Biochar Price Research Articles

The Pyrolysis of Biosolids in a Novel Closed Coupled Pyrolysis and Gasification Technology: Pilot Plant Trials, Aspen Plus Modelling, and a Techno-Economic Analysis

Pyrolysis is gaining recognition as a sustainable solution for biosolid management, though scaling it commercially presents challenges. To address this, RMIT developed a novel integrated pyrolysis and gasification technology called PYROCO™, which was successfully tested in pilot-scale trials. This study introduces PYROCO™ and its application to produce biochar, highlighting the biochar properties of the results of the initial trials. In addition, an energy analysis using semi-empirical Aspen Plus modelling, paired with a preliminary techno-economic assessment, was carried out to evaluate the feasibility of this technology. The results show that the PYROCO™ pilot plant produced biochar with a ~30 wt% yield, featuring beneficial agronomic properties such as high organic carbon (210–220 g/kg) and nutrient contents (total P: 36–42 g/kg and total N: 16–18 g/kg). The system also effectively removed contaminants such as PFASs, PAHs, pharmaceuticals, and microplastics from the biochar and scrubber water and stack gas emissions. An energy analysis and Aspen Plus modelling showed that a commercial-scale PYROCO™ plant could operate energy self-sufficiently with biosolids containing >30% solids and with a minimum calorific value of 11 MJ/kg. The process generates excess energy for drying biosolids and for electricity generation. Profitability is sensitive to biochar price; prices rise from AUD 300 to AUD 1000 per tonne, the NPV improves from AUD 0.24 million to AUD 4.31 million, and the payback period shortens from 26 to 12 years. The low NPV and high payback period reflect the use of a relatively high discount rate of 8%, chosen to be on the conservative side given the novel nature of the technology.

Techno-economic assessment of swine manure biochar production in large-scale piggeries in China

Biochar production using swine manure (SM) from large-scale piggeries is increasingly needed. However, little is known about the economic feasibility for SM biochar production. Herein, SM biochar production was simulated via Aspen Plus, and techno-economic model was applied to calculate the net present value (NPV), internal rate of return (IRR), and discounted payback period (DPP) for SM biochar production with a processing capacity of 8000 tons SM per year. Results suggest that this project is susceptible to biochar selling price and operation cost. When the biochar price is > 116 USD/ton, the NPV is positive. When the biochar selling price is increased from 154 to 193 USD/ton, the IRR is increased from 11 % to 41 %. The DPP analyses show that the investment payback period for this project is 4.6 years. Moreover, compared to conventional SM treatment routes, valorization of SM into biochar in large-scale piggery in China has a shorter investment period. Finally, this study suggests that swine manure biochar production in large-scale piggeries in China is profitable, deserving investment.

Nitrate Absorption and Desorption by Biochar

Biochar is a potential solution for addressing environmental problems related to excessive nitrogen (N). However, there is still some debate about the absorption and desorption of nitrate nitrogen (NO3−-N). Therefore, this study investigated the NO3−-N adsorption and desorption performance onto biochar and biochar-soil mixture to address this gap. The results showed that the biochar produced from apple branches had the ability to absorb NO3−-N with an absorption capacity of 3.51 mg·g−1. The absorption data fitted well with the pseudo-second-order kinetic model and Langmuir model. The application of biochar significantly improved soil absorption capacity and slow release of NO3−-N. While higher NO3−-N concentrations had better NO3−-N supply capacity and poorer slow-release effect. Integrating nutrient supply and slow-release effect, it is recommended to control the application ratio of biochar to NO3−-N at 34–42.75 g·g−1. Although the unoptimized biochar application rate cannot be directly applied to the soil as a slow-release fertilizer carrier to meet commercial standards, biochar modification provides new possibilities for this purpose. Moreover, compared with traditional slow-release fertilizer, biochar had good stability and regeneration performance, alleviating the high cost due to the biochar price. In general, biochar still has potential and prospects as a slow-release material. This study provides support for biochar in mitigating environmental problems associated with excess N.

