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Anergy networks with ductile iron pipes


The main focus of the so called Swiss Energy Strategy 2050 lies in the use of local, renewable energy sources. Their most important aims are a sustainable guarantee of energy supply, consistent development of existing energy efficiency potentials, reduction of CO2 emissions and full utilisation of existing potentials of new renewable energy sources. So, in Switzerland, the final energy consumption (final energy = primary energy after energy conversion and transmission losses) per person should decrease in the medium term to 2035 by 43 % and in fact in the long term to 2050 by 54 % as compared with the base year of 2000.

When considering new renewable energy sources, the thermal utilisation of water and wastewater – in so-called Anergy networks for heating or cooling buildings – offers enormous potential. With the continued technical development of heat pumps and heat exchangers, a serious improvement has been achieved in their efficiency levels, which makes these technologies very interesting for the utilisation of heat from water and wastewater.

Diagram showing an example of an Anergy network.

Diagram showing an example of an Anergy network.

Thermal utilisation of lake and river water

With the aims of a sustainable supply of energy and a reduction of CO2 emissions, the use of heat or cold from lakes or rivers is increasingly attractive. Since the larger Swiss lakes – such as Lake Constance, Lake Neuchâtel, Lake Zurich, Lake Lucerne or Lake Geneva – are also the locations of larger towns, it is precisely here that using the enormous heat potential of the lakes is a must.

Utilising heat from wastewater or industrial process water

Wastewater is considerably warmer in winter and cooler in summer than the air outside and so can be used for heating or cooling buildings. A precondition for an economical use of energy from wastewater and process water is the proximity of the energy consumers to a large sewer, a sewage treatment plant or the industrial plant using the process water.

The technology of heat and cold recovery

Anergy networks are a combination of pumping stations, heat exchangers, a network of pipelines and heat pumps, by means of which the energy in water or wastewater can be used. These days the recovery of heat and cold respectively by heat exchangers and the recovery by compression and expansion by heat pumps into heating energy and for water heating are simple, tried and tested technologies which, in many cases, are very economical and competitive.

In order to generate power, a lot of energy is needed to drive the pumps in the piping network, which places high requirements on energy efficiency and particularly on the hydraulic capacity of the pipe material used. Pressure and/or energy losses can be reduced to a minimum by selecting the ideal pipeline dimensions and by the choice of pipes with a hydraulically smooth internal lining.

Anergy network – energy production in the low temperature range

An Anergy network is a low temperature network for supplying low-temperature energy from waste heat or from renewable sources. It consists of a closed-circuit system, often designed as double pipelines for feed and return flows as well as inlet and outlet pipelines to the heat pumps in the buildings.

Ductile iron pipes with polyurethane lining promote energy efficiency

For the construction of the pipeline system, high operational reliability, economical operation and a long service life are decisive criteria when selecting the suitable pipe material. Cast iron pipes with polyurethane (PUR) lining are perfectly suited for energy-efficient use in Anergy networks. The proven, innovative vonRoll PUR lining has unbeatable performance levels.

DUCPUR ductile iron pipes with active zinc-aluminium corrosion protection and final coating to EN 545 can be laid in many types of soil. Soils of different aggression classes require special attention. Therefore, ductile cast iron pipes ECOPUR or CEMPUR with reinforced coating can be used under difficult conditions. These two full protection pipes are the solution for every installation situation, they

–   give lasting protection against mechanical and chemical attack
–   are suitable for all types of soil with any level of aggressiveness
–   allow the ballast grain sizes permissible for the pipe coating of 0 – 63 mm, maximum size 100 mm
–   have passive and active corrosion protection and are stable over their entire working life
–   are resistant to galvanic corrosion due to stray currents (e.g. by earthing, along railway lines or by mixed soils).

DUCPUR double DN 700 pipeline with feed and return flow.

DUCPUR double DN 700 pipeline with feed and return flow.

Optimised installation with flexible push-in joints

With full protection ECOPUR and CEMPUR pipes, the pipeline system is effectively and integrally protected against all underground influences. At the same time, the HYDROTIGHT and BLS® flexible push-in joints guarantee the best possible operational reliability in Anergy networks.

The ductile iron pipes, often used in Anergy networks as double, feed-and-return pipelines, often have to be provided with multiple fittings and valves due to limited space. With the flexible HYDROTIGHT and BLS® push-in joints, the installation process is massively accelerated, reliability is extremely high and laying quality is at its best. As proven and secure connection techniques, they offer enormous advantages resulting in high cost savings in civil engineering and pipe laying work.

The vonRoll ECOSYS pipe system is perfectly matched to the area of application in Anergy networks. The ECOPUR, DUCPUR and CEMPUR type pressure pipes are available from DN 80 to DN 700. Integral full-protection ECOFIT fittings in HYDROTIGHT and BLS® versions, protected with epoxy coating, as well as full-protection fittings complete the range.

Roger Saner, vonRoll hydro (suisse) ag


The article was slightly shortened by the editors. You can find the complete article with various illustrations as a PDF in the download area under Downloads Annual Issues EADIPS FGR.