Benchmarking energy efficiency in vertical farming: Status and prospects

Energy efficiency is a critical yet challenging key performance indicator for vertical farming. The absence of a representative benchmark has thus far hindered comparison with traditional agricultural techniques. This paper aims to establish the current status and future prospects of energy efficiency in vertical farming by exploring the interplay between plant physiology and facility design and operation. Energy use is primarily driven by the need to control the physical environment for crop productivity and quality, resulting in specific lighting and climate control requirements. While artificial lighting technologies are advancing towards the current biological limits of photosynthesis, climate control is increasingly influenced by plant physiological activity. An analysis of studies focusing on energy use in vertical farming reveals a current specific energy consumption of 10–18 kWh kg−1 for lettuce production, corresponding to an energy use intensity of 850–1150 kWh m−2 year−1. Consideration of theoretical crop energy requirements, together with expected advances in equipment efficiency and operational control strategies, suggests a technical energy benchmark of 3.1–7.4 kWh kg−1. Despite projected gains in energy efficiency, the current economic costs and environmental impacts associated with increased electricity use highlight significant challenges to the short-term energy sustainability of vertical farming.