Introductory Notes
Data on the fuel mix used for generating Britain’s electricity for each half hour settlement period in the British electricity market is available from the official Balancing Mechanism Reporting System (BMRS) site at www.bmreports.com, and is displayed graphically for one moving snapshot covering an approximately 48 hour period.
The BMRS site is a valuable data resource, but does not enable the user to view graphical representations of historical data, or to arrange the data in user specified sequences. The REF Electricity Fuel Mix database consists of the historical BM data, covering the period 2009 to the present, and can be configured by the user to perform sorting, consolidating and graphing at different levels. The current version is already a powerful tool, but we are keen to improve it and make it more serviceable, and users are invited to send comments and suggestions for further features to This e-mail address is being protected from spambots. You need JavaScript enabled to view it .
Users should note that this REF database records output only from those power stations that are participants in the Balancing Mechanism (BM) and/or are 'visible' to the system operator, National Grid. Normally participation in the BM indicates that the generator is connected to the Transmission System (i.e. higher voltage cables) and its output is metered and instantaneously visible to the system operator. Typically, these are larger generators. The BMRS data does not cover “embedded generators”, i.e. smaller generators that are connected to the Distribution Network (lower voltage cables), the output of which is not usually made available to the system operator.
In recent years the quantity of embedded generation, particularly wind and solar, has grown significantly. About 14 GW of on- and off-shore wind is generating as of Q1 2016; approximately 65% of this is visible in the BMRS data and thus the REF Electricity Fuel Mix database. From this ratio, the approximate output from the embedded windpower can be inferred. Unfortunately, we have no half-hourly data source for output from the UK’s solar fleet which has grown to nearly 9 GW as at Q1 2016. (Site by site data on a monthly resolution is available in the Renewable Energy Generation dataset for the larger installations).
Menu options
The entry page shows five tabs which display the following data:
1. MW per Half Hour for a day
2. MWh per Day for a Month
3. MWh per Day for a Year
4. GWh per Month since 2009
5. GWh per Year since 2009
Clicking on one these options lists a table of the data described, and offering a number of sorting and graphing options. The columns in each table list the relevant data for generators of each particular fuel type, as follows:
Gas : Gas powered generation output from Combined Cycle Gas Turbines
Coal: Generation output from Coal burning power stations. It should be noted that this will include some generation from renewable sources where the generators are co-firing with biomass.
Nuclear: Generation output from nuclear power stations
Hydro: Generation from non-pumped storage hydro, i.e. Hydro generation that does not use pumping to replenish its reservoir.
Net Pumped: Pumped Storage Hydro, i.e. hydro reservoirs that pump water to replenish their reservoirs. Figures for pumped storage may be positive when net generation is occurring or negative when electricity is consumed to refill the reservoirs.
Wind: Generation output from the larger wind farm sites 'visible' to National Grid.
OCGT: Gas powered generation from Open Cycle Gas Turbines which are small scale engines, often based on aircraft engines, and which typically provide short term energy on demand.
Oil: Generation from oil fired power stations
Biomass: At present this is dedicated biomass generation from the converted coal units at Drax and Ironbridge, and Stevens Croft. From early 2012 to August 2013 it also included Tilbury.
French Int: 2 GW Interconnector between England and France
Dutch Int: 1 GW Interconnector between England and the Netherlands
NI Int: 500 MW Moyle Interconnector between Scotland and Ireland
Eire Int: 500 MW East-West Interconnector between Eire and Wales.
Note that the four interconnectors may show positive or negative values. Positive values indicate energy is being supplied to Britain and negative values indicate the net energy flow is from Britain to the country at the other terminus of the interconnector.
NET SUPPLY: This represents total generation within Great Britain and imports to Britain, less energy used by the generators themselves and that exported from Britain.
Tab 1. MW per Half Hour for a Settlement Date
This data shows the fuel mix for each of the 48 half hour periods of a particular day. Each half hour is known in the British market as a Settlement Period (SP), and the day in which this occurs as a Settlement Date (SD). Note that on the two days of the year when the clocks are changed for summer time/GMT, there are necessarily 50 and 46 settlement periods in those days. This view of the data is useful for understanding the various technologies that are being used to meet instantaneous demand for electricity (ie. MW) in Britain.
