Benchmark UK offshore wind load factors seen rising to 57% in 2030: BEIS

London — Benchmark UK offshore wind load factors are seen rising to 57% in 2030 and 63% in 2040 by the Department of Business, Energy and Industrial Strategy.

The UK has a target of 40 GW of offshore wind capacity by 2030 which, using BEIS's current assumed offshore load factor of 47.3%, would generate 166 TWh/year.

"Larger turbines are expected to produce higher load factors for several reasons, most importantly that larger turbines can access higher winds due to their increased height, and that a wind farm with fewer, larger turbines has increased efficiency," BEIS said in an Aug. 24 report on electricity generation costs.

Current UK offshore wind capacity stands at 10.365 GW. Last year the sector produced 32 TWh, implying an average load factor of around 42%.

From 9 MW in 2020, the BEIS model assumes offshore turbine sizes of 12 MW in 2025, 15 MW in 2030, 17.5 MW in 2035 and 20 MW in 2040.

The ministry noted significant differences of opinion on the evolution of offshore turbine size, some stakeholders predicting 20 MW turbines as early as 2030, others doubting the feasibility of such large turbines.

"Our estimates represent a balanced consideration of multiple internal and external views," the ministry said.

Significant improvements in forecast offshore wind load factors contrasted with projected load factors for onshore wind and solar.

BEIS quoted fixed load factors across five-year projections from 2025 to 2040 of 34% for onshore wind and 11% for large-scale (5 MW-plus) solar.

Large solar cheapest

Nevertheless, large-scale solar and onshore wind emerged from the analysis as the cheapest generation technologies on a levelized cost of electricity basis -- the discounted lifetime cost of building and operating a generation asset expressed as a cost per unit.

Furthermore, the projections were made prior to the proposal in the CFD Allocation Round 4 Consultation for the inclusion of Pot 1 technologies -– onshore solar and wind.

"The potential impact of a competitive auction on onshore wind and large-scale solar PV costs will be reflected in future reports," BEIS said.

BEIS noted that September 2019's contract for difference auction cleared at GBP39.65/MWh ($52.1/MWh) and GBP41.61/MWh for offshore wind projects commissioning in 2023/4 and 2024/5, respectively.

These prices were lower than would be expected from the ministry's generic levelized costs because the Dogger Bank projects (which accounted for 5 GW of the 5.5 GW awarded) were significantly larger than BEIS's reference plant size assumption, leading to economies of scale, BEIS said.

Also, projects, situated far from shore, benefited from good wind resource as well as relatively shallow water depth, "leading to expected load factors significantly higher than average, without significantly higher construction costs," it said.

CCGT system benefits

While dispatchable technologies like combined cycle gas turbines "generally help to reduce system costs, they run at less than maximum load factors and therefore their levelized costs increase", BEIS said.

A set of enhanced LCOE cost scenarios, designed to reflect wider system costs, generally saw system savings outweigh load factor impacts for CCGTs, resulting in an overall cost reduction.

"Intermittent technologies (e.g. wind and solar) generally impose a wider system cost, which is more severe in scenarios with lower flexibility or a less diverse generation mix," BEIS said.

For 2030, for instance, CCGT H Class plants had an enhanced LCOE range of GBP40-82/MWh, versus GBP59-87/MWh for onshore wind, GBP48-66/MWh for large-scale solar, and GBP62-82/MWh for offshore wind.

UK LEVELIZED GENERATION COST ESTIMATES (GBP/MWh)

All Nth Of A Kind projects except CCGT+CCS, of which 2025/2030 estimates are First Of A Kind. All estimates in real 2018 prices.

Source: BEIS