Buyers of Swiss vegetables would like to see greenhouses no longer heated with fossil fuels in the future. The nursery SwissPlant LLC has been heating with wood from the region since this winter.
Migros announced at the beginning of the year that from 2025 it will only sell Swiss vegetables from fossil fuel-free heated greenhouses. Young plant producer SwissPlant Gmbh in Müntschemier has been heating its greenhouses largely CO2-neutral with wood chips since this autumn.
Company owner Martin Löffel and his son Sandro started planning the conversion of the energy source from oil to wood chips two years ago. Together with a planning office and DM Energieberatung AG, which calculated the energy requirements. "For ecological reasons, we decided on the CO2-neutral wood chips," explains Martin Löffel. Compared to oil heating, the initial investment is about four times higher. But over the years, the costs would balance out again compared to oil, he says. The annual costs for the procurement of raw materials are halved compared to the past because wood chips are cheaper than oil.
For the same heating capacity, Sandro Löffel reckons with an annual saving of around 190,000 litres of heating oil, or 123 tonnes of CO2. For the CO2 saved, they can trade certificates as compensation, which are currently worth around 100 Swiss francs per tonne. Around 85 percent of the heat requirement of the 3.2 hectares of heated greenhouse area will in future be generated from wood chips in Müntschemier. "Generating all this energy with wood chips would not have been economical," explains Martin Löffel. The two previous oil heating systems will therefore be left standing and used to cover the energy peaks.
Heat is temporarily stored
The woodchip heating system with a capacity of 1200 kilowatts was designed and installed by Schmid Energy from Eschlikon. This required the construction of a new building, with an additional store for 300 m3 of chips and two 100,000-liter heat storage tanks over 11 meters high, in which the wood heat produced as base load energy is temporarily stored. Including new buildings, the plant cost a total of around CHF 1.5 million.
Multi-year supply contract
The wood chips come from the region, and this process is contractually regulated. For this purpose, a supply contract of several years was concluded with a company specialising in the trade with wood chips, which ensures the supply. During the full-load period in the spring months, 40 m3 of wood chips are needed daily. However, only the heat actually supplied is invoiced, explains Sandro Löffel. This is because the heat output varies greatly depending on the wood. The prices are fixed for five years.
With the environmentally friendly heating system, the young plant company is meeting the stricter requirements for energy sources used to heat greenhouses, which have already been set by customers and are expected to become even stricter in the future. "Migros suppliers now know that our young plants have already been produced in a CO2-neutral way," says Martin Löffel.