Dry Tons Research Articles

From waste to advanced resource: Techno-economic and life cycle assessment behind the integration of polyester recycling and glucose production to valorize fast fashion garments

This work demonstrates the technical, economic, and environmental viability of integrating enzymatic hydrolysis, mechanical refining, and total chlorine-free (TCF) bleaching processes for industrial-scale production of glucose from textile waste. The process features an innovative mechanical refining pretreatment coupled with TCF oxidation of dyes to achieve over 90% improvement in enzymatic hydrolysis yields of cotton textile waste while also promoting the purification and recycling of synthetic fibers. A comprehensive techno-economic analysis was performed based on a 14,000 bone dry tons (BD tons) annual glucose production line, utilizing both 100% cotton and cotton/polyester blends, which reveals capital investments ranging from USD 5.6 to 7.9 million, with manufacturing costs per ton of glucose varying between USD 215 and USD 475, depending on the textile blend used. The cotton/polyester 50/50 blend scenario had the lowest minimum selling price (USD 290 per ton of glucose) due to the revenue from the unhydrolyzed synthetic fibers, which are a valuable and key co-product. A sensitivity analysis highlights the significant influence of recycled polyester content and market prices on the economics. Additionally, a life cycle assessment was performed to compare the carbon footprint of the four scenarios. In contrast to other existing pretreatments that can contribute to up to 70% of the emissions in enzymatic hydrolysis of textiles, the mechanical refining pretreatment can contribute as low as 10% of the total emissions in the process proposed in this work. Even when certain challenges remain, such as the development of a robust supply chain model, the conversion pathway shown in this work for upcycling cotton textile waste into value-added chemicals represents a promising opportunity to combat textile landfilling and foster the circular economy within the industry.

Understanding the potential of bamboo fibers in the USA: A comprehensive techno‐economic comparison of bamboo fiber production through mechanical and chemical processes

AbstractThe growing interest in bamboo fibers for pulp, paper, and board production in the USA necessitates a comprehensive financial viability assessment. This study conducts a detailed technoeconomic analysis (TEA) of bamboo fiber production, primarily for the consumer hygiene tissue market although it is also applicable to other industrial uses. The economic viability of two pulping methods – alkaline peroxide mechanical pulping (APMP) and ammonium bisulfite chemical pulping (ABS) – was explored within three different pulp mill settings to supply pulp to two nonintegrated tissue and towel mills in South Carolina, USA. The target was to produce wet lap bamboo bleached pulp at 50% consistency and 70% ISO brightness. Despite higher initial capital invesment and operating costs, ABS achieved a lower minimum required selling price – USD 544 to 686 per bone dry metric ton (BDt = 1000 BDkg) – in comparison with USD 766 to 899 BDt−1 for APMP. This price advantage is partly due to an additional revenue stream (lignosulfonate byproduct), which not only boosts revenue but also circumvents the need for expensive chemical recovery systems. When compared with traditional kraft pulping, both methods require significantly lower capital investments, with minimum required selling prices (estimated to achieve 16% IRR) below current market rates for extensively used bleached kraft pulps in the USA tissue industry. The economic benefits derive from several factors: the low cost of bamboo as raw material, reduced capital needs for new pulping technologies, lower transportation costs from the pulp mill to tissue and towel manufacturing facilities, and the high market price of bleached kraft pulp.

Economic and environmental assessment of a multifunctional poplar plantation for roundwood and wood chip production in Spain

Aim of study: To analyze the environmental and economic performance of a multifunctional poplar plantation (MPP), which was managed to produce timber for sawn wood and chips for bioenergy. Area of study: The plantation was located in Southern Spain producing roundwood and woodchips (from tops and branches). Material and methods: The life cycle assessment (LCA) methodology was chosen to perform the environmental impact assessment from a cradle-to-gate perspective. Capital goods, including machinery-manufacturing processes, were included. One oven dry tonne (odt) of forest biomass was chosen as functional unit. The economic analysis was performed using present costs and common indicators: net present value (NPV) and internal rate of return (IRR). Main results: The harvest operations are the most environmental impacting subsystem and cultivation the costliest. Chipping was the process contributing the most to the environmental burden. The use of fertilizers, within the cultivation subsystem, had a notable impact on certain midpoint categories. In terms of climate change potential, 1 odt of delivered wood chips generated 64.1 kg CO2-eq. When considering the whole system (including the roundwood fraction), this value was 45.2 kg CO2-eq odt-1. MPP was hardly profitable with land rental and irrigation being the most expensive items. NPV, including harvesting and transport subsystems, was 1,582 € ha-1, while IRR reached 6.3%. Research highlights: Our results allow to identify the costliest operations and those with the greatest impact to improve the system. Finally, these figures can be compared with other crop alternatives such us poplar short rotation coppice (SRC).

