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This paper evaluates the environmental impacts of different alternatives for handling of sludge from paper and pulp mills in Sweden, using Life Cycle Assessment (LCA). The common practice of incineration of biosludge with energy recovery followed by landfilling of ash (System A) was compared with the alternative of digesting sludge anaerobically to produce biogas using different digestate residue management options. The digestate produced from anaerobic digestion (AD) was assumed to be incinerated for heat energy recovery in System B or pyrolyzed for biochar production in System C to be mixed with forest soils. The impact categories considered in this work are climate change, non-renewable energy use, mineral extraction, aquatic ecotoxicity, carcinogens and non-carcinogens. The LCA results demonstrate that the two proposed systems significantly reduce the environmental impacts of biosludge management relative to incineration. An 85% reduction in the aquatic ecotoxicity impact is achieved in System C, due to the reduced mobility of heavy metals in biochar relative to ash. System C, on the whole, outperformed the other two, leading the authors to the recommendation that the use of pulp and paper mill biosludge in biogas-biochar production systems is preferable to merely recovering energy from it.

The paper drying process has the highest level of energy consumption in the pulp and paper production process. Analysis and optimization of the energy system during the paper drying process is critical for improving the energy efficiency of the entire paper mill. In the existing model for the paper drying process, the solution requires accurate boundary conditions such as the air temperature and humidity of the pocket area and the cylinder surface temperature, which are very difficult to obtain in the papermaking process. This can result in significant deviations between the model solution and the actual production process. This paper focuses on the single-tier dryer cylinder-based paper drying process that has been widely used with high-speed papermaking machines in recent years. A mathematical model is proposed based on real-time data. The verification via industrial production demonstrates that the proposed model is reliable for the paper drying process. Based on the simulation results, two optimization operations have been proposed. The energy consumption decreases from 1.51 t steam/t paper to 1.44 t steam/t paper, 4.6% of the steam and 1.26 × 106 RMB can be saved for a medium-scale paper mill with the annual production capacity of 105 t paper.

This study aims at to make a heuristic analysis of energy efficiency performance of Indian paper industry in a non-parametric production theoretic approach. Using the data for 2004–05 to 2013–14, radial and non-radial variants of DEA were employed to estimate energy saving potential and identify the relative position of paper industry across the states. Preliminary analysis in terms of energy intensity scores showed declining trends of energy intensity over the period of analysis for most of the states except states like Assam, Chhattisgarh, Kerala and Punjab where it does not decline much. Assuming a variable returns to scale (VRS) technology under the conditions of inherent heterogeneity and market imperfection, the slack-based measure (SBM) reported a much higher energy saving potential than reported by other measures in the study. Further by taking scale efficiency into account, the study documented the higher contribution of pure energy inefficiency in explaining the total energy inefficiency within the paper industry relative to scale inefficiency. Finally, the study recommends the propagation of energy efficiency program through a market-based and regulatory mechanism along with consolidation and technological advancement of individual units, in order to tap vast energy saving potential and thereby ensure the growth and environmental sustainability.

A kind of wood pulp fiber paper (WPFP) was proposed as candidate for the matrix of desiccant wheel. Silica gel was coated on WPFP by impregnation method and the corresponding coating ratio was obtained and analyzed. Then the thermal conductivity, pore structure and adsorption/desorption performances of WPFP coated with silica gel were tested and analyzed. The results indicated that the WPFP has high coating ratio for silica gel due to its hydrophilic characteristic. The thermal conductivity of WPFP coated with silica gel after the first coating increases obviously compared with raw WPFP and reaches to 0.1292 W/(m⋅K). In addition, the WPFP coated with silica gel after the first coating has high specific surface area and its maximal adsorption quantity for water vapor can be 0.240 g/g. Finally, the DCOP of the desiccant wheel using WPFP as matrix obtained by numerical simulation can be 1.75 under the given working condition that the temperature of regeneration air is set as 90 °C and the inlet condition of process air is set as 34.3 °C and 56.2% RH. It is indicated that the desiccant wheel using WPFP as matrix can meet the requirement of air dehumidification and save energy by 7.35% simultaneously.

Bio-oil and pyrolysis gas (py-gas) are two pyrolysis products available for potential energy recovery. Crude bio-oil, however, is typically corrosive and unstable, requiring special combustion equipment or catalytic upgrading to produce drop-in-grade fuel. In contrast, py-gas is readily useable in standard equipment for energy recovery. Previous research revealed that Ca-impregnated biochar catalyst improved bio-oil to py-gas conversion. Biochar produced from paper mill sludge (p-sludge) has very high Ca content. In this study, the catalytic ability of p-sludge biochar was systematically evaluated for the first time in pyrolysis. P-sludge biochar resulted in higher py-gas yield (40 wt% of total pyrolysis products) and py-gas energy (8400 kJ of py-gas per biosolids pyrolyzed) than other biochar catalysts (e.g. wood and corn stover biochars) and mineral catalysts (e.g. calcined dolomite). Under some conditions (e.g. high temperature and catalyst loading), catalysis completely eliminated the nonaqueous phase condensate. A lower catalyst-to-feedstock ratio was required using p-sludge biochar compared to other biochars for similar performance. P-sludge biochar also had a longer catalyst lifetime based on the effectiveness over five reuse cycles. Bio-oil catalyzed by p-sludge biochar contained fewer organic constituents based on GC-MS and GC-FID analyses (e.g. toluene, ethylbenzene, styrene, phenol, cresol, and indole were not identified after catalysis).

