Generators subsidised by the Renewables Obligation (RO), are listed in the section entitled Green Generators - Large Scale. The RO came into force in 2002 and is an obligation on UK electricity suppliers (not generators) to source an increasing proportion of their electricity from renewable sources or pay a penalty, referred to as the ‘buy-out price’. The legislation covering the RO has been revised a number of times and is complex. For a detailed explanation of its history and current status, the DECC and Ofgem websites provide useful documentation.
In summary, the generation of renewable electricity is authenticated by Renewables Obligation Certificates (ROC) issued by Ofgem. Until April 2009, one ROC was issued for each megawatt hour (MWh) of green electricity, but from April 2009 the different renewable technologies have been ‘banded’, with different technologies receiving different numbers of ROCs per MWh.
Banding of ROCs
The following table shows the latest bandings for England Scotland and Wales. For more details, and details of the bandings for renewable energy generators in Northern Ireland, see Ofgem’s guidance for generators
Table 1: Renewable Technologies and Renewable Obligation Certificates per MWh, 2013. Source: DECC / Ofgem
| Technology | pre 2013 | 2013/2014 | 2014/2015 | 2015/2016 | 2016/2017 |
| Anaerobic Digestion | 2 | 2 | 2 | 1.9 | 1.8 |
| Co-firing high range | New | 0.7 | 0.9 | 0.9 | 0.9 |
| Co-firing high range + CHP * | New | 1.2 | 1.4 | 1.4 | 1.4 |
| Co-firing low range | New | 0.3 | 0.3 | 0.5 | 0.5 |
| Co-firing low range + CHP* | New | 0.8 | 0.8 | 1 | 1 |
| Co-firing mid range | New | 0.6 | 0.6 | 0.6 | 0.6 |
| Co-firing mid range + CHP* | New | 1.1 | 1.1 | 1.1 | 1.1 |
| Co-firing of Biomass | 0.5 | 0 | 0 | 0 | 0 |
| Co-firing of biomass with CHP | 1 | 0 | 0 | 0 | 0 |
| Co-firing of energy crops | 1 | 0 | 0 | 0 | 0 |
| Co-firing of energy crops with CHP | 1.5 | 0 | 0 | 0 | 0 |
| Co-firing of regular bioliquid | 0.5 | 0.3 | 0.3 | 0.5 | 0.5 |
| Co-firing of regular bioliquid + CHP* | 1 | 0.8 | 0.8 | 1 | 1 |
| Co-firing of relevant energy crops low range | New | 0.8 | 0.8 | 1 | 1 |
| Co-firing of relevant energy crops low range + CHP | New | 1.3 | 1.3 | 1.5 | 1.5 |
| Landfill Gas | 0.25 | 0 | 0 | 0 | 0 |
| Landfill Gas - closed sites | New | 0.2 | 0.2 | 0.2 | 0.2 |
| Landfill Gas - heat recovery | New | 0.1 | 0.1 | 0.1 | 0.1 |
| Sewage Gas | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 |
| Conversion | 1 | 1 | 1 | 1 | |
| Conversion + CHP | 1.5 | 1.5 | 1.5 | 1.5 | |
| Dedicated biomass | 1.5 | 1.5 | 1.5 | 1.5 | 1.4 |
| Dedicated biomass with CHP | 2 | 2 | 2 | 1.9 | 1.8 |
| Dedicated energy crops | 2 | 2 | 2 | 1.9 | 1.8 |
| Dedicated energy crops with CHP | 2 | ||||
| Energy from Waste with CHP | 1 | 1 | 1 | 1 | 1 |
| Advanced gasification/pyrolysis | 2 | 2 | 2 | 1.9 | 1.8 |
| Standard gasification/pyrolysis | 1 | 2 | 2 | 1.9 | 1.8 |
| Geopressure | 1 | 1 | 1 | 1 | 1 |
| Geothermal | 2 | 2 | 2 | 1.9 | 1.8 |
| Hydroelectric power - except Scotland | 1 | 0.7 | 0.7 | 0.7 | 0.7 |
| Hydroelectric power - Scotland | 1 | 1 | 1 | 1 | 1 |
| Enhanced tidal stream (Scotland only) | 3 | ||||
| Tidal barrage (< 1GW DNC) | 2 | 2 | 2 | 1.9 | 1.8 |
| Tidal lagoon (<1gw dnc="" td=""> | 2 | 2 | 2 | 1.9 | 1.8 |
| Tidal Stream < 30MW | 2 | 5 | 5 | 5 | 5 |
| Enhanced wave (Scotland only) | 5 | 5 | 5 | 5 | 5 |
| Wave | 2 | 2 | 2 | 2 | 2 |
| Solar photovoltaic | 2 | ||||
| Solar photovoltaic - building mounted | New | 1.7 | 1.6 | 1.5 | 1.4 |
| Solar photovoltaic - ground mounted | New | 1.6 | 1.4 | 1.3 | 1.2 |
| Offshore wind** | 2 | 2 | 2 | 1.9 | 1.8 |
| Onshore wind | 1 | 0.9 | 0.9 | 0.9 | 0.9 |
| Microgeneration (<=50kW DNC) | 2 | 2 | 2 | 1.9 | 1.8 |
* Conditional upon whether support is available via the RHI
** Note that offshore wind farms accredited prior to 1 April 2007 receive 1 ROC per MWh, between 1 April 2007 and 1 April 2010, 1.5 ROCs per MWh and after 1 April 2010 are awarded two ROCs per MWh.
