Deicing of Roadways Using Reclaimed Salt-rich Biochar Obtained from Roadside Halophytes
Every year more than 22 million tons of salt (primarily NaCl) and other de-icing agents are applied to U.S. roads to maintain safe driving conditions in inclement weather. These chemicals eventually migrate from the pavement to the surrounding environment, contaminating soils and waters, and compromising drinking water supplies. Roadway runoff and salt particulates also adversely affect crops, aquatic and roadside life, and transportation infrastructure. The life-cycle costs associated with salt production through mining or other means, distribution, and storage of roadway de-icing salts are significant as substantial energy is used and greenhouse gases (GHG) are produced. Although alternative methods for de-icing and anti-icing application are constantly being developed, there are currently no economically and/or environmentally viable alternatives to salt. The proposed research would establish proof-of-concept for increasing the sustainability of roadway winter maintenance operations through recovery and reuse of applied salts. Biochar and biofuel would be produced from salt accumulating plants (halophytes) planted along roadsides. The aboveground tissues of these native perennial plants would be harvested for subsequent biomass-to-fuel biochemical conversion. The biofuel would be used in winter maintenance vehicles. The resulting biochar would be reapplied as a component of roadway de-icing agents and as a roadside soil amendment. To establish proof-of-concept, a pilot-scale experimental site on the Virginia Smart Road facility will be established for a controlled study. This site would allow practical demonstration of all components of the proposed salt reclamation cycle other than the biofuel conversion process. Salt could be applied to the roadway, harvested through roadside crops, extracted in off-site biofuel production, and then reapplied to the roadway as a deicing agent to evaluate its effectiveness.
The proposed research is aimed at sustainable water and energy, and renewable materials. This innovative research relies upon interdisciplinary collaboration, and if proven feasible, will benefit human and environmental health through improved water and soil quality, and decreased adverse environmental impact through reuse of materials typically mined. Other benefits include decreased energy usage and GHG production and increased energy security. The proposed experimental site, if implemented, would expand the utilization of the Smart Road to include untapped aspects of sustainability.
Virginia Tech Transp. Institute
June 1, 2016
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