Multi-Building Microgrids for a Distributed Energy Future in Portugal

Within the research field of distributed generation, special attention has been lately drawn to the concept of microgrids, an alternative for realizing the potential of dispersed and localized supply of heat and power. A microgrid is a locally organized group of electricity generation, storage and loads that operate together in a grid-connected fashion, through a single point of common coupling and being able to work in stand-alone conditions if circumstances so dictate. Waste heat from generators can be ideally recovered to meet heating loads of the system. Effective design of microgrid systems can be supported by optimization methods incorporating multi-building modeling capabilities. Previous work from the authors has suggested DER-CAM, which features a robust and flexible optimization algorithm, as a viable tool for exploring integrated energy microgrid systems’ design modeling (Mendes et al., 2011). This study looks at the potential penetration of multibuilding integrated energy microgrids in the urban context. Its main objectives are: 1)To realize how differently would distinct building typologies adopt the microgrid concept; 2)To understand the patterns by which this adoption would take place; 3)To identify the added costs or benefits and GHG emissions at which adoption effectively occurs. The research steps related to algorithm expansion to cope with multi-buildings microgrids modeling and to the adaptation of DER-CAM to the Portuguese case-study economic, environmental and technological setting are firstly explained. Essential load data as well as updated technology specifications have been collected by the authors from Portuguese energy services companies. The research results presented suggest that if optimally designed, the microgrid form can provide economic and environmental improvements at a given site of four different studied typologies, adding to increases in the overall reliability. The latter is valued differently by each complex typology. Urban mixes of different typologies also have significant importance and represent benefits to the customers. The average economic benefit from microgrid adoption in the investigated cases was found to be of 20%. Scale economies from joint investments in microgrid capabilities can reach 10%, compared to separate investment by each one of the single typologies. Also, load complementarity is an important aspect to take into account. Moreover, economic gains can be enhanced if, through a point of common coupling, energy sales to the macrogrid operator take place. From the environmental point of view, average GHG emissions reduction was of 20%. Particularly, Health and Office complexes might find microgrid adoption exceptionally attractive. Such benefits through investments in DG, especially the economic ones, can constitute attractive field for entrance of ESCO businesses in the microgrid market. The Portuguese technical-economic context and climate currently favor investments in solar energy technologies rather than on fuel-fired ICEs, FCs and MTs due to capital prices and increasing natural gas tariffs. Electrical battery storage has also considerable importance as a backup for energy management and reliability purposes. However, if investments in microgrid adoption become driven by environmental criteria, CHP DG as well as absorption cooling equipments might have an important role to play. The results for the case-study in Portugal suggest that multibuilding microgrids might play a significant future role in providing building complexes with its energy needs.