Estimating the environmental impacts of global lithium-ion battery supply chain: A temporal, geographical, and technological perspective.

A sustainable low-carbon transition via electric vehicles will require a comprehensive understanding of lithium-ion batteries' global supply chain environmental impacts. Here, we analyze the cradle-to-gate energy use and greenhouse gas emissions of current and future nickel-manganese-cobalt and lithium-iron-phosphate battery technologies. We consider existing battery supply chains and future electricity grid decarbonization prospects for countries involved in material mining and battery production. Currently, around two-thirds of the total global emissions associated with battery production are highly concentrated in three countries as follows: China (45%), Indonesia (13%), and Australia (9%). On a unit basis, projected electricity grid decarbonization could reduce emissions of future battery production by up to 38% by 2050. An aggressive electric vehicle uptake scenario could result in cumulative emissions of 8.1 GtCO2eq by 2050 due to the manufacturing of nickel-based chemistries. However, a switch to lithium iron phosphate-based chemistry could enable emission savings of about 1.5 GtCO2eq. Secondary materials, via recycling, can help reduce primary supply requirements and alleviate the environmental burdens associated with the extraction and processing of materials from primary sources, where direct recycling offers the lowest impacts, followed by hydrometallurgical and pyrometallurgical, reducing greenhouse gas emissions by 61, 51, and 17%, respectively. This study can inform global and regional clean energy strategies to boost technology innovations, decarbonize the electricity grid, and optimize the global supply chain toward a net-zero future.

Wind turbine blade wastes and the environmental impacts in Canada.

Electricity production by wind turbines is considered a clean energy technology, but the life cycle of wind turbines could introduce environmental risks due to waste generation, especially at the decommissioning process. This study predicts the future wind turbine blade waste arising in Canada, throughout all life cycle stages, from manufacturing until end of life, based on the installed capacities of existing Canadian wind farms and projected future installations. Five alternative strategies for managing this waste stream are assessed in terms of life cycle greenhouse gas emissions and primary energy demand, including landfilling, incineration, and mechanical recycling. For the base case scenario, it is observed that the total cumulative waste until 2050 is 275,299 tonnes, with on-site waste accounting for around 75% of this total. Waste generation is concentrated in provinces with greater wind power deployment: Ontario and Quebec alone account for 70% of total blade waste. Life cycle environmental impacts of waste management strategies are dependent on background energy systems, with incineration a significant source of greenhouse gas emissions, particularly when displacing low-carbon grid mixes. Cement kiln coprocessing achieves net zero emission by converting waste into energy and raw materials for the cement. Mechanical recycling can achieve substantial reductions in primary energy demand and greenhouse gas emissions but achieving financial viability would likely require substantial regulatory support.

Challenges in Quantifying Greenhouse Gas Impacts of Waste-Based Biofuels in EU and US Biofuel Policies: Case Study of Butanol and Ethanol Production from Municipal Solid Waste.

Conversion of wastes to biofuels is a promising route to provide renewable low-carbon fuels, based on a low- or negative-cost feedstock, whose use can avoid negative environmental impacts of conventional waste treatment. However, current policies that employ LCA as a quantitative measure are not adequate for assessing this type of fuel, given their cross-sector interactions and multiple potential product/service streams (energy, fuels, materials, waste treatment service). We employ a case study of butanol and ethanol production from mixed municipal solid waste to demonstrate the challenges in using life cycle assessment to appropriately inform decision-makers. Greenhouse gas emissions results vary from -566 gCO2 eq/MJbiofuel (under US policies that employ system expansion approach) to +86 gCO2 eq/MJbiofuel and +23 gCO2 eq/MJbiofuel (under initial and current EU policies that employ energy-based allocation), relative to gasoline emissions of +94 gCO2 eq. LCA methods used in existing policies thus provide contradictory information to decision-makers regarding the potential for waste-based biofuels. A key factor differentiating life cycle assessment methodologies is the inclusion of avoided impacts of conventional waste treatment in US policies and their exclusion in EU policies. Present EU rules risk discouraging the valorisation of wastes to biofuels thus forcing waste toward lower-value treatment processes and products.

