Sjaak Twisk has a Demeter certificate besides his organic certificate. In the summer his cows graze in the adjoining nature reserve. In the winter they are housed in the stables which have recently been rebuilt and have solar cells on the roof. These solar cells provide a sizeable chunk of the energy used on the farm. Sjaak Twisk is specialised in the long term (mechanical) storage of onions and shallots, which requires quite a bit of energy.
Weather permitting the onions and shallots are dried on the fields. They are then transferred to the stores and cooled back. Temperature and humidity are monitored. While in store the onions are regularly checked with regard to internal growth and other parameters.