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Although Beijing has carried out municipal solid waste （MSW） source separation since 1996, it has largely been ineffective. In 2012, a ＂Green House＂ program was established as a new attempt for central sorting. In this study, the authors used material flow analysis （MFA） and cost benefit analysis （CBA） methods to investigate Green House＇s environment and economic feasibility. Results showed that the program did have significant environmental benefits on waste reduction, which reduced the amount of waste by 34%. If the Green House program is implemented in a residential community with wet waste ratio of 66%, the proportion of waste reduction can reach 37%. However, the Green House is now running with a monthly loss of 1982 CNY. This is mainly because most of its benefits come from waste reduction （i.e., 5878 CNY per month）, which does not turn a monetary benefit, but is instead distributed to the whole of society as positive environmental externalities. Lack of government involvement, small program scale, and technical/managerial deficiency are three main barriers of the Green House. We, thus, make three recommendations： involve government authority and financial support, expand the program scale to separate 91.4 tons of waste every month, and use more professional equipment/technologies. If the Green House program can successfully adopt these suggestions, 33.8 tons of waste can be reduced monthly, and it would be able to flip the loss into a profit worth 35034 CNY.

A study combining wind power with pumped hydro energy storage for the Jordanian utility grid is presented. Three solvers of the Matlab optimization toolbox are used to find the optimal solution for the cost of energy in a combined on-grid system. Genetic algorithm, simulated annealing (SA), and pattern search (PS) solvers are used to find the optimal solution. The GA solution of 0.0955388 $/kWh is economically feasible. This is 28.7% lower than the electricity purchased from the conventional utility grid. The discounted payback period to recover the total cost is 10.271 years. The suggested configuration is shown to be feasible by comparing it to real measurements for this case and a previous wind-only case. It is shown that the indicators of the optimal solution are improved. For instance, carbon dioxide emissions (ECO2) and conventional grid energy purchases are reduced by 24.69% and 24.68%, respectively. Moreover, it is shown that the benefits of adding hydro storage, combined with increasing the number of wind turbine units, reduces the cost of energy of renewables (COERenewables). Therefore, combining hydro storage with wind power is economically, environmentally, and technically a more efficient alternative to the conventional power generation.

The global amount of solid waste has dramatically increased as a result of rapid population growth, accelerated urbanization, agricultural demand, and industrial development. The world's population is expected to reach 8.5 billion by 2030, while solid waste production will reach 2.59 billion tons. This will deteriorate the already strained environment and climate situation. Consequently, there is an urgent need for methods to recycle solid waste. Here, we review recent technologies to treat solid waste, and we assess the economic feasibility of transforming waste into energy. We focus on municipal, agricultural, and industrial waste. We found that methane captured from landfilled-municipal solid waste in Delhi could supply 8–18 million houses with electricity and generate 7140 gigawatt-hour, with a prospected potential of 31,346 and 77,748 gigawatt-hour by 2030 and 2060, respectively. Valorization of agricultural solid waste and food waste by anaerobic digestion systems could replace 61.46% of natural gas and 38.54% of coal use in the United Kingdom, and could reduce land use of 1.8 million hectares if provided as animal feeds. We also estimated a levelized cost of landfill solid and anaerobic digestion waste-to-energy technologies of $0.04/kilowatt-hour and $0.07/kilowatt-hour, with a payback time of 0.73–1.86 years and 1.17–2.37 years, respectively. Nonetheless, current landfill waste treatment methods are still inefficient, in particular for treating food waste containing over 60% water.

