Can Public Construction and Demolition Data Describe Trends in Building Material Recycling? Observations From Philadelphia

There is a significant amount of waste generated during construction and demolition (C&D) activities, but few data to understand the sources, age, spatial origin, and its fate following entry into the waste management system. With few public records that track C&D waste flows, we turned to industry and Leadership in Energy and Environmental Design (LEED) to quantify C&D data and meta-data using material flow analysis (MFA). LEED databases are not normally used to build life cycle inventories or material flow accounts because they do not house sufficiently detailed data. We propose using the geo-referenced data on reused C&D waste in LEED databases to source parameters needed to build MFA models that support a circular building materials economy. By quantifying the change in C&D waste flow over years 2007–2017 and the diversion of materials from landfills from buildings in the United States City of Philadelphia, we found that, on average, 81% of total incoming waste was diverted from landfill and recycled into secondary materials markets. From LEED spatial data, we found that 77% of buildings sampled diverted C&D waste activities and installed building materials with recycled content. Although these findings describe material reuse metrics from different system boundaries in the built environment that cannot be statistically validated, they provide complementary data to describe C&D recycling performance benchmarks and incentive for future data collection to study and track trends in building material reuse. This case study highlights observations of C&D recovery and reuse from two separate but related operations, which could suggest that policies that incentivize C&D material reuse could promote a circular flow of building materials

Environmental impacts of using desalinated water in concrete production in areas affected by freshwater scarcity

Up to 500 litres of water may be consumed at the batching plant per cubic meter of ready mix concrete, if water for washing mixing trucks and equipment is included. Demand for concrete is growing almost everywhere, regardless of local availability of freshwater. The use of freshwater for concrete production exacerbates stress on natural water resources. In water-stressed coastal countries such as Israel, desalinated seawater (DSW) is often used in the production of concrete. However, the environmental impacts of this practice have not yet been assessed. In this study the effect of using DSW on the water and carbon footprints of concrete was investigated using life cycle assessment. Water footprint results highlight the benefits of using DSW rather than freshwater to produce concrete in Israel. In contrast, because desalination is an energy intensive process, using DSW increases the greenhouse gas intensity of concrete. Nevertheless, this increase (0.27 kg CO2e/m3 concrete) is small, if compared to the life cycle greenhouse gas emissions of concrete. Our results show that using untreated seawater in the mix (transported by truck from the coast) in place of DSW, would be beneficial in terms of water and carbon footprints if the batching plant were located less than 13 km from the withdrawal point. However, use of untreated seawater increases steel reinforcement corrosion, resulting in loss of structural integrity of the reinforced concrete composite. Sustainability of replacing steel with non-corrosive materials should be explored as a way to reduce both water and carbon footprints of concrete

Effects of Recycled HDPE and Nanoclay on Stress Cracking of HDPE by Correlating \u3ci\u3eJ\u3csub\u3ec\u3c/sub\u3e\u3c/i\u3e with Slow Crack Growth

The effects of recycled high density polyethylene (HDPE) and nanoclay on the stress crack resistance (SCR) of pristine HDPE were evaluated using the Notched Constant Ligament Stress (NCLS) test. The test data were analyzed by both linear elastic fracture mechanics (LEFM) and elastic plastic fracture mechanics (EPFM). The LEFM approach uses the stress intensity factor K to define the two failure mechanisms: creep and slow crack growth (SCG). In contrast, using the J-integral in EPFM, which emphasizes the nonlinear elastic-plastic strain field at the crack-tip, revealed a short-term failure stage prior to the creep failure. In this article, a power law correlation between the fracture toughness Jc and SCG was found under a planestrain condition. Increasing recycled HDPE content lowered the SCG resistance of pristine HDPE by decreasing Jc. Adding nanoclay up to 6 wt% also decreased Jc while simultaneously, lowering the stress relaxation of nanocomposites, leading to longer SCG failure times at low J values

