Energy and carbon dioxide intensity of Thailand's steel industry and greenhouse gas emission projection toward the year 2050

The purpose of this article is to study the energy and carbon dioxide intensities of Thailand's steel industry and to propose greenhouse gas emission trends from the year 2011 to 2050 under plausible scenarios. The amount of CO₂ emission from iron and steel production was calculated using the 2006 Intergovernmental Panel on Climate Change (IPCC) guidelines in the boundary of production process (gate to gate). The results showed that energy intensity of semi-finished steel product was 2.84 GJ/t semi-finished steel and CO₂ intensity was 0.37 tCO_2eq/t semi-finished steel. Energy intensity of steel finishing process was 1.86 GJ/t finished steel and CO₂ intensity was 0.16 tCO_2eq/t finished steel. Using three plausible scenarios from Thailand's steel industry, S1: without integrated steel plant (baseline scenario), S2: with a traditional integrated BF–BOF route and S3: with an alternative integrated DR-EAF route; the Greenhouse Gas emissions from the year 2011 to 2050 were projected. In 2050, the CO₂ emission from S1 (baseline scenario) was 4.84 million tonnes, S2 was 21.96 million tonnes increasing 4.54 times from baseline scenario. The CO₂ emission from S3 was 7.12 million tonnes increasing 1.47 times from baseline scenario.     

Paper and biomass for energy?: The impact of paper recycling on energy and CO2 emissions

The pulp and paper industry is placed in a unique position as biomass used as feedstock is now in increasingly high demand from the energy sector. Increased demand for biomass increases pressure on the availability of this resource, which might strengthen the need for recycling of paper. In this study, we calculate the energy use and carbon dioxide emissions for paper production from three pulp types. Increased recycling enables an increase in biomass availability and reduces life-cycle energy use and carbon dioxide emissions. Recovered paper as feedstock leads to lowest energy use (22 GJ/t) and CO₂ emissions (−1100 kg CO₂/t) when biomass not used for paper production is assumed to be converted into bio-energy. Large differences exist between paper grades in e.g. electricity and heat use during production, fibre furnish, filler content and recyclability. We found large variation in energy use over the life-cycle of different grades. However, in all paper grades, life-cycle energy use decreases with increased recycling rates and increased use of recovered fibres. The average life-cycle energy use of the paper mix produced in The Netherlands, where the recycling rate is approximately 75%, is about 14 GJ/t. This equals CO₂ savings of about 1 t CO₂/t paper if no recycled fibres would be used.     

CO2 capture from power plants: Part I. A parametric study of the technical performance based on monoethanolamine

Capture and storage of CO₂ from fossil fuel fired power plants is drawing increasing interest as a potential method for the control of greenhouse gas emissions. An optimization and technical parameter study for a CO₂ capture process from flue gas of a 600 MWe bituminous coal fired power plant, based on absorption/desorption process with MEA solutions, using ASPEN Plus with the RADFRAC subroutine, was performed. This optimization aimed to reduce the energy requirement for solvent regeneration, by investigating the effects of CO₂ removal percentage, MEA concentration, lean solvent loading, stripper operating pressure and lean solvent temperature.Major energy savings can be realized by optimizing the lean solvent loading, the amine solvent concentration as well as the stripper operating pressure. A minimum thermal energy requirement was found at a lean MEA loading of 0.3, using a 40 wt.% MEA solution and a stripper operating pressure of 210 kPa, resulting in a thermal energy requirement of 3.0 GJ/ton CO₂, which is 23% lower than the base case of 3.9 GJ/ton CO₂. Although the solvent process conditions might not be realisable for MEA due to constraints imposed by corrosion and solvent degradation, the results show that a parametric study will point towards possibilities for process optimisation.     

The contemporary European silver cycle

This paper examines the 1-year anthropogenic stocks and flows of silver as it progresses from extraction to final disposal on the European continent. The primary flows of silver include production, fabrication and manufacturing, use, and waste management. A substance flow analysis (SFA) was used to trace the flows and inventory data, and mass balance equations were used to determine the quantity of flows. The results reveal that Europe has a low level of silver mine production (1580 Mg Ag/year) and instead relies on silver imports and the recycling of scrap in production and fabrication. In the year 1997, Europe imported 1160 Mg Ag of ore concentrate and 2010 Mg Ag of refined silver, and recycled 2750 Mg Ag of new and old scrap. There is a net addition of 3320 Mg Ag/year into silver reservoirs at the use stage. This is the result of a greater amount of silver entering the system from manufacturing than is leaving the system into waste management. The waste flow with the highest content of silver is municipal solid waste, which contains 1180 Mg Ag/year. In total, 62% of all discarded silver is recycled and 38% is sent to landfills. The results of this study and other element and material flow analyses can help guide resource managers, environmental policy makers, and environmental scientists in their efforts to increase material recovery and recycling, address resource sustainability, and ameliorate environmental problems.     

