Pre-Commercial Demonstration of a Photosynthetic Upgrading Plant: Investment and Operating Cost Analysis

Pig farms have been identified as one of the most important sources of greenhouse gas emissions. This study demonstrates the production of vehicle biomethane in a demonstration prototype plant based on photosynthetic upgrading technology, where the CO2 and H2S present in biogas are consumed by a microalgae culture. The information collected during the prototype construction allowed for an assessment of the capital and operating costs of this novel biogas upgrading technology with other conventional systems. With this objective, the costs of the equipment comprising the biogas cleaning and purification system were calculated considering a biogas flow rate of 5 m3 h−1, corresponding to a small–medium biogas plant and an average pig farm size. The sustainability and competitiveness of the algae upgrading system and the low capital and operating costs vis à vis other upgrading technologies were proven. With a net energy production of 687 kWh day−1 and an annual profit of €30,348 in a 3500 head pig farm, this technology can be easily installed in livestock farms, increasing the benefits and reducing the carbon footprint.