Professor Cees Buisman, Head of a department in WUR NL, researcher and entrepreneur in microbial heat generation. He is a very busy man, so we had to meet over dinner in a restaurant called ‘the conversation’ in Wageningen.

He told about a gigantic natural heat installation which needed to be moved away fast and Jurrien promised to take it from him within only 10 days.

The silo is 9m high and 4m diameter. It is filled from the top, which is quite expensive. It’s emptied from the bottom by a [vijzel] turning screw, which did not work properly. It uses an 11 kW air blower to actively aerate the silo from below. From the top there is a spraying system.

There were many things not working very easily, it heated up very well, but the swimming pool wanted to get rit of it. After disconnecting everything according to the drawings, by accident the pool started draining because of the sensors giving off a wrong signal.

Together with her businesspartner Hans they tried to move it to Haarlem. The moving to Haarlem was very hard, but they managed to get it there. The plan is now to rebuild it and use it to heat a building with workshops.

Jurrien explains how it used to work and how they plan on changing it. The little available data only shows a maximum temperature of 37°C, so they are doubtful about the possibilities as a heat source. However the setup is very useful for experiments, so they plan on using it for doing several test projects. The main benefit of this setup is that it can be filled and emptied continuously. Sadly there is no insulation in the wall of the silo, it’s only a few cm of polyurethane.

Total volume is 80m3, idea is to start with filling in 20m3 batches. The plan is to do that with a mixture of water and wood chips that is pumped up by a big pump. On top the water will be drained in a special shaking sif and reused and the drained wood chips will fall into the silo by gravity.

Also three vertical heat exchangers will be added of 600 liter each to take the heat out.

There are now two different places in Haarlem interested in using the heat, but the question is wether this will be enough to finance it. Because of the ‘Haarlemmer Kweektuin’ is a place where also a large local community is involved Jurrien is looking into different business models.

Suggestions for extra financing are:

- selling the compost to local farmers or small businesses

- creating a membership for green waste management

- adding a social network, community building, by bringing people together you create value

- using it for researching projects in collaboration with the botanic gardens or universities

There should be an extra € 50.000 for getting the project up and running.