SCS Energy: RNG Design-Build for the University of New Hampshire

UNH Ecoline Project

SCS Energy unh gas plantThe University of New Hampshire (UNH) Ecoline Project consists of a Renewable Natural Gas (RNG), plant located at the Turnkey Landfill in Rochester, New Hampshire, which includes a landfill gas to RNG plant; a 12.7-mile dedicated RNG pipeline; and a cogeneration plant, located at UNH’s main campus in Durham, New Hampshire.

SCS is responsible for the RNG plants design and construction. The RNG is used to fire combustion turbines., which require pipeline quality gas. The RNG plant has an inlet capacity of 6,000 standard cubic feet per minute (scfm), and a product gas capacity of 3,700 million British Thermal Units per day (mmBtu)/day. The RNG plant incorporates the following technologies:

  • Inlet booster blowers and air-to-gas coolers;
  • Darco for hydrogen sulfide (H2S) removal;
  • 3.2-megawatt (MW), LFG fired power plant, which supplies all of the RNG plant’s power requirements;
  • Compression with flooded-screw type compressors and refrigeration;
  • Temperature swing adsorption (TSA) for volatile organic compound (VOC) and siloxane removal;
  • Pressure Swing Adsorption (PSA) for carbon dioxide (CO2) removal; and
  • Thermal oxidizer (TOX) destruction of TSA and PSA waste gas.

SCS completed a feasibility study to select the process chain to be employed for the RNG plant. SCS then designed and constructed the RNG plant on a design/construct basis. SCS was responsible for securing the air permit for the project. The RNG plant began commercial operation in September 2009 with operations-maintenance performed by SCS on a contract basis.