Integration of energy systems in urban areas: A case study in the Cuban municipality of Placetas

Sammanfattning: The massive global use of fossil fuels has resulted in a lack of oil that opens up for an increased demand for renewable resources. Decreasing the dependence on fossil fuels is a global goal where a fossil free energy market is a vital part in the solution. Cuba is a country whose electricity production is very dependent of oil, although there is a national goal to achieve a 24 percent renewable electricity until year 2030. The incentives behind this decision are that the production cost for electricity is high in Cuba and the emissions of carbon dioxide and other particles are causing local and global environmental problems. Placetas is a municipality in Cuba that have the largest pork production in the country and furthermore many aluminum industries. These industries have been shown to emit particles that significantly reduces the air quality in the municipality and hence also the inhabitant’s quality of life.    Biogas is a mixture of gases and mainly consists of methane and carbon dioxide. It is manufactured by anaerobic digestion of biomass, which refers to for example pig manure. For a municipality like Placetas with severe air pollutions, biogas possesses a potential to replace a part of the current fuel that is used in the industries and reduce the emissions of air pollutions. Hence, this study aims to investigate, by literature and field study, the potential to replace the fuel oil in the aluminum industries in Placetas with biogas from pig manure. Furthermore, it will investigate whether the biogas can be used in the households to reduce the consumption of electricity, which is generated from fossil fuels. The potential of generating electricity directly from biogas is also assessed. These scenarios with different utilizations of biogas are based on a central assumption where if all municipalities in Cuba achieve an electricity generation from renewable resources of 24 percent of the consumption, the whole country does. Hence, the study investigates if it is possible to achieve this in Placetas. To do this and still meet the electricity demand, the potential of solar photovoltaic (PV) to complement the biogas will be investigated. Moreover, an environmental assessment and economic evaluation of the costs and savings due to the transition to renewable will be done. Also, the required area for the solar PV and the volume of the digester will be calculated.    These investigations and calculations result in two different scenarios in which the biogas in both is assumed to be primarily distributed to the aluminum industries. The remaining biogas will in the first scenario be generated as electricity and together with solar power aim to cover 24 percent of the consumption in Placetas. In the second scenario the biogases potential to replace the consumed electricity in the households is investigated. To reach the goal of 24 percent, 24 percent of the electricity will be generated from solar power. The conclusions show an annual electricity consumption in Placetas of 2,526.2 MWh. From the crude oil used in this electricity generation, 260 tons of CO2emissions can be derived. The energy consumption in the industries using fuel oil is 21,271 GJ and the emissions of particles due to this was in some locations 270 percent higher than allowed. The generated biogas from pig manure corresponds to 24,430 GJ energy or2,375,000 kWh electricity. Lastly, scenario 1 is found to be most feasible in terms of environmental and social aspects.