Due to the availability of natural gas sources large parts of the province Southern Holland have changed .During the 1960's into a sea of glass. The main source for natural gas, a gas field in Slochteren (situated in Groningen province), was easily accessible, which resulted in very low prices for natural gas. This almost priceless energy has been used for decennia to grow flowers, vegetables and plants in glasshouses. Nowadays, the sources for natural gas become more and more exhausted, prices increase and society gets aware of the inefficient way, we use energy in glasshouses. This has lead to new innovations in glasshouse industry. One of the most elaborated proposals so far is the 'Zonneterp'. This concept is developed by a consortium that consists of architects, engineers, glasshouse companies and glasshouse building companies.
In the Dutch glasshouse industry, heating one square meter glasshouse is ten times more expensive then heating on square meter of housing. In the Zonneterp , the glasshouse will produce energy. By combining urban glasshouses and urban housing an exchange of energy, but also of CO2, water and nutrients, comes into existence.

Heatingsystem: Sun heating is catched and saved in a waterlayer in the earth, using a heat exchanger. This heat is used for heating the glasshouse and the build environment. With the same system, housing can be cooled in summer.

CO2 cycle:
Bio-mass like kitchen and garden waste, urine and faeces (black water) are fermented. This produces biogas which can be used for warming water and electricity. CO2 emissions coming from this process can be used for the growth of vegetables.

Grey water from households is revised in combination with the effluent coming from the fermentation process into a nutrient containing water that can be used for the plants in the glasshouse. Due to evaporation and condensation, clean water can subsequently be recovered.

Nutrient system: Nutrients from bio-mass and waterflows are used in the glasshouse as fertilizer and nourishing water.

One of the purposes of Zonneterp is to use regular sources only in the first phase of the development. The cycles mentioned above have to stabilize as quick as possible, so that the project can become self maintaining. To reduce the loss and the costs due to transportation, housing and glasshouses must be developed close to each other. Residents and horticulturists must become educated about the particular systems, in order to maintain the cycles. An example is that horticulturists can't cool the glasshouses by opening windows (what they normally do), but that the heat must be drained with the heat exchanger towards the earth. Another example is the input of CO2, the basic ingredient for photosynthesis, which is delivered by pipelines coming from houses instead of coming from open air.



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