Sustainable District Research Articles

Techno-economic analysis of implementing thermal storage for peak load shaving in a campus district heating system with waste heat from the data centre

Peak load has significant impacts on the economic and environmental performance of district heating systems. Future sustainable district heating systems will integrate thermal storages and renewables to shave their peak heat demand from traditional heat sources. This article analysed the techno-economic potential of implementing thermal storage for peak load shaving, especially for the district heating systems with waste heat recovery. A campus district heating system in Norway was chosen as the case study. The system takes advantage of the waste heat from the campus data centre. Currently, about 20% of the heating bill is paid for the peak load, and a mismatch between the available waste heat and heat demand was detected. The results showed that introducing water tank thermal storage brought significant effects on peak load shaving and waste heat recovery. Those effects saved up to 112 000 EUR heating bills annually, and the heating bill paid for the peak load could be reduced by 15%. Meanwhile, with the optimal sizing and operation, the payback period of the water tank could be decreased to 13 years. Findings from this study might help the heat users to evaluate the economic feasibility of introducing thermal storage.

Sustainable district energy integrating biomass peaking with geothermal baseload heating: A case study of decarbonizing Cornell's energy system

Many governments and institutions are advocating for higher renewable energy deployment to lower their carbon footprint and mitigate the effects of climate change. Cornell University instituted the “climate action plan” to achieve carbon neutrality, of which geothermal heat extracted from deep rocks (Earth source heat) is a critical component. This paper proposes coupling baseload geothermal heating with energy from waste biomass from Cornell's dairy farms to meet the campus' peak heating demand. The envisioned biomass peaking system, consisting of a hybrid anaerobic digestion/hydrothermal liquefaction/biomethanation process, produces renewable natural gas (RNG) for injection and storage into the natural gas (NG) distribution grid and uses NG withdrawals at times of peak heating demand. We show that 97% of the total annual peak heating demand (9661 MW h) can be met using continuous RNG production using manure from Cornell's 600 dairy cows, which provides 910 × 106 l of RNG/year. The overall RNG system requires $8.9 million of capital investment and, assuming favorable policies, could achieve an effective levelized cost of heat (LCOH) of $32/GJ (minimum RNG selling price) and a net present value of $7.5 million after a 30-year project lifetime. Favorable policies were quantified by examining a range of incentivized prices for RNG injection ($47/MJ) and assuming wholesale utilities costs (NG withdrawals and electric imports). Selling RNG at the New York commercial NG price ($7/GJ) with utilities imports at commercial rates produces an LCOH ($70/GJ) in excess of the RNG selling price, highlighting the importance of carbon credits for financial profitability.

Development of an Evaluation Framework for Smartness and Sustainability in Cities

The transformation of cities into smarter and more sustainable environments is essential towards achieving the objectives of the decarbonization of the economy. In this sense, holistic strategies are required to design and implement urban regeneration strategies. The EU-funded REMOURBAN project has developed an Urban Regeneration Model which provides the mechanisms to implement more efficiently these processes, integrating technologies, business models, management procedures and evaluation mechanisms, where the evaluation is sought as the main supporting mechanism throughout the various phases of the city transformation process. The framework developed considers two levels of evaluation: city level, to assess both sustainability and smartness of the city as a whole from a comprehensive and integrated perspective, and project level, to provide a clear identification of the impact of implementation of technologies and solutions on three key priority areas (sustainable districts and built environment, sustainable urban mobility and integrated infrastructures and processes) aimed at achieving the city high-level goals. This paper introduces the Urban Regeneration Model and describes the evaluation framework and its implementation in the city of Valladolid (Spain).

Energy, exergy and exergoeconomic analysis of an ultra low-grade heat-driven ammonia-water combined absorption power-cooling cycle for district space cooling, sub-zero refrigeration, power and LNG regasification