The present study investigates the effect on methane production from waste paper when co-digested with macroalgal biomass. Both feedstocks were previously mechanically pretreated to reduce their particle size. The study was planned according two factors: the feedstock to inoculum (F/I) ratio and the waste paper to macroalgae (WP/MA) ratio. The F/I ratios checked were 0.2, 0.3 and 0.4 and the WP/MA ratios were 0:100, 25:75, 50:50, 75:25 and 100:0. The highest methane yield (386 L kg−1 VSadded) was achieved at an F/I ratio of 0.2 and a WP/MA ratio of 50:50. A biodegradability index of 0.87 obtained in this study indicates complete conversion of feedstock at an optimum C/N ratio of 26. Synergistic effect was found for WP/MA 25:75, 50:50 and 75:25 mixing ratios compared with the substrates mono-digestion.

The Swedish pulp and paper industry (PPI) must increase energy efficiency to remain competitive on the global market, which has experienced entries from countries with cheaper energy and raw material supplies. Interactions among variables for energy use, production, energy management, electricity price and firm characteristics (FC), in different types of mills, i.e., pulp, paper and integrated mills, in Sweden from 2006 to 2015 indicate that correlations among the studied variables were different in different types of mills. This difference between types of mills seemed to originate partly from varying accessibility to production residue that could be used for energy. For all types of mills, variation of electricity prices did not correlate significantly with energy efficiency during the study period. The studied FC were firm's age, number of employees, number of companies in company group, net sales and profit for the year. Energy efficiency was more affected by the variables characterizing energy and production compared to the variables representing FC. This study also suggested presence of possible discrepancies between FC that were perceived as barriers to energy management towards energy efficiency, according to previous studies, and what was shown by the data combining variables representing energy use, production and FC.

In this paper an original and exhaustive mathematical modelling of air impingement drying systems for the production of tissue paper in the Yankee-hoods configurations is reported, which offers the possibility to optimize its energy performance. The model takes into account many detailed operative parameters of the overall drying process with the aim to execute its energy and mass balance and to evaluate its energy performances. The validity of the mathematical model has been assessed by comparison with actual data from an existing tissue paper mill. Finally, the energy performances of two different layouts of the air system have been evaluated and compared. Changing the operative parameters of the drying process, such as air jet temperature and speed and moisture content of the extraction air, it is possible to obtain the same paper production with an energy saving of about 4.5%. In average, the layout with two parallel air circuits assure an energy saving of about 1% with respect to the layout with a single air circuit.

The effects of five commercially available hydrolytic enzyme additives on methane yields from dehydrated paper pulp sludge (DPPS) were determined in 5L pilot-scale reactors operated in semi-continuous mode for 60 days. Methane production was 40% and 43% higher in reactors receiving Novozymes and Novalin additives, respectively, compared to controls. Effects of time of DPPS inclusion on bacterial and archaeal microbial communities were many times larger than effects of enzyme type as enzyme addition did not produce rearrangements larger than random fluctuations observed in reactors receiving only DPPS. The ratio between volatile organic acids and alkalinity signified progressive decrease in process stability until day 45 irrespective of enzyme supplementation. Complementation with clarified pig slurry (1.5% vol.) for subsequent 15 days effectively stabilized process parameters and was sufficient for microbial communities to maintain DPPS hydrolytic capacity and process additional carbon flow derived from hydrolytic activity of enzyme additives. Consequently, initially unadapted full-scale biogas plant inoculum was capable of significantly increased methane yields from DPPS. Based on annual DPPS availability in EU the potential for additional energy recovery was estimated to be in the range of nearly 1 TJ.

In order to explore hydrothermal carbonization (HTC) behavior of municipal solid wastes (MSW), four typical components, waste textile, wood, paper and food, were employed to perform HTC and co-HTC process. The experiments were conducted at 240 ○C and 90 min with a 1:12 solid/liquid ratio, where blending ratios of 1:3, 1:1 and 3:1 with waste textile were investigated. As expected, the increase of fixed carbon and carbon content improved the fuel potential of hydrochar. The synergistic index (SI) analysis clearly indicated that significant synergistic effects occurred during co-HTC process. Specifically, all the SI values of hydrochar yield from co-HTC of waste textile with wood and paper were negative, while all SI values of hydrochar yield for waste textile with food were positive. Particularly, the SI values of fuel ratio for all hydrochars were positive which suggested co-HTC could promote to enhance the coalification degree of hydrochars. However, the undesirable increment of O content for hydrochars (derived from 75%waste textile-25% waste food and 50%waste textile-50% waste food) decreased the high heating value. The combustion behavior and nth-order kinetic model analysis showed that hydrochars derived from co-HTC rendered a more stable and lasting combustion profile.