The first data presented to the user is that for the most recent day. Previous days can be selected by clicking on words Previous Day; later days by clicking on Next Day, etc. Clicking on the Switch to% Share option above the tabs represents the data as a percentage of the total net output in that settlement period. Clicking on the Switch to MW/MWh returns the user to the data table of the MW data.
Clicking on Graph dynamically draws the data in graphical format. See below for information on the Graph functionality.
The column headings in the tables are to be understood as follows:
SD: Settlement date, given in the form YYYY-MM-DD.SP:
Settlement period, given by numbers 1 to 48, indicating each half-hour settlement period in a day where 1 is the period from midnight to 00:30, 2 from 00:30 to 01:00, etc.
The remaining columns are net MW for the Fuel Mix Types as described above for the given settlement period and settlement date.
Note that the data in the columns can be sorted. Clicking on a column heading reorders the data by magnitude (descending order), clicking again re-sorts the data in ascending order.
Tab 2. MWh per Day for a Month
This data shows the net quantities of energy generated (in megawatt hours, MWh) by the various technologies for each day in a month.
In the first instance, the present month will be displayed. Previous months can be viewed by clicking on the words “Previous Month”. The columns are as above, though without SP (Settlement Period). They may be sorted by clicking on the column headings. Clicking on any of the Settlement Dates transfers the user to the MW per settlement period visible at Tab 1 above for the selected settlement date.
By clicking on “Switch to % Share” option above the tabs shows the output for each day as a percentage of total output for all technologies. On the Share per Day page, clicking on “Switch to MW/MWh” option returns the page to the MWh view. Clicking on Graph in any of the windows will redraw the data in graphical form. See below for information on the Graph functionality.
Tab 3. MWh per Day for a Year
This data shows the net quantities of energy generated (in megawatt hours, MWh) by the various technologies for each day in a year and otherwise behaves in an analogous manner to Tab 2. The exception is that the Graph option is 'greyed out' and is not available because of the demands of plotting such a large volume of data.
Tab 4. GWh per Month
This version of the data shows the quantities of energy generated (in GWh) by the various technologies for each month in the years covered by the database.
The first column indicates the Month and the Year of the data in that row. The other column headings are to be understood as above, and are sortable in the same way. Clicking on any of the months in the first column displays all the data for the days in the selected month. Clicking on the “Switch to % Share” option shows the data as a percentage of total output in that month. Clicking on “Switch to MW/MWh” option on the percentage share page returns the user to the GWh view. Clicking on the word “Graph” redraws the data in graphical form. See below for information on the Graph functionality.
Tab 5. GWh Per Year
This version of the data shows the net quantities of energy generated (in GWh) by the various technologies for each year in the years currently covered by the database.
The first column indicates the year of the data in that row. The other column headings are to be understood as above, and are sortable in the same way.Clicking on any of the years in the first column displays all the data for the days in the selected year. It is possible to switch between GWh and percentage share of the total annual output using the Switch option above the tabs. Clicking on the word Graph redraws the data in graphical form. See below for information on the Graph functionality.
5. Graph Functionality
Clicking on the Graph option on any of the data table pages will produce a pop up window showing a stacked bar chart of the relevant quantities (of power or energy or percentage share) by fuel type in the relevant time period.
It is possible to tailor the graph in two ways:
- The number of fuel types plotted may be varied; and
- The order of the fuel types in the stacked bars may be altered.
To remove a particular fuel type from the graph:- Click to highlight the fuel type name in the box headed ‘Fuel Types in Graph’, then- Click the Exclude button (his will move that Fuel Type name to the table headed ‘Fuel Types not in Graph’), then- Click the ReDraw button to redraw the graph.
To move fuel types back into the graph, analogous steps are required to move the names from the ‘Fuel Types not in Graph’ list to the ‘Fuel Types in Graph’ in list, using the Include button. Users should not forget to select ReDraw to redraw the graph.
To re-order the fuel types within a plot:- Click to highlight the fuel type name in the ‘Fuel Types in Graph’ list, then- Click on either the Up or Down arrow buttons to move the highlighted fuel type up or down in the list, then- Click on the ReDraw button to redraw the graph
The Previous and Next buttons above the chart will plot the data for the previous or next day or month.
In order to return to the table of data underpinning the chart data visible, click on the ‘X’ close link on the top right of the pop-up window.