At the moment, wastewater from households and industry flows to the sewage treatment plant at around 16 degrees Celsius; in winter it is between eight and twelve degrees. The thermal energy contained in it is no longer used – on the contrary, it heats the rivers and streams into which the wastewater is channeled after treatment. As a result, an energy potential of around 485,000 megawatt hours is lost in Upper Austria every year, as the survey by the Environment and Climate Department shows. This amount of energy could supply 55,000 households with thermal energy. “If we want to make this country climate-fit, then we must stop wasting energy,” says Kaineder, pointing out that less solar energy is available, especially in winter when heating is used.
Technically, the thermal use of wastewater is not a problem, says Ulrike Rabmer-Koller, Managing Director of the Rabmer Group. Her company from Altenberg near Linz has been working on generating energy from wastewater for ten years. In principle, the same technology is used as with a ground or air heat pump, except that the energy is drawn from the warm wastewater instead of from the air or earth. “The average temperature of the wastewater is higher than that of the ambient air, groundwater or geothermal energy. This means that less electricity is needed for the heat pump,” says Rabmer-Koller, emphasizing the economic aspect. With modern heat pumps, the function can also be reversed: the heat is pumped outside, so to speak, and the house is cooled.
However, a few special features must be taken into account for implementation. The canals used should have a minimum size and flow rate. “We assume that canals with 5,000 or more inhabitants are suitable,” says Rabmer-Koller. Before the wastewater enters the sewage treatment plant, the water can only be cooled by 0.5 degrees, as a minimum temperature is necessary for the biological processes in the treatment. After cleaning, scientists expect a possible cooling of up to five degrees. Rabmer-Koller expects that this temperature difference will be even higher in practice, meaning more energy will be available.
Opportunity for city and industry
Table of Contents
- 1 Opportunity for city and industry
- 2 Here are some People Also Ask (PAA) related questions for the title: **Harnessing the Power of Wastewater: A Renewable Energy Source**.
- 3 Here are some People Also Ask (PAA) related questions for the title **”Harnessing the Power of Wastewater: A Renewable Energy Source”**:
Table of Contents
Based on the above-mentioned restrictions, the Water Management Department has drawn up a register of 30 areas of use in Upper Austria whose wastewater could be used. Many of them are located in the central area, which Rabmer-Koller says is no coincidence: “In urban areas, consumers and energy sources are close to each other.” There is also a great need for cooling here. In addition to households, which can be supplied with heat from wastewater via local and district heating networks, the sewage treatment plants are intended to cover their own needs. Kaineder also sees a lot of potential for heavy consumers such as hospitals: “These have large sewer systems and need a lot of heat.”
The technology could also be an opportunity for industrial companies. They often have to cool their wastewater before they can discharge it into the sewer. This step could be avoided if the wastewater is used for heating or hot water. The potential of such measures has not yet been included in the current survey, however, because only the energy potential from the point of discharge into the sewer was taken into account.
Next, State Councilor Kaineder would like to start a dialogue with the operators of the sewage treatment plants. One possible model is Switzerland: there are already more than 200 systems for heating and cooling with wastewater. In Austria, the Rabmer Group has implemented several projects, such as for the new Wienkanal office headquarters, which is heated and cooled exclusively with wastewater. Another system is currently being completed in an industrial plant in Linz and is due to go into operation in October.
ePaper
Harnessing the Power of Wastewater: A Renewable Energy Source
The treatment of wastewater is a crucial process that not only maintains public health and environmental safety but also presents an opportunity to recover thermal energy. Currently, wastewater from households and industries flows into sewage treatment plants at a temperature of around 16°C, with winter temperatures ranging from 8°C to 12°C. This thermal energy is lost when the wastewater is discharged into rivers and streams, amounting to approximately 485,000 megawatt hours per year in Upper Austria alone. This energy potential is sufficient to supply 55,000 households with thermal energy, emphasizing the need to stop wasting energy and work towards a climate-fit country.
The Technology Behind Wastewater Energy Recovery
The thermal use of wastewater is not a new concept, with companies like the Rabmer Group in Austria already working on generating energy from wastewater for over a decade. The technology employed is similar to that of ground or air heat pumps, except that the energy is drawn from the warm wastewater instead of the air or earth. This approach has several advantages, including:
Lower electricity requirements due to the higher average temperature of wastewater compared to ambient air, groundwater, or geothermal energy [[1]].