In this study, the methane production potential of paper industry waste sludge (PPWS) was investigated using consortium of hydrolytic enzymes (CHE) mediated poly3hydroxybutyrate (P3HB) method. Initially, P3HB was extracted from municipal aerated waste sludge (MARWS) by optimizing extraction time and dimethyl carbonate dosage. Maximum of P3HB (910 mg/g) was extracted at 60 min of extraction time and 4 mL of dimethyl carbonate dosage. Then, the influence of extracted P3HB dosage (5–120 mg) on methane production from PPWS was examined. 75 mg of P3HB dosage was exhibited higher methane production (153 mL/g VS) when compared to other P3HB dosage. Further, CHE mediated pretreatment was performed by varying CHE dosage and temperature. At optimized CHE dosage (2.5 mL) and temperature (45 °C), maximum of chemical oxygen demand (COD) liquefaction, suspended solids reduction (SSR) and lignin removal were found respectively to be 23.7%, 18% and 61% which was higher than control (COD liquefaction (0.9%), SSR (0.5%) and lignin removal (0.7%)). Also, biomethane potential assay was carried out in which CHE mediated P3HB method attained higher methane production (280 mL/g VS) when compared to CHE method (217 mL/g VS) and control (47 mL/g VS).

Production of transportation fuels from biorefineries via biomass gasification has been suggested as a way of introducing renewable alternatives in the transportation system with an aim to reduce greenhouse gas emissions to the atmosphere. By co-locating gasification-based processes within heat demanding industries, excess heat from the gasification process can replace fossil or renewable fuels. The objective of this study was to compare the heat integration potential of four different gasification-based biorefinery concepts with a chemical pulp and paper mill. The results showed that the choice of end product which was either methanol, Fischer-Tropsch crude, synthetic natural gas or electricity, can have significant impact on the heat integration potential with a pulp and paper mill and that the heat saving measures implemented in the mill in connection to integration of a gasification process can increase the biomass resource efficiency by up to 3%-points. Heat saving measures can reduce the necessary biomass input to the biorefinery by 50% if the sizing constraint is to replace the bark boiler with excess heat from the biorefinery. A large integrated gasification process with excess steam utilisation in a condensing turbine was beneficial only if grid electricity is produced at below 30% electrical efficiency.

This paper presents a comparison between four gasification-based biorefineries integrated with a pulp and paper mill. It is a continuation of 'Transportation fuel production from gasified biomass integrated with a pulp and paper mill - Part A: Heat integration and system performance'. Synthesis into methanol, Fischer-Tropsch crude or synthetic natural gas, or electricity generation in a gas turbine combined cycle, were evaluated. The concepts were assessed in terms of GHG (greenhouse gas) emissions and economic performance. Net annual profits were positive for all biofuel cases for an annuity factor of 0.1 in the year 2030; however, the results are sensitive to biofuel selling prices and CO2,eq charge. Additionally, GHG emissions from grid electricity are highly influential on the results since all biofuel processes require external power. Credits for stored CO2 might be necessary for processes to be competitive, i.e. storage of separated CO2 from the syngas conditioning has an important role to play. Without CO2 storage, the gas turbine case is better than, or equal to, biofuels regarding GHG emissions. Efficiency measures at the host mill prior to heat integration of a gasification process are beneficial from the perspective of GHG emissions, while having a negative impact on the economy.

Paper mill sludge (PMS) can be efficiently utilized to produce fuels and chemicals. However, wastewater is usually generated during the de-ashing step of the PMS for fibrous materials recovery. Per process requirements, the wastewater stream must be treated which results in an increase in the overall process production cost. Therefore, this research aims at reusing the wastewater produced during the de-ashing step as a substitute for freshwater addition during the conversion of PMS into ethanol. The advantages of this approach include reducing the amount of wastewater produced and enhancing the overall efficiency of the process. It will contribute to the circular economy of zero waste discharges. The results showed that 30% of the process wastewater can be recycled without affecting the enzymatic hydrolysis and ethanol fermentation. Hence, the amount of wastewater that needs to be treated is reduced by 30% resulting in a cost reduction of 22.5%. The results also showed that wastewater recycling minimized the energy demands in the distillation and evaporation units by 1206 kJ/kg. The energy reduction is due to the increase of metals and total soluble solids in the broth stream after fermentation. This process configuration enhanced the process economy, saved energy and managed waste streams.

In this study, through orthogonal experiments design, the influences of ultrasonic pretreatment (frequency, power and treatment time) on co-pyrolysis and catalytic pyrolysis of municipal solid waste and paper mill sludge were explored. The differential thermogravimetry curves became steeper and the peak values were larger after pretreatment, which made the pyrolysis reaction rapidly and the volatile separated out timely. However, the change of pyrolysis characteristics was not obvious after adding MgO. The catalytic effect of MgO increased with the increase of sludge ratio. After pretreatment, the average activation energy of the samples had an overall increasing trend, but the change was small. MgO had a decreasing effect on activation energy, and with the increasing proportion of sludge the degree of reduction became significant. In addition, high ultrasonic frequency had a negative effect on reducing activation energy.

The preparation and application of heteroatom doped carbons have attracted lots of attention in the past years. In the current work, a facile synthesis of nitrogen doped carbon with filter paper as the carbon source and urea as the nitrogen source was presented. Filter paper was first impregnated with urea solution, and was then carbonized and activated. The carbons’ physical and chemical properties were studied. For the application in CO2 adsorption, impacts from porous characteristics and nitrogen doping were discussed and differentiated. The results suggested that nitrogen doping was beneficial to the improvement of CO2 uptake, but suitable porous properties were the most important factors. Nitrogen doping showed more significant effects on enhancing the adsorption heat and selectivity. The research of carbonaceous CO2 adsorbent should focus on nitrogen doped carbons with high porosity.