Bio-Based Polyisoprene Can Mitigate Climate Change and Deforestation in Expanding Rubber Production

Biomass is a promising renewable feedstock to produce polyisoprene for the rubber industry. Through metabolic engineering, sugars derived from pretreated and hydrolyzed cellulose and hemicellulose can be directly fermented to isoprene to produce rubber. Here we investigate the life cycle environmental impact of isoprene fermentation to produce bio-polyisoprene from agricultural residues (of Zea mays L.). Results show that the greenhouse gas (GHG) intensity of bio-polyisoprene (−4.59 kg CO2e kg−1) is significantly lower than that of natural rubber (Hevea brasiliensis) and synthetic rubber (−0.79 and 2.41 kg CO2e kg−1, respectively), while supporting a circular biogenic carbon economy. We found the land use intensity of bio-polyisoprene to be 0.25 ha metric ton−1, which is 84% lower than that from rubber tree plantations. We compare the direct fermentation to isoprene results with indirect fermentation to isoprene through the intermediate, methyl butyl ether, where dehydration to isoprene is required. The direct fermentation of isoprene reduces reaction steps and unit operations, an expected outcome when employing process intensification, but our results show additional energy conservation and reduced contribution to climate change. Among the ReCiPe life cycle environmental impact metrics evaluated, air emission related impacts are high for bio-polyisoprene compared to those for natural and synthetic rubber. Those impacts can be reduced with air emission controls during production. All other metrics showed an improvement for bio-polyisoprene compared to natural and synthetic rubber

Life Cycle Design of a Fuel Tank System

This life cycle design (LCD) project was a collaborative effort between the National Pollution Prevention Center at the University of Michigan, General Motors (GM), and the U.S. Environmental Protection Agency (EPA). The primary objective of this project was to apply life cycle design tools to guide the improvement of fuel tank systems. Two alternative fuel tank systems used in a 1996 GM vehicle line were investigated: a multi-layer high density polyethylene (HDPE) tank system, and a steel tank system. The design analysis included a life cycle inventory (LCI) analysis, performance analysis and preliminary life cycle cost analysis. The scope of the LCI study encompassed materials production, the manufacturing processes for each tank system, the contribution of each tank system to the use phase burdens of the vehicle, and the end-of-life management processes based on the current vehicle retirement infrastructure. The LCI analysis indicated lower energy burdens for the HDPE tank system and comparable solid waste burdens for both systems. Based on the results of the LCI, streamlined environmental metrics were proposed. While both systems meet basic performance requirements, the HDPE system offers design flexibility in meeting capacity requirements, and also provided a fuel cost savings. The life cycle design framework was useful in evaluating environmental, performance, and cost trade-offs among and between both fuel tank systems.http://deepblue.lib.umich.edu/bitstream/2027.42/192097/1/CSS97-01.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/192097/2/CSS97-01_summary.pdfDescription of CSS97-01.pdf : ReportDescription of CSS97-01_summary.pdf : SummarySEL

Uncertainties in Life Cycle Greenhouse Gas Emissions from Advanced Biomass Feedstock Logistics Supply Chains in Kansas

