Used Railroad Tie Conversion via Torrefaction

The North American railroad industry replaces millions of railroad ties each year.  The vast majority of ties removed, as well as those replacing them, are made of hardwood.  CSR, its research collaborators NRRI, and sponsors, such as the Indiana Rail Road (INRD), have teamed up to begin investigating the efficacy of converting a portion of those ties into torrefied biomass that can be used to fuel utilities and, ultimately, preserved steam locomotives.

According to the Railway Tie Association:

  • 15,063,539 crossties were replaced by the major U.S. railroads in 2011, of which:
    • 14,148,012 were new wood ties;
    • 544,652 were second-hand wood ties and
    • 370,875 were of materials other than wood (primarily concrete).
  • 93% of all ties installed are made from hardwood
  • Approximately 4,000,000 crossties are landfilled per year (equivalent ~290,000 tons of wood per annum)

Consider those approximately 4,000,000 crossties another way.  If burned efficiently in a power plant, the four million crossties landfilled is equivalent to  approximately 543.9 Gigawatt hours (GWh) of energy that is being wasted per year. That is equivalent to the amount of energy needed to power more than 50,000 homes for an entire year.

 CSR's research focuses on torrefaction, a technology that modifies the structure of wood into an energy-dense, hydrophobic and homogenous end-product that is easily pelletized and transported. The ability to "upcylce" used railroad ties into a fuel that is able to blend one-for-one with coal to lower emissions at power plants is an exciting opportunity, one that CSR is thrilled to work with INRD and NRRI in pursuing.

Researchers at NRRI are working with CSR to characterize the emissions profile of raw railroad ties with those following torrefaction. The initial, laboratory-scale tests performed by NRRI yielded very promising results, and the two entities are pursuing avenues to fund a large scale (6-12 ton) conversion of used ties into torrefied biomass to verify the "scalability" of the process.