TEACHING SUSTAINABLE ENERGY SYSTEMS A CASE STUDY

Transcription

1 M. Brito 1,3, K. Lobato 2,3, P. Nunes 2,3, F. Serra 2,3 1 Instituto Dom Luiz, University of Lisbon (PORTUGAL) 2 SESUL Sustainable Energy Systems at University of Lisbon (PORTUGAL) 3 FCUL, University of Lisbon (PORTUGAL) mcbrito@fc.ul.pt, klobato@fc.ul.pt, pmnunes@fc.ul.pt, fcserra@fc.ul.pt

2 Abstract A bottom up methodology for the analysis of sustainable energy systems applied to a case study of an imaginary isolated island is developed for the purpose of introducing the most relevant concepts of energy systems. Model results and guidelines for in class discussion are illustrated with student results. Keywords: Learning and Teaching Methodologies, Collaborative and Problem based Learning, Sustainable Energy Systems

3 Objective To project a fossil free sustainble energy system, including electricity, heat and mobility for na island with 5, people, a population density of 1 person/km2 and 2, cars. Inputs Hourly time series of solar radiation, wind velocity and ambient temperature. Global radiation [kw/m 2 ] Wind [m/s] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Daily precipitation [mm/day] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec River flow [m 3 /year] Temperature [ºC] Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

4 Energy supply Source Potential Cost Main assumptions Solar PV 42 MW.7 /kwh Wind power 1.8 MW/turbine.6 /kwh Conversion efficiency 15%; 25 years lifetime Only of roofs; 2, homes with average roof area 7m 2 only on 2% of available area Wind park located in the north side of the island (north is assumed to be the dominant wind direction); 2 years lifetime Hydropower 1.5 MW.5 /kwh Run of the river dam; 6 years lifetime; capacity factor 8% Biomass 13 MW.6 /kwh Waste 1 MW.15 /kwh Residues from agriculture (including from biofuel production), forestry, energy crops 1.4 kg/person/day; 2% recycled; 1% compost; the rest is incinerated with electricity production Solar thermal 1 MWh/m 2 /year.8 /kwh 1m 2 per person; 5% efficiency Biofuels.8 kwh/m 2.4 /kwh Colza and sunflower, the best adapted to the local climate

5 Energy demand Energy Use Demand Observations & main assumptions Heat Hot water 2.1 kwh/person/day 6 liters/person/day; 45ºC; pipe water at annual atmosphere average temperature Thermal comfort 2. kwh/person/day No cooling needs due to mild summer Electricity Load diagram 1 kwh/person/day Mobility Individual cars 3.5 kwh/person/day From load data of comparable island (e.g. Faial, Azores) Energy efficiency depends on fuel used (e.g. electric vehicle or biodiesel) Public transport 1.7 kwh/person/day Different scenarios ought to be considered

6 Energy storage and transmission Costs Observations & main assumptions Storage Pumped hydropower.5 /kwh Cost of installation of upstream pump; Evaporation losses neglected EV batteries.1 /kwh Shorter battery lifetime due to storage ( 3%) Transmission.1 /kwh Considering medium voltage and local low voltage distribution

7 5 2 Power [MW] Stored energy (MWh) Power [MW] Stored Energy (MWh) Load and supply power curves (left) and stored energy in electric vehicles (right) for winter (top) and summer (bottom), including biomass (brown), hydropower (blue), waste (green), wind (grey) and solar power (yellow). For the stored energy plot, blue represents the stored energy, red the demand and black the hourly net electricity balance.

8 5 2 Power [MW] Stored energy (MWh) Power [MW] Stored energy (MWh) Load and supply power curves (left) and stored energy in dam reservoir (right) for winter (top) and summer (bottom) including biomass (brown), waste (green), wind (grey) and solar power (yellow). For the stored energy plot, blue represents the stored energy, red the demand and black the hourly net electricity balance

9 Model Storage Installed capacity Cost Observations 1 n/a 26 MW.6 /kwh Cost does not include underwater cable 2 n/a 32 MW 1.79 /kwh Requires 168 turbines 3A EV 57 MW.1 /kwh All cars are EV 3B Dam 47 MW.8 /kwh Would require 7% land area in the island for energy crops and storage

10 CONCLUSIONS We have presented a methodology for the bottom up analysis of an integrated fossil free energy system in a remote island. Using standard climate data, a spread sheet tool and some key input parameters to be identified by the students, the methodology proved successful in a one semester introductory course in energy systems for advanced undergraduate engineering students. It requires a tutorial like approach from the teacher and a high degree of autonomy and teamwork skills from the students. Given the number of students in our classes, there are different teams working on the energy system of islands with slightly different characteristics. This approach is chosen to lean to different optimized solutions. Throughout the course, different sub teams present the different topics to their colleagues. The final presentation which includes the overall energy system, sensitivity analysis and discussion, is an open to the public session that often leads to interesting debates between teachers, researchers and students from all levels.

11 ACKNOWLEDGEMENT The authors would like to acknowledge the contributions from all the students of the Energy and Environmental Engineering MSc class for whom this course was developed. Part of this work was supported by PEST OE/CTE/LA19/ , the MIT Portugal Program on Sustainable Energy Systems and FCT (SFRH / BPD / 4553 / 28, SFRH/BD/51377/211, SFRH/BD/5113/21). REFERENCES Connolly, D. et al (21). A review of computer tools for analyzing the integration of renewable energy into various energy systems, Applied Energy, 87(4), pp MacKay, D (28). Sustainable Energy without the hot air, UIT Cambridge. ISBN