ABSTRACT
Submitted for the Mid-Continent Transportation Research Symposium to be held at Iowa
State University in Ames, Iowa
August 18-19, 2011
Use of Hydrogen from Renewable Energy Sources in Hot-Mix Asphalt
(HMA) Plant Production
by
Kasthurirangan (Rangan) Gopalakrishnan, Ph.D.
Research Assistant Professor
Department of Civil, Construction and Environmental Engineering
353 Town Engineering Building
Iowa State University, Ames, IA 50011-3232
Phone: 515-294-3044
E-mail: rangan@iastate.edu
Siddhartha K. Khaitan, Ph.D.
Post-doctoral Research Associate
Department of Electrical and Computer Engineering
1113 Coover Hall
Iowa State University, Ames, IA 50011-1041
Phone: 515-294-5499
E-mail: skhaitan@iastate.edu
and
Mandhapati Raju, Ph.D.
Research Engineer
Convergent Science Inc.
6405, Century Ave, Middleton, WI 53562
Email: mandhapati.raju@convergecfd.com
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Use of Hydrogen from Renewable Energy Sources in Hot-Mix Asphalt (HMA) Plant
Production
Kasthurirangan Gopalakrishnan,1 Siddhartha K. Khaitan,2 and Mandhapati Raju3
Abstract
More than 94% of roads in the US are paved with Hot-Mix Asphalt (HMA). The process
of HMA manufacturing is an energy-intensive process which involves sorting and
heating the aggregate to remove moisture from the aggregate, heating the asphalt binder
to obtain sufficient fluidity of the asphalt binder for proper mixing in either batch mix
plants or drum mix plants. Environmental Life-Cycle Assessment (LCA) studies have
shown that, in the production of HMA pavements, major consumption of energy takes
place during asphalt mixing and drying of aggregates, more than what is consumed
during the extraction of crude oil and the distillation of bitumen. Currently, natural gas is
the primarily source of fossil fuel used to produce 70 to 90 percent of the HMA in the
US, while the remainder of the HMA is produced using oil, propane, waste oil, or other
fuels. It has been estimated that energy-related CO2 emissions, resulting from the use of
petroleum and natural gas, represent 82 percent of total U.S. human-made greenhouse gas
emissions.
According to some estimates, the production of HMA consumes 237,000 BTU/t
(275 MJ/t) energy and produces 44 lb CO2/t (22 kg CO2/t). With the recent push towards
sustainable, low-energy, low-emissions and environmentally friendly pavement
construction methods, recent studies are focusing on low-temperature asphalt
technologies (Warm-Mix Asphalt [WMA], Cold-Mix Asphalt [CMA], foamed bitumen,
etc.) that have reduced production energy requirements apart from other benefits and
development and implementation of energy saving guidelines targeting changes in
1
Research Assistant Professor, Iowa State University, Ames, IA
Post-Doctoral Research Associate, Iowa State University, Ames, IA
3
Research Engineer, Convergent Science Inc., Middleton, WI
2
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aggregate storage and drying processes, and plant combustion efficiencies for optimized
fuel usage.
This study proposes and investigates the feasibility of using of wind energy stored
in hydrogen fuel cells as a clean source of energy for operating an HMA production
facility. On-site installation of wind turbines, photo-voltaic panels, and solar water
heaters are currently being contemplated and investigated upon by factory owners and
companies with a commitment to move to carbon neutral operations and generating all
energy from renewable sources to power their facilities. Thus, it is not inconceivable that
the HMA production facilities could be equipped with wind mills in the near future to
extract wind energy. Since wind blows intermittently, the extracted wind energy will be
stored in the form of hydrogen which is considered a lightweight, compact energy carrier,
for later use, thus creating a ready source of electricity for the HMA plant when wind is
not present or when electricity demand is high. Through the use of hydrogen-based
energy, the primary sources of greenhouse gas emissions from the HMA plant can be
significantly cut down and the resulting cost savings can be enormous. The same
technology can be employed in the production of low-temperature asphalt mixes which
can yield even greater environmental and economic benefits.
Keywords: Hot-Mix Asphalt (HMA), renewable energy, greenhouse gas emissions,
hydrogen, wind.
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