Colloquia

Summary

The HyTES project aims to develop an innovative heating system for Multi-Family houses in Switzerland, employing a solar-powered heat pump. This system harnesses solar energy to generate heat for Domestic Hot Water and Spacial heating or stores it in a Seasonal Thermal Energy Storage (STES) system with both latent and sensible heat storage. To identify the best system configuration, the project utilizes an optimization process based on an existing system model.

This thesis extends the existing model to include an evaluation of the system's carbon footprint. The global warming potential of the main components is calculated based on their size/capacity using equations derived from relevant literature. Additionally, the thesis focuses on developing an optimization strategy and formulating a multi-objective function to consider three key performance indicators: minimal system costs, self-sufficiency, and carbon footprint. The function incorporates specific weighting and normalization factors.

The optimization analysis explores various variables, such as tank types and dimensions, domestic hot water tank size, number, and orientation of solar panels. The sensitivity analysis results highlight the significant influence of the dimensions of the HyTES tank and solar system variables. In contrast, variables related to the Domestic Hot Water tank have a minimal effect.

The preliminary optimization results present potential outcomes and interpretations, showcasing three scenarios with different levels of self-sufficiency (78%, 84%, 97%). The initial optimal system, with 78% self-sufficiency, demonstrates the lowest Levelized Cost of Heat (LCOH) among the optimized systems and becomes almost cost-competitive with oil boilers when considering incentives. Moreover, its Global Warming Potential (GWP) is three times lower than the base case. Notably, the HyTES tank volume significantly increases with self-sufficiency.

The results highlight the substantial impact of subsidies and feed-in tariffs on system costs. An analysis of the main cost contributors and carbon footprint across different scenarios reveals that Operation and Maintenance costs and the solar system are the most significant cost drivers, while the solar system and grid electricity influence the carbon footprint. Interestingly, the Seasonal Thermal Energy Storage's contribution to both system costs and carbon footprint escalates notably at higher levels of self-sufficiency. These findings demonstrate the effectiveness of the carbon footprint implementation and optimization strategy in optimizing the HyTES system.