Municipal solid waste management in China: Status,problems and challenges

This paper presents an examination of MSW generation and composition in China, providing an overview of the current state of MSW management, an analysis of existing problems in MSW collection, separation, recycling and disposal, and some suggestions for improving MSW systems in the future. In China, along with urbanization, population growth and industrialization, the quantity of municipal solid waste (MSW) generation has been increasing rapidly. The total MSW amount increased from 31.3 million tonnes in 1980 to 212 million tonnes in 2006, and the waste generation rate increased from 0.50 kg/capita/day in 1980 to 0.98 kg/capita/year in 2006. Currently, waste composition in China is dominated by a high organic and moisture content, since the concentration of kitchen waste in urban solid waste makes up the highest proportion (at approximately 60%) of the waste stream. The total amount of MSW collected and transported was 148 million tonnes in 2006, of which 91.4% was landfilled, 6.4% was incinerated and 2.2% was composted. The overall MSW treatment rate in China was approximately 62% in 2007. In 2007, there were 460 facilities, including 366 landfill sites, 17 composing plants, and 66 incineration plants. This paper also considers the challenges faced and opportunities for MSW management in China, and a number of recommendations are made aimed at improving the MSW management system.     

Design and implementation study of a Permanent Selective Collection Program (PSCP) on a University campus in Brazil

The selective collection and recycling of municipal solid waste are presented as stages of an integrated program of solid waste management to minimize the environmental impact of the treatment and final disposal of solid waste. Therefore, this program aims to save natural resources, such as energy and raw materials, in the manufacture of new products and to conserve areas for sites, such as to minimize the use of existing landfill sites, and to minimize the need for new waste treatment sites. A university is composed of educational professionals aware of their societal responsibilities, and, therefore, they play a fundamental role in the management of the university's solid waste. This study presents the design and implementation of a Permanent Selective Collection Program (PSCP) at the Federal University of Itajubá (Universidade Federal de Itajubá, UNIFEI), Itajubá-MG, Brazil. The material requirements for initiating the PSCP have been identified, and an action plan for continuous program improvement, which is initially based on the collection of performance indicator data for the PSCP campus, has been developed. Finally, the data from the PSCP performance indicators and software from the United States Environmental Protection Agency, the Landfill Gas Generation Model (LandGEM) and the Waste Reduction Model (WARM), were used to evaluate the impact of implementing PSCP in terms of energy and the generation of greenhouse gases (GHG). The results were promising, showing that there has been an improvement, since the inception of PSCP in 2006, in separating materials for selective collection, even though paper (41.00 wt%), plastic (6.00 wt%) and organic matter (26.00 wt%) are still highly generated wastes. The WARM simulations for a scenario in which 90% of the waste is sent for recycling resulted in an economy of −7 tCO₂ or −74.91 GJ (on an energy basis). The LandGEM (USEPA) simulations estimated 1424.60 kWh of energy in the peak production year.     

Environmental benefits from the use of the residual biomass in nurseries

Every year, nurseries waste about 40 t of residual biomass for each ha of potted plants cultivation. The European nursery sector deals with about 90,000 ha of cultivated land and 120,000 ha of nurseries, with a turnover of 19.8 billion Euros in 2011. In recent years, a number of Italian projects highlighted that GHG (greenhouse gas) emissions for the nursery sector range between 37 tCO₂eq/ha/year and 45 tCO₂eq/ha/year for potted plants, mainly due to the consumption of electric energy, plastics and peat. Moreover, other studies analyse the impacts associated to nurseries, recommending best practices for energy reductions and waste recycle or reuse. Therefore, the present work focused its attention to the possible environmental benefits associated to the reuse of residues (wood and substrate) of potted plants that are discarded from the nursery production chain. GHG emissions and fossil energy requirement were quantified by considering the CO₂eq (CO₂ equivalent) and the CER (cumulative energy requirement) respectively, in order to assess the environmental impacts of two different scenarios proposed for the materials recovery. Final results highlighted that the solutions which are able to recover the substrate and the wood allow impact reductions compared to landfill disposal. In particular, the scenario consisting in the immediate separation of the substrate from the root-plant system and the successive chipping of wood for energetic reuse, allows higher savings than those obtainable through shredding and subsequent wind separation. Moreover, for what concerns the CO₂eq, an adequate use of the residual biomass make it possible to compensate the GHG emissions of the nurseries up to 15%.     