Accurate understanding of the marginal energy-saving costs of energy-using entities is critical for regulatory authorities to formulate and implement energy-saving policies. This article brings out an easy-to-operate analytical framework to measure the marginal energy-saving cost and construct energy conservation supply curve with the help of data envelopment analysis and quantitative model. Furthermore, taking China’s pulp and paper industry as an example, the authors discuss the difference of economic costs between industry energy-saving task assignment with and without considering the difference of marginal energy-saving costs of different energy using entities with the help of linear programming model. The main empirical results are as follow. First, there is a big difference in the industrial marginal energy-saving costs in different provinces. The difference between the highest and lowest energy-saving costs is twice as large. Second, the optimal energy-saving task assignment based on an accurate energy conservation supply curve can help to save nearly 35% of total economic cost.

This study investigates heat integrated production of FT (Fischer-Tropsch) crude, where excess heat from the FT crude plant is delivered to a typical Scandinavian pulp and paper mill that produces fine paper. The sizes of FT crude plants are quantified, when the amount of excess heat from the FT plant exactly matches the heating demand otherwise satisfied by the bark boiler at the mill, considering a number of development pathways at the mill, including various degrees of steam savings and biorefinery options, such as lignin extraction. Performance of integrated production is compared with that of an FT stand-alone plant on the basis of wood fuel-to-FT crude efficiency, GHG (greenhouse gas) emissions balances and FT crude production cost. The results show that there exists a heat integration opportunity for an FT crude plant ranging from 0 up to 350 MW (LHV) of wood fuel depending on the development pathway for the mill. The results indicate higher overall efficiency and a generally lower production cost for the heat integrated, co-located production. Heat integrated production has a larger potential to contribute to GHG emission mitigation, assuming a future generation of grid electricity emitting equal to or less than an NGCC (natural gas combined cycle) power plant. © 2013 Elsevier Ltd. All rights reserved.

The waste biomass has immense opportunities and plenty of potentials to be an efficient source of renewable energy. Initially, native unripe coconut husk (NCH) was used as raw material for fluidized bed gasification. Then NCH was treated with paper and pulp waste water to impregnate metals present in it for getting enhanced H2 yield in fuel gas. Humidified air was used as gasifying medium, which served the purpose of introducing water vapour to take part in the gasification process. Then after, gasification medium was retrofitted with CO2, which enhanced both the higher heating value (HHV), and CO and H2 content in the fuel gas. This research serves the dual benefit of energy generation and waste minimization. HHV of unripe coconut husk was investigated and found to be 20.95 MJ/kg. H2 yield and HHV from impregnated coconut husk (ICH) were obtained as 55.55 vol % and 5.24 MJ/Nm3, respectively at HER 0.1 and gasification temperature of 850 °C in case of fluidized bed gasification. The GC-MS analysis of fuel oil obtained from ICH gasification was done to get the information about high yield of fuel gas as promise product of fluidized bed gasification.

The objective of this paper is to estimate the energy saving potential in China's paper industry by determining energy intensity under different scenarios. Cointegration model and stability test are applied to formulate the equilibrium equation. Results show that energy price, industry structure, profit margin and technology have significant impact as they are negatively correlated to changes in energy intensity. Three scenarios (BAU (business as usual), intermediate and active) are designed to estimate the future trend of energy intensity in paper industry. In 2010, the energy intensity (energy consumption per unit of value added) was 4 tce/10,000 RMB, and by the scenarios it is expected to considerably decline. According to the BAU (business as usual) scenario, the energy intensity will decrease to 2.56, 1.43 and 0.70 tce/10,000 RMB by 2015, 2020 and 2025, respectively. With respect to the intermediate scenario it is expected to drop further to 0.44 tce/10,000 RMB. Yet by the active scenario, the energy intensity is expected to considerably decline to 0.36 tce/10,000 RMB by 2025. Using the BAU forecast as a baseline, the quantity of energy savings is estimated to be 185.6 billion tce by 2025. Considering this important potential, we also provided some policy suggestions.

The generated gas bubbles in microfluidic fuel cells (MFCs) cover the active surface area of the electrode and greatly limit the cell performance. In this study, a feasible approach is proposed to effectively accelerate bubbles removal and enhance cell performance by embedding a paper separator in the middle of the microchannel. Visualization of bubble behaviors and the corresponding electrochemical measurements are performed to investigate the effect of bubbles on the cell performance. Periodical process of the bubble growth and removal leads to the fluctuation in the current density of the MFC. The rapid gas removal and the low ohmic resistance are observed after embedding a layer of filter paper in the microchannel, causing improved fuel transfer and smaller ohmic loss. Although the current density fluctuates more frequently, the fluctuation amplitude decreases and the cell performance is enhanced. Compared with the MFC without paper separator, the maximum power density and the limiting current density of the MFC with paper separator is increased by 25.2% and 130%, respectively. Moreover, the cell performance is improved with increasing the flow rate of reactant solution and the peak power density achieves 25.9 mW cm−2 under flow rate of 1500 μL min−1.

