(ID:191) Thermal energy recovery from waste water (Riothermie)..ESCo

Tauw Group
Tauw is an independent European consulting and engineering company specialised in the design, improvement and management of the natural environment, built-up environment and infrastructure.

AddressHandelskade 11, 7417 DE, Deventer, The Netherlands
URLhttp://www.tauw.com/
ContactNaomi Keijser, Project Leader, naomi.keijser@tauw.nl
Line of industryConsulting and Design services; Financial services; Research
Area of expertiseDesign; Construction; Sustainability; Power generation and conversion; Installations
Sizemore than 1000 employees

Role of company/organisation

Tauw is an expert and leading company in the field of environmental consultancy, spatial development, civil engineering and the monitoring of environmental quality. In these fields a prominent reputation has been acquired in studies and design. We are used to working in multidisciplinary teams on projects for a broad range of clients: public authorities, private companies and non-governmental organisations. State of the art expertise on content and understanding of the local context are the pillars of our consultancy. Tauw’s vision is that the best solutions come from passionate cooperation at an early stage of the planning process.

Description of idea

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Thermal energy recovery from waste water (Riothermie) “Riothermie” is the Dutch name for the principle by which thermal energy can be recovered from sewage water. This energy can be used for heating or cooling of buildings or installations that are located in the vicinity of the respective sewer. Heat or cold is recovered by implementing a heat exchanger in the sewer system. Usually, the exchanger is implemented in the sewer wall and does not influence the hydraulics of the sewage water. The sewage flows over the heat exchanger and thus exchanges energy with a transportation fluid. This fluid is pumped through a conduit from the sewer to the customer to deliver its heat or cold. The temperatures are still relatively low-quality and usually not immediately usable. A heat pump increases or decreases the temperature to the desired level. A well designed system will use approximately 75% free energy from the sewer and 25% electricity, compared to a 100% powered conventional energy source. Riothermie can be well combined with Aquifer Thermal Energy Storage (ATES). This combination creates the possibility to recover high sewer temperatures in summer and store them for usage in winter. Also this combination can restore imbalances in ATES systems. The company Tauw has created a Riothermie opportunity map for the City of Eindhoven. This map gives insight into the thermal potential of the sewage system of Eindhoven. The map is included in the annex and shows that some sewer pipes with sufficient thermal potential are located in the vicinity of the focus area. It turns out that especially the sewer along the river Dommel has a high thermal potential. Approximately 500 kW of thermal energy can be extracted from this sewer by reducing its temperature by one degree Celsius. Installing a Riothermie plant is not cheap (the costs can be compared to an ATES system) and is therefore only feasible for larger consumers like office and apartment buildings, hotels, swimming pools, etcetera. Financing the investment can be done in different ways. An ESCo, or Energy Service Company, is a form of performance-based contracting that applies well to Riothermie projects. An ESCo is a business that develops, installs, and arranges financing for projects designed to improve the energy efficiency and maintenance costs for facilities over a period of time. ESCos generally act as project developers for a wide range of tasks and assume the technical and performance risk associated with the project. Typically, they offer the following services: - develop, design, and arrange financing for energy efficiency projects; - install and maintain the energy efficient equipment involved; - measure, monitor, and verify the project's energy savings; and - assume the risk that the project will save the amount of energy guaranteed. These services are bundled into the project's cost and are repaid through the savings generated. Tauw can support in conducting feasibility studies, system design and consulting on technical, operational, cooperation, legal and financial matters.

Illustrating fileTauw-Riothermie.pdf
Type of ideacombination of product and service
Category of ideatechnical; design; work flow; financial
Enabling conditionsTauw must be involved in the development of the plans in an early stage. To succeed we need sewer pipes with sufficient thermal potential. We created a Riothermie opportunity map for the city of Eindhoven. The map shows that some sewer pipes with sufficient thermal potential are located in the vicinity of the focus area. Especially the sewer along the river Dommel has a high thermal potential. Approximately 500 kW of thermal energy can be extracted from this sewer by reducing its temperature by one degree Celsius.

Stage of development

Proven innovation: it has been used in practice on a small scale.

Substantiation stage of development

Approximately 50 riothermie plants are operational world wide. Most are located in Switserland and Germany. The first were built in the late 90’s. Especially the ones that have been realized in the last years are showing large reductions in CO2 emissions. By now the technique has evolved to a proven concept and is being implemented on a larger scale. It has not yet been applied to waste water systems in the Netherlands, although wide interest exists.

Provability contribution to sustainability

Proven contribution to sustainability; this has been shown in practice.

Step in the right direction

A well designed Riothermie system will use approximately 75% free energy from the sewer and 25% electricity, compared to a 100% powered conventional energy source.

Flexible idea

Using sewers has no impact on the environment. The system wil be designed in accordance with the actual building plans.

Good investment

A well designed Riothermie system saves energy and reduces CO2 emissions. The initial costs can be repaid through energy savings generated when using an ESCo.

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