Nth-plant scenario for blended pellets of Miscanthus, Switchgrass, and Corn Stover using multi-modal transportation: Biorefineries and depots in the contiguous U.S.

The sustainability of the biofuel industry depends on the development of a mature conversion technology on a national level that can take advantage of the economies of scale: the nth-plant. This study addresses the logistic challenge of mobilizing national cellulosic feedstock supplies for a sustainable bioenergy industry. A Mixed Integer Linear Programming (MILP) model was developed and updated to deliver on-spec biomass that considers both a desired quantity and quality at the biorefinery. Our supply chain analysis includes multi-modal transport (truck and rail), varying depot and biorefinery sizes, and feedstock blends of corn stover (harvested by either a two- or three-pass method), switchgrass, and miscanthus. The following US states: Illinois, Kansas, Missouri, North Carolina, Oklahoma, Georgia, and Texas were identified as key locations for producing accessible miscanthus. Based on our most optimistic scenario, using trucks as the only transportation mode in 2040 with a cost target of $79/dt, corn stover, switchgrass, and miscanthus could help meet 48% of the EPA target, 173 million dry tons that translate into 7.8 billion GGE. The addition of rail transportation for biomass delivery to biorefineries could help meet 79% of the EPA target, 283 million dry tons that translate into 12.7 billion GGE.

Availability of Employing Biomass Resources From Forest Residues for Bioenergy Production in Ethiopia

The urgency of addressing environmental challenges has become more apparent than ever in recent years. Using existing renewable resources and reducing environmental impacts is critical for boosting economic growth and sustainable development. Ethiopia has limited access to modern bioenergy because of insufficient biomass data and policy gaps. This study estimated the theoretical potential of forest residue biomass resources for modern bioenergy production in Ethiopia. A combination of forest statistics data, publicly available data, literature models, and standard procedures was utilized. Ethiopia generates approximately 16.4 million dry tons of recoverable forest residue biomass each year. This indicates that the theoretical energy potential of forest residue available in Ethiopia is about 1.8–4.93 billion liters of ethanol each year, equivalent to 172%–469% of the country’s gasoline consumption. Alternatively, the same amount of residue could generate 1.23–3.29 billion liters of biodiesel (biomass to Fischer–Tropsch) each year, accounting for 40%–107% of the country’s biodiesel consumption. The theoretical estimations also show that the recoverable forest residues have the potential to produce about 12.7–34 TWh of electricity. This could significantly improve remote rural household electrification while decreasing the country’s reliance on fuel wood biomass for traditional biofuels by 26%. The findings indicate that generating modern bioenergy from forest biomass residue has the potential to contribute to Ethiopia’s energy mix, boost rural power access, and open new avenues for socioeconomic development. Finally, it can be concluded that the study findings reported in this study are useful to energy professionals, researchers, and policymakers interested in biomass fuel.

Application of an integrated pyrolysis and chemical leaching process for pulper waste conversion into coal, hydrogen and chemical flocculating agent

