Carbon Dioxide Based Co-Products from Renewable Natural Gas Fuel Production

Improving the cost of renewable natural gas production with value-added co-products

University of California, Riverside


Riverside, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project was completed on June 30, 2016.

The Issue

Renewable Natural Gas (RNG) is often produced from waste matter through anaerobic digestion and feedstock decomposition. These methods are often inefficient and the product gas quality is inferior to natural gas that originates from fossil sources. These methods produce product streams of varying fuel composition, calorific value, and quantities depending on a number of parameters. Irrespective of the technology chosen, the product gas stream must undergo considerable gas conditioning to upgrade the quality of the final product to allow it to be used for transportation purposes. [?[o:p][/o:p]

Project Innovation

The goal of this Agreement was to develop 1) a cost-effective technology for  CO2 conversion into a commercially valuable co-product such as methanol or Dimethyl Ether (DME), and 2) a combined CO2 separation and conversion technology that converts the CO2 into a commercially valuable co-product such as potassium carbonate. An important benefit of this approach is that the technology demonstrated in this project could be used in conjunction with any RNG production process and therefore would result in the maximum benefit in terms of enabling a number of existing and new RNG production processes to be commercially competitive. The ultimate goal of this project was to develop a CO2-based co-product synthesis technology that would reduce the production cost of the RNG transportation fuel by a minimum of $0.50 per mmBtu compared to the current preferred production methods for the specific feedstocks. Project results show cost reduction is possible but is dependent on hydrogen costs.

Project Benefits

The technology used in this project improved the total feedstock utilization efficiency of RNG production processes by converting the otherwise wasted CO2 to commercially valuable products. The technology increases the commercial viability of RNG production through the revenue stream generated from the co-products.

Lower Costs


Economic analysis result shows the estimated RNG production cost reduction is strongly dependent of the required hydrogen feed cost and DME sale price. For the DME sale price of $500 per tonne, estimated price reduction in the RNG production cost, was $0.26 per MMBTU with the $1/kg of hydrogen cost.

Key Project Members

Project Member

Gouyuan Wu

Postdoctoral Scholar

Contact the Team