National Grid Profile
The UK National grid is play an important role in power generation to transmission the electric power to household and city. The EVs growth rate has been related with the demand consumption in electric generation of UK and making the peak demand of the gird which effect to the grid carbon content [1] [6].
Electricity has an associated carbon content depending on electrical production method
(such as emissions from burning fossil fuels)
Carbon intensity is dynamic, constantly in flux with demand and renewable generation
Different regions have varying intensities dependent on their local production methods as u can see on the picture of Regional UK carbon intensity.
Southern Scotland has the lowest average intensity (Because of Wind and nuclear generation), North Wales has a highly variable energy mix (Some wind, and nuclear generation, with a large degree of gas)
Demand Consumption Profile
Source:
The total average demand profile was calculated over the course of the year. This demand was once again averaged out to determine a daily demand profile which was then plotted on two graphs representing the winter and summer months.
From the graphs, we were able to determine that the winter months required a much higher range of demands, ranging from 20,000 MW to its peak at 30,000 MW. Whereas, the summer months have a lower demand profile ranging from 15,500 MW to its peak at 22,000 MW. It is therefore evident that the most suitable time for Carbon conscious electric vehicle charging is during the summer months.
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The demand profile has been split into several subsections to determine how the average demand each energy source produces each day over the course of the year.
Grid Supply Profile
Source:
The UK national grid is generated electric power by CCGT, renewable energy, nuclear, and fossil fuel. The pie chart shows the majority generation is by CCGT which is 45%, followed by nuclear with 21%. renewable energy represents by wind 18%, biomass 7%, solar 4%, hydro 2%, and pumped hydro 1%. Renewable power is showing strong growth, while fossil fuel generator use in general and coal use, in particular, is shrinking, with coal generators now mainly being run in winter due to pollution and costs [2] [6].
Grid Power Generation
Source:
The energy demand produced from coal power is significantly higher in the winter months compared to the summer months. During the winter, there is a sharp increase in energy demand in the afternoon until it reaches its peak of 1,600 MW at 6 pm before steadily falling off. Whereas, the summer months have a considerably lower demand which ranges between 120 -170 MW.
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However, for nuclear power, there is a noticeable feature that the generation mainly constant from 4,000 MW to 4,500 MW throughout the day in winter and summer.
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Lastly, combined cycle gas turbines produce a substantial amount of energy demand for the grid. During the winter months, the demand is at its lowest early in the morning and gradually begins to increase to its peak at 13,500 MW at 6 pm where it then begins to decrease. At its lowest CCGT power still produces 6,000 MW of energy. During the summer months, the lowest energy demand is similar to the winter months with the demand being just short of 6,000 MW early in the morning. There demand increases throughout the course of the day until it reaches its peak of 11,000 MW in the evening. However, there is a small drop in demand around midday. This is still a large sum of energy being produce by an energy source which is not 100% clean.
Renewable Energy Power Generation
Source:
Wind power is one of the most abundant sources of energy the UK has to offer and therefore results in a large portion of the UK energy demand. In the winter months, the demand maintained between 4,300 MW - 4,900 MW. However, the demand during the summer months is less generated and maintained between 3,200 MW - 3,500 MW.
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Biomass power produces an energy demand throughout the course of the day. In the winter mornings, the energy demand is at 1,200 MW until 12 am, where it begins to increase until it reaches its peak of 1,500 MW at 6 am. The demand for the summer months is 1,400 MW which is maintained as a constant throughout the course of the day.
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In the winter months, solar power produces very little energy when compared to the summer months and during a shorter period of time. Solar power only begins to be generated at 9 am and the demand increases until it reaches its peak of 2,000 MW at noon before steadily decreasing until 4 pm. Whereas, in the summer months, generation begins a lot earlier and rises to a peak of 3,700 MW at noon before steadily decreasing as the Sun disappears.
Hydropower is used continuously throughout the course of the day. It gradually increases from its lowest point of generation at 3 am, where the demand is 200 MW until it reaches 500 MW at 5 pm where it gradually begins to decrease. Whereas, during the summer months the demand increases and decreases throughout the course of the day. Demand is at its peak when it reaches 450 MW at 6 pm and then sharply decreases to its lowest demand of 125 MW at 11 pm.