Techno-economic and environmental assessment of decentralized pyrolysis for crop residue management: Rice and wheat cultivation system in India

The current study evaluates a decentralized biorefinery's economic and environmental performance, which uses two-step pyrolysis for converting rice and wheat straw to bio-oil and biochar. The biorefinery was located in Punjab (India), where open burning of residue is prevalent. The decentralized biorefinery was evaluated regarding the energy required for pyrolysis, product yield and applications, and global warming potential (GWP). Pyrolysis of unwashed, water-washed, and acid-washed straws was performed. The net GWP for pyrolysis of unwashed rice straw was −121 kg CO2eq/ton when biochar was used as a carbon sink. But pyrolysis of water-washed (159 kg CO2eq/ton) and acid-washed rice straw (311 kg CO2eq/ton) was a net contributor to GWP, which was undesirable. Similar trends were observed for wheat straw pyrolysis.The GWP of washed rice and wheat straw pyrolysis was higher than unwashed straw because 37–50% biochar generated was used for drying the washed straw, leaving less biochar for further application. Amongst the biochar applications considered, its use as a carbon sink offered more GWP reduction than its use as a substitute for coal in power and heat generation. The net GWP for direct transfer of residues to a centralized refinery for pyrolysis was −75 kg CO2eq/ton for rice straw and −384 kg CO2eq/ton for wheat straw. Therefore, it was environmentally beneficial to treat biomass locally rather than in a centralized unit. Finally, the minimum selling price for biochar was calculated to be 172–623 USD/ton, which was within the range of commercial biochar price. Therefore, the proposed biorefinery was expected to be environmentally and economically viable with an appropriate selection of pretreatment options and end-uses of the products.

Effects of Biochar on Biointensive Horticultural Crops and Its Economic Viability in the Mediterranean Climate

The effects of biochar on different horticultural crops (lettuce, tomato, sweet pepper, and radish) were evaluated in the Mediterranean climate. Biochar was produced by pyrolysis of Pinus pinaster wood chips at 550 °C and used at 1 (B1) and 2 (B2) kg/m2 application rates on six 3.5 m2 plots in each treatment, with two control plots (B0). No fertilizer was used. Treatment B1 led to a significant increase (p < 0.01) of 35.4%, 98.1%, 28.4%, and 35.2% in the mean fresh weight of radishes, lettuce, tomatoes, and sweet peppers, respectively. Treatment B2 resulted in an improvement of 70.7% in radishes, 126.1% in lettuce, 38.4% in tomatoes, and 95.0% in sweet peppers (p < 0.01). Significant differences between treatments B1 and B2 were observed in the radish, tomato, and sweet pepper crops but not in lettuce. The profitability of biochar application to these crops was studied by considering a biochar price of 800 EUR/t and applying a CO2 fixation subsidy, assuming the updated February 2022 price (90 EUR/t). In lettuce, tomato, and sweet pepper crops, the investment payback period was approximately one year. Application of biochar generated economic benefit either from the first harvest or in the second year. In radish, this period was longer than two years; however, an increase in the annual frequency of cultivation should be studied to optimize the benefit. The dose that provided the greatest benefit was B1 (for all crops, except for sweet pepper). Biochar considerably improved fruit and vegetable yield under the Mediterranean climate; however, further studies are needed to assess the effects of biochar on soil properties and yield to estimate long-term environmental and economic benefits.

Life cycle assessment of sewage sludge pretreatment for biogas production: From laboratory tests to full-scale applicability

In this work, different pretreatment technologies (low temperature thermal treatment, ultrasonication, alkali treatment, combined alkali-thermal treatment, icing-thawing) were investigated together with biochar addition to increase biogas yield from sewage sludge. The aim of the work was to develop a standardized protocol, including physicochemical characterization, biochemical methane potential (BMP) tests, digestate characterization, life cycle assessment (LCA) and economic analysis, to verify the techno-economic suitability and the related environmental impacts of upgrading conventional full-scale anaerobic digesters. Low-temperature (65–85 °C) thermal pretreatment showed the best performances in enhancing sludge solubilization and methane yield (up to 110%), followed by ultrasonication (up to 53%) and biochar addition (about 16%). The solubilization rate obtained after each pretreatment was similar for municipal and industrial sludge; however, it did not correspond to a proportional increase in methane yield. LCA showed that ultrasonication led to the worst environmental impacts at laboratory scale, due to the huge electricity request; however, at full-scale conditions, green-house gases (GHG) emissions could be reduced by 22%, fossil depletion by 25% and stratospheric ozone depletion by 18%, when compared to the baseline scenario (raw sludge anaerobic digestion). The economic analysis proved that the high ultrasonication capital costs could not be recovered in the considered timeframe (15 yr), while biochar price should be significantly lowered (down to 6.5 €/ton) to give an overall positive outcome. Finally, the thermal scenario would be convenient only when considering waste heat recovery. The proposed protocol, including physicochemical sludge characterization, BMP tests, digestate characterization, LCA and economic analysis, could be extended to other existing digesters to compare alternative pretreatment strategies, enhancing renewable energy generation in biogas form.

