Cooling and waste heat recovery
The pre-cooler consists of a plate heat exchanger through which milk is passed. Tap water or groundwater flows in the opposite direction, reducing the temperature of the milk in the pre-cooler from 37°C to about 18°C. The slightly warmed water discharged from this system is used as drinking water for the cows at Jan Borgman’s photon farm. This pre-cooler produces energy savings of about 40% in the cooling of milk in the milk cooling tank at 't Spieker in Vierakker.
Photograph of the milk cooling tank.
Waste heat recovery
A heat pump cools the milk by extracting energy, which is then dissipated into water or the surrounding air. Without a pre-cooler, cooling two litres of warm milk would produce about one litre of hot water (55°C). The combined use of pre-cooling and waste heat recovery produces about one litre of hot water (55°C) for each four litres of warm milk. The Photon Farmer system uses this hot water to heat the solar water heater’s storage tank. This delivers significant savings in terms of the energy costs of heating water.
"We fully expect that people of our generation will live to see the day when renewable energy passes the break-even point in terms of its cost price and yield price” says Jan Borgman.