Obtaining energy from water is no new concept for water boards. When wastewater is treated, sludge is collected and is often fermented, whereby biogas is produced. This biogas can be used in a combined heat and power installation (CHP). A gas engine powers a generator to generate electricity. The heat released in this process is reused to optimise the sludge fermentation process and to heat adjacent buildings at the treatment plant.
“This works differently at the Sleeuwijk Energy Factory,” Paul Kloet, Deputy Director of Iv-Water explains. “At Sleeuwijk, the sludge is collected from the nine surrounding wastewater treatment plants. Because of the size of this operation, a large amount of green gas is produced with the help of sludge fermentation. Given the scale of the treatment plant, it was an attractive option to upgrade the quality of the gas to that of natural gas to make it suitable for consumption by third parties. In fact, the water board has become a gas supplier, which places high demands on the operational management at the wastewater treatment plant. There are many other aspects related to safety which must be considered.” In Sleeuwijk, approximately two million cubic metres of natural gas is now produced per year. This is undoubtedly an exciting project in light of the objective for the Netherlands to be natural gas-free by 2050. Iv-Water provided the integral design of the Energy Factory and supported the water board with the land permit application. In addition, Iv-Water took care of the start-up and coordinated the entire installation’s technical process.
The Dutch water boards produce approximately 125 million cubic metres of biogas. This is approximately 17% of the biogas production in the Netherlands; currently, only a small portion of this biogas is upgraded to green gas for external consumption.