Waste Power, More Produce: Lettuce Growth Jumps 24%

Surplus renewable electricity could be used to increase domestic food production after an early-stage UK horticulture trial delivered a 24% rise in lettuce biomass.

The ADOPT-funded Green Light Project is investigating whether horticultural businesses could act as flexible users of excess renewable energy, drawing electricity when generation is high but demand on the national grid is low.

Initial spring trials at hot-house lettuce grower Forshaws Salads recorded a 24% increase in biomass between April and May when supplementary lighting was introduced.

The findings raise the prospect of converting renewable electricity that might otherwise be curtailed into additional crop production, potentially improving productivity for growers and supporting a more efficient energy system.

Project Facilitator and Technical Lead Henry Birt said: “At times, the UK generates more renewable electricity than the grid can use. Rather than curtailing that generation, we’re investigating whether some of the surplus energy could be redirected into productive agricultural use.

“The question we’re trying to answer is whether growers can use those periods of excess renewable generation to increase crop production sufficiently to make the model commercially viable.”

The project is testing the use of surplus renewable electricity to power supplementary lighting in commercial horticulture, particularly during periods when lower natural light restricts production.

Researchers ultimately hope the approach could enable growers to achieve additional crop cycles and potentially reduce the UK’s reliance on imported produce during the winter months.

Birt said the early findings were particularly encouraging because the increase was achieved during spring, when daylight hours were already rising.

“The result is particularly encouraging because it was achieved at a time of year when daylight hours are already increasing, suggesting there may be greater potential during the autumn and winter growing periods,” he explained.

“The most important measure for commercial lettuce growers is speed of production. Increased biomass is an important indicator crops could reach harvest sooner, helping growers increase productivity through a higher number of crop cycles per year.”

Forshaws Salads Technical Director Jayne Harris said further work would be needed to examine the impact on crop quality as well as yield.

“These are interesting initial results from the Green Light Project. While we have seen an increase in a biomass in the first crop cycle, more work is needed to see how agronomic quality may also be affected,” she said.

“We are now looking to the autumn and winter seasons to see maximal impact, when we are expecting to see a larger impact as the days shorten. It is great to be contributing to how future renewable deployment can support food security in the UK.”

The next phase of the project will assess performance across different seasons, crops and growing conditions. Researchers will also examine commercial viability, infrastructure requirements, potential carbon benefits and whether increased plant growth could contribute additional carbon sequestration.

“If the concept proves successful, we believe growers could benefit from additional winter production, improved annual productivity and access to new revenue opportunities linked to demand-side response energy markets,” Birt added.

“The project could also provide a blueprint for using surplus renewable electricity to support domestic food production while helping balance the UK’s increasingly renewable energy system.”

Further trial results are due to be published later this year, with a full project report expected in 2027.