LFG to Energy Complex Process Evaluation

Location: Altamont, California
Date Completed: 2010

Project Scope
Venture Engineering & Construction was contracted to provide, under its Master Service Agreement, a process review of the existing Altamont Landfill Gas to Energy complex. The study was intended to identify potential process improvements to reduce or eliminate the need to burn supplemental fuel at the existing enclosed flare [which is used to control the off-gases (tail gas) from the new LFG to LNG plant), as well as to evaluate potential improvements to the overall functionality of the facility with respect to gas utilization as it impacts the existing engine gensets and LNG plant.

A new LFG to LNG plant was built and became operation in September 2009 (Medal Membrane/Guild/Linde). This was the third LFG to Energy asset located at the Altamont Landfill. The facility also includes LFG to electricity production via a turbine plant and an IC engine plant, in addition to the new LFG to LNG facility.

The LNG plant had performed fairly well, following minor process control changes made during commissioning. However, since it became operational, the facility had experienced various LFG “balancing” issues that resulted in non-steady state operation of the previously installed assets. Namely, electricity production was significantly curtailed because of the level of excessive raw LFG usage at the enclosed flare to combust the tail gas from the new LNG plant. This drastically reduced the total energy output at the facility, and revenues were down significantly from projections.

Study Results
Venture provided an exhaustive review of the entire LFG to Energy complex, and made a series of recommendations to improve the overall energy production of the facility.
Improvements were presented in order from least cost to highest. Several of the options were installed and resulted in an overall 40% increase in total energy production across the entire complex.

Improvements included:

  1. Additional pipe modifications at the LNG plant membrane process to eliminate recycle gas surges that were resulting in LFG being bypassed to the flare unnecessarily,
  2. Modifying existing control valves and PLC logic from pressure control to flow control facility wide,
  3. Replacement of the existing enclosed flare with a new,
    smaller flare sized to combust the LNG plant tail gas without any additional LFG gas as fuel.