Growth in the Renewables Obligation
The required proportion of all electricity supplied to consumers that must be met from renewable sources is determined by DECC, and up until March 2010, when banding was introduced, was a simple percentage of all electricity supplied. At that point the proportions were changed to an obligation to present a specified number of ROCs per 100 MWhs of electricity supplied, as is shown in the following table.
Table 2: Size of Renewable Obligation. Source: Ofgem.
| End of RO period | RO as a Proportion of Electricity Supplied | |
| 31-Mar-03 | 3.0 | % |
| 31-Mar-04 | 4.3 | % |
| 31-Mar-05 | 4.9 | % |
| 31-Mar-06 | 5.5 | % |
| 31-Mar-07 | 6.7 | % |
| 31-Mar-08 | 7.9 | % |
| 31-Mar-09 | 9.1 | % |
| 31-Mar-10 | 9.7 | % |
| 31-Mar-11 | 11.1 | ROCs per 100 MWh |
| 31-Mar-12 | 12.4 | ROCs per 100 MWh |
| 31-Mar-13 | 15.8 | ROCs per 100 MWh |
| 31-Mar-14 | 20.6 | ROCs per 100 MWh |
| 31-Mar-15 | 24.4 | ROCs per 100 MWh |
To put these figures into context, the current level of electricity supplied per annum is approximately 310 TWh. Thus, the 2011 Obligation of 11.1 ROCs per 100 MWh of supplied electricity implies an Obligation of approximately 38.4 million ROCs.
If this requirement was satisfied by technologies receiving 2 ROCs per MWh then the obligation would be met by 19 TWh of renewable electricity or 6% of the whole. Conversely, if the Obligation was met from technologies receiving 0.25 ROCs per MWh, then the Obligation would be met by 154 TWh of renewable electricity or 50% of all electricity. In practice the Obligation is met by a mix of technologies in the different bands.
Value of Renewable Obligation Certificates
ROCs have an economic value made up of two parts. The first is the so-called ‘Buy-out’ price, which is effectively the saved penalty value of failing to meet the Obligation. This was set initially at £30 per MWh or per ROC, and has increased annually in line with the Retail Price Index (RPI). In addition, ROCs have a value representing the fact that the fines paid by any suppliers who fail to meet the obligation are distributed to other suppliers according to the ROCs produced. Thus, when a generator sells a ROC the price obtained reflects both the Buy-Out price, and the expected distribution of fines. The following table summarises this matter over the life of the scheme.
| Period | Buy Out Price per ROC | Recycle Payment per ROC | Total ROC value |
| 2002/2003 | £30.00 | £15.94 | £45.94 |
| 2003/2004 | £30.51 | £22.92 | £53.43 |
| 2004/2005 | £31.39 | £13.66 | £45.05 |
| 2005/2006 | £32.33 | £10.21 | £42.54 |
| 2006/2007 | £33.24 | £16.04 | £49.28 |
| 2007/2008 | £34.30 | £18.65 | £52.95 |
| 2008/2009 | £35.76 | £18.61 | £54.37 |
| 2009/2010 | £37.19 | £15.17 | £52.36 |
| 2010/2011 | £36.99 | £14.35 | £51.34 |
| 2011/2012 | £38.69 | £ 3.58 | £42.27 |
| 2012/2013 | £40.71 | £ 3.59 | £44.30 |
| 2013/2014 | £42.02 |
Each year Ofgem reports on the Buy-out price and the recycle payments for the previous RO period.
ROC data in REF online database:
Main Page
Ofgem publishes raw details of the ROCs issued in each month to each accredited RO generating station. This data is collected and processed by REF to produce a user-friendly summary of the performance of these generators. This information that is published free of charge on the website along with additional data.
The first page of the database lists all the generators for which we have data, initially in descending order of annual MWh generated. The heading of this list provides a count of generators in the database, and gives the sum of the installed capacity. It should be noted that this installed capacity figure does not include the installed capacity of co-firing coal power stations because this would distort the figures and render less them informative.