Techno-economic analysis of a grape pomace biorefinery: Production of seed oil, polyphenols, and biochar

Processing grape pomace (GP), a major waste from the wine industry, into multiple value-added products based on the biorefinery concept has a potential to reduce waste disposal and promote a sustainable bioeconomy. However, its economic feasibility at a commercial scale remains unknown. The present study aims to evaluate the economics of a biorefinery process of GP, by performing comparative techno-economic analysis of three processing scenarios: (1) a whole biorefinery process that fully utilizes GP biomass and produces grape seed oil, polyphenols, and biochar (GSO+GSKP+GB), (2) a process that produces grape seed oil and polyphenols (GSO+GSKP), and (3) a process that produces only grape seed oil (GSO). A plant capacity of about 33,000 metric tons/year was considered in the analysis. Among the three scenarios, the whole biorefinery process (GSO+GSKP+GB) showed the highest economic performance with the net present value (NPV), internal rate of return (IRR), and payback period of 111.7 million US-$, 34.3%, and 2.5 years, respectively, due to the diverse revenues and minimized waste disposal cost. The GSO plant showed the lowest economic performance with a negative NPV. Sensitivity analysis revealed that plant capacity, polyphenol price, polyphenol concentration (percentage) in grape pomace, and biochar price had dominating influences on the economic performance of the biorefinery process.

A comparative techno-economic assessment of biochar production from different residue streams using conventional and microwave pyrolysis

A comparative techno-economic assessment and Monte Carlo risk analysis is performed on large scale (3 tonne/h) biochar production plants for conventional (CPS) and microwave (MWP) pyrolysis using six different residue streams. Both plants are viable with minimum selling prices between € 436/tonne and € 863/tonne for CPS, and between € 564/tonne and € 979/tonne for MWP. The CPS is therefore more viable than MWP as it is a simpler and more established technology. However, a 20% biochar price increase due to higher biochar quality makes the MWP technology more viable. Nevertheless, the discounted payback period remains higher than this of CPS due to the increased CAPEX. Biochar price is the most important determinant of a biochar production plant’s feasibility, motivating the need for economic and market research on biochar prices in function of biochar characteristics to reduce fluctuations in widely varying biochar prices.

Retrofitting Municipal Wastewater Treatment Facilities toward a Greener and Circular Economy by Virtue of Resource Recovery: Techno-Economic Analysis and Life Cycle Assessment

A promising route to transition wastewater treatment facilities (WWTFs) from energy-consuming to net energy-positive is to retrofit existing facilities with process modifications, residual biosolid upcycling, and effluent thermal energy recovery. This study assesses the economics and life cycle environmental impacts of three proposed retrofits of WWTFs that consider thermochemical conversion technologies, namely, hydrothermal liquefaction, slow pyrolysis, and fast pyrolysis, along with advanced bioreactors. The results are in turn compared to the reference design, showing the retrofitting design with hydrothermal liquefaction, and an up-flow anaerobic sludge blanket has the highest net present value (NPV) of $177.36MM over a 20-year plant lifetime despite 15% higher annual production costs than the reference design. According to the ReCiPe method, chlorination is identified as the major contributor for most impact categories in all cases. There are several uncertainties embedded in the techno-economic analysis and life cycle assessment, including the discount rate, capital investment, sewer rate, and prices of main products; among which, the price of biochar presents the widest variation from $50 to $1900/t. Sensitivity analyses reveal that the variation of discount rates causes the most significant changes in NPVs. The impact of the biochar price is more pronounced in the slow pyrolysis-based pathway compared to the fast pyrolysis since biochar is the main product of slow pyrolysis.

Techno-economic Feasibility of Thermochemical Conversion Pathways for Regional Agricultural Waste Biomass

This study examines four prominent thermochemical conversion technologies such as slow pyrolysis (SP), fast pyrolysis (FP), gasification (GA) and hydrothermal liquefaction (HTL), for treating poultry litter in New York State (NYS). Nine cases involving various combinations of the four technologies and different downstream processing options such as bio-oil upgrading, Fischer-Tropsch conversion and combined heat and power generation are chosen based on the product composition and distribution. High-fidelity process simulations for each technological platform are performed to derive the mass and energy balance information. Calculations and breakdown of the equipment costs, capital costs, operating and maintenance costs and utilities are provided and compared extensively for each of the nine cases. The economic performance is further analyzed by calculating and comparing the resultant net present values (NPV), ranging from $10 M to $170 M (SP), $89 M to $314.5 M (FP), $28 M to $196 M (HTL) and $25 M to $234 M (GA). The greenhouse gas emission inventories are also compiled to understand the corresponding impacts of different downstream processing choices (ranging from 217 to 494.5 kg CO2-eq/t feedstock with both the pyrolysis technologies outperforming the others in most cases) and to highlight the trade-off with economic performance. Through sensitivity analysis, the influential factors requiring further investigation are identified and it is found that plant capacity and bio-oil yield are the most important parameters for the fast pyrolysis systems, biochar price for SP is the single most important parameter.

