SCS Energy: Digester Gas Methanization, La Farfana and Metrogas in Chile

The new Metrogas plant converts digester gas from wastewater treatment to renewable natural gas.

Aguas Andinas’s La Farfana Wastewater Treatment Plant near Santiago, Chile

Metrogas, the owner of the plant, is the chief natural gas distribution company in Chile. Metrogas launched commercial operation of this new plant, which converts digester gas (DG) into renewable natural gas (RNG).

La Farfana Methanization utilizes DG which is produced at Santiago, Chile’s La Farfana Wastewater Treatment Plant. The project proceeded in two phases.

In Phase I, the DG was compressed, dehydrated, delivered by dedicated pipeline to a remote site, and then cleaned to reduce H2S and VOCs to very low levels for use as feedstock for a town gas manufacturing plant. Phase I  incorporated compression, refrigeration, Darco media for hydrogen sulfide removal and activated carbon polishing. SCS designed the Phase I project and assisted with equipment procurement and startup. The Phase I project commenced operation in October 2008.

Phase II completed upgrades to produce pipeline quality renewable natural gas, by adding CO2 removal, additional compression, and a TOX. SCS completed a feasibility study to select the carbon dioxide removal technology to produce RNG, to estimate RNG plant construction, operation-maintenance costs, power consumption, and plant performance. SCS was then authorized to move forward with the design. SCS also was responsible for providing assistance in equipment procurement, construction oversight, and startup. The RNG project has an inlet capacity of 2,300 scfm and a product gas capacity of 2,000 MMBtu/day.