In this study, a pulp and paper mill (PPM) in the SEKA Papermaking Plant in Izmit, Turkey, is analysed through energy and exergy balances. The plant utilises recycled waste paper for papermaking. This type of raw material input makes the process highly sophisticated. The pulping uses strictly mechanical processes, such as digestion, separation by screening and hydrocyclone, and refining. The milling, as an integrated process, provides the final operations necessary to prepare the conditions required for the end-product by stock-preparation, wiring, rolling, and drying by dewatering, pressing, and evaporation. The possibility of making the entire process more thermodynamically efficient is discussed by calculating the energy and exergy losses for all the mechanical and physical sub-processes. The study shows that the energy efficiencies for each of the mechanical and physical steps in the PPM vary between 34% and 97.4%, whereas the exergy efficiencies vary between 30.2% and 94.2%. In conclusion, based on the results from the energy and exergy flow analyses, the exergy output can be improved through more efforts directed primarily to further measurements toward more efficient energy utilisation in the PPM.

In this work, an analysis of co-pyrolysis municipal solid waste and paper sludge with additive (MgO) were investigated by TG-FTIR and Py-GC/MS. The proportions of paper sludge in the blends were 10%, 30% and 50%, respectively. The pyrolysis characteristics, the yields of pollutants (CO, SO2, NO, HCl) and CO2, the products and chemical composition, the kinetic behaviors and the distribution activation energy model were investigated. After adding paper sludge, the sums of pollutants reduced, the amount of aliphatic hydrocarbons decreased and oxygenates compounds increased. After adding MgO, the results showed that the residue mass decreased, the emission of pollutants reduced, the ratio of aliphatic hydrocarbons became larger, the ratio of oxygenates compounds became smaller, and the activation energy reduced. According to the beforementioned results, the 30% percentage of paper sludge in the mixture with MgO might be the most suitable ratio for co-pyrolysis.

Thin, lightweight, stackable, solid-state supercapacitors are in great demand in the electronics industry because of their use in miniaturized devices. Herein, we report a simple and novel strategy to fabricate ultra-thin, lightweight, and stackable symmetric supercapacitors using MnO 2 -incorporated carbon nanotube (CNT)-web paper. SEM and TEM analyses revealed a uniform nanometer-scale coating of MnO 2 on the individual fibers of the CNT-web paper after simple deposition at room temperature. The network structure of free-standing conductive CNT-web paper provides a short diffusion path, allowing for complete utilization of MnO 2 in the charge storage process. A MnO 2 /CNT-web paper electrode showed an excellent areal capacitance of 135 mF cm −2 at 5 mV s −1 with a remarkable capacitance retention of 95% after 10,000 cycles. A symmetric solid-state supercapacitor containing MnO 2 /CNT-web paper displayed a high areal capacitance of 57 mF cm −2 with an energy density of 0.018 mWh cm −2 and a capacitance retention as high as 86% after 10,000 cycles. In addition, the voltage and capacitance were tripled by simply stacking three symmetric supercapacitors and connecting them in series and in parallel, respectively. We are optimistic that the excellent performance of the ultra-thin CNT-web paper-based supercapacitors demonstrated here will facilitate the development of compact supercapacitor banks in the near future.

The Scandinavian mechanical pulp and paper industry has been facing great challenges during the past decades, mainly because of declining demand for newsprint, and higher prices on raw material and energy. One way of increasing profitability is to produce more value-added products besides the production of pulp and paper. In this study, integration potentials of three possible future biomass gasification-based energy mills with an existing thermo-mechanical pulp (TMP) mill, co-located with a sawmill, have been evaluated. The product gas was utilized for electricity production in a gas turbine, for production of methanol or for production of Fischer–Tropsch (FT) liquids. Integration of the energy mills showed good potential as the TMP mill constitutes a heat sink for which the excess heat from the energy mills can be utilized all year round. However, since there is little excess heat from the TMP mill at the required level to be utilized for biomass drying, for example, heat integration is typically one way. It has also been shown that integration of biomass gasification with a TMP mill results in larger CO2 emissions reduction than stand-alone operation. Still, compared to co-firing biomass in a coal power plant, the energy mills all have lower potentials for CO2 emissions reduction.

Increasing levels of variable renewable energy require additional flexible resources in the global energy system. In countries with energy-intensive industries, flexibility may be increased through industrial demand side management (IDSM). In most studies, the potential of IDSM is estimated from a technical or theoretical viewpoint. However, IDSM capacity is only utilized if the industry finds it profitable, and thus the economic potential should also be assessed. The focus of this paper is on the intra-day IDSM potential of a paper mill site that is active in the Nordic power market. An optimization model is built to estimate the costs that occur when the paper mill executes regulating power bids, if the original production schedule has been optimized against a spot price forecast. The costs are estimated for different sizes of bids and a marginal cost curve is provided for pricing them. Using this marginal cost curve, the market potential of the case mill site is assessed. It is found that this potential is greatly influenced by the costs of executing regulating power bids. The results indicate that transmission system operators and policy makers should account for economic factors when assessing the potential of market based IDSM.