An ultra low-grade waste heat (≤100 °C) driven ammonia-water combined absorption power-cooling (APC) cycle-based multi-generation system with liquefied natural gas (LNG) cold exergy recovery is thermodynamically and exergoeconomically investigated for sustainable district cooling (DC) at two different temperature levels, and electricity generation in coastal hot climate regions serviced by LNG regasification terminals. At 70 °C heat source temperature, the system yields a specific net equivalent power output of 51.4 kWh/tonLNG at a cooling-to-power ratio of 7.3, and effective first-law and effective exergy efficiencies of 39% and 36%, respectively. Per million ton per annum (MTPA) LNG regasification capacity, the system would deliver 9.4 MW of space cooling, 6.5 MW of sub-zero refrigeration, and 2.2 MW of electricity for the district, while saving 8.4 ktons of natural gas and 19.3 kt of CO2-equivalent emissions per year, compared with conventional cooling, power and regasified LNG provision systems. The LNG refrigeration heat exchanger and APC absorber-evaporator are the most important components from exergoeconomic viewpoints. In addition to enhancing overall cooling and power generation capacity, the use of LNG as a cold source/sink reduces the minimum APC driving heat source temperature and rectification requirements, relative to an ambient water-cooled absorber sink. Additional benefits include the avoided use of conventional refrigerants, and reduced impact of LNG regasification on marine ecosystems.

The possibility of a Sustainable district energy independence city by bioenergy_ part 2

The possibility of a Sustainable district energy independence city by bioenergy_ part 2

The possibility of a Sustainable district energy independence city by bioenergy_ part 1

The possibility of a Sustainable district energy independence city by bioenergy_ part 1

Solutions and services for smart sustainable districts: innovative Key Performance Indicators to support transition

Solutions and services for smart sustainable districts: innovative Key Performance Indicators to support transition

Solutions and services for smart sustainable district: an innovative approach in KPI to support transition.

Here it will be presented the results of the research “SCC solutions for Positive Energy Districts - RdS / PAR2018 / 041”, a collaborative project between Sapienza University of Rome - PDTA Dept. and ENEA Energy Technology Dept. – Sustainable Energy Network. The broader purpose of the research has been to design a set of strategies to facilitate built environment transition to optimized urban models such as Energy District. The research consider as starting point the urban vision in SET-Plan on Action 3.2 Smart Cities and Communities which support planning, deployment and replication of 100 Positive Energy District by 2025, with the aim to promote innovative research on models, methodologies planning tools and technology solutions for the short-medium term implementation. The approach and methodology which support the research projects lays on an operational framework set up to identify gaps and commonalities for urban services implementation and to support life improvements for citizens, consumers / prosumers. Main output of this research project is a framework to facilitate a synthetic evaluation on positioning and improvements for each SCC solutions which has been considered in the study each referring to engagement phase (planning, design, construction, management) and engagement scale (functional unit, building, blocks of building, infrastructures, environment). Furthermore, the synoptic tool improves the identification of strategies and stakeholders’ commitment to promote Urban District or PEDs transition.

Towards a sustainable district: a streamlined Life cycle assessment applied to an Italian urban district

The literature shows a lack of environmental indicators able to support the transition from a sustainable to a smart city framework, since the priority area “built environment” is indeed more comprehensively addressed by urban sustainability assessment systems (13%), than by smart city frameworks (4%) [12].As “smaller cities inside a larger agglomerate” [19], urban districts play a key role in defining effective and innovative paths toward a smarter city, but defining a sustainable urban district is not straightforward, and even less is capturing the induced impacts due to interactions between individual buildings and their surround urban setting [23]. The adoption of a quantitative method for evaluation, such as Life Cycle Assessment (LCA), emerges as an essential step for this purpose [24].This article explores the application of a streamlined LCA on the urban district main issues (buildings, energy, water and waste), referring to an urban retrofitting intervention of Bolognina neighbourhood.A set of mitigation strategies developed by an interdisciplinary research group (joining researcher team from the Department of Architecture of the University of Bologna and Institute of Sustainability in Civil Engineering of the RWTH Aachen University) provides the reference framework for the application deepened within the article. This work is a first application of LCA to a case study but it not includes a comprehensive sustainability framework yet, further activities are planned to finalize the analysis, e.g. taking account of social dimension by applying Social Life Cycle Assessment.

Towards the development of a smart district: The application of an holistic planning approach

The most important challenge for planners and administrations is to identify optimal strategies for improving city life from a global point of view. Urban Planning models should therefore provide solutions in a coordinated and holistic way and should be flexible and adapted to different contexts and territorial levels. Currently, a global approach to the development of Smart Cities is still missing. In this paper the authors developed a planning methodology based on the qualitative and quantitative evaluation of the reciprocal impacts among Smart strategies applied at the district level. The aim is to assess if and to what extent these actions would influence the performance of the district from a global perspective (Economy, Energy, Mobility, Community, Environment) compared to the base case scenario. The methodology has been applied to a sustainable district ideally located in the suburb of Rome and seven Smart scenarios have been modeled and simulated (with Matlab® - Simulink). Absolute results show the differences among the seven scenarios; the application of the normalized and a-dimensional Smart Performance indicators allowed also to identify the best scenario from a holistic perspective.

