SCS Energy: CALGREN Digester Gas Utilization to RNG Using Dairy Feedstock

CALGREN Digester Gas Utilization 

SCS designed a 2,500 scfm dairy digester gas to a renewable natural gas (DG-to-RNG) plant in Pixley, California. The product gas capacity is 2,100 MMBtu/day. SCS also provided assistance in equipment procurement, construction oversight and startup/testing.

SCS provided the supervisory, control and data acquisition (SCADA) system on a turnkey basis. In the initial phase of this project, the RNG will be used to fire a combustion turbine, because the combustion turbine requires pipeline quality gas. The feedstock for the digester is dairy manure. The facility came online in August 2018, with gas being sent to the duct burner of an onsite gas turbine. The RNG plant is configured to allow RNG pipeline injection to the Southern California Gas Company (SoCalGas) interconnection following testing.

The RNG plant uses the following technologies:

• Liquid scrubber for H2S removal with solid media backup;
• DG refrigeration;
• Activated carbon treatment;
• DG compression with flooded-screw compression;
• Membranes for CO2 removal; and
• Product gas compressor (to 250 psig).

Related article on diary power, or return to read more SCS case studies.