Closing the water cycle for industrial laundries: An operational performance and techno-economic evaluation of a full-scale membrane bioreactor system

To reduce the consumption of freshwater in the laundry industry, a new trend of closing the water cycle has resulted in the reuse/recycling of water. In this study, the performance of a full-scale submerged aerobic membrane bioreactor (9 m³) used to treat/reuse industrial laundry wastewater was examined over a period of 288 days. The turbidity and total solids (TS) were reduced by 99%, and the chemical oxygen demand (COD) effluent removal efficiencies were between 70% and 99%. The levels of COD removed by the membrane were significantly greater than the levels of biodegraded COD. This enabled the bioreactor to sustain COD levels that were below 100 mg/L, even during periods of low wastewater biodegradation due to bioreactor sludge. An economic evaluation of the membrane bioreactor (MBR) system showed a savings of 1.13 € per 1 m³ of water. The payback period for this system is approximately 6 years. The energy and maintenance costs represent only 5% of the total cost of the MBR system.     

Global anthropogenic selenium cycles for 1940–2010

Selenium plays an important role in emerging thin film solar energy technologies. As solar energy is expected to have a larger share in the world's future energy portfolio, the long-term availability of selenium becomes a potential concern, yet no global cycles have ever been generated. In this work, the global cycles, stocks, and flows of selenium are characterized for the entire time period 1940–2010 by using principles of material flow analysis (MFA). The cycles present information on the production, fabrication and manufacturing, use, and resource management stages during that period. The results of the analysis show that during 1940–2010 approximately 90 Gg of refined selenium was produced and entered into fabrication and manufacturing worldwide. 60 Gg of this amount (two-thirds!) was dissipated into the environment through end-uses such as chemicals, pigments, glass manufacturing, metallurgical additives, and fertilizer and feed additives. The in-use stock of selenium is estimated at 2.7 Gg as of 2010. Because of data limitations such as proprietary and withheld information, these figures represent informed estimates rather than exact values. Selenium can be recovered from end-of-life electrical and electronic equipment, while for other end-uses recycling is difficult or impossible. One of the ways to buttress supplies of selenium for future technologies would be to deploy recycling schemes for photovoltaics as well as other electronics applications.     

Investigating the sustainability of the global silver supply,reserves, stocks in society and market price using different approaches

The authors have collected data for the silver market, shedding light on market size, stocks in society and silver flows in society. The world supply from mining, depletion of the remaining reserves, reducing ore grades, market price and turnover of silver was simulated using the SILVER model developed for this study. The model combines mining, trade markets, price mechanisms, populations dynamics, use in society and waste and recycling into an integrated system. At the same time the degree of sustainability and resource time horizon was estimated using different methods such as: 1: burn-off rates, 2: peak discovery early warning, 3: Hubbert's production model, and 4: System dynamic modelling. The Hubbert's model was run for the period of 6000 BC–3000 AD, the SILVER system dynamics model was run for the time range 1840–2340. We have estimated that the ultimately recoverable reserves of silver are in the range 2.7–3.1 million tonne silver at present, of which approximately 1.35–1.46 million tonne have already been mined. The timing estimate range for peak silver production is narrow, in the range 2027–2038, with the best estimate in 2034. By 2240, all silver mines will be nearly empty and exhausted. The outputs from all models converge to emphasize the importance of consistent recycling and the avoidance of irreversible losses to make society more sustainable with respect to silver market supply.     

Approaches for analyzing local carbon mitigation strategies: Tompkins County,New York,USA

A carbon budget was calculated for Tompkins County, NY, a semi-rural upstate county with a population density of 78 pp/km². The costs and potential for several carbon mitigation options were analyzed in four categories: terrestrial C sequestration, local power generation, transportation, and energy end-use efficiency. This study outlines a methodology for conducting this type of local-scale analysis, including sources and calculations adaptable to different localities. Effective carbon mitigation strategies for this county based on costs/Mg C and maximum potential include reforestation of abandoned agricultural lands, biomass production for residential heating and co-firing in coal power plants, changes in personal behavior related to transportation (e.g., public transportation), installation of residential energy efficient products such as programmable thermostats or compact fluorescent light bulbs, and development of local wind power. The total county emissions are about 340 Gg C/year, with biomass sequestration rates of 121 Gg C/year. The potential for mitigation, assuming full market penetration, amounts to about 234 Gg C/year (69%), with 100 Gg C/year (29%) at no net cost to the consumer. The development of local-scale C mitigation plans based on this sort of model of analysis is feasible and would be useful for guiding investments in climate change prevention.     