This work analyzed the energy flow of the pulp and paper industry in Taiwan. The potential technology options that were examined focus on how to capture some of the energy currently lost in the processes and then identifying the areas with energy-saving potential that could also have large impacts across a variety of industries. In addition, the energy-saving potential of these options was evaluated. The energy-saving potential of the pulp and paper industry would be around 6939.9 KLOE/M. The greatest energy-saving potential lies with improving energy distribution and equipment efficiency, which would together potentially comprise 86.8% of total energy conservation. This analysis can serve as a benchmark for current pulp and paper making operations, and as a base case for stimulating changes toward more efficient energy utilization in the pulp and paper industry.

Co-liquefaction of secondary pulp/paper-mill sludge (solids concentration: 1.6 wt%) and waste newspaper with a total solids concentration of 11.3 wt% was investigated with and without the addition of catalysts in a 75 ml Parr High-Pressure reactor at temperatures of 250–380 °C for 20 min. The yield of heavy oil (HO) without catalyst was between 16.7 and 28.0 wt% within this temperature range, and peaked at 350 °C. The addition of HCO 2 H, FeS, or KOH at 5 wt% of the total solids (on a dry basis) was found to enhance the HO yield at 300 °C, particularly HCO 2 H, which increased the yield of HO from 24.9 to 34.4 wt%. More interestingly, synergistic effects between secondary pulp/paper-mill sludge and waste newspaper were observed in the co-liquefaction operations. For example, the HO yield attained was 26.9 wt% at 300 °C in the co-liquefaction of the mixture of 33 wt% sludge and 67 wt% waste newspaper, and was noted to be 9 wt% and 6 wt% higher than the yields obtained from liquefaction of sludge and waste newspaper alone, respectively. The HOs from liquefaction or co-liquefaction at 300 °C for 20 min exhibited significantly higher energy contents (HHV ≥ 30 MJ/kg), almost doubled those (˜16 MJ/kg) of the original feedstocks.

In this paper an approach for analysing the potential for implementation of different technology pathways for the European pulp and paper industry (PPI) is presented. The approach is based on detailed technical research and aggregates the knowledge from previous studies to incorporate the whole European PPI. Thus, the potential for different technology pathways can be estimated on a European level whilst still considering important characteristics of individual mills. The usefulness of the approach was exemplified by applying it to a case study of the potential for introduction of carbon capture and storage (CCS) within the European PPI. The results from the case study show that for the European PM, CCS has an up-hill road in order to be a viable, large scale alternative for reduction of CO2 emissions. If CCS is to be introduced in large scale within the European PPI, large biomass-based point sources of CO2 emissions need to be included when planning for CCS infrastructure and also the infrastructure needs to be built out for clusters emitting

Long term annual electricity consumption forecasting is very important for country's energy planning. These forecasts are influenced by several factors (political, technological, social, environmental and economic), and brings with itself a high uncertainty degree in its results and difficulties in the evaluation of such factors over them. A methodology that eases to take into account these factors aiming improve the results and help understanding the electricity consumption annual trajectory till the forecast horizon is, therefore, very much useful and desired. So, we propose a modelling structure using the bottom-up approach to cope with these matters and to evaluate the trajectory of long term annual electricity consumption of a sector of the Brazilian industry up to 2050 considering energy efficiency (EE) scenarios. It is important to emphasize that Brazil is a developing country, and to build a bottom-up approach was a challenge, mainly due to the fact that this model is data intensive. In particular, this modelling was applied in the pulp and paper sector. The main goal was to consider technological diffusion scenarios in EE measures, and show the energy savings achieved. The results point an energy savings in the order of 25% when an actual scenario is considered.

Microfluidic electrolyzers have been fabricated using graphite coated paper electrodes to electrolyze sea water into oxygen (O2) and hydrogen (H2) when integrated with a photovoltaic (PV) cell. The ‘open’ electrolyzer (OME) consists of a microchannel confined by a pair of graphite electrodes, which is drawn with the help of pencil tips. A sea water microdroplet has been dispensed at the junction of the electrodes while the PV cell is integrated to the electrodes to supply current. The microscale width of channel generates a high intensity electric field even at a lower potential, which facilitates the microdroplets to electrolyze into H2 and O2 near the cathode and anode. The rate of production of the gases increased with field intensity. In the ‘close’ electrolyzer (CME), the paper decorated with graphite electrodes is covered with a substrate embedded with polymeric microchannels. The microcapillaries are placed closer to the anode and cathode for in situ separation of H2 and O2. The economic, flexible, and metal-free micro-electrolyzer facilitates the water-splitting at a much lower applied voltage at an efficiency of 1–2%. Use of multiple separation channels in CME for production and separation of H2 and O2 shows the potential for micro-very-large-scale-integration (μ-VLSI).

Urgent need for waste disposal and renewable energy have opened up promising pathways for renewable and sustainable fuel production to substitute traditional fossil fuels. In this study, catalytic co-pyrolysis of waste paper (WP) and polyvinyl chloride (PVC) as typical municipal solid wastes was experimentally investigated towards hydrogen-rich syngas production. Results indicated the maximum H2 yield (429 μmol·gcat−1·min−1) was obtained with 60% PVC weight ratio under 900 °C which was higher than single component pyrolysis. Higher hydrogen yield (681.76 μmol·gcat−1·min−1) appeared over Fe/CeO2–CaO under the optimal conditions compared to that of Ru/ZSM-5-CaO (445.54 μmol·gcat−1·min−1). From the calculated non-isothermal kinetic parameters, both catalysts could reduce activation energies. Proper porous structure and CaO content in the catalyst could enhance hydrogen production via carbon species fixation.

