The potential of wastewater heat and exergy: Decentralized high-temperature recovery with a heat pump

Meggers, Forrest; Leibundgut, Hansjürg

doi:10.1016/j.enbuild.2010.12.008

Cited by 130 publications

(55 citation statements)

References 6 publications

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“…Usually passive houses are extremely air tight and insulated, with a focus on reducing the space heating/cooling demand [6]. Before the development of these types of buildings, the hot water demand was about 10-20% of the total energy consumed within a building.…”

Section: Scopementioning

confidence: 99%

“…Hence the availability of usage data of GW is scarce and mostly available from a different viewpoint [6]. The first step in the harnessing of heat is to determine the sources, measure the usage patterns and assess the potential of GW Broadly speaking there are three types of water in the plumbing system of a conventional household as defined in Table 1 [15,[20][21][22].…”

Section: Characteristics Of Greywatermentioning

confidence: 99%

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A Key Review of Non-Industrial Greywater Heat Harnessing

2018

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Abstract:The ever-growing concerns about making buildings more energy efficient and increasing the share of renewable energy used in them, has led to the development of ultra-low carbon buildings or passive houses. However, a huge potential still exists to lower the hot water energy demand, especially by harnessing heat from waste water exiting these buildings. Reusing this heat makes buildings more energy-efficient and this source is considered as a third-generation renewable energy technology, both factors conforming to energy policies throughout the world. Based on several theoretical and experimental studies, the potential to harness non-industrial waste water is quite high.As an estimate about 3.5 kWh of energy, per person per day could be harnessed and used directly, in many applications. A promising example of such an application, are low temperature fourth generation District Heating grids, with decentralized sources of heat. At the moment, heat exchangers and heat pumps are the only viable options to harness non-industrial waste heat. Both are used at different scales and levels of the waste-water treatment hierarchical pyramid. Apart from several unfavourable characteristics of these technologies, the associated exergetic efficiencies are low, in the range of 20-50%, even when cascaded combinations of both are used. To tackle these shortcomings, several promising trends and technologies are in the pipeline, to scavenge this small-scale source of heat to a large-scale benefit.

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Section: Scopementioning

confidence: 99%

Section: Characteristics Of Greywatermentioning

confidence: 99%

A Key Review of Non-Industrial Greywater Heat Harnessing

2018

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“…Case studies show that technologies for wastewater heat recovery have been successfully implemented in three locations of the wastewater infrastructure [7]: (1) inside buildings [8]; (2) from the sewer [9] and (3) at the wastewater treatment plant (WWTP) [10]. This article focuses on energy provision options related to thermal energy recovery from WWTPs which is reasoned as follows: One major restriction of heat recovery in buildings and sewers concerns the reduction of wastewater temperature.…”

Section: Introductionmentioning

confidence: 99%

Mapping Thermal Energy Resource Potentials from Wastewater Treatment Plants

et al. 2015

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Wastewater heat recovery via heat exchangers and heat pumps constitutes an environmentally friendly, approved and economically competitive, but often underestimated technology. By introducing the spatial dimension in feasibility studies, the results of calculations change considerably. This paper presents a methodology to estimate thermal energy resource potentials of wastewater treatment plants taking spatial contexts into account. In close proximity to settlement areas, wastewater energy can ideally be applied for heating in mixed-function areas, which very likely have a continuous heat demand and allow for an increased amount of full-load hours compared to most single-use areas. For the Austrian case, it is demonstrated that the proposed methodology leads to feasible results and that the suggested technology might reduce up to 17% of the Austrian global warming potential of room heating. The method is transferrable to other countries as the input data and calculation formula are made available. A broad application of wastewater energy with regard to spatial structures and spatial development potentials can lead to (1) increasing OPEN ACCESSSustainability 2015, 7 12989 energy efficiency by using a maximum of waste heat and (2) a significant reduction of (fossil) energy consumption which results in a considerable reduction of the global warming potential of the heat supply (GWP) if electricity from renewables is used for the operation of heat pumps.

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“…Assuming that this energy could be technically exploited, the current energy sink of wastewater treatment can be transformed into a resource with an energy balanced water resource recovery facility being a grand step ahead. Besides physical processes for wastewater valorization, e.g., by exploiting its thermal energy content (Meggers and Leibundgut, 2011) and nutrient recovery (e.g., nitrogen, phosphorus), technologies based on anaerobic and phototropic metabolisms are under examination (McCarty et al, 2011;Shoener et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Estimating the Energy Content of Wastewater Using Combustion Calorimetry and Different Drying Processes

2017

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The energy content of wastewater is routinely assessed by chemical oxygen demand (COD) measurements that only provide an incomplete picture and the data fundament of other energy parameters remains scarce. The volumetric heat of combustion (ΔCH) of raw wastewater from a municipal wastewater treatment plant (WWTP) was assessed using oven drying method (ΔCHvol = −6.8 ± 4.3 kJ L , n = 6) illustrating the substantial loss during the oven drying approach. Normalizing ΔCH to COD of raw wastewater yielded −6.2 ± 3.5 kJ gCOD −1 for oven-dried samples (n = 14) and −13.0 ± 1.6 kJ gCOD −1 for freeze-dried samples (n = 3). A subsequent correlation analysis with further chemical wastewater parameters revealed a dependency of ΔCHvol on COD, total organic carbon (TOC), C:N ratio, and total sulfur content. To verify these correlations, wastewater of a second WWTP was sampled and analyzed. Only COD and TOC were in accordance with the data set from the first WWTP representing potential predictors for the chemical energy stored in wastewater for comparable WWTPs. Unfortunately, during the most practical method (oven drying), a certain loss of volatile compounds is inevitable so that the derived ΔCHvol systematically underestimates the total energetic potential of wastewater. Nevertheless, this work expands the, so far, little data fundament on the energy resource wastewater and implies the requirement for further long-term studies on different sites and different wastewater types with a highly standardized sample treatment protocol.

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The potential of wastewater heat and exergy: Decentralized high-temperature recovery with a heat pump

Cited by 130 publications

References 6 publications

A Key Review of Non-Industrial Greywater Heat Harnessing

A Key Review of Non-Industrial Greywater Heat Harnessing

Mapping Thermal Energy Resource Potentials from Wastewater Treatment Plants

Estimating the Energy Content of Wastewater Using Combustion Calorimetry and Different Drying Processes

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