Value chain · CLM-0782
In plain terms
UK rules limit the overhead line between a generating unit and the grid to 5 km for units producing at least 2000 gigawatt-hours a year and 20 km otherwise. A 2 gigawatt plant counted as one unit would cross that threshold even if it ran only about 11 per cent of the time, but the rules define a generating unit as any apparatus which produces electricity, and counted that way a receiving site made of many converters would fall under the 20 km limit. Which reading applies is not settled.
The claim as recorded
GB SQSS clause 2.7 limits the maximum length of overhead line in a generation circuit to 5 km for generating units of expected annual energy output greater than or equal to 2000 GWh and to 20 km otherwise, and, by the knowledge base's arithmetic, a 2000 MW plant taken as a whole reaches 2000 GWh per year at an annual load factor of 11.42 per cent; whether the 5 km limit binds a 2 GW rectenna is an open reading of the standard, because it does so only if expected annual energy output is assessed on the plant as a whole, while the standard defines an onshore generating unit as any apparatus which produces electricity, and if output is assessed per such unit the 20 km limit applies instead.
Scope and limits
This constrains overhead line length only. It says nothing about underground cable length, which clause 2.7 does not address in the text read. It is not a statement that any particular site is unsuitable, and it does not quantify the cost of siting nearer the network or of undergrounding.
What it assumes
That the rectenna is treated as one or more "generating units ... directly connected to the onshore transmission system" under clause 2.7, and that "expected annual energy output" is assessed on the plant as a whole rather than per generation circuit. The latter is a real ambiguity: if the 2 GW is split across two circuits per CLM-0781, each circuit's share still exceeds 2000 GWh at any load factor above about 23 per cent, so the conclusion is unchanged in practice. A further alternative reverses the answer: because the standard defines an onshore generating unit as any apparatus which produces electricity, and a power park module as a collection of such units, expected annual energy output may be assessed per converter unit, in which case no unit reaches 2000 GWh and the 20 km limit of clause 2.7.2 applies.
Where it comes from
This is the project's own working, shown in full:
Verbatim, SRC-238 clause 2.7: "The maximum length of overhead line connections in a generation circuit for generating units which are directly connected to the onshore transmission system shall not exceed: 2.7.1 5km for generating units of expected annual energy output greater than or equal to 2000GWh; otherwise 2.7.2 20km ." Arithmetic in full: a 2000 MW plant at 100 per cent load factor produces 2000 MW x 8760 h = 17,520,000 MWh = 17,520 GWh per year. The load factor at which annual output equals 2000 GWh is 2000 / 17,520 = 0.11416, that is 11.42 per cent. Definitions, verbatim, SRC-238 PDF p.70: Onshore Generating Unit, "Any apparatus which produces electricity including a synchronous generating unit and non-synchronous generating unit but excluding an offshore generating unit."; Onshore Power Park Module, "A collection of non-synchronous generating units (registered as a power park module under the Planning Code in the Grid Code) that are powered by an intermittent power source, joined together by a system with a single point of electrical connection to the onshore transmission system".
Basis: SQSS clause 2.7 overhead line length limit, triggered on expected annual energy output in GWh; derived load-factor threshold for a 2000 MW plant
Related records
- Answers question
- QST-012 not published in this release
Cite this
energyaperture.com/c/clm-0782
CLM-0782, Energy Aperture, as of 2026-09-04.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-238
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