Supercritical water gasification (SCWG) is a method by which biomass can be converted into a hydrogen-rich gas product. Wet industrial waste streams, which contain both organic and inorganic material, are well suited for treatment by SCWG. In this study, the gasification of two streams of biomass resulting from the pulp and paper industry, black liquor and paper sludge, has been investigated. The purpose is to convert these to useful products, both gaseous and solids, which can be used either in the papermaking process or in external applications. Simple compounds, such as glucose, have been fully gasified in SCWG, but gasification of more complex compounds, such as biomass and waste, have not reached as high conversions. The investigated paper sludge was not easily gasified. Improving gasification results with catalysts is an option and the use of alkali salts for this purpose was studied. The relationship between alkali concentration, temperature, and gasification yields was studied with the addition of KOH, K2CO3, NaOH and black liquor to the paper sludge. Addition of black liquor to the paper sludge resulted in similarly enhancing effects as when the alkali salts were added, which made it possible to raise the dry matter content and gasification yield without expensive additives.

This paper evaluates system aspects of biorefineries based on biomass gasification integrated with pulp and paper production. As a case the Billerud Karlsborg mill is used. Two biomass gasification concepts are considered: BIGDME (biomass integrated gasification dimethyl ether production) and BIGCC (biomass integrated gasification combined cycle). The systems analysis is made with respect to economic performance, global CO2 emissions and primary energy use. As reference cases. BIGDME and BIGCC integrated with district heating are considered. Biomass gasification is shown to be potentially profitable for the mill. The results are highly dependent on assumed energy market parameters, particularly policy support. With strong policies promoting biofuels or renewable electricity, the calculated opportunity to invest in a gasification-based biorefinery exceeds investment cost estimates from the literature. When integrated with district heating the BIGDME case performs better than the BIGCC case, which shows high sensitivity to heat price and annual operating time. The BIGCC cases show potential to contribute to decreased global CO2 emissions and energy use, which the BIGDME cases do not, mainly due to high biomass demand. As biomass is a limited resource, increased biomass use due to investments in gasification plants will lead to increased use of fossil fuels elsewhere in the system. Original Publication:Elisabeth Wetterlund, Karin Pettersson and Simon Harvey, Systems analysis of integrating biomass gasification with pulp and paper production - Effects on economic performance, CO2 emissions and energy use, 2011, ENERGY, (36), 2, 932-941.http://dx.doi.org/10.1016/j.energy.2010.12.017Copyright: Elsevier Science B.V., Amsterdam.http://www.elsevier.com/

A facile strategy is designed for the fabrication of flexible and free-standing ternary CoSnO 3 /graphene/carbon nanotubes (CoSnO 3 /GN/CNTs) composite papers through a simple filtration, followed by annealing process. The CoSnO 3 /GN/CNTs composite papers with high flexibility and tailorability can be easily fabricated. The CoSn(OH) 6 nanoparticles/graphene oxide/carbon nanotubes (CoSn(OH) 6 /GO/CNTs) composite papers obtained by a simple filtration method are transformed into CoSnO 3 /GN/CNTs composite papers after a thermal treatment process. In this unique composite structure, CoSnO 3 nanoparticles (nanocubes and nanoboxes) are embedded homogenously into the 3D framework of graphene and carbon nanotubes, respectively, in which offers not only a 3D conductive network and a dual restriction on the aggregation of CoSnO 3 nanoparticles, but also accommodates the large volume expansion of CoSnO 3 nanoparticles. When used directly as binder- and conductive agent-free anodes for lithium-ion batteries, the CoSnO 3 /GN/CNTs composite papers exhibit superb electrochemical properties including extraordinary reversible capacities, superior rate capabilities and stable cycle performances compared to CoSnO 3 nanoparticles and GN/CNTs paper, suggesting a new pathway for the rational engineering of anode materials.

The success of any process improvement study depends on the quality of the available data and the way in which the plant-specific characteristics are incorporated in the applied conceptual models; in the context of process integration studies these issues are directly related to the rules followed during the data extraction stage. Improving energy efficiency in a pulp and paper Kraft mill requires the identification of the most promising heat recovery network retrofit projects. In a retrofit analysis using pinch technology/process integration methods, only the process streams associated to the existing heat exchangers and some outlet streams (such as wastewater/effluent streams and vents) with high potential for heat recovery are usually included, while the energy exchanged through non-isothermal stream mixing (NIM) or direct heat transfer (DHT) is often assumed fixed and is not considered in the analysis. Relaxing this assumption requires extracting more data to represent the DHT design configuration that exists in the plant. However, different data extraction options can be considered to represent the DHT configuration depending on the associated process/operation constraints. This work describes a systematic procedure to extract and analyse the impacts of DHT on the overall energy efficiency of a Kraft process with a specific focus on mixing along the pulp line and in water tanks.