The header also tells the user when the database was last updated. By and large, the REF RO database is three months in arrears, due to the time taken by Ofgem to produce the base data that we reprocess. We attempt to update the database on a monthly basis.
Clicking on the heading cell of any column sorts the data by that column. A second click reverses the order. Hovering the pointer over a heading cell provides a short note describing the data in that column. We describe these fields below.
RID: This field gives the unique identifier of the renewable generator as issued by Ofgem. Clicking on any single RID takes the viewer to a new page of data relating to that specific generator (described in detail below).
Generator Name: Users should note that in most cases this is the name given to the generator by Ofgem, but in some instances REF has corrected or expanded the reference to include the common name for a site, in order to help users find the information they are seeking. For example, Ofgem refer to the second Swaffham turbine as ‘Lowick Beacon’, but the REF database uses the widely known name of ‘Swaffham II’. Similarly, High Volts, Harehill and Holmside wind farms are known colloquially as the ‘3H’ wind farms, and the REF database adds the term 3H to all of their names to aid identification.
Country: This is determined by Ofgem and is one of England, Wales, Scotland, Northern Ireland
Installed Capacity in kW. This is also derived from Ofgem records, but is occasionally doubtful, either because it does not tally with the generator size as recorded in other sources, or because the load factors derived from it are implausible. In some cases, REF has corrected these values using authoritative sources (for example developer websites), and is continually reviewing this data to improve the accuracy of the overall database. Note that the installed capacity can change over time as sites are modified. The capacity on the main page is the latest available data from Ofgem.
Technology Group and Subgroup: These fields assign the site to a technology category at both a high and lower level of granularity. For example, ‘Wind’ is a high level descriptor, with ‘On-shore’ and ‘Offshore’ as lower level sub groups descriptors.
CHP: This indicator is only relevant to thermal generators, and will be set at ‘Y’ (i.e. Yes) if the generator provides Combined Heat and Power (CHP).
Accreditation date: This is the date from which Ofgem accorded the generator accredited status and from which the Renewables Obligation subsidy lifetime applies.
Rolling Load Factor: This is the rolling annual load factor for the generator which is calculated by REF as follows. Monthly load factors are calculated by determining the actual energy (MWh) generated as a proportion of the total theoretical maximum energy generation based on the appropriate installed capacity for that month. The ‘Rolling Load Factor’ is the average of all consecutive 12 month periods of generation data. For example, if there were 18 months of generation data, there would be 7 consecutive 12 month sets of annual MWh from which we could calculate the Rolling Load Factor. (See, also, ‘Annual Load Factor’ below.)
Annual Load Factor: This is calculated by REF and is the load factor for the most recent available 12 months of data. It is useful to compare the ‘Rolling Load Factor’ and the ‘Annual Load Factor’. If there is a significant difference between the two it can indicate a variation in output over time implying past or present problems with the generator.
Latest ROC date: This gives the date of the latest available month of ROC data for the generator.
Accessing Detailed Data per Generator
By clicking on the RID number the user will be transferred to a new page giving further data, which is separated into four areas, accessible by clicking on the tabs across the page: “General”; “Map”; “Summary”; and “Graph”, while the Generator Name and RID appears at the top of the page.
General: This gives extra data, where it is available, on the location and type of the generator. Some of this information is derived from Ofgem, but much is the result of further research by REF, work that is continually being updated, corrected, and enriched.
Map: Where REF has been able to locate the generator, a Google Map view is provided.
Summary: The annual energy generation (MWh) and Renewable Obligation Certificates (ROCs) claimed in each Renewable Obligation year (which runs from April to March) is listed, together with the annual load factor. The rolling load factor is also provided at the bottom of the table.
Graph: This presents in a graphical format the monthly load factors achieved and the monthly energy generated (MWh). Due to the width of the chart it is necessary to use the horizontal scroll bar to see all the available years of data.
Searching the ROC Data
Clicking on the ‘Search’ option above the lists of ROC generators takes the user to a page where multiple search parameters can be specified to filter the main generator list. This is a very powerful tool, offering the user the ability to find generators by RID, Generator Name, Country, Installed capacity (kWs), Technology Group, Technology Code, Accreditation Date, Location, CHP, Number of Turbines, Turbine Model, Hub Height (in metres), Blade Diameter (in metres), Developer, Operator, Site Owner, and Postcode. The user should note that selected combinations of these parameters are possible.
For example, the user can request all Landfill Gas generators with a capacity greater than or equal to 1,000 kWs in England; or all onshore wind farms with exactly 12 turbines.The search results are returned in table form, as described above.
The user should also be aware that fragments of text may be entered in the name search field. For example, inputting the fragment ‘Bradwo’, into the Generator Name box and clicking on search will return the two parts of the wind farm, popularly known as ‘Bradworthy’. Similarly, entering the letters “view” into the search field will return all generators with that combination somewhere in the full name.