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Uitvouwen

title	Resource use

In the table below the consumption of different sources resources is compared.

Greenhouses can achieve net negative electricity use
Scenario 1.5 (LED + CHP) has a net negative electricity use. This mean that on an annual basis the greenhouse sells more electricity to the grid than in buys. This is the result of a higher efficiency of LEDs and increased CHP operation for heating, compared with HPS-lamps.
Illumination results in a higher water use
The higher greenhouse temperatures in combination with higher PAR sums result in a higher water use for illuminated scenarios.
HPS results in a higher water use than LEDs
When using LEDs instead of HPS, the water use is reduced. LEDs does not emit Near-InfraRed radiation to the crop, resulting in lower crop temperatures and consequently less transpiration.

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The overall performance is expressed in terms of environmental and economical feasibility and sustainability and compared in the Table below.

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Conclusions

Scenario with lowest energy use
Scenario 1.1 with no illumination requires the lowest energy use. Using illumination increases both energy use, variable costs and crop production significantly.
Scenario with lowest CO2 emissions in future energy net
Scenario 1.2 (HPS without CHP) has the highest electricity consumption, but the lowest CO2 emissions. In these scenarios it was assumed that the electricity from the grid stems from renewable sources. If the average CO2 emission of electricity in the public grid of the Netherlands (350 gram per kWh in the early 2020s) is assumed, the Scenario 1.2 becomes the greenhouse with the highest CO2-emission: 51.5+234.6 x 0.350 = 134 kg/(m² yr). The dominant share of emissions is then produced elsewhere.
Scenarios with lowest CO2 emissions in current energy net
Assigning this 350 gram CO2 - emission to public grid electricity would mean that the CO2 emission associated with Scenario 1.4 would increase with 87.1 x 0.35 = 20 kg/(m² yr), whereas the CO2 emissions associated with Scenario 1.5 would decrease by 32.7 x 0.35=11.4 kg/(m² yr).
This shows that LEDs always outperform HPS lighting.

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