Assessment of basin-scale hydrologic impacts of CO2 sequestration,Illinois basin

Idealized, basin-scale sharp-interface models of CO₂ injection were constructed for the Illinois basin. Porosity and permeability were decreased with depth within the Mount Simon Formation. Eau Claire confining unit porosity and permeability were kept fixed. We used 726 injection wells located near 42 power plants to deliver 80 million metric tons of CO₂/year. After 100 years of continuous injection, deviatoric fluid pressures varied between 5.6 and 18 MPa across central and southern part of the Illinois basin. Maximum deviatoric pressure reached about 50% of lithostatic levels to the south. The pressure disturbance (>0.03 MPa) propagated 10–25 km away from the injection wells resulting in significant well–well pressure interference. These findings are consistent with single-phase analytical solutions of injection. The radial footprint of the CO₂ plume at each well was only 0.5–2 km after 100 years of injection. Net lateral brine displacement was insignificant due to increasing radial distance from injection well and leakage across the Eau Claire confining unit. On geologic time scales CO₂ would migrate northward at a rate of about 6 m/1000 years. Because of paleo-seismic events in this region (M5.5–M7.5), care should be taken to avoid high pore pressures in the southern Illinois basin.     

Coupled reservoir-geomechanical analysis of CO2 injection and ground deformations at In Salah,Algeria

In Salah Gas Project in Algeria has been injecting 0.5–1 million tonnes CO₂ per year over the past 5 years into a water-filled strata at a depth of about 1800–1900 m. Unlike most CO₂ storage sites, the permeability of the storage formation is relatively low and comparatively thin with a thickness of about 20 m. To ensure adequate CO₂ flow-rates across the low-permeability sand-face, the In Salah Gas Project decided to use long-reach (about 1–1.5 km) horizontal injection wells. In an ongoing research project we use field data and coupled reservoir-geomechanical numerical modeling to assess the effectiveness of this approach and to investigate monitoring techniques to evaluate the performance of a CO₂ injection operation in relatively low-permeability formations. Among the field data used are ground surface deformations evaluated from recently acquired satellite-based inferrometry (InSAR). The InSAR data shows a surface uplift on the order of 5 mm per year above active CO₂ injection wells and the uplift pattern extends several km from the injection wells. In this paper we use the observed surface uplift to constrain our coupled reservoir-geomechanical model and conduct sensitivity studies to investigate potential causes and mechanisms of the observed uplift. The results of our analysis indicate that most of the observed uplift magnitude can be explained by pressure-induced, poro-elastic expansion of the 20-m-thick injection zone, but there could also be a significant contribution from pressure-induced deformations within a 100-m-thick zone of shaly sands immediately above the injection zone.     

The potential contribution of sustainable waste management to energy use and greenhouse gas emission reduction in the Netherlands

Future limitations on the availability of selected resources stress the need for increased material efficiency. In addition, in a climate-constrained world the impact of resource use on greenhouse gas emissions should be minimized. Waste management is key to achieve sustainable resource management. Ways to use resources more efficiently include prevention of waste, reuse of products and materials, and recycling of materials, while incineration and anaerobic digestion may recover part of the embodied energy of materials. This study used iWaste, a simulation model, to investigate the extent to which savings in energy consumption and CO₂ emissions can be achieved in the Netherlands through recycling of waste streams versus waste incineration, and to assess the extent to which this potential is reflected in the LAP2 (currently initiated policy). Three waste streams (i.e. household waste, bulky household waste, and construction and demolition waste) and three scenarios compare current policy to scenarios that focus on high-quality recycling (Recycling+) or incineration with increased efficiency (Incineration+). The results show that aiming for more and high-quality recycling can result in emission reductions of 2.3 MtCO₂ annually in the Netherlands compared to the reference situation in 2008. The main contributors to this reduction potential are found in optimizing the recycling of plastics (PET, PE and PP), textiles, paper, and organic waste. A scenario assuming a higher energy conversion efficiency of the incinerator treating the residual waste stream, achieves an emission reduction equivalent to only one third (0.7 MtCO₂/year) of the reduction achieved in the Recycling+ scenario. Furthermore, the results of the study show that currently initiated policy only partially realizes the full potential identified. A focus on highest quality use of recovered materials is essential to realize the full potential energy and CO₂ emission reduction identified for the Netherlands. Detailed economic and technical analyses of high quality recycling are recommended to further evaluate viable integrated waste management policies.     

