You can use the gas from a waste landfill to produce electricity, then use the excess heat to warm greenhouses. This is the solution-based thinking that empowers SIA Getliņi Eko - one of the most advanced greenhouses in the Baltic region. On just over 1 hectare they grow tomatoes, cucumbers and potted flowers.
The Latvian company Getliņi manages the largest municipal solid waste landfills in the Baltic States. Recycling waste produces biogas, which is burned to produce electricity, which is then in turn sold to the grid. This process produces a lot of heat, and this heat is used to keep more than a hectare of greenhouses warm."Our attitude to environmental safety does not allow us to simply release the heat “into the air", they explained a couple of years ago. "That's how we got the idea to construct greenhouses and grow vegetables in them, since the heat we produce is relatively cheap."
And so has been done. The 5.5 m high greenhouses span a total area of 11.412m2. The plants grow in rock wool on gutters. The tomatoes are pollinated by bumblebees and IPM plays an important roll in the cultivation.
The company started their tomato cultivation in 2011 and has been innovating ever since. For example Getlini was one of the first greenhouses in the world that implemented LED lighting for cucumber growing.
Even though they create their own heat, they're still very strict on using it to the very best. “We are fighting for every half of a degree,” says the chief agronomist Guntars Strauts, “energy efficiency is our utmost concern.”
But you can’t optimize if you don’t measure, and this is where Aranet comes in. The company supplies sensors to help get better control over all of your greenhouse. "It is not enough to measure the temperature only in the center of the greenhouse with a climate box. This does not give you all the information you need to optimize costs", they explain. "It would be like taking the average patient temperature in a hospital. Twelve people with a fever and one dead. The average temperature is 36.6 °C (98 °F), which is perfect, but there is most definitely something wrong."
Aranet T/RH sensor with Convection Radiation Shield (left) and Aranet Weight sensor (right)
The same goes for a greenhouse. "You need to know what is going on everywhere, even in remote corners. Is one side colder? Did someone forget to close the window? You would never know if you were measuring only in the center."
The Aranet system offers flexibility by using wireless sensors for all measurements. "Put the sensors anywhere you want. Change the location as often as you need. That's how you can get a true oversight of your crop."
Aranet PAR sensor (left) and Aranet T/RH IP68 sensor (right)
Top, middle and bottom
Getliņi took it a step further. They now use the Aranet system to measure on 3 levels of the plant – top, middle and bottom. "Maybe the lower level is fine, but the tops of the tomato plants are overheating. Time to close the shades."
Plant weight is another important matter and it can also be measured in the same Aranet system, all in one dashboard. Aranet temperature sensors also measure relative humidity. "It’s very satisfying that it can be measured in the same Aranet system. All in one dashboard. You know how much water is coming in. You weigh the plants. You weigh the drainage. You get your biomass increase. You can be even more precise if you want. Aranet temperature sensors also measure relative humidity. You can use this to get the use vapor pressure defcit. Then calculate the evaporation and subtract it", the Aranet team it explains. "The ﬂexibility oﬀered by wireless sensors is immense. It takes time to comprehend all the applications. It takes time to escape the “wired” thinking. Time to break loose from the limitations of wires."