Cost estimation of biogas upgrading by PSA for small scale applications

Pushed by the undeniable changes in Earth climate, the interest of the policymakers and the industrial world has been shifting towards an increased protection of the environment and sustainable development. For this reason, the generation of energy from renewable sources plays an increasingly important role when it comes to energy supply. Biogas and its further upgrading to biomethane is an already used technique for substitution of fossil fuels, namely natural gas. One of the most important advantages of the biogas is its decentralized production which allows application of the process in almost every place of the world. Pressure Swing Adsorption (PSA) is a well-known technology for gas separation and has been one of the most popular choices for the biomethane purification. However, the high investment costs of PSA technology lead to the conclusion that the process is feasible for large and intermediate scales, inhibiting its growth to small-scale applications. In order to conquer small-scale farm-based markets, further developments of the PSA technology have to be done. The main focus is to make the process more effective and attractive, especially in terms of financial considerations. For this reason, it is important to understand the structure of the cost of biogas upgrading plants. The cost estimation model, which constitute the main deliverable of this thesis, allows not only to have a better view of the cost of PSA plants for biogas upgrading but also to understand what change of the PSA design will have a real effect in bringing the cost down. The results show that, when downscaling the process, the specific investment cost increases significantly causing troubles in implementing the technology for small biogas capacities. Furthermore, the major part of the total investment cost is influenced by the total installed cost of pressure vessels. Additionally, the influence of the adsorbent cost is decreasing for smaller plants. The conclusions entail the need for new developments with respect to the PSA cycle configuration as well as new adsorbent materials approaching a decrease of the overall size of the plant and a reduction in the total number of columns.