Current results and future perspectives for Japanese recycling of home electrical appliances

The Japanese system of recycling home electrical appliances has several unique aspects, including (1) a limited number of target appliances, (2) a recycling fee system that requires consumers to pay a recycling fee at the time of disposal, and (3) a direct recycling obligation for manufacturers, who have a physical, rather than a financial, responsibility for their end-of-life products. We studied data from 2001 to 2007 and found that the amount of four specified home electrical appliances and their materials that was recycled increased from about 319,249 tonnes in 2001 to about 447,262 tonnes—or 3.5 kg per inhabitant—in 2006. Recycling yield and development of recycling technologies have also improved. New recycling technologies have enabled a higher rate of material recycling of plastics (i.e., a closed-loop recycling). Improved eco-design, such as design for easier disassembly, has been promoted, and the higher quality of discarded appliances has enhanced the reuse market. Hazardous substances and fluorocarbons are being well managed. Problems with the recycling system include inelastic recycling fees, illegal dumping, illegal transfer by retailers, and the limited number of target appliances. Recycling fees could be reduced; this move might reduce the incidence of illegal dumping, as would engage stakeholders in collaborative efforts against illegal dumping. Illegal transfers could be reduced by improved traceability for retailers. Products such as liquid crystal displays, plasma display panels and clothes dryers have become increasingly common and should be also be targeted for recycling.     

A comparison of on-site nutrient and energy recycling technologies in algal oil production

Research on biofuel production pathways from algae continues because among other potential advantages they avoid key consequential effects of terrestrial oil crops, such as competition for cropland. However, the economics, energetic balance, and climate change emissions from algal biofuels pathways do not always show great potential, due in part to high fertilizer demand. Nutrient recycling from algal biomass residue is likely to be essential for reducing the environmental impacts and cost associated with algae-derived fuels. After a review of available technologies, anaerobic digestion (AD) and hydrothermal liquefaction (HTL) were selected and compared on their nutrient recycling and energy recovery potential for lipid-extracted algal biomass using the microalgae strain Scenedesmus dimorphus. For 1 kg (dry weight) of algae cultivated in an open raceway pond, 40.7 g N and 3.8 g P can be recycled through AD, while 26.0 g N and 6.8 g P can be recycled through HTL. In terms of energy production, 2.49 MJ heat and 2.61 MJ electricity are generated from AD biogas combustion to meet production system demands, while 3.30 MJ heat and 0.95 MJ electricity from HTL products are generated and used within the production system.Assuming recycled nutrient products from AD or HTL technologies displace demand for synthetic fertilizers, and energy products displace natural gas and electricity, the life cycle greenhouse gas reduction achieved by adding AD to the simulated algal oil production system is between 622 and 808 g carbon dioxide equivalent (CO₂e)/kg biomass depending on substitution assumptions, while the life cycle GHG reduction achieved by HTL is between 513 and 535 g CO₂e/kg biomass depending on substitution assumptions. Based on the effectiveness of nutrient recycling and energy recovery, as well as technology maturity, AD appears to perform better than HTL as a nutrient and energy recycling technology in algae oil production systems.     

