New Altstetten energy network

The Altstetten energy network uses the Werhölzli wastewater treatment plant (WWTP) as a local renewable energy source for heating and cooling. Heat is primarily generated from the treated wastewater and sewage sludge recycling. In total, the heat pumps produce 20 MW of heating power and 15 MW of cooling power. Dual-fuel burners cover the peak power requirement with a further 20 MW.

Fast Facts

Reversible heat pumps with 20 MW heating capacity and 15 MW cooling capacity

Large storage systems - each storage tank has a capacity of 100,000 liters

> 90 % renewable energies

Natural refrigerant ammonia is used

2,000-watt society

as target

Altstetten energy center, view 1

Reference Willers Energy Hub - Graphic model of the Altstetten energy network

Altstetten energy center, view 2

challenges

Sustainability, operational reliability and cost-effectiveness must be harmonized - while at the same time ensuring low-maintenance, energy-efficient and future-oriented system operation in the long term.

A highly complex technical infrastructure is required to supply a new urban area with sustainable heating and cooling energy. The particular challenge is to create a functional purpose-built building that ensures optimum operation of the systems and at the same time meets the highest sustainability requirements.

When completed, the energy center will comprise six reversible heat pumps, four large storage systems and various pump systems with a total heat output of 40 MW. Ammonia (NH₃) is used as a natural refrigerant, which places high demands on safety standards. Coordination with existing and new utility lines on the site and efficient integration into the anergy grid are also crucial in order to maximize the proportion of renewable energy and minimize energy consumption.

SOLUTIONS

Sustainable and economical solutions are created when all project participants work together on an interdisciplinary basis and can actively contribute their specialist knowledge.

An economical and sustainable energy supply can only be achieved through state-of-the-art technologies and a holistic planning concept. The interdisciplinary approach includes a purpose-built building that not only optimizes the room volume, but also provides optimal conditions for the technology.

The energy center therefore relies on reversible heat pumps with ammonia, which provide both heating and cooling and enable more than 90 % of renewable energy. On very cold winter days, dual-fuel burners are used - with the aim of reducing fossil fuels to a minimum.

The overall hydraulic concept was designed in such a way that cooling and heating production are optimally coordinated and efficient system operation is guaranteed. Careful selection of materials, a well thought-out building design and separate technical systems have resulted in a durable, low-maintenance infrastructure building.

The cooperative planning of the district heating and cooling lines and the integration into the city's anergy network ensure a sustainable energy supply. This is in line with the goals of the «2,000-watt society' and the sustainable development of the city of Zurich.

Our engineers have decades of experience in the realization of state-of-the-art critical infrastructures.

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