Process simulation and life cycle assessment of converting autoclaved municipal solid waste into butanol and ethanol as transport fuels.

In 2015/2016, the total municipal solid waste (MSW) collected by local authority in the U.K. was 26 million tonnes and over 57% is still put into landfill or incinerated. MSW is a promising feedstock for bio-butanol production as it has a high lignocellulosic fibre content such as paper, wood, and food waste, about 50 wt% of a typical MSW stream. The study evaluates acetone, butanol, ethanol and hydrogen production from autoclaved municipal solid waste feedstock. Life cycle assessment is undertaken to evaluate the acetone, butanol, ethanol and hydrogen production process, considering cogeneration of heat and power from residual biogenic waste based on experimental data and process modelling. Acetone, butanol, and ethanol product yield can be achieved at 12.2 kg butanol, 1.5 kg ethanol, 5.7 kg acetone, and 0.9 kg hydrogen per tonne MSW. The product yield is relatively low compared to other lignocellulosic feedstocks primarily because of the lower hydrolysis yield (38% for glucose) achieved in this study; however, hydrolysis yields could be improved in future optimisation work. The conversion shows a net primary energy demand of -1.11 MJ/MJ liquid biofuels (butanol and ethanol) and net greenhouse gas emission of -12.57 g CO2eq/MJ liquid biofuels, achieving a greenhouse gas reduction of 115% compared to gasoline comparator.

Environmental Aspects of Use of Recycled Carbon Fiber Composites in Automotive Applications.

The high cost and energy intensity of virgin carbon fiber manufacture provides an opportunity to recover substantial value from carbon fiber reinforced plastic wastes. In this study, we assess the life cycle environmental implications of recovering carbon fiber and producing composite materials as substitutes for conventional and proposed lightweight materials in automotive applications (e.g., steel, aluminum, virgin carbon fiber). Key parameters for the recycled carbon fiber materials, including fiber volume fraction and fiber alignment, are investigated to identify beneficial uses of recycled carbon fiber in the automotive sector. Recycled carbon fiber components can achieve the lowest life cycle environmental impacts of all materials considered, although the actual impact is highly dependent on the design criteria (λ value) of the specific component. Low production impacts associated with recycled carbon fiber components are observed relative to lightweight competitor materials (e.g., aluminum, virgin carbon fiber reinforced plastic). In addition, recycled carbon fiber components have low in-use energy use due to mass reductions and associated reduction in mass-induced fuel consumption. The results demonstrate environmental feasibility of the CFRP recycling materials, supporting the emerging commercialization of CF recycling technologies and identifying significant potential market opportunities in the automotive sector.

Forest bioenergy or forest carbon? Assessing trade-offs in greenhouse gas mitigation with wood-based fuels.

The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies.

Life cycle emissions and cost of producing electricity from coal, natural gas, and wood pellets in Ontario, Canada.

The use of coal is responsible for (1)/(5) of global greenhouse gas (GHG) emissions. Substitution of coal with biomass fuels is one of a limited set of near-term options to significantly reduce these emissions. We investigate, on a life cycle basis, 100% wood pellet firing and cofiring with coal in two coal generating stations (GS) in Ontario, Canada. GHG and criteria air pollutant emissions are compared with current coal and hypothetical natural gas combined cycle (NGCC) facilities. 100% pellet utilization provides the greatest GHG benefit on a kilowatt-hour basis, reducing emissions by 91% and 78% relative to coal and NGCC systems, respectively. Compared to coal, using 100% pellets reduces NO(x) emissions by 40-47% and SO(x) emissions by 76-81%. At $160/metric ton of pellets and $7/GJ natural gas, either cofiring or NGCC provides the most cost-effective GHG mitigation ($70 and $47/metric ton of CO2 equivalent, respectively). The differences in coal price, electricity generation cost, and emissions at the two GS are responsible for the different options being preferred. A sensitivity analysis on fuel costs reveals considerable overlap in results for all options. A lower pellet price ($100/metric ton) results in a mitigation cost of $34/metric ton of CO2 equivalent for 10% cofiring at one of the GS. The study results suggest that biomass utilization in coal GS should be considered for its potential to cost-effectively mitigate GHGs from coal-based electricity in the near term.