This work aims to investigate the potentials of integrating slow pyrolysis and chemical leaching to recycle pulper waste (PW), the waste generated by paper mills, and consists of plastics, metallic films, and biobased polymers. The concentration of chlorine and metals is a barrier against PW valorisation by combustion or high temperature thermochemical processes. In this study, PW was tested by slow pyrolysis at 400 °C and 500 °C. Chemical leaching tests were performed by processing both chars in a 1.4 M HCl solution, at 80 °C for 2 h, to remove inorganic compounds and upgrade the char to a coal-like material. Then, precipitation by NaOH was conducted on the leachate. Slow pyrolysis led to a char mass yield around 30 %. Due to the high inorganic matter concentration (almost 36 %, mainly including chlorine, calcium, and aluminium), the char retained only 25 % of the feedstock’s chemical energy, while the remaining 75 % was recovered in the pyrogas. Leaching of the 500 °C pyrolysis char led to extract 93 % of aluminium, and almost 100 % of calcium and chlorine, resulting in an upgraded char containing 15.5 % ash, comparable to a fossil coal. By char leaching, the oxidation reaction of aluminium could produce 8 kg hydrogen per dry ton PW. The effectiveness of the precipitated compounds as flocculating agents was demonstrated, enabling a closed-loop recycling in the same paper mill. In conclusion, the proposed process demonstrated to be an effective solution to convert PW into high quality products.

Microwave wood chip treatment use in chemical pulp manufacturing (technical-economic assessment)

The low permeability of many wood species causes problems in the chemical pulp industry. These include very long cooking times, high chemical consumption, large material losses, high energy consumption, and environmental pollution. New microwave (MW) wood modification technology can provide an increase in wood permeability for liquids and gases that solves many of these problems. MW wood pre-treatment can increase pulp mill throughput, reduce chemical and power consumption, increase pulp quality and yield, and improve environmental performance. Economic modelling of this new technology use in different chemical pulp mill conditions allowed to assess the effect of capital costs, electricity costs, labour costs and other cost components to specific total costs of MW chip processing. MW chip treatment costs for pulp mills with output 50,000 to 500,000 ait dry ton (ADT) per year at electricity cost range US$0.04 to US$0.24/kWh vary in the range from US$17.7 to US$60.8 per air dry ton of pulp. Electricity costs form the most significant part – 51- 69% of the total specific costs of MW chip processing at electricity costs US$0.08 to US$0.12/kWh. New technology applications in different Russian conditions can provide benefits up to 7 – 22 Mil US$ per year for pulp mills with output of more than 200,000 ADT/year. The ecological effect and high economic advantages of this MW technology provide a good opportunity for commercialisation.

Quantification and specification of agricultural by-products as local resources for mycelium-bound composites

The research focuses on Upstate New York and quantifies the available agricultural wastes and by-products to identify their application as substrates for mycelium-bound composites (hereinafter MBC) functioning as nutrient, aggregate, and reinforcement in the production of local biological building materials. The literature review indicates that the biggest contributor to the mechanical strength of MBC is the substrate’s ability to support strong and dense mycelial growth. To estimate the locally available agricultural wastes in the Finger Lakes region of New York, yield data, residue-to-grain ratio, moisture content, and weight are used to determine the dry tons of residue produced in 2021 in New York. Reports suggest that agricultural residues, particularly corn stover, are widespread and underutilized in the United States, representing a major potential resource. This research explores the potential of using corn stover, especially cobs as a material resource for new circular construction paradigms in the Finger Lakes region’s circular economy. Further research aims to increase control of growth parameters and material specification in the production of local biological building materials.

Forest Biomass Feedstock Availability and Economic Contribution of Biopower Facilities in the Lake States Region

Abstract The Lake States (MI, MN, WI) region holds 54.8 million acres of forest and offers the potential to meet the increasing demand for sustainable energy through forest biomass. The objective of this study is to estimate the annual availability of biomass, after considering the sustainability threshold, for a wood price and its economic impact in the Lake States region. This study identified twenty-seven active power facilities using biomass in addition to oil, gas, and coal, with a total capacity of 3.85 million MWh per year. They consumed 2.80 million dry tons of biomass in 2019. At the current delivered wood price, an additional 9.72 million dry tons of biomass is economically available, which, if used, would generate an additional 11,112 jobs (1,583 direct and 9,529 indirect and induced), $1.54 billion in value added ($803 million direct and $733 million indirect and induced), and $2.71 billion ($1.46 billion direct and $1.25 billion indirect and induced) in total output. Operating at least one-third of the existing capacity for biomass-based power generation would add 1,969 jobs, $293 million in value added, and $413 million in total output. The expansion of the biomass biopower industry has the potential to significantly increase economic impact, especially in rural areas. Study Implications: Mapping procurement zones for resource allocation using delivered wood prices for biomass helps identify the economic availability of biomass for electric power production in the Lake States. Our results establish the market extent for biomass and identify potential areas where investment in biopower production or capacity upgrade is feasible. This study also provides insight into the economic impacts of additional biomass utilization to produce power. Most of these impacts would come about in rural areas, improving economic growth in these communities. A combined analysis estimating the potential supply and demand and the economic effects of biopower industry expansion provides valuable insight into decision-making for state forest action plans and private sector forest management plans. Furthermore, the findings from this study will help inform effective regional policy and investment decisions on biomass power industries. The method used can also be tailored to a specific facility to estimate its procurement zone, feedstock availability, and economic impacts.