Thermoeconomic analysis of integrated production of biochar and process heat from quinoa and lupin residual biomass

Quinoa and lupin are emergent sectors recognized as major promoters of social and economic development in the producer indigenous communities of Ecuador. The associated industrial process requires thermal energy typically produced using subsidized diesel or LPG. This analysis shows that 37.7% of the fuel costs of the analyzed industries are covered by the government in the form of subsidies. Hence, a major risk could be induced into this sector under a subsidy removal scenario. On this regard, the residual biomass generated during quinoa and lupin threshing represents an opportunity for the combined production of biochar for soil amendment and heat as an alternative to replace fossil fuels in the agro-industry sector. This analysis shows that the heat produced during the carbonization of the residual biomass from threshing exceeds the thermal energy required for saponins removal. A positive cash flow was verified in all the considered scenarios. However, the economic performance of the energy system is strongly related to the biochar price rather than the income in result of CO2 emissions trading and fuel costs savings. Furthermore, the current tax incentive represents a subsidy of 39.2% of the initial investment costs to implement a valorization infrastructure.

Techno-economic and greenhouse gas savings assessment of decentralized biomass gasification for electrifying the rural areas of Indonesia

This study explored the feasibility of decentralized gasification of oil palm biomass in Indonesia to relieve its over-dependence on fossil fuel-based power generation and facilitate the electrification of its rural areas. The techno-feasibility of the gasification of oil palm biomass was first evaluated by reviewing existing literature. Subsequently, two scenarios (V1 and V2, and M1 and M2) were proposed regarding the use cases of the village and mill, respectively. The capacity of the gasification systems in the V1 and M1 scenarios are determined by the total amount of oil palm biomass available in the village and mill, respectively. The capacity of the gasification systems in the V2 and M2 scenarios is determined by the respective electricity demand of the village and mill. The global warming impact and economic feasibility (net present value (NPV) and levelized cost of electricity (LCOE)) of the proposed systems were compared with that of the current practices (diesel generator for the village use case and biomass boiler combustion for the mill use case) using life cycle assessment (LCA) and cost-benefit analysis (CBA). Under the current daily demand per household (0.4 kWh), deploying the V2 system in 104 villages with 500 households each could save up to 17.9 thousand tons of CO2-eq per year compared to the current diesel-based practice. If the electricity could be fed into the national grid, the M1 system with 100% capacity factor could provide yearly GHG emissions mitigation of 5.8 × 104 ton CO2-eq, relative to the current boiler combustion-based reference scenario. M1 had a positive mean NPV if the electricity could be fed into the national grid, while M2 had a positive mean NPV at the biochar price of 500 USD/ton. Under the current electricity tariff (ET) (0.11 kWh) and the biochar price of 2650 USD/ton, daily household demands of 2 and 1.8 kWh were required to reach the break-even point of the mean NPV for the V2 system for the cases of 300 and 500 households, respectively. The average LCOE of V2 is approximately one-fourth that of the reference scenario, while the average LCOE of V1 is larger than that of the reference scenario. The average LCOE of M1 decreased to around 0.06 USD/kWh for the case of a 100% capacity factor. Sensitivity analysis showed that the capital cost of gasification system and its overall electrical efficiency had the most significant effects on the NPV. Finally, practical system deployment was discussed, with consideration of policy formulation and fiscal incentives.

Glory and misery of biochar

Biochar refers to carbon-based dusty residues obtained from biomass pyrolysis. This recently rediscovered traditional soil improver is currently being glorified for its wide portfolio of favorable environmental aspects. With its lifetime of several centuries, it is being widely accepted as a promising method of carbon sequestration. Moreover, it has been demonstrated that biochar can reduce bioavailability of some heavy metals and that it has a high adsorption capacity to persistent organic pollutants. These effects are explained by a complex of physical, chemical and biological mechanisms. Besides agriculture, it has been currently used in food and chemical industries, as well as in the building industry. Many other promising applications are under investigation. However, contrary to many enthusiastic proclamations, no revolution in agriculture or environmental management is taking place. Despite significant achievements in reduction of biochar production costs, high demand from the industry and energy sector keeps the biochar price still high, which prevents a return of the ancient farming practice on a commercial scale.

