The Dutch water boards would like to become one of the largest suppliers of green energy in the Netherlands.
The water boards would like to realise energy production and the re-use of heat at 350 sewage treatment plants. Eventually more than one million Dutch will be provided with green energy from the water boards; a start has been made in the cities of Den Bosch, Tilburg and Nieuwegein.
The Waterschap Aa en Maas will use the produced energy firstly for its own use; the surplus will be turned over to the power grid and can be bought through the green energy provider Greenchoice by citizens in the region. This is in line with the ambitions of the municipality of Den Bosch to be energy-neutral by 2050. Not only the recovery of heat from wastewater and the energy production from anaerobic digestion but also the recovery of nutrients for agriculture helps to close the cycles. Minerals such as phosphates and potassium are recovered from the sludge and supplied to the agricultural sector.
The project is also investigating whether it is cost-effective to separate faeces from sewage water before it enters the treatment plant. This is more efficient for the biological treatment; it produces more sludge and twice as much biogas can be produced.
Thermal pressure-mediated hydrolysis is also being studied for the anaerobic digestion process. Anaerobic digestion works better under high pressure and high temperatures; this delivers much more energy.
Some of the waste management company lorries at Treurenburg in Den Bosch will run on biogas. Another part of the biogas will be used to drive the motors of the treatment plant that produce electricity. The energy will be sold through Greenchoice. Greenchoice guarantees that the consumers will pay less for the water board’s green energy than the usual rates for grey energy in the region.
With the renovation of the treatment plant the surroundings will also be improved. The plant itself will be surrounded by trees and an observation tower will be added. From this tower there is a view of the entire property but also of the new nature and recreation area on the other side. The treated wastewater flows through this water-rich nature area into the Dieze river
A new project is the provision of biogas to Heineken. The wastewater treatment in Den Bosch daily cleans 45 million liters of sewage. The water is cleaned so well that people can swim and fish in it. During the cleaning process, energy is extracted from stool: biogas. This biogas is now already converted to power. When the new building of the RWZI is complete, the biogas will be upgraded to natural gas quality. Heineken will be using it to heat its business processes. Furthermore, 50 garbage trucks of the municipality will run on the gas. This is a profit for the climate and for the pockets; driving on biogas is ten times cleaner than diesel for half the price.