credit: Dogger Bank
Solar

The current installed capacity of utility scale solar power is 13GW peak but an astonishing additional 13GW is at the planning stage.  Many are 50MW sites which do not require government approval and there are two local ones, the Belvoir Solar Farm near Barkestone and Green Farm Solar near Bottesford.  These are ten times bigger than ones we are used to seeing and occupy a great deal of (low grade?) agricultural land so there has been some local opposition.



One example of the larger schemes is the 350MW Cleve Hill Solar Park in Kent, granted planning permission in 2020.  Many of these solar farms are now combined with batteries to help in the management of the grid.

There are more renewable energy sites that you might think

Below is a map of current grid-connected renewable schemes, an an illustration of just how much effort has been put into clean power over the past few years.  Just pan up or across to view the UK, zoom in and then click on a marker to show details of individual schemes.

Can we have too much renewable energy?

Electricity market prices have surged tenfold in a day to reach a new record high of £1,000 per megawatt hour, as colder than normal temperatures and lower electricity generation left a dent in Great Britain’s power supplies. (Guardian, 5th Jan 2021)

Fortunately, most consumers in the UK are protected against spikes of this sort though some electricity traders are not (hard luck on them).  A similar cold period in Texas in February has caused blackouts as well as serious financial problems for unprotected domestic consumers.  The problems in Texas were (unfairly) blamed on the State having too much renewable energy and it is a fact that integrating renewables into any grid presents many challenges to do with intermittancy and other factors.

In conclusion - a remarkable reduction in carbon intensity

The electricity supply sector leads the UK in the process of decarbonisation mainly due to the decline in the use of coal.  For example, whereas coal has a carbon intensity of about 1,000g CO2/kWh, oil is 800g CO2/kWh, natural gas is around 500g CO2/kWh, nuclear, hydro, wind and solar are all less than 50g CO2/kWh.  The figure below covering the period from 1970 summarises this progress as first nuclear plant,  then gas-fired plant, then renewables displaced coal so that the average for 2020 had fallen to 181 g/kWhr.  By 2035, emissions are projected to be less than 10% of those in 1970.


These annual averages hide the fact that there is considerable hourly variation - see below for December 2020.  In May last year, levels dropped to an 
all-time low of 46g of CO2 per kWh on the 24th.  It is likely that domestic consumers will be able to take advantages of these variations to reduce their own carbon footprint, making use of the features of their smart meters and even to trade the power from their electric vehicles back into the grid.

STEM update - The Fall of Coal

This is the first in a series of blog posts to try to keep the Bingham u3a STEM Group alive in 2021.  The format is different obviously from the monthly meetings and will consist of regular, short posts, initially following on from last year's presentations on Your Carbon Footprint but hopefully on other STEM subjects.  The next posts will cover Renewable Energy then Carbon Intensity but if you have any ideas on any future topics, preferably topical or local then please let me know.  Or even better, send me some material to post.

Dave Hobson

The Fall of Coal?

  • "Overall, coal provided just 1.6 per cent of the electricity mix in 2020, a dramatic decline from 25 per cent just five years ago"
  • "Emissions from Britain's electricity system drop 66 per cent in seven years, as coal fired power plants have rapidly been phased out"
  • "During the spring and summer, the electricity grid saw its longest ever coal-free record, going almost 68 days without generating power from coal"

Well, not quite the end of coal - on 8 January 2021, coal represented as much as 7% of generation.  
And although several plants closed in 2020, Ratcliffe and West Burton are yet to announce closure plans.  Clearly, at the moment, coal is still needed to provide back-up on cold, dark windless days at 4 o'clock in the afternoon.  Perhaps coal will survive a bit longer than expected.


The fall and rise(?) of nuclear generation

But will (low carbon) nuclear fill the gap as the coal stations close?  Well, there were interesting developments in 2020 as follows.
  • "Hunterston (AGR) nuclear power station, one of the UK’s oldest remaining nuclear plants, is to close down in 2021 after encountering a series of safety-critical problems in its reactors." These safety issues relate to cracking of the graphite core of the reactor and are common to all the existing gas cooled reactors.
  • "In 2020 it was reported that Rolls-Royce has plans to construct up to sixteen 440 MWe small and medium sized reactors UK", "And 6000 new jobs", 11th November 2020
  • "The UK to start talks with EDF on funding for Sizewell C". Sizewell C is a proposed project to construct a 3,200 MWe nuclear power station with two so called EPR (pressurised water) reactors in Suffolk, due to start in 2031. This will be similar to the Hinkley Point C nuclear power station which has two 1600 MW units under construction, more than twice the size of any other unit in the UK.
Two further EPR units had been proposed but are unlikely to go ahead

The first gas-cooled Magnox reactor started at Calder Hall in 1955 and the first of the Advanced Gas Cooled Reactors at Hinkley Point in 1976.  More AGRs were built, the last starting generating in 1988.  These were followed by the single PWR (pressurised water reactor) at Sizewell which opened in 1995

And as for nuclear fusion reactors.
  • "Nuclear fusion power is slowly getting closer", New Scientist 16th December 2020. 
The world’s biggest nuclear fusion power project, ITER in southern France, began its assembly phase on 28 July 2020. ITER’s commercial fusion power plant isn’t expected until 2054.

An excellent video making the case for fusion power, with reference to the UK's efforts at JET (Joint European Taurus) as well as ITER, was published by The Royal Society in January 2021.  An equally interesting and watchable video entitled Fusion power has major problems -  what no one is telling you about puts an opposite view.