The majority of rural communities in developing countries (such as Peru) are not connected to the electrical grid. Hybrid energy production from available renewable resources (e.g., wind and solar) and diesel engines is considered as an economically viable and environmentally friendly alternative for electrification in these areas. Motivated by the lack of a comprehensive investigation dedicated to the techno-economic analysis of hybrid systems (PV–wind–diesel) for off-grid electrification in Peru, the present work is focused on determining the optimal configuration of these systems for remote Peruvian villages. Three small communities without access to the grid (Campo serio, El potrero, and Silicucho), which are located in different climatic zones of Peru, have been accordingly selected as case studies. Seven different configurations including single component systems (solar, wind, and diesel) and hybrid ones are considered. While taking into account the meteorological data and load characteristics of the communities along with the diesel fuel’s price and the cost of components, HOMER software is utilized to determine the optimal sizing of the system [resulting in the lowest net present cost (NPC)] considering different scenarios. The obtained configurations are then compared considering other state-of-the-art economic indices [initial capital cost, total annual operating cost, and the cost of energy (COE)], the generation fractions, and the resulting CO2 emissions. The obtained results have revealed that, for all of the investigated communities, the hybrid solar–wind–diesel system is the most economically viable scenario. Considering the latter scenario, the obtained optimal configuration leads to an NPC of USD 227,335 (COE: 0.478 USD/kWh) for Campo serio, USD 183,851 (COE: 0.460 USD/kWh) for El potrero, and USD 146,583 (COE: 0.504 USD/kWh) for Silicucho. Furthermore, employing the optimal configurations a renewable fraction (with respect to the total generation) of 94% is obtained for Campo serio and Silicucho, while the achieved renewable fraction for El potrero is 97%. Moreover, for the case of Campo serio, the resulting CO2 emission of the obtained optimal system is determined to be 6.1% of that of a diesel-only unit, while the latter ratio is determined to be 2.7% for El potrero and 9.9% for that of Silicucho. The optimal configurations that are obtained and presented in the present paper can be utilized as guideline for designing electrification systems (with a minimized cost) for the considered communities and other villages with similar characteristics (population and climatic conditions).Graphic abstract

Biogas production is rising in the context of fossil fuel decline and the future circular economy, yet raw biogas requires purification steps before use. Here, we review biogas upgrading using physical, chemical and biological methods such as water scrubbing, physical absorption, pressure swing adsorption, cryogenic separation, membrane separation, chemical scrubbing, chemoautotrophic methods, photosynthetic upgrading and desorption. We also discuss their techno-economic feasibility. We found that physical and chemical upgrading technologies are near-optimal, but still require high energy and resources. Biological methods are less explored despite their promising potential. High-pressure water scrubbing is more economic for small-sized plants, whereas potassium carbonate scrubbing provides the maximum net value for large-sized plants.

PurposeProducing biochar from forest residues can help resolve environmental issues by reducing forest fires and mitigating climate change. However, transportation and storage of biomass to a centralized facility are often cost-prohibitive and a major hurdle for the economic feasibility of producing biobased products, including biochar. The purpose of this study was to evaluate the environmental impacts and economic feasibility of manufacturing biochar from forest residues with small-scale portable production systems.MethodsThis study evaluated the environmental performance and economic feasibility of biochar produced through three portable systems (biochar solutions incorporated (BSI), Oregon Kiln (OK), and air curtain burner (ACB)) using forest residues in the United States (US). Cradle-to-grave life-cycle assessment (LCA) and techno-economic analysis (TEA) were used to quantify environmental impacts and minimal selling price (MSP) of biochar respectively considering different power sources, production sites, and feedstock qualities.Results and discussionsThe results illustrated that the global warming (GW) impact of biochar production through BSI, OK, and ACB was 0.25–1.0, 0.55, and 0.61-t CO2eq/t biochar applied to the field, respectively. Considering carbon-sequestration, 1-t of biochar produced with the portable system at a near-forest site and applied to the field reduced the GW impact by 0.89–2.6 t CO2eq. For biochar production, the environmental performance of the BSI system improved substantially (60–70%) when it was powered by a gasifier-based generator instead of a diesel generator. Similarly, near-forest(off-grid) biochar production operations performed better environmentally than the operations at in-town sites due to the reduction in the forest residues transportation emissions. Overall, the net GW impact of biochar produced from forest residues can reduce environmental impacts (i.e., 1–10 times lower CO2eq emissions) compared with slash-pile burning. The MSP per tonne of biochar produced through BSI, OK, and ACB was$3,000–$ 5,000,$1,600, and $ 580 respectively considering 100 working days per year. However, with improved BSI systems when allowed to operate throughout the year, the MSP can be reduced to below$1000/t of biochar. Furthermore, considering current government grants and subsidies (i.e.,$ 12,600/ha for making biochar production from forest residues), the MSP of biochar can be reduced substantially (30–387%) depending on the type of portable system used.ConclusionThe portable small-scale production systems could be environmentally beneficial and economically feasible options to make biochar from forest residues at competitive prices given current government incentives in the US where excess forest biomass and forest residues left in the forest increase the risk of forest fires.