Climate change mitigation potential of kitchen waste utilization in China for combined heat and power production

Given the concerns about climate change, energy sustainability, and public health, the reuse of kitchen wastes (KW) is attracting increasing interest. In China, the municipal solid waste sorting scheme has increased the available KW. To assess the available KW and the climate change mitigation potential of KW utilization for bioenergy in China, three scenarios (base, conservative, and ambitious) were defined. A new framework was implemented to assess the climate change impacts of bioenergy. The annual available KW ranged from 11.450 million dry tons (in metric) under the conservative scenario to 22.898 million dry tons in the ambitious scenario, and had the potential to produce 12.37 × 106–24.74 × 106 MWh heat and 9.62 × 106–19.24 × 106 MWh power. The total potential climate change impacts of KW for combined heat and power were 3.339–6.717 million tons CO2 eq in China. The highest eight provinces and municipalities contributed over half of the national total. Among the three components of the new framework, fossil fuel-derived greenhouse gas emissions and biogenic CO2 emissions were positive. The difference in carbon sequestration was negative and ensured a lower integrated life-cycle climate change impacts than that of natural gas-derived combined heat and power. The mitigation effects of using KW as a substitute for natural gas and synthetic fertilizers were 2.477–8.080 million tons CO2 eq. These outcomes can inform relevant policymaking and benchmark climate change mitigation in China. The conceptual framework of this study can also be adapted for applications in other countries or regions worldwide.

Oilfield Technology Leads the Way in Pursuit of Undersea Metals Vital to Energy Transition

A carbon-free world and green economy have a lot riding on the future of electricity generation and storage. As the world moves away from hydrocarbons and toward electricity to power everything from cars to the factories that make them and beyond, there is yet another crucial hurdle to clear. To meet the expected electric future for vehicles alone, it will take more manganese, cobalt, nickel, copper, and lithium than we as a planet are currently producing. These elements are the building blocks for the batteries that power the electrified future—and they are finite. Supply concerns have already hit automakers as more and more look to grow their electric vehicle (EV) footprints. Representatives from Tesla, Ford, and Mercedes-Benz were among the delegates at a recent metals and mining conference in Florida—a gathering usually attended by metals producers. The auto managers were in attendance to learn more about potential obstacles to their supply chains when it comes to lithium, nickel, and cobalt, all critical battery components. An answer to the supply conundrum may lie in a most curious place—the ocean floor. Specifically, in deposits of polymetallic nodules—black lumps of mineral matter about the size of a potato that are strewn throughout certain areas of the Earth’s seabeds. These nodules are present in deposits across the globe, but mostly in the Pacific and Indian oceans. The existence of these nodules has been known for decades. In fact, it would be the idea of deep-sea mining for manganese nodules that would act as cover for a Cold War expedition known as Project Azorian, a CIA-led mission in the Pacific Ocean that would use a converted drilling rig—the Glomar Explorer—to retrieve a sunken Soviet submarine in the early 1970s. The mission was a partial success as only a portion of the crippled vessel was retrieved. In the North Pacific between Hawaii and Mexico, there is an area called the Clarion-Clipperton Zone (CCZ) that is estimated to hold a field comprised of 21 billion dry tons of nodules at water depths ranging from 4 to 6 km. The CCZ is broken up into licenses, much like what is common for offshore oil and gas exploration. “The amount of metals in the nodules themselves surpasses anything on land—far more nickel, far more cobalt, far more manganese, and a fair amount of copper as well,” said Rory Usher with The Metals Company, a deep-sea miner with licenses in the CCZ. “In the face of massive resource demand and constrained supply, we think this abundant and potentially lower-impact alternative is something that absolutely has to be responsibly considered. And through our extensive deep-sea science program to provide definitive answers as to the impacts, that’s exactly what’s been done.”

