Outdoor Contactor Data Analysis

Our “Outdoor Contactor” prototype successfully wrapped operations this past October. After our initial run in the summer/fall of 2011, a big goal for us this year was to log performance data in a continuous, long-term operation mode. It took a lot of effort from the whole team to achieve this goal, but in the end we were very happy with both the operation and the performance of the outdoor contactor. (See the first image below for our aggregated long-term data) We spent a lot of time in summer/fall 2012 operating in our proprietary "pulsed liquid flow" mode, where we only periodically supply the packing material with our CO2-absorbent liquid. This allows us to cut our pumping work and pressure drop, which in turn reduce our energy usage, while retaining the majority of our full CO2 capture rate. (The second image below illustrates roughly one day of our pulsed flow operation) In fall of 2012, we were able to conduct a whole battery of sensitivity experiments with the outdoor contactor, to quantify our CO2 absorption response to liquid flow rate, solution conditions, and air velocity. And now, by mining our long term dataset, we are building up quantitative responses to the environmental variables - like temperature, humidity, or wind speed - that slowly varied while we ran in steady state. One interesting example of this is shown in the third image (below), which correlates temperature and inlet air CO2 concentration versus the time of day for roughly one month of data. The viewer can see that during the sunny mid-day and afternoon hours, where temperature is commonly at its maximum, the CO2 in our inlet air is at a minimum due the draw-down from the vegetation around our site. During the night, when the plants stop consuming CO2 by photosynthesis, the CO2 concentration rises. The successful long-term operation of our contactor prototype has given us real validation of our contactor design. We are now turning our sights to our upcoming end-to-end pilot plant of our full air capture system! -GH.