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During the winter months pumped hydropower produces an average energy demand of 300-400 MW of energy throughout the course the day. However, there is a sharp spike in demand at 6 pm when the demand reaches 700 MW before gradually returning to the average demand. This sharp peak in demand could be the result of the population returning home from work and turning on lights and other electrical supplies. Throughout the Summer months, energy from pumped hydropower is only produced in the morning and early in the evening. However, the greatest peak of demand happens in the evening at 6 pm and reaches a demand of 500 MW.
Carbon Content Profile
Source:
The Grid Carbon Factor is measured in kilograms of CO2 equivalent emitted for each kWh of electricity generated on the National Grid: kilograms CO2e/kWh [3]. Grid Carbon Intensity also follows a daily cycle with the Grid Carbon Intensity falling steeply around 11 pm each night and remaining low until around 6 am each morning. This provides a major Demand Side Response opportunity for those using electric heating systems to raise the core temperature of buildings in the small hours because the lower carbon intensity is achieved when electricity demand is lowest and the Grid can agree lower prices when demand is low [4] [6].
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The UK National Grid plays an important role in power generation to transmission the electric power to household and city. The EVs growth rate has been related to the demand consumption in the electric generation of the UK and making the peak demand of the gird which effect the grid carbon content [3] [4].
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The peak in grid demand and supply should not exceed than the normal curve since the impact will happen eg. the massive drop in frequency or grid voltage, which leads to grid overload. The effect of these to the grid, such as Grid Carbon. The grid carbon content has a high level when the demand is a peak that makes the national grid generate the power immediately for responding to the need for consumption. By doing this the fastest and the easiest way to generate an amount of energy is a fossil fuel which emits the CO2 [6].
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From the figure above, the seasonal carbon content of electricity in the UK by the time of day has the same behaviour of peak carbon. The carbon content climbs up at the peak of 25 kgCO2/kWh in summer and 38 kgCO2/kWh in winter. The highest curve is by winter because of the temperature and the need for power consumption in the household for heating and in EVs for charging which has a low efficient when the temperature is cold.
Consequence, the motivation for solving this problem is to create controlled charging for EVs and reducing the peak demand that the grid is capable of supplying, and also the potential for selectively charging based on carbon content.
References
[1]. UK Government Report. (2019). Reducing UK emissions 2019 Progress Report to Parliament [online].
Available from: https://www.theccc.org.uk/publication/reducing-uk-emissions-2019-progress-report-to-parliament/ [Accessed 1 Apr 2020]
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[2]. Carbon Breif Clean on Climate, (2019). Analysis: UK low-carbon electricity generation stalls [online].
Available from : www.carbonbrief.org/analysis-uk-low-carbon-electricity-generation-stalls [Accessed 1 Apr 2020]
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[3]. Leo, S. (2020). Limitations of 'Renewable' Energy [online].
Available from: www.gridwatch.templar.co.uk/ [Accessed 1 Apr 2020]
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[4]. GB National Grid Status. (2020) [online].
Available from: https://gridwatch.co.uk/ [Accessed 1 Apr 2020]
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[5]. National Grid (2020) [online].
Available from: Nationalgrid.com/britain-hits-historic-clean-energy-milestone-zero-carbon-electricity-outstrips-fossil-fuels-2019 [Accessed 2 Apr 2020]
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[6]. Margaret B. ,2013. Analysis of electric vehicle driver recharging demand profiles and subsequent impacts on the carbon content of electric vehicle trips, 3(6), pp 337–348 [online].
Available from: https://www.sciencedirect.com/science/article/pii/S0301421513004266[Accessed 2 Apr 2020]
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[7]. Department of Environment GOV UK (2012). UK's carbon footprint [online].
Available from: www.gov.uk/government/statistics/uks-carbon-footprint [Accessed 6 Apr 2020]
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[8]. ICAX Interseasonal Heat Transfer. (2019). Grid Carbon Factors [online].
Available from: www.icax.co.uk/Grid_Carbon_Factors.html [Accessed 7 Apr 2020]
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[9]. Carbon Intensity API. (2018). National Data [online].
Available from: www.carbonintensity.org.uk/ [Accessed 7 Apr 2020]