Dynamic model and preliminary design of a small-scale renewable methanol system

Abstract

Zero Emission Fuels B.V. develops a standalone System that produces renewable methanol from air and sunlight. In this thesis the steady-state model of this System is replaced with a Simulation Tool that can predict its behaviour for every minute of a year. The goal is to verify how technical design parameters influence methanol production and to determine if the business case target of 6.7 mole methanol per day is achievable. This thesis will contribute to the understanding of the System, speeds-up the design process and makes it possible to see the impact of fluctuating weather conditions throughout the year at different locations on earth. The System as it was at January 1, 2018 is implemented in the Simulation Tool and its production determined for Tucson, Arizona in the year 2005. The result is an average daily production of 3.0 mole methanol with fluctuations from 1.0 mole during a cloudy winter day to 4.2 mole during a sunny summer day. The minute by minute production is found to be influenced by all System design parameters. They must thus be designed together to make sure the System performs optimally. The Alkaline Electrolysis uses the most energy of all subsystems. Four options to improve the System are identified. These are 1) improving the power the Solar Panel produces, 2) improving the efficiency of each subsystem, 3) improving how the System is controlled and 4) integrating heat. A selection of these improvements shows that it is possible to produce 4.8 mole methanol per day. The observed seasonal and daily fluctuating methanol production demonstrates the importance of the dynamic model developed in this thesis. Compared to the steady-state model it gives a more realistic view of methanol production and can be used to improve System design. However, to reach the business case target more technical improvements are needed. It should be realised that the design decisions will be based on technical, economical and political arguments.