A shift in energy distribution can significantly reduce the carbon footprint of a cucumber crop. That conclusion researchers draw after an exposed cucumber crop during the winter of 2023-2024 at Botany. The trial, which took place from October 2023 to March 2024, focused on further reducing the energy input per kilogram of cucumber.
Frank Huijs from Botany shares on Kas als Energiebron at the final report, "During the 2022 - 2023 cultivation, calculations to the assimilate balance showed that a different balance in energy input - more kWh's for lighting and fewer cubic meters of gas for heat - can further reduce the carbon footprint of a kilogram of cucumber. During this cultivation, we aimed for electricity consumption of 140 kWh/m² for lighting (14 m³/m² of natural gas equivalents for electricity) and 6 m³/m² of gas for (pipe) heat, compared to 100 kWh/m² (10 m³/m² of natural gas equivalents for electricity) and 10 m³/m² during the 2022 - 2023 cultivation. Both years thus revolved around an overall equal energy input: 20 m³/m² of natural gas equivalents.
Less evaporation
Because of the greenhouse's good insulation, evaporation is the biggest loss on the greenhouse's energy balance. By closely monitoring evaporation, it can be reduced if necessary to further minimize energy consumption. Here, the target was a relative evaporation of less than 100 ml/mol PAR. Indeed, when evaporation is higher, (above 120 ml/mol PAR), additional lighting no longer contributes positively to greenhouse heating because the additional lighting energy compared to the 2022 - 2023 crop is converted entirely into evaporation."
By using more energy for lighting (140 kWh/m²) and less for heat (6 m³/m²), the total energy input remained the same as the 2022-2023 crop (20 m³/m² of natural gas equivalents), but more energy was used for lighting and less energy for (tube) heat. Production was 48.8 kg/m², an increase of 45% compared to 2022-2023, while the energy required per kilogram of cucumber was 19% lower.
Source: Kas als Energiebron