A closed greenhouse saves energy, water, soil and nutrients.
For stratified cultivation the planned closed wooden greenhouse is much more efficient than the traditional glass greenhouse based on the experimental hall built in Piikkiö in April. About it said Aalto University on Monday.
In Finland, greenhouse production accounts for about one-fifth of agricultural energy consumption. Compared to a traditional glass greenhouse, a new type of wood greenhouse uses up to 95 percent less water in year-round cultivation.
“Apart from water in plants, no other water leaves the greenhouse,” greenhouse developer, doctoral student Pasi Herranen comments to Aalto University in April.
In the greenhouse so-called stratified farming has been utilized.
It has many layers of cultivation and the greenhouse is closed, meaning that its nutrients, chemicals or water do not leave the space. Because of this, the farming method uses significantly less resources.
Due to the isolation of the farm, hundreds can be harvested during the year, and the overlapping layers can increase the yields by several times a year.
Layered farming is not yet widespread because it is expensive and technically more demanding, and in addition the sector is new.
Birch plywood wall and ceiling elements have been built into the wood greenhouse, which have been vacuum-dried.
The wood has been vacuum dried for more than a hundred years, but the entire wall element has been dried in Herranen’s wood greenhouse.
Between the plywood boards, he developed a wooden interior structure, for which Aalto University has applied for patent protection in six countries in addition to European countries.
The elements are covered with aluminum, which reflects light to the plants. The greenhouse does not need any heating at all, as all the heat comes from the LED lamps. About four percent of the energy in LEDs goes to plant growth and the rest of the plants convert into heat.
Bridge at the moment, Herrane’s woody greenhouse uses about half as much energy as a conventional glasshouse.
According to him, in the future, layer farming can be built more and more upwards, which will increase the amount of heat available.
“According to my calculations, up to 90 percent of the energy used for lighting could then be fed into the district grid as thermal energy, ie greenhouses would become heat producers,” Herranen told Aalto University.
In layer culture no natural light is used at all. Herranen tells her the reason is either too much or too little sun, which in the case of natural light could not be controlled in the same way.
In a hot climate, energy goes to cooling instead of heating. Greenhouse doors have to be opened, which means that the carbon dioxide needed to connect the plants escapes and the yields become smaller.
According to Herranen, for this reason, for example, cucumber yields in Finland are half as low in summer as in winter.
“Vertical farming is on the rise in the world because it can also be used to grow food in places that are too hot for traditional greenhouses,” he says.
Layered farming could produce food in really cold, hot or dry conditions precisely because of the isolation of the farm.
So far, layer farming has been used mainly for lettuce, but according to Herranen, the method could be extended to more nutritious plants as well.
To the spike the built 65-square-meter greenhouse has proven to be a success. The dense plywood elements are so durable that they could also be used for construction like concrete.
In April, it was estimated that the invention could have a market worth up to billions.
Next, Herranen plans to build a ten times larger greenhouse for Aalto University in Otaniemi. The future project aims to show how the technology would work on a larger scale as well.
In Otaniemi, it is planned to try a greenhouse as a heat producer. Waste heat would be transferred to Otaniemi’s new heating network.
“In this way, it will be possible to grow vegetables negatively in the future.”
Read more: Can a revolutionary way of farming solve the world’s food crises? Finland has become a pioneer in vertical culture, which looks futuristic