• Energy Research

Aquifer thermal energy storage (ATES) is a cost-effective technology that enables the reduction of energy use and CO2 emissions associated with the heating and cooling of buildings by storage and recovery of large quantities of thermal energy in the subsurface. Reducing the distance between wells in large-scale application of ATES increases the total amount of energy that can be provided by ATES in a given area. However, due to thermal interference the performance of individual systems can decrease. In this study a novel method is presented that can be used to (a) determine the impact of thermal interference on the economic and environmental performance of ATES and (b) optimize well distances in large-scale applications. The method is demonstrated using the hydrogeological conditions of Amsterdam, Netherlands. Results for this case study show that it is cost-effective to allow a limited amount of thermal interference, such that 30–40% more energy can be provided in a given area compared to the case in which all negative thermal interference is avoided. Sensitivity analysis indicates that optimal well distance is moderately insensitive to changes in hydrogeological and economic conditions. Maximum economic benefit compared to conventional heating and cooling systems on the other hand is sensitive, especially to changes in the gas price and storage temperatures.

With accelerating global changes, cities have to cope with growing pressures, especially for resource supply. Cities may be considered as resources reservoirs and producers of secondary resources. This paper introduces the concept of urban harvesting as a management tool to change inefficient linear urban resource usage and waste production into sustainable urban metabolism. The Urban Harvest concept includes urban metabolism and closing urban cycles by harvesting urban resources. The purpose of this study was to quantify the potentials to harvest water and energy at different scales. We investigated potentials for the Netherlands. Results show that at national scale, potentials can cover up to 100% of electricity demand, 55% of heat demand and 52% of tap water demand. At neighborhood level, similar percentages were found for energy. Only 43% of water demand was achieved, due to fact that treatment measures were not considered. These results indicate the large potential of cities as providers of their own resources. Therefore urban resources management is a key element of future city design towards more resilient cities.

The large-scale integration of intermittent distributed energy resources has led to increased uncertainty in the planning and operation of distribution networks. The optimal flexibility dispatch is a recently introduced, power flow-based method that a distribution system operator can use to effectively determine the amount of flexibility it needs to procure from the controllable resources available on the demand side. However, the drawback of this method is that the optimal flexibility dispatch is inexact due to the relaxation error inherent in the second-order cone formulation. In this paper we propose a novel bi-level optimization problem, where the upper level problem seeks to minimize the relaxation error and the lower level solves the earlier introduced convex second-order cone optimal flexibility dispatch (SOC-OFD) problem. To make the problem tractable, we introduce an innovative reformulation to recast the bi-level problem as a non-linear, single level optimization problem which results in no loss of accuracy. We subsequently investigate the sensitivity of the optimal flexibility schedules and the locational flexibility prices with respect to uncertainty in load forecast and flexibility ranges of the demand response providers which are input parameters to the problem. The sensitivity analysis is performed based on the perturbed Karush–Kuhn–Tucker (KKT) conditions. We investigate the feasibility and scalability of the proposed method in three case studies of standardized 9-bus, 30-bus, and 300-bus test systems. Simulation results in terms of local flexibility prices are interpreted in economic terms and show the effectiveness of the proposed approach.

Vision on eco-innovation in our society and the role of technology in it.

Underground thermal energy storage (UTES) use has showed a sharp rise in numbers in the last decades, with aquifer thermal energy storage (ATES) and borehole thermal energy storage (BTES) most widely used. In many urban areas with contaminated aquifers, there exists a desire for sustainable heating and cooling with UTES and a need for remediation. We investigated the potential synergy between UTES and bioremediation with batch experiments to simulate the effects of changing temperature and liquid exchange that occur in ATES systems, and of only temperature change occurring in BTES systems on cis-DCE reductive dechlorination. Compared to the natural situation (NS) at a constant temperature of 10 °C, both UTES systems with 25/5 °C for warm and cold well performed significantly better in cis-DCE (cis-1,2-dichloroethene) removal. The overall removal efficiency under mimicked ATES and BTES conditions were respectively 13 and 8.6 times higher than in NS. Inoculation with Dehalococcoides revealed that their initial presence is a determining factor for the dechlorination process. Temperature was the dominating factor when Dehalococcoides abundance was sufficient. Stimulated biodegradation was shown to be most effective in the mimicked ATES warm well because of the combined effect of suitable temperature, sustaining biomass growth, and regular cis-DCE supply.

Activated sludge systems are commonly used for robust and efficient treatment of municipal wastewater. However, these systems cannot achieve their maximum potential to recover valuable resources from wastewater. This study demonstrates a procedure to design a feasible novel configuration for maximizing energy and nutrient recovery. A simulation model was developed based on literature data and recent experimental research using steady-state energy and mass balances with conversions. The analysis showed that in the Netherlands, proposed configuration consists of four technologies: bioflocculation, cold partial nitritation/Anammox, P recovery, and anaerobic digestion. Results indicate the possibility to increase net energy yield up to 0.24 kWh/m3 of wastewater, while reducing carbon emissions by 35%. Moreover, sensitivity analysis points out the dominant influence of wastewater organic matter on energy production and consumption. This study provides a good starting point for the design of promising layouts that will improve sustainability of municipal wastewater management in the future.

Microalgae-based technologies can be used for the removal of organic micropollutants (OMPs) from different types of wastewater. However, the effect of wastewater characteristics on the removal is still poorly understood. In this study, the removal of sixteen OMPs by Chlorella sorokiniana, cultivated in three types of wastewater (anaerobically digested black water (AnBW), municipal wastewater (MW), and secondary clarified effluent (SCE)), were assessed. During batch operational mode, eleven OMPs were removed from AnBW and MW. When switching from batch to continuous mode (0.8 d HRT), the removal of most OMPs from AnBW and MW decreased, suggesting that a longer retention time enhances the removal of some OMPs. Most OMPs were not removed from SCE since poor nutrient availability limited C. sorokiniana growth. Further correlation analyses between wastewater characteristics, biomass and OMPs removal indicated that the wastewater soluble COD and biomass concentration predominantly affected the removal of OMPs. Lastly, carbon uptake rate had a higher effect on the removal of OMPs than nitrogen and phosphate uptake rate. These data will give an insight on the implementation of microalgae-based technologies for the removal of OMPs in wastewater with varying strengths and nutrient availability.

Due to fast urbanization and increasing living standards, the environmental sustainability of our global society becomes more and more questionable. In this historical review we investigate the role of resources management (RM) and urban planning (UP) and propose ways for integration in sustainable development (SD). RM follows the principle of circular causation, and we reflect on to what extent RM has been an element for urban planning. Since the existence of the first settlements, a close relationship between RM, urbanization and technological development has been present. RM followed the demand for urban resources like water, energy, and food. In history, RM has been fostered by innovation and technology developments and has driven population growth and urbanization. Recent massive resource demand, especially in relation to energy and material flows, has altered natural ecosystems and has resulted in environmental degradation. UP has developed separately in response to different questions. UP followed the demand for improved living conditions, often associated to safety, good manufacturing and trading conditions and appropriate sanitation and waste management. In history UP has been a developing research area, especially since the industrial era and the related strong urbanization at the end of the 18th century. UP responded to new emerging problems in urban areas and became increasingly complex. Nowadays, UP has to address many objectives that are often conflicting, including, the urban sustainability. Our current urban un-sustainability is rooted in massive resource consumption and waste production beyond natural limits, and the absence of flows from waste to resources. Therefore, sustainable urban development requires integration of RM into UP. We propose new ways to this integration.