Techno‐economic and policy analysis of hydrogen and gasoline production from forest biomass, agricultural residues and municipal solid waste in California

AbstractTechno‐economic and policy analyses were performed of hydrogen and gasoline production from forest biomass (FB). They were compared with fuels produced using agricultural residues and municipal solid waste in California. Twelve process designs were analyzed, with and without carbon capture and storage, and life‐cycle analysis was performed, using California's Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) 3.0 model, to calculate the average life‐cycle carbon intensity of different process designs for hydrogen and gasoline. Discounted cash flow models were developed to assess profitability in terms of the net present value and internal rate of return (IRR). The results showed that forest‐to‐fuel pathways (positive IRR between 2%−16%) were the least competitive biomass‐based pathway option. Sensitivity analysis was performed on economic parameters including feedstock price and renewable identification number (RIN) credit price. In the case of RIN credits, profitability declined significantly as the proportion of FB from federal lands increased given existing statutory limitations. Given the importance of increasing forest management to reduce wildfire risks, the necessary additional policy incentives were quantified to equalize the cost of forest‐to‐fuels pathways with the other biofuels pathways. To ensure FB‐to‐fuels pathways are cost competitive with agricultural residues, policymakers could increase the low carbon fuel standard (LCFS) credit price for forest fuels (additional credit price support of $41–75 t/CO2e), give additional credit to lifecycle emissions reductions from forest fuels (additional carbon intensity decrease of 19–76 gCO2e MJ−1), provide concessionary debt or equity with a target weighted average cost of capital (WACC) = 3–4%, subsidize capital costs (12–22% of costs), or subsidize FB delivery ($35–66 per dry ton delivered).

Chipping operations and chip quality from mixed hardwood forests for bioenergy

ABSTRACT A mechanized 1 harvesting system combined with whole-tree chipping was investigated on two harvesting sites in central and eastern Ohio, USA. Production and machine rate data of the operations were collected through time-motion studies, with chipping sub-tasks (elements) defined as: feeding, chipping, and loading. Chipping cycles averaged 21.5 min to produce 13.3 dry (21.3 green) tonnes per truckload, providing an hourly rate of 37.3 dry tonnes per productive machine hour (PMH), excluding delays. Total cycle time including truck delivery averaged 183 min, resulting in an hourly production rate of 4.4 dry tonnes/PMH delivered. The complete harvesting system included one feller-buncher, two grapple skidders, and a chipper. Harvesting cost ranged from (USD) $22.2 to $27.8/dry tonne, at the landing. Trucking cost was $0.48/dry tonne/km for the average hauling distance of 78 km. The total delivered cost amounted to $59.9–$65.5 per dry tonne. Chips were sampled from the operations and characterized to evaluate their quality as a bioenergy fuel, according to ANSI Standard AD17225–4:2014 Solid Biofuels. Results of chip properties indicated 37.5% green moisture (i.e. water mass fraction), 0.212 g/cm3 bulk density, 10.5% bark content, 0.49% ash, and 18.59 MJ/Kg calorific heating value. Size distribution of wood chips was categorized into small (3–<16 mm) 46%, medium (16–<45 mm) 45%, and large (45–63 mm) 3%, respectively. Fines (<3 mm) composed less than 1% while 4.5% were oversize (>63 mm). These whole-tree chips were found to meet the requirements of the highest grade (A1) of the U.S. wood chip fuel quality standard for bioenergy applications.

