Pepperell Hydro Company
P.O. Box 149A, Hamilton, Massachusetts, United States

Swift River Hydro Operations Company (SRHOCO) purchased the Pepperell dam and hydro facilities from the liquidators of the Pepperell Paper Company in 2004.  Built in 1918, the hydro plant was designed for 3 vertical Francis turbines selected for a net head of 28 feet and a design flow of 1,035 cfs.  The intake at the dam on the Nashua River is connected to the forebay of the powerhouse by a 13 foot diameter, 600 foot long wood stave penstock.  This penstock was replaced over 60 years ago and will be replaced in 2012 before it is damaged by winter ice and spring floods. Of the original Leffel B turbines, the T-1 runner was replaced in 1997 with an American Hydro Corp. runner with greater efficiency.  SRHOCO bought the plant in 2004 and purchased and installed a new runner fabricated by American Hydro Corp for T-3 in 2005.  T-2 was taken out of service in 1962 and in the early 1980's the generator was cannibalized for parts.  SRHOCO's strategy then was to install a Leffel B2 runner in T-2 connected to a new 675 kW Dong Fang generator. The new equipment, together with installation of an Atlas Polar trash rake and PLC controlled switchgear with remote sensors and pond level controls increased long-term average production to 7,123 MWh per year.

The Pepperell Hydro station was formerly the primary electricity supply for Pepperell Paper Company's (PPC) paper mill.  Manufacturing was located at that site in the mid 19th century because of its hydropower potential.  When the mill was closed in 2002, the powerplant operators were fired and the facility was maintained by a single security guard.  Thus, maintenance ceased at the dam and the hydropower producing green energy on the Nashua River for more than a century was nearly lost. The PPC story is typical of many mills in the Commonwealth.  Swift River Company (SRC) and its affiliate SRHOCO were formed to preserve the skills needed to finance and rehabilitate existing renewable energy projects and to preserve civil structures and equipment that convert water into green, non-polluting electricity.  SRHOCO has acquired the engineering plans, shop drawings, repair equipment and skills necessary to maintain and operate hydro turbines and generators that have decades of useful life left before they must be replaced.  Most importantly, Swift River believes that there are a few select sites where river flows and head combine for efficient hydro generation.  Plants at existing dams were located at such efficient hydro sites, so repowering them helps Massachusetts to rely on local renewable energy resources.  The Massachusetts Green Power Partnership (MGPP) recognized this potential and awarded Pepperell Hydro Company with a 10-year contract to purchase renewable energy certificates (RECs) enabling the Webster Five Cents Savings Bank to finance purchase and rehabilitation of the century-old Pepperell hydro plant.  SRHOCO repaired or replaced one turbine at a time while continuing to generate power with the other turbines during the construction period in 2004 through 2006.  SRHOCO has a machine shop with specialized tools and the shop equipment necessary to restore the mechanical and electrical equipment but SRHOCO left the penstock to last, believing that it had at least another decade of useful life.  However, a fire (caused by a lighting strike on National Grid's interconnecting transmission line during a fall storm) burned out some of the new electrical control equipment, station wiring and one generator in the powerhouse.  Fire insurance funds then paid for replacement of all station wiring, windows and to rebuild the damaged generator, leaving the plant in "like new" condition.. The hydro plant was disconnected from the rest of the paper mill across the river and began to sell all of its output to ISO at local nodal marginal prices. In March 2011, bundled energy, capacity and RECs started to be sold to the Reading Municipal Light Department (RMLD) on a 15-year contract.

In New England, reliance on locally generated "green" power is widely supported by consumers willing to pay more to increase the distribution systems share supplied by renewable hydro generated electricity.  When restructuring the electric sector, the state legislature mandated that renewable energy must increase annually by enforcing the Massachusetts Renewable Portfolio Standard (RPS), but hydro was omitted from the RPS.  Therefore Pepperell Hydro applied and has been certified as a Class 1 generator in Connecticut and as a "new" source for the output of  T-2 and T-3 in Rhode Island.  RECs represent the "renewable attribute" of hydropower that is separate from energy generation and may be sold to Connecticut and Rhode Island distribution companies.  (See Energy Sales and Green Certificates for an explanation of renewable energy certificates -- RECs).  Each year the share of renewable energy purchased by distribution companies must increase to levels set by the state's RPS.  Thus the price of RECs is expected to rise over time.