There have been a lot of discussions, about how the energy crisis is affecting consumers. Recently, the impact of the price of energy on production has come up for discussion. Lassi Remes and Elina Vuori have written about it on Puutarha & Kauppa 14\/2022.<\/p>\n
On the Lepaa campus, we are cultivating tomatoes with assimilation light, from August to June. That is the same period as when our students are studying. In the period between November and 15th February natural light is not enough for cultivation. Lighting is also increasing the yield, outside of this period. The glasshouse, where tomatoes are growing, is built in 2007. Its gross area is 1\u202f300 m<\/span>\u1dbe<\/span>.<\/span><\/p>\n In Northern-European glasshouses, we are optimizing climate to increase yields of tomatoes. Temperature, air humidity, light- level and CO2, are controlled by climate computers all the time. We are harvesting tomatoes 70 kg\/m2\/y. Optimizing the climate is an important way to keep energy consumption \/tomato kg reasonably.<\/span><\/p>\n Total electricity consumption is 1\u202f000 MWH\/y, which is 770 kWh\/m<\/span>\u00b2<\/span> and 11 kWh\/kg. We are using wood chips for heating. Heat need varies year to year. Total heat consumption is between 600 \u2013 780 MWH\/y, which is 460 – 600 kWh\/m2 and 6,5 \u2013 8,5 kWh\/kg.<\/span><\/p>\n The following aspects of the greenhouse have been taken into account to reduce energy consumption:<\/span>\u00a0<\/span><\/p>\n There is less information currently available about energy consumption in vertical farming. In the literature, it has been reported that electricity consumption is 10 kWh\/kg of lettuce in the Finnish climate. It is also written, that in Japan total electricity consumption is about 2 kWh\/head of lettuce. Normally lettuce is harvested in Japan when the weight is 50\u201380 g. It was not mentioned, what was average weight in this study. These numbers are not widely tested in commercial vertical farms in Finland.<\/span><\/p>\n Heat conduction through the walls and ceiling is not a problem, because the vertical farm is well insulated. This cultivating method is very dependent on electricity and electricity price. All assimilation light is coming from LED lighting. During the heating season, waste heat can be used for other buildings\u2019 heating.<\/span><\/p>\n Electricity and natural gas prices have raised dramatically. Electricity prices are especially affecting Finnish glasshouse growers and vertical farming. Natural gas is not so important, because mainly glasshouses are heated by wood chips.\u00a0 Annual average electricity price in Nord Pool has been 2019 44 <\/span>\u20ac<\/span>\/MWh vat 0 %, 2020 28 <\/span>\u20ac<\/span>\/MWh vat 0 %, and 2021 72 <\/span>\u20ac<\/span>\/MWh vat 0 %.<\/span><\/p>\n \u00a0<\/span>Today (5.9.) daily average market price in Nord Pool FI- area is 366 <\/span>\u20ac<\/span>\/MWh vat 0 %. It is very likely, that when winter comes, the prices will rise. If the price is for example 400 <\/span>\u20ac<\/span>\/MWh vat 0 % higher than last year, it will have a great influence on production cost. If we need 11 kWh to produce 1 kg of tomatoes. 40 c\/kWh vat 0 % means that production costs are 4,4 <\/span>\u20ac<\/span>\/kg vat 0 % higher than earlier.<\/span><\/p>\n\n