The Logistics of Production and Supply of Ag Pellets for Industrial Applications in Canada

In this work we analyze the supply of biomass from field to an in-land or port destination. The biomass is pelletized to increase its bulk density to extend its storage period and for ease of its transport. The pellet may be used for conversion to chemicals and animal bedding or for straight combustion. We analyzed supply chain in Saskatchewan where there are plenty of crop residues but widely dispersed and harvest seasons are short. We envisioned that the farmer collects bales from field and transports the bales to farmstead during the harvest season. The bales are then processed into pellets using small scale pellet equipment. A custom operator with expertise in pelletization may engage in handling and densifying the biomass. The business case for the mobile mill will be similar to the well established custom grain and forage harvesting operations. The pellets are stored in hopper bottom grain bins at the farmstead. From this point, the handling of pellets would be similar to the handling and marketing of grain. The farmer trucks a specified volume of pellets from farmstead to the nearest elevator where the pellets are transferred to larger bins or silos. Pellets are extracted from silos and loaded onto the rail cars. The Canadian freight rail companies (mainly CN) currently transport over 3 million dry tonne (dt) of wood pellets in rail cars. The pellets are hauled to marine ports on the West Coast or East Coast for export. The cost of delivering ag pellets to biorefinery or to the shipping port is $86.09/dt. This cost does not include the equivalent value of removing biomass from the farm (e.g. fertilizer replacement) and return on investment. The GHG emissions to produce and transport ag pellets add up to 185.9 kg of CO2 per dt of biomass. The cost of producing pellets without drying feedstock is $35.05/dt and the corresponding GHG for palletization amounts $146.30/dt.

Roadmap for Deployment of Modularized Hydrothermal Liquefaction: Understanding the Impacts of Industry Learning, Optimal Plant Scale, and Delivery Costs on Biofuel Pricing

Hydrothermal liquefaction (HTL) is a promising technology for converting abundant organic wastes into fuels. Previous techno-economic analyses (TEAs) of HTL have been used to estimate the minimum fuel selling price (MFSP) of biofuel products, but these analyses often assume a bespoke plant design where each plant operates under unique process conditions and neglect transportation costs. However, transportation costs must be included in realistic TEAs, and further, a mass-produced fixed-scale modular plant design approach may be more effective than case-by-case plant design, provided that there is sufficient market capacity to benefit from modularization. This study estimates fuel price behavior in the presence of transportation costs and benefits stemming from modular plant design. This analysis indicates that a modular process capable of handling 60 dry tons per day (DTPD) is optimal, resulting in a ∼25% reduction in MFSP (from $4.70/GGE, fully upgraded) at complete market feedstock utilization compared with case-by-case design. The associated cost reductions are attributable to learning benefits and modularization. Several HTL deployment “roadmaps” are then explored, with each roadmap consisting of different periods of case-by-case design followed by adoption of a modularized approach. A period of nonmodular industry growth up to market saturation of ∼7% followed by implementation of modular plant design strikes a balance between the investment risk and learned cost reductions associated with modular plant design. However, if bespoke plants built during this period of nonmodular growth saturate more than 23% of available feedstock, learned cost reductions are significantly diminished. This study points to the potential benefits of modularized and decentralized waste-to-energy processes when the modularization follows an optimal deployment strategy.

The use of soybean and rice straw harvest waste for increasing P uptake and organic maize production in inceptisols

This study aimed to evaluate the potential of harvest waste (soybean and rice straw) at various doses on the efficiency of P uptake and maize yields. The study used a factorial randomized block design, the first factor being the type of harvest waste (C) two levels; C1= Rice Straw, C2= Soybean. The second factor is the dose of four levels of compost; D1 = dose of 5 tons ha-1, D2 = dose of 10 tons ha-1, D3 = dose of 15 tons ha-1, and D4 = dose of 20 tons ha-1, plus control treatment as a comparison. The results showed that there was a significant effect of the type of harvested waste compost and the dose on the parameters of plant height, leaf area, dry weight of 1000 seeds, total dry weight of plants, root uptake, crown, and total P and efficiency of P use. Treatment of soybean compost 10 tons ha-1 (C2D2) is the best treatment that can increase plant height (11.25%), stem diameter (41.38%), number of leaves and leaf area of 37.36% and 39.60%, respectively. In yield and P uptake parameters, C2D2 increased dry weight ton ha-1 (39.08%), root P uptake (258.86%), shoot P uptake (142.57%), total P uptake (158.29% ), and the efficiency P os use (12.45%). The optimum dose of straw compost was 16.76 tons ha-1 with maize yields of 5.38 tons ha-1, while the optimum dose of soybean compost was 12.85 tons ha-1 with maize yields of 5.32 tons ha-1.