Reversible functionality, allowing for cooling as well as heating [[1]].
Implementation Considerations
To implement wastewater energy recovery, certain special features must be taken into account:
Minimum canal size and flow rate, with canals serving 5,000 or more inhabitants considered suitable [[1]].
Limited cooling of wastewater before entering the sewage treatment plant to maintain the minimum temperature required for biological processes [[1]].
* Potential for higher temperature differences after cleaning, resulting in more available energy [[1]].
Opportunities for Cities and Industry
The Water Management Department has identified 30 areas in Upper Austria where wastewater energy recovery can be utilized. Many of these areas are located in urban centers, where consumers and energy sources are in close proximity, and there is a high demand for cooling. Households can be supplied with heat from wastewater via local and district heating networks, while sewage treatment plants can cover their own energy needs. Heavy consumers like hospitals, with large sewer systems and high heating demands, also stand to benefit from this technology.
Industrial companies can also leverage wastewater energy recovery to avoid having to cool their wastewater before discharge. By using wastewater for heating or hot water, these companies can reduce their energy consumption and costs. Although not accounted for in the current survey, this potential is substantial and warrants further exploration.
A Model for Success
Switzerland has already implemented over 200 systems for heating and cooling with wastewater, serving as a model for countries like Austria to follow. The Rabmer Group has successfully implemented projects in Austria, including the Wienkanal office headquarters, which is heated and cooled solely with wastewater. Another system is currently being completed in an industrial plant in Linz and is expected to come online in October.
harnessing the thermal energy contained in wastewater is a viable solution for reducing energy waste and promoting a climate-fit country. By adopting wastewater energy recovery technology, cities and industries can reduce their energy consumption, lower costs, and contribute to a more sustainable future.
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Harnessing the Power of Wastewater: A Renewable Energy Source
Wastewater from households and industry is often overlooked as a potential source of thermal energy. However, this wastewater contains a significant amount of thermal energy that can be harnessed and utilized. In Upper Austria, for example, an energy potential of around 485,000 megawatt hours is lost every year, which could supply 55,000 households with thermal energy [[1]].
The thermal use of wastewater is not a technical problem, according to Ulrike Rabmer-Koller, Managing Director of the Rabmer Group. The same technology used in ground or air heat pumps can be applied to wastewater, with the added benefit of requiring less electricity due to the higher temperature of the wastewater [[1]]. With modern heat pumps, the function can also be reversed, allowing for cooling.
To implement this technology, certain requirements must be met. The canals used must have a minimum size and flow rate, with canals serving 5,000 or more inhabitants considered suitable [[1]]. Before the wastewater enters the sewage treatment plant, it can only be cooled by 0.5 degrees, as a minimum temperature is necessary for biological processes in the treatment. After cleaning, scientists expect a possible cooling of up to five degrees, with Rabmer-Koller expecting an even higher temperature difference in practice, resulting in more available energy [[1]].
Opportunity for City and Industry
The Water Management Department has identified 30 areas in Upper Austria where wastewater could be utilized for thermal energy. Many of these areas are located in urban centers, where consumers and energy sources are close to each other, and there is a high demand for cooling [[1]]. In addition to households, sewage treatment plants could cover their own energy needs, and heavy consumers such as hospitals could also benefit from this technology [[1]].
Industrial companies could also benefit from using wastewater for heating or hot water, avoiding the need to cool their wastewater before discharge into the sewer [[1]]. The potential of such measures has not yet been included in surveys, as only the energy potential from the point of discharge into the sewer was taken into account.
Case Studies and Future Prospects
State Councilor Kaineder aims to start a dialogue with sewage treatment plant operators, with Switzerland serving as a model, where over 200 systems for heating and cooling with wastewater are already in place [[1]]. In Austria, the Rabmer Group has implemented several projects, including one for the new Wienkanal office headquarters, which is heated and cooled exclusively with wastewater, and another system currently being completed in an industrial plant in Linz, set to go into operation in October [[1]].
Heat Recovery from Wastewater
Heat recovery from wastewater is a viable option, with technology available to recover up to 90% of the thermal energy contained in wastewater [[2]]. This is significantly higher than the potential for chemical energy recovery, which stands at around 10% [[3]].
harnessing the power of wastewater as a renewable energy source is a promising opportunity for cities
