Comparative Assessment of Electrical Generating Systems for a Greek Island

This master thesis is the last part of the master studies in the department of Energy Management and Sustainability, at the Swiss Federal Institute of Technology (EPFL) in Lausanne. This work has been performed in collaboration with the company Renenig Energy, in Athens. The reader should note that the report is an academical work. Results and conclusion are influenced by hypothesis and should not be taken as general truths. The case study is a fictive project but it is composed of values adapted from another real but confidential project, which makes the analysis plausible. The owner of a private island in Greece wants to build a luxury resort on his island. Therefore, he will also need an electrical generating system that must cover the future electricity demand. Usually, diesel generators are used in remote areas in order to produce electricity. However, this technology is very expensive, and harmful for the environment. This master thesis covers the estimation of the electricity demand and the technico-economical assessment of different energy systems. The objective is to evaluate the potential of a microgrid composed of different renewable energy technologies and compare it to the a baseline system composed of generators only. The hourly electricity demand of the entire island has been modeled using a bottom-up approach with a list of representative types of locals. The consumption of these locals have been divided into three categories : The appliances, the lighting and the heating/cooling. For the energy system which must produce electricity, supply strategies have been defined based on the type of technology. For all strategies, an optimization of the technology installed capacities is performed with the software HOMERPro. It is used as a tool to minimize the net present cost of the energy system and analyze the microgrid energetic behavior. The yearly electricity demand of the island has been estimated to around 11 GWh, with a peak load of 2,5 MW during the summer. The cost of serving this load with generators is $63 million with a levelized cost of electricity of 0.467$ /kWh. When integrating solar panels, the system cost decreases to $51.3 million with a LCOE of 0.378$ /kWh. Moreover, wind turbines and a battery storage system are also economically viable. The last strategy consists of distributed PV panels on building roofs, wind turbines and a battery storage system. Results show that this energy system can decrease the cost to $ 39.8 million while emitting half of the carbon dioxide compared with the baseline system. However, the battery bank has a large impact on CO2 emissions due to its manufacturing processes. Further work can be done for this case study, especially on the network stability assessment, which was not part of this master thesis. Moreover, the potential of implementing hydrogen in the microgrid could be interesting. This could bring a good storage alternative to batteries.

A review of sustainable energy access and technologies for healthcare facilities in the Global South

Andrea Franco, Silvia Hostettler, Dikolela Kalubi, Marjan Shaker

Access to reliable, affordable and sustainable energy is essential for improving living standards, development and economic growth. From a healthcare perspective, energy is a critical parameter for delivering and improving healthcare services and life-saving interventions in the Global South. This review provides an estimation of the energy needs of different healthcare facilities as a function of patient capacity and services provided. It also presents the strengths and limitations of several energy sources that can be used to meet these needs. The review focuses on energy provision in off-grid scenarios and for satisfying peak demands of grid-connected hospitals. The initial key observations are that fossil-fuel generators are the main energy source because of their low investment costs. However, this technology can no longer compete with the energy produced from renewable sources in terms of levelized cost of electricity (LCOE). Photovoltaics (PV) has an LCOE of 0.09 USD/kWh, versus an average 0.25 USD/kWh for diesel generators. Moreover, PV is a modular technology that can efficiently meet energy demands in an environment-friendly way. Wind turbines share many strengths of PV and yet both technologies suffer from intermittent energy sources. They must therefore be coupled with a storage system that provides continuous and stable electricity. Today, energy is mainly stored electrochemically, in the form of lead-acid batteries. However, this review shows that nickel-metal hydride (NiMH) should be used when possible for their higher energy density (200 Wh/l versus 80 Wh/l), non-toxicity, safety and simple maintenance. Alternatively, lithium-based batteries should be used when the energy density and number of cycles is a priority. Other energy production means (e.g., hydropower) and storage technologies (e.g., flywheels) are reviewed as well. In conclusion, the optimal energy solution for medium-to-large healthcare facilities, especially for those in off-grid settings, is a hybrid system wherein the strengths of a renewable energy source coupled with efficient batteries is combined with a diesel generator to minimize the LCOE.

Elsevier Science Bv2017

Improving the energy sustainability of a Swiss village through building renovation and renewable energy integration

Silvia Coccolo, Morgane Le Guen, Nahid Mohajeri Pour Rayeni, Lucas Mosca, Amarasinghage Tharindu Dasun Perera, Jean-Louis Scartezzini

The integration of renewable energy technologies and building renovation are the two main procedures for improving energy sustainability of buildings at neighborhood scale. It is difficult, however, to optimize these procedures simultaneously. This study focuses on improving energy sustainability of Hemberg, a Swiss village with a population of about 900, through optimizing these two procedures. For this purpose a computational platform was developed, combining software CitySim, HOMER Pro, QGIS and Rhinoceros. The energy demand on hourly basis for the buildings in the village was analyzed through comparing the current demand with that after retrofitting according to the Swiss energy labels (i) Minergie and (ii) Minergie-P. Swiss energy maps were used to identify the most promising renewable energy sources while three scenarios were considered for solar PV integration and energy system improvements. The first scenario presents the current condition in the village, while the second scenario explores improvements in electricity generation and the third in both electricity and heat generation. The results show that retrofitting of all buildings according to Minergie reduces the space heating demand by 70–85% and reduces the fluctuations in energy demand, thereby allowing the integration of more renewable energy. According to the simulations, building-integrated solar PV panels can cover the total annual energy demand of the village when considering the Minergie and Minergie-P scenarios. However, the energy system assessment shows that it is difficult to reach beyond 60% when integrating non-dispatchable renewable energy technologies. Finally, and more importantly, integration of wind energy at system level has an important impact in the hub.

Elsevier2018

Evaluating the sensitivity of grid integration level for a multi energy hubs

Dasaraden Mauree, Vahid Moussavi Nik, Amarasinghage Tharindu Dasun Perera, Jean-Louis Scartezzini

Renewable energy integration into multi energy grids (MEG) is gradually getting popular due to the rapid depletion of fossil fuel resources and the global concern on GHG emissions through fossil fuel based energy conversion technologies. However, seasonal changes in solar and wind energy potentials make it challenging to increase the renewable energy capacity especially for urban applications where demand for energy services show a complex variation. According to recent literature, connecting multi energy hubs (MEHs) to a MEG can be a promising method to address the aforementioned challenge. However, a quantitative analysis of the improvement of system autonomy and renewable energy integration through multi energy hubs is missing. In this work, Homer microgrid design tool is used to analyze the sensitivity of the grid integration level to the renewable energy integration process of a multi energy hub. Heating and electricity demand of the MEH and the energy flow through Solar PV panels, wind turbines, boiler and battery bank are evaluated on hourly basis. Homer, microgrid simulation tool is used to evaluate the sensitivity of electricity cost to renewable energy capacity and energy storage.