The economic impact of biochar use in Central Europe

ABSTRACT Over the last two decades, it has been repeatedly stated that biochar might sequester gigatons of carbon from the atmosphere, reduce greenhouse gases, reverse soil degradation, etc. Most of the submitted environmental, societal, and ethical arguments originated in laboratories and were based on pot experiments, small-scale field trials, and mathematical models. Huge amounts of public money were subsequently invested worldwide into efforts to achieve the outlined ambitious goals. In reality, however, the rise of biochar has failed to materialize anywhere. Doubts have therefore been raised about the feasibility of the vision for biochar. This article assesses the first results obtained from a commercial scale project in Central Europe. The success seems to be dependent on reduction of the biochar price.

Financial Performance of a Mobile Pyrolysis System Used to Produce Biochar from Sawmill Residues

Abstract Primary wood products manufacturers generate significant amounts of woody biomass residues that can be used as feedstocks for distributed-scale thermochemical conversion systems that produce valuable bioenergy and bioproducts. However, private investment in these technologies is driven primarily by financial performance, which is often unknown for new technologies with limited industrial deployment. In this paper, we use shift-level production data collected during a 25-day field study to characterize the conversion rate and system productivity and costs for a commercially available pyrolysis system co-located at a sawmill, and then evaluate the net present value (NPV) of the operation in light of a cost structure that is realistic for the industry. Baseline costs on a feedstock throughput basis were estimated as $16.41 t−1 for feedstock preparation, $308.14 t−1 for conversion, and $65.99 t−1 for biochar bagging. The NPV estimated for the worst-case scenario of observed productivity and conversion rate was −$536,031 for a 10-year project period, while the best case scenario generated an NPV of $467,353. In general, NPV is highly sensitive to labor costs and biochar price, and less sensitive to fuel cost and interest rate. Results also show clear opportunities for technical and operational improvements that are expected to increase the financial viability of this system.

An economic analysis of biochar production using residues from Eucalypt plantations

Producing biochar from organic residues is a potential method to integrate carbon sequestration and residue management costs while enhancing conventional agricultural and forestry production systems. Plantation forestry is an important industry in Tasmania, and is based on large scale plantations of Pinus radiata and Eucalyptus (Eucalyptus globulus and E. nitens). The area covered by forestry plantations in Tasmania (on State land) exceeds 100 000 ha, while plantations on private land double this number. Eucalypt plantations are managed primarily for the production of high-value pruned logs for industry; however, unpruned saw logs, peelers, poles, posts and pulp are also produced, and significant quantities of residue are produced as a byproduct. This study was an economic analysis that considered on-site biochar production system using post-harvest forestry residues, with biochar being utilized within the system, or sold as a product. The financial analysis was based on previous experimental outcomes on the use of Macadamia shell biochar in Eucalyptus nitens plantations, and the local operating environment in Tasmania; including current forestry procedures used for managing plantations. A number of assumptions were considered concerning a) production costs, b) savings enjoyed by traditional operations, following biochar scenario implementation, and c) biochar sales. The analysis revealed a potential annual income of over 179 k$ (2014 value) and the sensitivity analysis identified the crucial factors responsible for scenario profitability, namely biochar price and final product distribution.

Techno-economic assessment of biomass slow pyrolysis into different biochar and methanol concepts

Methanol is one of the fuels that are an alternative to petroleum-based liquid transport fuels. This paper assesses the feasibility of co-production of methanol and biochar from thermal treatment of pine in a two-stage process; pyrolysis or gasification to produce biochar and volatiles, and the processing of the volatiles to produce methanol using process data for large-scale conversions based on natural gas. Three concepts were studied: (i) slow pyrolysis at 300°C; (ii) slow pyrolysis at 450°C; and (iii) gasification at 800°C, all of them followed by processing of the volatiles into syngas and the conversion of the syngas into methanol. Gasification was able to generate methanol at or below current (2012) prices of methanol produced from fossil fuel ($422/t) from a plant size of 100t/h upwards. Pyrolysis is not competitive without valuing the biochar as a product. Considering both biochar and methanol as marketable products improves the viability of slow pyrolysis concepts. Their profitability is sensitive to the biochar selling price between, with a break-even at a biochar price of about $220/t for the pyrolysis at 300°C and about $280/t for pyrolysis at 450°C.