Geothermal and thermo-photovoltaics, how to combine this two technologies to cut down the consumption of agricultural greenhouses?
A group of scientists from South Korea’s Rural Development Administration has addressed that question, coming up with a new system that mixes thermo-photovoltaic technology and heat pumps.
Nowadays, the competitiveness and quality of agricultural production worldwide depend heavily on greenhouse crops. The latter are responsible annually for energy consumption ranging from 2 to 80 kWh/m2, depending on the technological complexity of the system, in the Mediterranean area alone. A value that can even reach 900 kWh/m2 in northern Europe.
How to ensure energy savings in greenhouses?
Low-enthalpy geothermal is a widely employed solution, including in South Korea, for winter and summer conditioning of greenhouses.
Therefore, the South Korean research team decided to combine geothermal heat pumps with thermal photovoltaic technology – a hybrid solution that allows both heat and electricity to be generated through solar radiation.
The Korean administration has developed a project divided into two macro-periods: in winter, geothermal probes and PVT collectors supply heat to the pump in order to produce hot water between 48 and 50°C.
From spring to fall, the heat produced by the panels is stored, in the underground phreatic layer, and preserved to warm the greenhouse in the cold season.
This hybrid solution, compared with the use of geothermal heat alone, increases energy savings by up to 20 percent through the installation of PVT panels on just 10 percent of the greenhouse area.
The development of this hybrid technology should promote research aimed at the combination of different energy solutions in order to promote a wide deployment of PVT panels in greenhouses and, more generally, in the agricultural sector.