Electricity solutions for specific needs: Cultivation with grow lighting in greenhouses uses a lot of electricity for the needs of growing


05.05.2021 at 11:58
In Finland, the growing season is naturally short, but by using grow lighting, Finnish crops can be produced year round. Lighting that provides strength to growth is the biggest electricity user in a greenhouse, and annual usage can easily reach tens of thousands of megawatt hours. Electricity for the Juntti market garden will soon be delivered via their own Caruna primary substation

The rise of green values and the strong increase in diets in which Finnish, clean vegetables are emphasised, drive the development of market gardens toward larger units. As production volumes increase, more electricity is also consumed. Own primary substation can offer a solution that secures sufficient electricity supply and offers room for growth.

"That is the point where the companies start thinking about what the smartest way would be to implement electricity distribution to greenhouses so that it serves the needs of the garden long into the future. The lines of a normal 20 kV distribution network can become too small," says Caruna's Key Account Manager Lassi Vuokko.

It was almost exactly two years ago that this consideration became current also in Puutarha Timo Juntti Oy, a market garden that cultivates cucumber in their greenhouses in Kaarina in the south-westerly coast of Finland. The company made the most significant investment in its 60-year history, and Caruna was involved in it as a partner.

"We have two hectares of surface area that is lit around the clock as well as our own transformers, and therefore also our own usage supervisor. He notified Caruna of our need for a higher power level. As a solution, they first proposed and then started planning our own primary substation, which will be completed in July 2020. The construction works are still being carried out," says entrepreneur Tero Juntti.

This kind of a partnership between an electricity distributor and customer serves not only the needs of the customer but also the continuous development of the entire network.

Aerial photo of Puutarha Timo Juntti Oy's greenhouses.

Natural flexibility in the electricity demand of a greenhouse

In large market gardens, cultivation takes place throughout the year. However, electricity consumption is heaviest during dark. That makes a greenhouse a natural leveller of electricity network usage and a good pair for example for renewable solar or wind power that is fed into the electricity network in accordance with the conditions.

"We use the most amount of electricity when it is otherwise used less. Finnish greenhouses are also an important part of a more extensive Nordic disturbance reserve. It means that if there is a big disturbance somewhere in the electricity network, the power of our lighting falls within seconds," Tero Juntti says.

Juntti's greenhouses are lit by sodium-vapor lamps. Their overall efficiency is good, and it is further improved by the plants benefitting from their heat radiation. Indeed, lights clearly consume the most amount of electricity in a greenhouse. In addition, general electricity is consumed by motors, packing machines as well as industrial heat pumps used for cooling.

The spectra of low-consumption LED lamps could also be adjusted precisely to the needs of a plant, but they lack heat radiation. Indeed, the word of the day is hybrid lighting in which the lacking spectrum of heat radiating sodium-vapor lamps is complemented with LEDs.

"We started cultivation with grow lighting in the 1980s. At the time, electricity consumption rose dramatically, and it has been growing quite steadily. Annual usage is in tens of thousands of megawatt hours," estimates Tero Juntti.

When our own primary substation is soon completed, the future electricity needs of Juntti market garden will be well looked after also with a view to possible expansion.

"This primary substation and the 10 megawatt transformer are sufficient to cover the needs of the coming years. After that, we may need to consider a larger transformer or add another transformer," says Juntti.

Own contact person brings additional value to a customer in infrastructure projects

The Juntti market garden has its own contact person with whom the primary substation construction project has been advanced. According to Tero Juntti, this has been a very good thing. From the perspective of a large customer, the most efficient way is to make long-term plans relating to electricity distribution and contracts, charting and anticipating the needs for future growth or change.

"We have been working together on this project with a good understanding, and when we have concluded contracts relating to the project, the contact person has come here to meet with us and we have carefully gone through the papers together over a cup of coffee. I have only positive things to say about that," praises Juntti.

Greenhouses are an important large customer segment for Caruna. Southwest Finland has traditionally been a strong area for market gardens. Another specific area is also the Närpiö region in South Ostrobothnia where Caruna's network serves several dozens of greenhouses of various sizes. Lassi Vuokko praises the entrepreneurs' proactive attitude in connection-related matters.

"Our most recent contract was concluded in March, and in the last year, a connection contract into a 110 kilovolt network has been made for three greenhouses. So, demand has been quite good," Vuokko says satisfied.


Images: Puutarha Timo Juntti Oy

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