Characterization, Optimization and Design of the Sorbent System for a Continuous Direct Air Capture System

With the influx of the industrial revolution of the past centuries, the global energy demand has grown proportional to the global economical growth. Consequently, an enormous rise in greenhouse gas emissions has been observed, where the major contribution to global warming comes from the rising concentration of CO2. Therefore, the concept of capturing CO2 directly from the air (DAC) has gained world wide attention as it can reduce the carbon footprint of men kind.Zero Emission Fuels (ZEF), an inspiring start-up based in Delft, aims to develop a micro plant that utilizes the DAC concept to produce methanol as a fuel, using only the sun as its energy source. CO2 and H2O is captured directly from the atmosphere by the DAC unit which operates continuously with the help of an amine sorbent that flows through an absorption and stripping column. Previous research shows pure tetraethylenepentamine (TEPA) having great potential as a CO2 capturing sorbent. However, it has some limitations regarding slow absorption and desorption kinetics due to a high sorbent viscosity, that prevent ZEF from reaching their goal of capturing 825 grams of CO2 per DAC unit ineight hours of operation. The focus of this research is on the sorbent selection process of ZEF’s DAC system. Research has shown that adding a diluent to TEPA could potentially improve the performance of the ZEF DAC unit. Therefore, a total of nine diluents, DEG, PEG-200, PEG-400, PEG-600, selexol-250, selexol-500, glycerol, 1,4-butanediol, sulfolane, mixed in different ratio’s with TEPA, have been put to the test through the developed framework of sorbent selection.In the framework of sorbent selection all the sorbents are tested through four different experiments, keeping efficiency and costs in consideration. The Airfarm experiments are used to evaluate absorption capacity and viscosity of the sorbent at specific ambient conditions. The Vapor-Liquid-Equilibrium (VLE) experiments are utilized to evaluate the desorption characteristics of the sorbent from where the regeneration energy demand can be calculated with the help of a mathematical model. The re-pumping experiments are used to evaluate the absorption kinetics of the sorbent and lastly, the degradation experimentsare used to evaluate the sorbent life time performance. After the experimental procedure the sorbents can be judged on the key performance indicators regarding the ZEF DAC unit operated in a specific climate. It was concluded through the literature research and proved by an extensive experimental researchthat selexol, glycerol and sulfolane did not improve the characteristics of the sorbent. However, adding DEG, PEG or 1,4-butanediol to TEPA did have a profound positive effect on the overall performance of the DAC unit. Since the diluents reduce the sorbent viscosity, and therefore, increase the absorptionand desorption kinetics. Based on the experimental results and the design specifications set by ZEF, PEG-200 proved the most promising out of all diluents in the mixing ratio TEPA:PEG-200 2:5. This sorbent has been tested for two different climates; the dry Sahara climate and the more humid Mediterranean climate to see how the sorbent would have to be changed for different climates. It was concluded, for a more humid climate, it requires less diluent for the sorbent to stay within the 2 푃푎 ⋅ 푠 viscosity limit. The experimental results were included in a full DAC model to design the DAC unit utilizing the optimized sorbent for the two different climates considering the design specifications set by ZEF. Followinga sensitivity analysis an optimized conceptual DAC design was obtained for both climates. Where it was concluded that the optimized sorbent resulted in reduction in energy requirement for regeneration of the sorbent, where 1554 푘푊ℎ/푡표푛 of CO2 is needed for the Sahara climate and 1636 푘푊ℎ/푡표푛 of CO2 for the Mediterranean climate. Finally, a cost analysis has been performed regarding the operational and capital costs of the newly designed conceptual DAC units for both climates

Water productivity assessment of rice paddies in Indonesia

IHE-Delft in cooperation with the Asian Development Bank (ADB) conducts a pilot project on assessing Crop Water Productivity in Asia, aiming to contribute to sustainable development in Asia’s irrigation sector, and create more value from scarce water resources. Indonesia is one of the 6 pilot countries where advanced technologies to measure Water Productivity (WP) from satellite data were introduced. Indonesia is the third largest rice producer of the world. Given the challenges such as growing population, degrading land and increasing water scarcity in upcoming decades, the Indonesian government aims to rehabilitate its irrigation systems. More insights in the spatial distribution of irrigation water and water productivity of rice paddies could contribute to decision-making in future rehabilitation investments. This report describes the assessment of Water Productivity (WP) of paddy rice in Indonesia using the Surface Energy Balance Algorithm for Land (SEBAL). SEBAL is a tool that translates raw satellite measurements into maps of actual evapotranspiration and crop production, among others. The actual crop water consumption (i.e. actual evapotranspiration) and crop yield can now be estimated for every 30 m x 30 m, even if data on irrigation water application is not available. With this information, rice production per unit of land (kg/ha) as well as per unit of water consumed (kg/m3) can be computed. Focus of this study are sites in Bali, West Java and Lombok. Fieldwork is conducted in Bali and West Java to support the maps with ‘ground truth’ data. Data is collected from local governmental institutes and farmers to verify the remote sensing outputs. This research shows promising results linking SEBAL outputs with the ground truth even though the amount of fieldwork was limited. The inclusion of the new HANTS algorithm will create the technical opportunity to make daily WP reports for all rice fields in Indonesia, also under cloudy conditions. This could be a big information boost to support irrigation managers with their daily services of bringing water to farmers. Whereas some key explanatory reasons were detected (i.e. distance to canal, salt water intrusion, water quality, erosion), it is recommended to further explore relations between WP and influencing factors in the local context together with local irrigation officers. Even though the research revealed some limitations causing uncertainties, this new remote sensing technologies can support an efficient and effective investment purposes on modernization of irrigation. It is recommended that the Directorate of Irrigation and Lowlands recognize WP as a new policy instrument and implement it both at central level and irrigation district level. MP238Master project repor