Sustainable enhancement of district heating and cooling configurations by combining thermal energy storage and life cycle assessment

Abstract

District heating and cooling systems are designed and optimized to respond to the latest challenges of reducing energy demands while fulfilling comfort standards. Thermal energy storage (TES) with phase change materials can be employed to reduce the energy demands of buildings. This study considers a residential district located in Spain, where a general framework has been established to identify optimal combinations of energy conversion, delivery technologies, and operating rules. The Life Cycle Assessment (LCA) methodology was implemented within a mathematical model, and the objective function considered the minimization of environmental loads. Two environmental impact assessment methods were applied within the LCA methodology: IPCC 2013 GWP 100y and ReCiPe. Four optimal configurations were considered: a reference system (gas boiler and split-type air conditioners) and then three TES-based systems: one sensible (STES, water) and two latent (LTES1-paraffin emulsion and LTES2-sodium acetate trihydrate). Hourly environmental loads associated with electricity imports from the national grid were available. The conventional energy system always presented the worst performance from an environmental viewpoint, being penalized by the high consumption of natural gas. Regarding carbon emissions, LTES1 showed the lowest emissions, followed by STES and LTES2. Reductions in energy demands compensated the impact of paraffin, and results of STES are strongly dependent on tank design. However, considering the ReCiPe method, STES presented the lowest loads, followed by LTES1 and LTES2. Overall impacts of LTES1 with paraffin are higher than STES with water, mainly due to the paraffin and the high volume required.

Distributed Thermal Energy Storage Configuration of an Urban Electric and Heat Integrated Energy System Considering Medium Temperature Characteristics

“…In the configuration process, the configuration heat capacity (S WTES cap,i ) is usually related to the volume of the container [8,20]. In this article, it indicates the heat when the water tank is full of the upper temperature medium, representing the maximum heat storage quantity in theory.…”

“…During the period of wind curtailment, most of the heat supply tasks were undertaken by electric boilers and storage devices, so the wind power consumption space was improved. From the perspective of future planning, in [20], the authors proposed a configuration method with minimum emissions in the whole life cycle, considering the growth of heat load, climate warming, and other factors. A community in Spain was taken as a case to study the impact of a DTES system with a different design life.…”

Research on a Solar Hybrid Trigeneration System Based on Exergy and Exergoenvironmental Assessments

“…The exergoenvironmental factor (f b,k ) is the ratio between non-exergy-related environmental impacts and the overall environmental impacts and indicates which type of impact is dominant. f b,k is calculated by Equation (13). (13) The LCA of natural gas was calculated with the aid of software SimaPro 9.1.1.1 [34], using the Ecoinvent 3.6 database [35] and Eco-indicator 99 (EI99) version 2.10 (within SimaPro).…”

“…The case study was developed in Mexico, and 80% GHG emission savings were obtained for the solar cooling system, along with an 85% and a 20% decreases in fossil fuel depletion and ecotoxicity, respectively. Spanish district heating and cooling systems were the focus of the LCAs in [13], whereby the authors studied different types of thermal energy storage and verified that the nonrenewable energy system always presented the highest emissions due to the consumption of fossil fuel (natural gas).…”

Optimization and environmental and economic impact evaluation of the micro-energy network system on the basis of the load characteristics analysis

“…Aberilla et al (2020) conducted an LCA concerning energy systems and found that household-scale photovoltaic systems integrated with wind turbines and lithium-ion batteries in rural areas were the most environmentally friendly system of the systems they assessed. Guillén-Lambea et al (2020) did an LCA evaluating heating and cooling configurations and found that the environmental impact of the thermal energy storage system they researched was highly dependent on tank design. Corcelli et al (2019) found that in the Mediterranean, the SPR system had a smaller environmental impact than the RTG system, especially when considering climate change and fossil fuel consumption.…”