HighlightsManaged aquifer recharge (MAR) schemes are promising solutions in water management.It is important to ensure the economic feasibility and viability of MAR schemes.Cost-benefit analysis (CBA) is a widely used approach for the economic feasibility assessment of MAR projects.Our findings support the importance of the MAR scheme’s non-use benefits.The accelerated growth of water demand globally calls for promising solutions in the field of water management. Managed aquifer recharge (MAR) systems are among the solutions that are capable of increasing water supply and improving water quality through natural attenuation processes. Along with hydrogeologic considerations and institutional feasibility assessments, economic analysis is essential when evaluating MAR projects. This study is the first one to provide an economic feasibility assessment of a MAR scheme in Poland by performing a cost-benefit analysis (CBA) combined with a contingent valuation study to identify the willingness-to-pay, sensitivity analysis to address uncertainty regarding the realisation of benefits and costs together with expert assessment of socio-economic risks associated with the MAR scheme implementation. The results suggest that the total economic value of the MAR scheme’s extension (which includes both use and non-use benefits) exceeds the costs of putting this system in place and maintaining it. This paper can contribute to the existing literature as a practical example providing the base for economic assessment and policy considerations of future sustainable water management projects.

Phosphorus recovery from wastewater has become a necessity for sustainable development because phosphorus is a non-renewable essential resource, and its discharge into the environment causes serious negative impacts. There are no economic incentives for the implementation of phosphorus recovery technologies because the selling price of rock phosphate is lower than phosphorus recovered from sewage. The methodologies used to determine the feasibility of such projects are usually focused on internal costs without considering environmental externalities. This article shows a methodology to assess the economic feasibility of wastewater phosphorus recovery projects that takes into account internal and external impacts. The shadow price of phosphorus is estimated using the directional distance function to measure the environmental benefits obtained by preventing the discharge of phosphorus into the environment. The economic feasibility analysis taking into account the environmental benefits shows that the phosphorus recovery is viable not only from sustainable development but also from an economic point of view.

This paper assesses the economic feasibility of a novel market-based instrument for wetland conservation—a certification scheme for agricultural products. Using a stated preference survey involving wheat flour purchase decisions, we estimate that consumers are willing to pay 25%–29% more for wheat flour produced on fields with restored wetlands. These consumer price premiums translate to a 11%-12% increase in the prices received by producers after accounting for supply chain costs. Producer benefits of adopting the wetland certification scheme generally outweigh the wetland restoration costs for a typical Saskatchewan field, but the change in profits is minimal. The results suggest that this voluntary wetland certification scheme may be a useful addition to the wetland conservation policy toolbox, but will face barriers to producer adoption.

Climate change issues are calling for advanced methods to produce materials and fuels in a carbon–neutral and circular way. For instance, biomass pyrolysis has been intensely investigated during the last years. Here we review the pyrolysis of algal and lignocellulosic biomass with focus on pyrolysis products and mechanisms, oil upgrading, combining pyrolysis and anaerobic digestion, economy, and life cycle assessment. Products include oil, gas, and biochar. Upgrading techniques comprise hot vapor filtration, solvent addition, emulsification, esterification and transesterification, hydrotreatment, steam reforming, and the use of supercritical fluids. We examined the economic viability in terms of profitability, internal rate of return, return on investment, carbon removal service, product pricing, and net present value. We also reviewed 20 recent studies of life cycle assessment. We found that the pyrolysis method highly influenced product yield, ranging from 9.07 to 40.59% for oil, from 10.1 to 41.25% for biochar, and from 11.93 to 28.16% for syngas. Feedstock type, pyrolytic temperature, heating rate, and reaction retention time were the main factors controlling the distribution of pyrolysis products. Pyrolysis mechanisms include bond breaking, cracking, polymerization and re-polymerization, and fragmentation. Biochar from residual forestry could sequester 2.74 tons of carbon dioxide equivalent per ton biochar when applied to the soil and has thus the potential to remove 0.2–2.75 gigatons of atmospheric carbon dioxide annually. The generation of biochar and bio-oil from the pyrolysis process is estimated to be economically feasible.