The 9.78 MW photovoltaic system on the Hellsiek landfill-site in Detmold, Germany, functions as a seal for the landfill. “This is the first time a PV system has been used on such a large scale to seal a landfill. The hybrid solution conserves resources, and is more cost-effective than conventional installations. The landfill is sealed by the PV system, preventing seepage and contamination of clean rain water into landfill. This type of renewable energy generation is a landscape and ecologically friendly option for supplying renewable energy. The construction also enables double use of the landfill site for energy production“, the Intersolar Award decision is outlined.
Use of standard and competitive PV components
“The jury was impressed by the high level of innovation, and the use of standard and cost competitive PV components in an innovative and important application. This scalable solution helps to prevent over 7,000 tons of CO2 emissions per year“, the award decision states. The landfill generates 8,0 Mio kWh of electricity annually.
No expensive water purification necessary
Landfills must be sealed with a membrane, to prevent polluted seepage water from contaminating the groundwater. Conventionally the seepage water is collected and treated in a cost-intensive process. Due to the flat roof sealing off the landfill, the rainwater is collected and diverted, so that no polluted seepage is formed. In addition, the generated electricity can be used for the landfill itself and as well for the local communities in the district of Lippe.
Savings can be used to reduce waste charges for the surrounding communities
Thanks to the combination of low-cost sheet metal and electricity-generating PV systems, for the most part a conventional landfill cover can be saved. The occupancy of the northern parts with an east-west system led to an additional enlargement of the sealable surfaces. Only a few areas in the south area have to be sealed. Due to the flat roof as a sealing of the landfill body, the rainwater is collected before the soil layer, so that none seepage water is formed. This reduces the cost of expensive water purification. The ventilation of the landfill body can also be operated with renewable energy and thus increasing the self-consumption rate. In addition, the photovoltaic plant generates feed-in tariffs. These savings can be used to reduce waste charges for the surrounding communities.
Challenging construction and planning
The particular challenge in the Hellsiek project was the difficult terrain of the landfill body, which could not be reshaped. Thus, Goldbeck Solar had to ram in very steep terrain (up to 25 ° inclination) and introduce substructures, in order to realize the landfill sealing with the profiled sheeting roof. Also, the necessary pile depths in the ground were not feasible in some areas. Therefore foundations were installed to mount the pillars of the substructure in these areas. An innovative planning software was used here, which in conjunction with a special piling machine, laid the foundation for the roofing. Another challenge was the requirement of a minimum distance of 1.30 meters to the ground. In order to guarantee a constant drainage of water, piles of up to 4 meters in height had to be installed
Solar modules in east-west orientation allow higher output
37,004 Canadian-Solar modules (260/265 W) were installed in east-west orientation. This allowed the partial use of the north face of the landfill, what resulted in a 110 percent higher output and 50 percent larger solar roof surface of total 66,000 m2. 111 Sungrow 60 KTL inverters have been installed and 2 transformer stations with 2,500 KVA. The construction period took ten months. (HCN)
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More useful information:
https://www.pveurope.eu/products/solar-generator/mounting
https://www.pveurope.eu/solar-modules/solar-milk-cooling-system-business-case