Substance flow analysis of cadmium in Korea

Substance flow analysis (SFA) of cadmium in Korea was carried out to analyze and predict cadmium flows, stocks, and future flows using both static and dynamic models. Cadmium is widely used in industry due to its strong corrosion and chemical resistance at high temperature, excellent electrical conduction, and low melting-point. Cadmium is produced as a by-product from the production processes for zinc and lead ingots. It is used for Ni–Cd batteries, polyvinylchloride (PVC) stabilizers, alloy products, pigments, and others.This examines the current cadmium flows and stocks using static SFA, and aims in predicting the future cadmium flows and stocks in Korea using dynamic SFA. From the static model, 2820 tonnes of cadmium ingots were produced, 0.04 tonnes imported and 2740 tons exported in Korea in 2009. In addition, 81 tonnes of cadmium were used in the manufacture of cadmium products: 80 tonnes for cadmium alloy products and 1 tonne for others. Finally, 175 tonnes of cadmium were imported into Korea for Ni–Cd batteries, 140 tonnes for PVC stabilizers, and 55 tonnes for pigments. Cadmium was used in various industries such as construction (221 tonnes), electrics and electronics (130 tonnes – including cadmium in imported products), transportation (30 tonnes) and others (30 tonnes). In 2009, 430 tonnes of industrial cadmium were discharged, with 10 tonnes being recycled and 420 tonnes discarded.From the dynamic model, cadmium stocks in Korea were estimated to be about 5120 tonnes in 2009. The industrial consumption in 2030 will be reduced to only 110 tonnes, only 27% of the current consumption of 410 tonnes in 2009, due to DIRECTIVE 2002/95/EC OF THE EUROPEAN PARLIAMENT of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS). One possible solution to the Cd oversupply problem is use in cadmium telluride photovoltaic (CdTe PV) systems which have low life cycle Cd emissions (0.02 g Cd/GWh) and high end-of-life semiconductor recycling yields (95%).     

An investigation into the likely impact of oxy-coal retrofit on fire-side corrosion behavior in utility boilers

Real-time electrochemical measurements of corrosion rate were performed to evaluate the respective corrosion rates of one boiler waterwall material (SA210) and three boiler superheater materials (T22, P91 and 347H) while firing Utah Western bituminous, Illinois high-sulfur bituminous and Powder River Basin (PRB) sub-bituminous coals in a 1.5 MW pulverized coal-fired furnace. The raw average measured corrosion rates were very low, between 0.0003 and 0.016 mm/year (0.012 and 0.63 mils/year) for most materials under air- and oxy-fired conditions. For some high-sulfur conditions measured corrosion rates were as high as 0.72 mm/year (28 mils/year). Waterwall corrosion rates decreased consistently when converting from air- to oxy-firing while superheater corrosion rates generally increased, although they were less than twice the air-fired rate under most conditions. Corrosion rates for the lower alloyed materials (SA210 and T22) increased significantly during transients from reducing to oxidizing conditions. Measured increases in the corrosion rate of 347H material under high sulfur and low temperature conditions, and associated decrease in corrosion rate at higher temperatures on this alloy, were consistent with the formation of trisulphates in the superheater deposits. The increase of corrosion rate with increased metal temperatures was demonstrated, as was the consistently repeatable nature of the observed results.     

Artificial aggregate made from waste stone sludge and waste silt

In this research, waste stone sludge obtained from slab stone processing and waste silt from aggregate washing plants were recycled to manufacture artificial aggregate. Fine-powdered stone sludge was mixed with waste silt of larger particle size; vibratory compaction was applied for good water permeability, resulting in a smaller amount of solidifying agent being used. For the densified packing used in this study, the mix proportion of waste stone sludge to waste silt was 35:50, which produced artificial aggregate of more compact structure with water absorption rate below 0.1%. In addition, applying vibratory compaction of 33.3 Hz to the artificial aggregate and curing for 28 days doubled the compressive strength to above 29.4 MPa. Hence, recycling of waste stone sludge and waste silt for the production of artificial aggregate not only offers a feasible substitute for sand and stone, but also an ecological alternative to waste management of sludge and silt.     

Impacts of urban forests on offsetting carbon emissions from industrial energy use in Hangzhou,China

This study quantified carbon storage and sequestration by urban forests and carbon emissions from energy consumption by several industrial sources in Hangzhou, China. Carbon (C) storage and sequestration were quantified using urban forest inventory data and by applying volume-derived biomass equations and other models relating net primary productivity (NPP) and mean annual biomass increments. Industrial energy use C emissions were estimated by accounting for fossil fuel use and assigning C emission factors. Total C storage by Hangzhou's urban forests was estimated at 11.74 Tg C, and C storage per hectare was 30.25 t C. Carbon sequestration by urban forests was 1,328, 166.55 t C/year, and C sequestration per ha was 1.66 t C/ha/year. Carbon emissions from industrial energy use in Hangzhou were 7 Tg C/year. Urban forests, through sequestration, annually offset 18.57% of the amount of carbon emitted by industrial enterprises, and store an amount of C equivalent to 1.75 times the amount of annual C emitted by industrial energy uses within the city. Management practices for improving Hangzhou's urban forests function of offsetting C emissions from energy consumption are explored. These results can be used to evaluate the urban forests' role in reducing atmospheric carbon dioxide.