Estimating production cost for large-scale seaweed farms

ABSTRACT Seaweed farming has the potential to produce feedstocks for many applications, including food, feeds, fertilizers, biostimulants, and biofuels. Seaweeds have advantages over land-based biomass in that they require no freshwater inputs and no allocation of arable land. To date, seaweed farming has not been practiced at scales relevant to meaningful biofuel production. Here we describe a techno-economic model of large-scale seaweed farms and its application to the cultivation of the cool temperate species Saccharina latissima (sugar kelp) and the tropical seaweed Eucheumatopsis isiformis. At farm scales of 1000 ha or more, our model suggests that farm gate production costs in waters up to 200 km from the onshore support base are likely to range between $200 and $300 per dry tonne. The model also suggests that production costs below $100 per dry tonne may be achievable in some settings, which would make these seaweeds economically competitive with land-based biofuel feedstocks. While encouraging, these model results and some assumptions on which they are based require further field validation.

Nth-plant scenario for forest resources and short rotation woody crops: Biorefineries and depots in the contiguous US

• Nationwide depots & biorefineries to meet target costs, quality & quantity from woody resources. • Forest residues: trees, tops & limbs. Short rotation crops: poplar, willow, pine, & eucalyptus. • Maximum accessible forest residues at $79.07/dt & $85.51/dt was 103 and 106 M dt at any ash target. • Short rotation woody crops increased total to 153 & 195 M dt at 1% & 1.75% ash & $85.51/dt cost targets. • Woody resources could address 55% of EPA’s goals, 195 M dt/year at $85.51/dt cost & 1.75% ash target. Estimating the US potential of woody material is of vital importance to ensure cost-effective supply logistics and develop a sustainable bioenergy and bioproducts industry. We analyzed a mature conversion technology for woody resources for the contiguous US that takes advantage of economies of scale: the nth-plant. We developed a database to quantify the total accessible woody biomass within a distributed network of preprocessing depots and biorefineries considering both quality specifications for conversion and a target cost to compete with fossil fuels. We considered two categories of woody biomass: 1) forest residues from trees, tops and limbs produced from conventional thinning and timber harvesting operations as well as non-timber tree removal; and 2) short rotation woody crops such as poplar, willow, pine, and eucalyptus. A mixed integer linear programming model was developed to analyze scenarios with woody feedstock blends at variable biomass ash contents and cost targets at the biorefinery. When considering a target cost of $85.51/dry ton (2016$) at the biorefinery, the maximum accessible biomass from forest residues in 2040 remained constant at 106 million dry tons regardless of ash targets. Including short rotation woody crops as part of the blend increased the total accessible biomass to 153 and 195 million dry tons at ash targets of 1% and 1.75%, respectively. We concluded from our analysis that woody resources could address about 55% of EPA’s (Environmental Protection Agency) target of 16 billion gallons of cellulosic biofuel.

Forest Biomass Policies and Regulations in the United States of America

Using woody biomass from public lands could attract private investments, increase carbon dioxide emission reductions from sustainably harvested low-grade wood to mitigate climate change, provide benefits for the environment, and support rural community economies. Available for use are about 210 million oven dry tons (in the western U.S. alone) of small-diameter wood and harvest residues that could be removed through hazard-fuel treatments and used for bioenergy and bioproducts; representing an economic value of approximately USD 5.97 billion (109). Reaching that utilization goal requires an assessment of current U.S. policies, regulations and directives influencing the use of forest biomass and identification of barriers, challenges, and potential opportunities associated with the use of woody biomass from public lands. One objective of this review is to support the implementation of the U.S. Department of Agriculture, Forest Service (USDA-FS) new effort called “Confronting the Wildfire Crisis: A Strategy for Protecting Communities and Improving Resilience in America’s Forests”, but greater coordination of public policies (regulatory legislation, government subsidies, support programs) at different government levels could increase adoption of forest biomass for bioenergy and bioproducts while also promoting different supply chains for long-term biomass supplies and industry investments. Harmonizing the definition of key biomass terms used by different programs that support using forest biomass for bioenergy and other bioproducts, including the Renewable Fuel Standard, may increase forest biomass use from public lands.

Circular utilization of urban tree waste contributes to the mitigation of climate change and eutrophication

Circular utilization of urban tree waste contributes to the mitigation of climate change and eutrophication