A Simplified Methodology for Existing Tertiary Buildings’ Cooling Energy Need Estimation at District Level: A Feasibility Study of a District Cooling System in Marrakech

In district energy systems planning, the calculation of energy needs is a crucial step in making the investment profitable. Although several computational approaches exist for estimating the thermal energy need of individual buildings, this is challenging at the district level due to the amount of data needed, the diversity of building types, and the uncertainty of connections. The aim of this paper is to present a simplified measurement-based methodology for estimating the cooling energy needs at the district level, which can be employed in the preliminary sizing and design of a district cooling network. The methodology proposed is suitable for tertiary buildings and is based on building electricity bills as historical data to calculate the yearly cooling demand. Then, the developed method is applied to a real case study: the feasibility analysis of a sustainable district cooling network for a hotel district in the city of Marrakech. The designed system foresees a 23-MWcold district cooling network that is 4 km long, supplying 26 GWh of cooling to the tourist area. The results show that the proposed methodology for cooling demand estimation is coherent with the other existing methods in the literature.

Integrated distribution system and urban district planning with high renewable penetrations

Recent efforts to reduce energy consumption and greenhouse gas emissions have resulted in the development of sustainable, smart districts with highly energy efficient buildings, renewable distributed energy resources (DERs), and support for alternative modes of transportation. However, there is typically little if any coordination between the district developers and the local utility. Most attention is paid to the district's annual net load and generation without considering their instantaneous imbalance or the connecting network's state. This presents an opportunity to learn lessons from the design of distribution feeders for districts characterized by low loads and high penetrations of DERs that can be applied to the distribution grid at large. The aim of this overview is to summarize current practices in sustainable district planning as well as advances in modeling and design tools for incorporating the power distribution system into the district planning process. Recent developments in the modeling and optimization of district power systems, including their coordination with multi‐energy systems and the impact of high penetration levels of renewable energy, are introduced. Sustainable districts in England and Japan are reviewed as case studies to illustrate the extent to which distribution system planning has been considered in practice. Finally, newly developed building‐to‐grid modeling tools that can facilitate coordinated district and power system design with utility involvement are introduced, along with suggestions for future research directions.This article is categorized under: Wind Power > Systems and Infrastructure Energy Policy and Planning > Systems and Infrastructure Energy Efficiency > Systems and Infrastructure

Sustainable District Cooling Systems: Status, Challenges, and Future Opportunities, with Emphasis on Cooling-Dominated Regions

A review of current and future district cooling (DC) technologies, operational, economic, and environmental aspects, and analysis and optimization methodologies is presented, focusing on the demands of cooling-dominated regions. Sustainable energy sources (i.e., renewable, waste/excess electricity and heat, natural/artificial cold) and cooling/storage technology options with emphasis on heat-driven refrigeration, and their integrations in published DC design and analysis studies are reviewed. Published DC system analysis, modeling, and optimization methodologies are analyzed in terms of their objectives, scope, sustainability-related criteria, and key findings. The current and future development of DC in the Gulf Cooperation Council (GCC) region, a major developing cooling-dominated market, is examined more specifically in terms of current and future energy sources and their use, and economic, environmental, and regulatory aspects, with potential technical and non-technical solutions identified to address regional DC sustainability challenges. From the review of published DC design and analysis studies presented, collective research trends in key thematic areas are analyzed, with suggested future research themes proposed towards the sustainability enhancement of DC systems in predominantly hot climates.