To meet Energy Independence and Security Act (EISA) cellulosic biofuel mandates, the United States will require an annual domestic supply of about 242 million Mg of biomass by 2022. To improve the feedstock logistics of lignocellulosic biofuels in order to access available biomass resources from areas with varying yields, commodity systems have been proposed and designed to deliver quality-controlled biomass feedstocks at preprocessing “depots”. Preprocessing depots densify and stabilize the biomass prior to long-distance transport and delivery to centralized biorefineries. The logistics of biomass commodity supply chains could introduce spatially variable environmental impacts into the biofuel life cycle due to needing to harvest, move, and preprocess biomass from multiple distances that have variable spatial density. This study examines the uncertainty in greenhouse gas (GHG) emissions of corn stover logistics within a bio-ethanol supply chain in the state of Kansas, where sustainable biomass supply varies spatially. Two scenarios were evaluated each having a different number of depots of varying capacity and location within Kansas relative to a central commodity-receiving biorefinery to test GHG emissions uncertainty. The first scenario sited four preprocessing depots evenly across the state of Kansas but within the vicinity of counties having high biomass supply density. The second scenario located five depots based on the shortest depot-to-biorefinery rail distance and biomass availability. The logistics supply chain consists of corn stover harvest, collection and storage, feedstock transport from field to biomass preprocessing depot, preprocessing depot operations, and commodity transport from the biomass preprocessing depot to the biorefinery. Monte Carlo simulation was used to estimate the spatial uncertainty in the feedstock logistics gate-to-gate sequence. Within the logistics supply chain GHG emissions are most sensitive to the transport of the densified biomass, which introduces the highest variability (0.2–13 g CO2e/MJ) to life cycle GHG emissions. Moreover, depending upon the biomass availability and its spatial density and surrounding transportation infrastructure (road and rail), logistics can increase the variability in life cycle environmental impacts for lignocellulosic biofuels. Within Kansas, life cycle GHG emissions could range from 24 g CO2e/MJ to 41 g CO2e/MJ depending upon the location, size and number of preprocessing depots constructed. However, this range can be minimized through optimizing the siting of preprocessing depots where ample rail infrastructure exists to supply biomass commodity to a regional biorefinery supply system

Life Cycle Environmental Impact of Underground Plastic Recharge Chambers in Stormwater Management

Life cycle assessment is used to systematically evaluate the environmental impact of underground plastic recharge chambers (RCs) used for stormwater management. Using cradle-to-gate life cycle assessment and a functional unit of 1 m3 stormwater capacity, different RC structure types, manufacturing processes and materials are considered. The inventory is based on various commercially available RCs, including injection-molded or extruded polypropylene and polyvinylchloride polymers and typical installation materials and methods. A new dataset is developed to estimate the manufacture and use of recycled polypropylene granulate. TRACI 2.1 is used to investigate the midpoint life cycle impact assessment metrics, acidification, eutrophication, global warming, and fossil fuel resources. Results indicate that plastic represents as much as 99% of the total cradle-to-gate impact, driven largely by the polymer processing method. Injection molding has on average a 50% higher impact per kg of material than extrusion. Processing and transport of backfill material to the project site is approximately 20% of the total cradle-to-gate impact. The transport distance is highly significant: long transport distances can cause the transportation impact to exceed the plastic impact

Trends in commitments to correctional institutions: an analysis from 1935 to 1977

Bio-oil produced from fast pyrolysis of biomass is a promising substitute for crude oil that can meet climate change mitigation goals, but due to its high oxygen content, it requires upgrading to remove oxygen in order to be used as a transportation fuel. Hydrodeoxygenation (HDO) is one means of upgrading fast pyrolysis oil; however, its main limitation is its large hydrogen requirement. We evaluate an alternative electrochemical deoxygenation (EDOx) method that uses catalytic electrode membranes on a ceramic, oxygen-permeable support to generate hydrogen in situ for deoxygenation at the cathode and oxygen removal at the anode. We analyze the life-cycle greenhouse gas (GHG) emissions and scale effects of gas-phase upgrading of pyrolysis oil [300 t/day (MTPD)] using different configurations of EDOx and compare it with the large-scale HDO process (2000 MTPD). We observe that the EDOx configurations have lower total GHG emissions of 5–8.4 and 7.4–11 g of CO₂ equiv/MJ for vehicles operated with diesel and gasoline, respectively, compared to HDO (39 g of CO₂ equiv/MJ). Furthermore, the EDOx processes offers potentially 10 times more small-scale pyrolysis upgrading facilities in the United States compared to HDO, suggesting that small-scale on-site EDOx processes can reach more inaccessible forest biomass resources