Advances made in renewable energy and storage over the past decade has seen the UK’s renewable electricity outpacing fossil fuel generation for the first time in 2020 and is likely to remain the largest source of electricity in the future.
But renewable energy isn’t only wind and solar – it includes hydro, bioenergy, landfill gas and sewage gas, each of which we will focus on, in turn.
- Watt (W) is a joule (J) of energy used or produced per second
- Megawatt (MW): A megawatt is equal to one million watts
- Gigawatt (GW): A gigawatt is equal to one billion watts; 1GW = 1000MW
- Terawatt (TW): A terawatt is equal to one trillion watts; 1TW = 1000GW
- Exajoule: The exajoule (EJ) is equal to one quintillion joules
The global view
Asia is responsible for the greatest share of renewable electricity generation worldwide. In 2019, some 2,448 terawatt (TW) hours of electricity were generated from renewable sources there. This was nearly double the volume produced in Europe, which ranked second.
The leading countries for installed renewable energy in 2020 were China, the US, and Brazil. China was leading in renewable energy installations with a capacity of around 895 gigawatts (GW). The US, in second place, had a capacity of around 292GW.
The top countries for renewable energy consumption are China, United States, and Germany, respectively, while China and Brazil are the top two countries in terms of generating the most energy through hydropower.
Geothermal energy has been on the rise as well with data showing an increase in capacity over the last decade.
The UK view - renewable energy generation in the United Kingdom by fuel
In 2001, the combined renewable generation in the UK was less than 10TW; in 2019, this had risen to 120.5TW, a 12-fold increase.
Renewable energy consumption in the United Kingdom between 1998 and 2019 increased significantly during this period, rising from 40 petajoules in 1998 to approximately 1.1 exajoules in 2019.
Between 2008 and 2020, the total installed wind power capacity in the UK increased by a factor of over seven, from just 3,447 MW to around 24,665 MW.
Onshore wind generation has historically outperformed offshore; however, in 2019, parity was achieved for the first time, with each accounting for just over 32 TW hours.
The load factor (the ratio of how much electricity was produced as a share of the total generating capacity) for electricity generation from both onshore and offshore wind in the UK has fluctuated since 2010. In 2019, the load factor of onshore and offshore wind increased from the previous year to 26.6% and 40.4%, respectively. Load factors were typically lower for onshore wind.
Today, there are around 10,000 wind power plants in the UK. Figures saw a particularly strong year-on-year growth between 2008 and 2014, with the market having become more saturated in recent years. In 2018, onshore and offshore wind farms generated a combined 56.9 TW hours’ worth of electricity and heat.
The cumulative installed capacity of solar photovoltaics (PV) over the past decade has increased massively, from just 95 MW in 2010 to 13.6 GW by the end of 2020. Since 2017, it’s started to plateau but continued to grow, just not at the same rate as the previous seven years.
The generation of solar energy in the UK increased rapidly after 2010, increasing more than five-fold from 2010 to 2011. In 2019, electricity and heat production from solar PV amounted to 13 GW hours.
The load factor of electricity from solar photovoltaics has seen an overall increase since 2010, amounting to 11.2% in 2019. However, this was a minor decrease from the previous year and significantly lower when compared to the load factors of other renewable sources.
This can be explained by the lack of consistency in the number of sunny days recorded - in comparison, the load factor for offshore wind reached 39%.
In 2018, solar PV accounted for 29.6 % of the total renewable capacity but its share of renewable electricity generation was just 11.7% due to the relatively low load factor.
In 2010, electricity generated by solar PV amounted to 41 GW hours but by 2018 this had increased to more than 12,800 GW.
In 2018, the UK`s solar PV industry reported a turnover of €1.8bn, an increase in excess of €500m when compared to the previous year. As turnover increased, so did employment figures - in 2018, there were approximately 6,600 employees in the sector – unfortunately, by the following year this number dropped by more than half due to cuts in government subsidies.
Solar photovoltaic sites in the UK numbered just over one million by the end of 2019. Following commercial distribution in 2007, installations boomed between 2009 and 2014. With the market becoming more competitive, installation costs have fallen in recent years, with prices for small scale solar PV systems oscillating between £1,185 and £1,867 per KW.
The UK is home to 1,520 hydropower plants. Between 2003 and 2019 numbers increased more than fivefold. Hydropower has been a source of electricity generation since the late 19th century but has gained in importance following growing awareness of the negative effects of fossil fuel burning.
The total hydropower capacity has remained very consistent over the last 10 years, increasing slightly and reaching 4.773 GW by 2020 (2010: 4.391GW).
Electricity generated from small and large scale hydro sources has increased over the years - as of 2019, the UK had recorded 4.5 TW hours’ worth of electricity from hydropower, with small scale hydropower plants generating 1.4 TW of the total.
The load factor for electricity generation from both small scale and large-scale hydropower in UK has fluctuated since 2010. In 2019, the load factor of small-scale hydro increased from the previous year to 39.8 %. Load factors were typically lower for large scale hydro, except in 2015.
In 2018, hydropower accounted for approximately 5% of renewable electricity generation, generating 5,464 GW hours of electricity. Most of this was produced by large scale hydro; however, generation from small scale hydro has increased significantly since 2010.
With its high levels of rainfall, mountains and lakes, Scotland unsurprisingly accounts for more than 80% of the hydroelectric resources in the UK. The cumulative capacity of hydropower in Scotland reached 1,655 MW in 2018. In comparison, the installed capacity in England was just 44 MW in the same year.
The use of biomass in the UK has increased in recent years, with a peak of 1,815 bioenergy power plants operational across landfill gas, sewage gas, and other bioenergy sources, in 2019. Apart from electricity generation, bioenergy is also used to produce heat, fuels, and industrial products.
Approximately 596 GW hours of electricity was derived from bioenergy sources in 1990, with figures climbing to 37,314 GW hours by 2019. Bioenergy includes landfill gas, sewage sludge digestion, waste combustion, co-firing with fossil fuel, animal biomass, plant biomass and anaerobic digestion. By 2018, production output of co-firing with fossil fuels had decreased to only one gigawatt hour.
The electricity load factor from animal biomass has remained largely stable over the past 10 years while the load factor from plant biomass has fluctuated significantly, year-on-year.
Landfill gas power
There are 456 operational landfill gas plants in the UK, a slight decrease compared to the previous years, with numbers peaking at 464 sites in 2017. Electricity production by landfill gas plants declined in recent years, falling from a peak of 5.2 TW hours generated in 2012 to 3.9 TW hours in 2018.
As of the end of 2020, the cumulative installed capacity stood at 1,055 MW. This was a minor decrease from the previous year; however, the overall cumulative installed capacity of renewables amounted to over 48k MW in the same year.
Electricity generated from landfill gas has declined since peaking at roughly 5.2 TW hours in 2012. Between 2010 and 2019, it decreased by 1.4 TW hours.
The load factor for electricity generation from landfill gas has declined every year since 2010.
Sewage gas power
Sewage gas is a form of biomass used as an energy source, with sewage sludge digestion adding 992 gigawatt hours of electricity to the UK's power mix in 2018. There are 194 operational sewage gas plants in the UK. Between 2007 and 2019, figures saw a net increase, peaking in the latter year.
Sewage sludge digestion-run power plants had a cumulative installed capacity of 247 MW by the end of 2020. Between 2010 and 2020, capacities increased by over 50 MW, with the only decrease recorded in 2013.
Electricity generated from sewage sludge digestion has increased over the years. peaking at some 1.05 TW 2019. Between 2010 and 2019, figures increased by 352 GW hours.
*Sources available on request