• Energy Research

Geothermal heated pavement systems (GHPS), viz., the use of geothermal energy to heat pavements, have been used as an efficient alternative to de-icing chemicals and mechanical snow-removal equipment. Although some previous studies on pavement-heating systems have focused on their efficiency and economic viability, up to this point none of them have systematically investigated their potential to contribute toward global warming. This study applies life cycle assessment to analyze and compare greenhouse gas (GHG) emissions resulting from the use of either GHPS or traditional snow-removal systems on airport runways and gate areas. A GHPS produces lower GHG emissions than a traditional snow-removal system in removing 2.5 cm of snow from an airport runway, and it is anticipated that the actual environmental benefits of using heated-pavement systems may become more evident at higher snowfall intensities or durations. The study also discovered that GHG emissions resulting from the use of GHPS at the airport gate area are about 100 times less in magnitude than those resulting from the use of either GHPS or traditional snow-removal strategies applied to airport runways. This indicates that the use of GHPS in selected airport areas such as airport gate areas (as opposed to runways) can result in much greater sustainability benefits, in terms of improved airport ground crew safety, cost-effectiveness, and reduced environmental impact.

Abstract Airports are moving toward utilizing clean energy technologies along with the implementation of practices that reduce local emissions. This includes replacing fossil fuel-based with electricity-based operations. These changes would significantly impact the energy demand profile of airports. Electrically-conductive concrete (ECON) is currently a focus of heated pavement design for replacing conventional snow removal practices. ECON heated pavement systems (HPSs) use electricity to heat the pavement surface. Since experimental studies are resource intensive and ECON HPS performance depends on weather conditions, developing a field data-validated numerical model enables its long term energy performance evaluation. In this research, a finite element (FE) model is developed and experimentally-validated using two proposed model-updating methods for full-scale ECON HPS test slabs constructed at Des Moines International Airport (DSM) in Iowa. The model predicts energy demands and average surface temperatures within 2% and 13% respectively. The estimated power demand ranges from 325 to 460 W/m2 for different weather conditions. The results of this study provide a validated tool that can be used to evaluate the energy demand of ECON HPS. Studying the energy demand of ECON HPS opens the way for developing control strategies to optimize its energy use which will contribute to developing sustainable communities.

AbstractSustainable use of biomass as a renewable source of energy can be an alternative solution to the cost of fossil-based energy and global warming. Production of biofuel from plant biomass results not only in bio-based energy, but also in coproducts containing lignin, modified lignin, and lignin derivatives. This paper discusses the moisture susceptibility of subgrade soil stabilized by bio-based energy coproducts containing lignin, with the aim of establishing a new application for bio-based energy coproducts in soil stabilization. An experimental test program was conducted to compare the moisture susceptibility of lignin coproduct-treated soils and traditional fly ash stabilizer-treated soil samples. Additive combinations were also evaluated. There were two types of laboratory tests for moisture susceptibility evaluation: (1) unconfined compression strength (UCS) tests after “dry” and “wet” conditioning, and (2) visual observation of soaked specimens. Results indicate that the biofuel coproducts ha...

Electrically conductive concrete (ECON) heated pavement system (HPS) is a newly developed clean technology to reduce the use of polluting chemicals for removal of snow and ice. This technology requires further comprehensive studies for achieving an energy-efficient design. To construct an energy-efficient system, ECON HPS design includes determining the most appropriate configuration of electrodes embedded in the ECON layer. The spacing, shape and dimensions of these electrodes are important design factors impacting the thermal and energy performance of the system. While field tests are resource-intensive, the use of numerical modeling can complement such experimental tests to provide a better overall understanding of the technology’s behavior. In this paper, the thermal and energy performance of ECON HPS is investigated through considering various system configuration designs, with an experimentally validated finite element model. A performance index is defined for comparing both thermal and energy performance of the configurations to obtain an energy-efficient design. The results indicate that a configuration with six circular electrodes at 100 cm spacing exhibited the best performance index and the highest energy efficiency. Since a test section with higher performance index would be capable of achieving a higher average surface temperature for the same energy input, such a section would have higher efficiency compared to other sections evaluated. This analysis results in narrowing down the ECON HPS’s configuration design options before performing experimental tests.

Abstract Many aviation and transportation agencies allocate significant time and resources each year to remove ice and snow from their paved surfaces to achieve a safe, accessible, and operational transportation network. An electrically conductive concrete (ECON) heated pavement system (HPS) has been shown to be a promising alternative to the conventional snow removal operations using snowplows and deicing chemicals, which is time-consuming, labor-intensive and environmentally unfriendly. ECON HPS utilizes the inherent electrical resistance of concrete to maintain the pavement surface above freezing and thus prevent snow and ice accumulation on the surface. This sustainable concrete pavement system improves the resiliency of infrastructure by allowing it to be safe, open, and accessible during even harsh winter storms. The purpose of this study was to demonstrate the full-scale implementation of 10 ECON HPS slabs at the Iowa Department of Transportation headquarter south parking lot in Ames, Iowa. This study consists of system design and control, field implementation, and sensor instrumentation procedures for the construction of the ECON system, which took place on October 2018. A programmable logic controller (PLC) was designed, programmed, and utilized to control, operate, and monitor the system remotely. The heating performance of the remotely-operated ECON slabs was evaluated using the instrumented sensors under snow and ice events in 2019. The performance evaluation showed promising results in providing snow, and ice-free pavement surfaces through several winter weather events.

By 2050, approximately 43 million tons of wind-turbine blade (WTB) waste materials will have accumulated, emphasizing the critical importance of effective waste management strategies for WTBs at the end of their life cycle to ensure sustainability. Comparing current WTB waste management methods, reuse emerges as a highly-sustainable method that can also serve as a sustainable solution to environmental challenges, including global warming and natural resource depletion associated with civil engineering activities. This paper presents a comprehensive review of sustainable solutions for reusing WTB waste materials in civil engineering applications. Repurposing WTB waste materials as structural elements in housing, urban furniture, recreational facilities, and slow-traffic infrastructure can be a viable option. WTB waste can also be utilized in powder, fiber, and aggregate forms as an eco-friendly material for construction and pavement (e.g., mortar, concrete, asphalt) to replace cement and natural resource aggregates while meeting necessary strength and performance standards. Through a detailed analysis of reusing WTB waste materials, economic and environmental challenges are also discussed. According to the findings, the properties of mortar, concrete, and asphalt can be affected by the type, shape, and content of fibers, polymers, and impurities present in the blades, as well as the cutting direction. Furthermore, while reuse is considered a sustainable end-of-life (EoL) option for WTB waste management from both economic and environmental perspectives, further research is required to fully understand the environmental consequences of this method.

Lignin is considered as nature's most abundant aromatic polymer co-generated during papermaking and biomass fractionation. There are different types of lignins depending on the source (hardwood, softwood, annual crops, etc.) and recovery process. Recently, an emerging class of lignin products, namely sulphur-free lignins, from biomass conversion processes, solvent pulping and soda pulping, have generated interesting new applications owing to their versatility. As the renewable energy industry is expanding into developing the next generation of biofuels based on cellulosic biomass (e.g. corn stover, forest products waste, switch grass), abundant supply of sulphur-free lignin will become available as co-products for which value-added engineering applications are being sought. This paper discusses the potential for utilising lignin-containing biofuel co-products for stabilisation of geo-foundation beneath road pavements. Laboratory test results indicate that the biofuel co-products were effective in stabilis...