Sustainable urban food districts (SUFD): Strategical spatial planning in urban food systems. An analysis to the Toronto food strategy policy

Sustainable urban food districts (SUFD): Strategical spatial planning in urban food systems. An analysis to the Toronto food strategy policy

Innovative and smart city: A theoretical study of adaptive solutions for sustainable solar urban districts

This paper is a theoretical study of governing solar urban districts using the smart city system. It first presents the major theme of the sustainable urban future, points out the position of the solar energy in urban sustainable development. Then it presents the opportunities and challenges of the solar energy system, states that the innovation of technology from both the soft side and the hard side are the key points for governing the solar urban districts. The paper also shows the relationship between innovation, economies, and social sustainable development. Finally, the paper presents the smart city system as an innovative system. It needs to govern the solar urban district from all aspects (including but not limited to public services, city administration, and management, economy, pro-business environment, built environment and city infrastructure, natural environment and ecological sustainability). The lifecycle thinking and the GUUD model can be used to analyse and monitor the system. However, managing those fragment elements is not that simple. One of the challenges of integrating a smart city system is to build a connection between fragmental elements and make individual islands communicate with each other in order to achieve common goals.

Automated Statistical Methods for Fault Detection in District Heating Customer Installations

In order to develop more sustainable district heating systems, the district heating sector is currently trying to increase the energy efficiency of these systems. One way of doing so is to identify customer installations in the systems that have poor cooling performance. This study aimed to develop an algorithm that was able to detect the poorly performing installations automatically using meter readings from the installations. The algorithm was developed using statistical methods and was tested on a data set consisting of data from 3000 installations located in a district heating system in Sweden. As many as 1273 installations were identified by the algorithm as having poor cooling performance. This clearly shows that it is of major interest to the district heating companies to identify the installations with poor cooling performance rapidly and automatically, in order to rectify them as soon as possible.

Energy planning of sustainable districts: Towards the exploitation of small size intermittent renewables in urban areas

An optimization model is formalized for the energy planning of urban districts equipped with renewable energy power plants (photovoltaic fields and wind micro-turbines), combined heat and power units, and traditional boilers; districts are connected to the public distribution grid. The main decision variables of the model are the number and typology of wind turbines and cogeneration plants, the size of photovoltaic fields and the power exchange with the public grid. The optimal values of the variables come from the minimization of installation, maintenance and operational costs, and satisfy load and technical constraints. The model is applied to three districts in the Savona Municipality that represent pilot sites of an extended project concerning the planning and management of smart urban areas. The analysis of different scenarios allows evaluating the role of uncertainties of renewable sources over the optimal solution of the planning problem.

Water conservation and management: case study in Siam University

Siam University (SU) is one of the leading Thai comprehensive private universities of which “Sustainability” is one of the main missions. The mission is guided by the concept of “Sustainable Development (SD)” and the principle of “Sufficiency Economy Philosophy (SEP)” bestowed by the late King Rama IX. SU has endorsed many sustainability policies and projects including those concerned with ecosystem and water management system. Our target groups include SU staff and students as well as members in Phasi Charoen district. SU has encouraged water conservation and management policies and practices including reduction of water usage program for quite some time. Although piped water is still mainly used, we have installed automated hand washing taps counting to more than 75% of total water appliances. Water from the campus natural pond is used and reused for gardening and washing. After this initial stage, we have planned to do more programs concerning water recycling, reuse, and treatment system under the principle of SEP. Considering that our pond and surrounding canals are connected to Phasi Charoen communities, we hope that our water conservation and management system will not only lead to a more sustainable campus but also a more sustainable district.

Industrial Energetic Districts: Impact Analysis on the Global Energy Efficiency and Business Competitiveness

Process industries located in emerging economies have relative low levels of production to similar ones located in developed countries, this fact influences the implementation feasibility of cogeneration and/or tri-generation systems that allow a substantial increase in the plant global energy efficiency. In this paper, an energy and economic analysis of several alternatives of cogeneration was done for a company located in Barranquilla (Colombia, South America) that produces vegetable oils and derivatives and its energy matrix is approximately 90% thermal and 10% electric. In this investigation two type of analysis were done, both supported by process simulation software, these are: 1) Taking the plant as the control volume and evaluating the entire electrical demand supply with natural gas engine and turbine – generator, plus exhaust gases heat recovery for refrigeration and/or preheating of thermal oil or water in boilers. 2) As an energy-industrial district, where the company takes advantage of the residual heat of a gas turbine and sells the excess of electrical power to nearby plants, a concept introduced by the authors as Sustainable Energetic Industrial District in Emerging Economies (SEIDEE). The input variable considered for this analysis was electric demand which restricts the technology implementation. It was found that the investment return period is notably lengthy when the thermal machine supplies the electric power demanded by the industrial plant. This period is considerably reduced when the SEIDEE concept is implemented, this period reduction is between 57% and 65%.

Energy and the city

Energy and the city