Combined Energy Solutions Applied to Dairy Farming in Bolivia and Latin America
Time: Wed 2023-02-22 13.00
Location: M235 , Brinellvägen 68
Video link: https://kth-se.zoom.us/j/61749230167
Subject area: Energy Technology
Doctoral student: Johnny Villarroel-Schneider , Kraft- och värmeteknologi, Polygeneration
Opponent: Docent Valentina Zaccaria, Mälardalens universitet
Supervisor: Professor Andrew R. Martin, Kraft- och värmeteknologi; Universitets lektor Anders Malmquist, Kraft- och värmeteknologi
The transition towards a sustainable world requires immediate action on the part of individuals and communities. Developing countries find the task of incorporating climate change policies difficult for various reasons including the negative effects that the Covid-19 pandemic left behind on the economy. One way to address this issue would be to focus on the productive sector, for example the dairy farming sector. This segment, along with others of similar characteristics, plays an essential part in developing countries’ economies and is characterized by the presence of small and medium production facilities that, in general, do not consider the concept of a circular economy, and where proper waste and energy management is not a priority. Nevertheless, several types of dairy farms have a high potential for the incorporation of energy solutions under the concept of waste-to-energy by producing biogas, having the potential to cover a wide range of energy demands, including those for electricity, heat, refrigeration, and gas for cooking. This can allow energy self-sufficiency, promote enhanced organic waste management and reduce dependence on conventional energy services (mostly based on fossil fuels). Biogas production also results in the supply of bio-slurry, an organic fertilizer. In addition, a biogas-based energy solution can be combined with other renewable energy sources, thus promoting the exploitation of local energy resources. Under this scenario, these solutions can allow enhanced waste and energy management, while reducing GHG emissions along the lines of sustainability.
This thesis explores these issues by considering biogas-based energy solutions applied on Bolivian dairy farms and, with a broader approach, on Latin American dairy farms. The energy solutions can supply electricity, hot water, refrigeration (by using absorption refrigeration systems), cooking gas and organic fertilizers. The first assessment was focused on evaluating the energy performance of a trigeneration (CCHP) system proposed for small dairy farms. Such a system was found to result in energy savings of up to 37% compared to conventional solutions. A techno-economic feasibility study was performed by comparing two polygeneration options aimed to cover the energy needs of a small association of Bolivian dairy farmers. The costs of producing biogas, electricity, refrigeration, and fertilizers were determined to confirm their feasibility in the market. To reinforce the techno-economic analysis and include solar PV energy, an open dynamic model was extended to allow for optimization of a hybrid biogas/solar PV system. The model determines the costs of producing electricity and heat, quantifies CO2 emission reductions, and displays the operation scheme and the percentage of solar energy use in the system. Finally, an investigation was performed on estimating the potential for biogas and organic fertilizers production on Latin American dairy farms; analyze whether energy self-sufficiency is possible in dairy farms; and quantify the potential reductions of GHG emissions. The combined findings of the techno-economic evaluations and the aforementioned study found that energy self-sufficiency is possible for almost all farm sizes with biogas and electricity production costs in the ranges of 0.017 to 0.037 and 0.06 to 0.16 USD/kWh, respectively. The proposed solutions applied on Latin American dairy farms can contribute reducing GHG emissions of up to 51 Mton CO2 per year.
The results from these evaluations are promising and show that an eventual implementation of polygeneration systems can yield benefits such as promoting an efficient use of local resources within the framework of a circular economy and adhere to the principles of several sustainable development goals. This work contributes to the understanding of an integrated evaluation of combined energy solutions by considering energy performance, techno-economic and environmental aspects. The evaluation methods can be replicated for the assessment of combined energy solutions applied to other productive sectors. Furthermore, the work proposes novel energy system configurations and offers an open access optimization tool that can be useful for further development and study of these type of energy solutions. This constitutes a foundation that should be supplemented and strengthened by future studies leading to the sustainability of the productive sectors, such as dairy farming, in pursuit of a green and efficient economy.