Implementation of absorption heat pumps (AHPs) in a Kraft pulping process was studied using a new methodology for the optimal integration of those devices in a process. Two generic opportunities were identified for an energy and water optimized mill: (i) integration of a double lift chiller in the bleaching chemical making plant to produce chilled and hot water simultaneously, using MP steam as the driving energy and, (ii) installation of a single stage heat pump to concentrate the black liquor and produce useful hot water by upgrading heat from the bleaching effluent and using MP steam as driving energy. The principles of AHPs operation and their efficient integration into a process are described. The simple payback time (SPB) and net present value (NPV) were used to evaluate the interest of such implementations. Considering 63 $/MWh for the steam price, SPB of 2.7 and 1.7 years have been estimated for the two cases.

In hot and dry climatic zones, direct evaporative cooling (DEC) system is used as an economical and efficient alternative to traditional air conditioning systems. The present paper concerns comprehensive experimental investigations and analysis of heat and mass transfer characteristics and thermal performance parameters of a bee-hive construction of corrugated-cellulose papers as a new cooling pad material. The performance parameters used to evaluate the effectiveness of the cooling pad materials are the outlet air temperature and relative humidity, pressure drop, humidifier effectiveness, rate of the evaporated water, sensible cooling capacity, specific cooling capacity (SCC), coefficient of performance (COP), specific water consumption (SWC), and Nusselt and Sherwood numbers. The cooling pad performance was investigated for a wide range of air and water temperatures and flow rates and pad thicknesses. The results show the enhancements of heat and mass transfer coefficients and the performance parameters with rising air temperature and water flow rate to humidifier. High values of the performance parameters (hc = 45 W/m2 oC and hm = 0.23 m/s, e h u m = 0.85 and COP = 170) are obtained compared to the traditional pad materials. Experimental correlations for the evaporative cooler performance parameters in terms of air and water temperatures and flow rates pad thicknesses are presented.

Magazines and newspapers, as two kinds of municipal solid waste, were investigated as the fuel feedstock in a hybrid direct carbon fuel cell. These carbon sources, together with a reference carbon source-activated charcoal, were characterized by such techniques as X-ray diffraction spectra, X-ray photoelectron spectroscopy, and thermal gravimetric analysis, among others. The results indicate that the carbon from magazine waste paper was more abundant in calcite and magnesium calcite, with more oxidation degree of carbon and higher thermal reactivity, compared with the other two carbon sources. Then, the cell performance fed with such carbon sources was tested in a homemade device. The cell fed with magazine waste paper carbon showed the highest performance among the three carbon sources, with a peak power density of 172 mW/cm2 at 650 °C. The cell performance results indicated that waste paper carbon sources, with a surface containing certain inherent impurities (calcite and magnesium calcite) and a high oxidation degree of carbon, could favor the thermal gasification of carbon fuel, and thus considerably enhance cell performance, especially for the operating temperatures below 700 °C. This study demonstrated that waste paper carbon sources could be promising fuel feedstock for hybrid direct carbon fuel cells.

Power generation by variable renewable energy (VRE) is expected to expand for decarbonization, although it is difficult to ensure stabilization of the energy demand due to fluctuations in the power output from VRE. To accelerate VRE implementation, wind-powered thermal energy systems (WTth-ES), which can provide dispatchable power using wind–thermal energy converter (WECth) and thermal energy storage (TES), have been proposed. In this study, we are tackling the installation of VRE, i.e., wind energy, by TES with WECth compared with wind turbine (WTp) in paper mills to demonstrate the applicability of TES in an industrial sector. Conventional and alternative energy systems in paper mills with TES were mathematically modeled and simulated to analyze the transmittable power output and the greenhouse gas (GHG) emissions by life cycle assessment. With the installation of TES and wind energy, transmittable power could be increased with GHG emissions reduction. However, their excess installation or unbalanced combination resulted in an increase in GHG emissions and a decrease in transmittable power. By comparing the cases, the combination of paper mill, TES, and WECth could convert thermal energy efficiently and mitigate fossil fuel consumption for multiple production of paper and power from the paper mill.

This paper deals with energy end-use models for pulp, paper, and paperboard mills. The models are consistent with data published in the U.S. Department of Energy's 1991 Manufacturing Energy Consumption Survey (MECS). A graphical framework for depicting these energy flows is presented. Development of these models is a key step in creating energy process-step models for pulp, paper, and paperboard production. The applicability of the modeling approach and framework to other industries is discussed.

A novel MEA (membrane electrode assembly) structure of passive μ-DMFC (micro-direct methanol fuel cell) controls water management and decreases methanol crossover. The CNT (carbon nanotube) paper replacing CP (carbon paper) as GDL (gas diffusion paper) enhances water back diffusion which passively prevents flooding in the cathode and promotes low methanol crossover. Moreover, the unique structure of CNT paper can also enhance efficiency of oxygen mass transport and catalyst utilization. The passive μ-DMFC with CNT-MEA exhibits significantly higher performance than passive μ-DMFC with CP-MEA and can operate in high methanol concentration, showing the peak power density of 23.2 mW cm −2 . The energy efficiency and fuel utilization efficiency are obviously improved from 11.54% to 22.7% and 36.61%–49.34%, respectively, and the water transport coefficient is 0.47 which is lower than previously reported passive μ-DMFC with CP.

The MIND method is used to optimize the operating costs of a pulp and paper mill. The optimization includes studies of the effects of material and energy flows, as well as non-linear relations between them. The results show that it is possible to achieve large savings in the pulp and paper mill simply by changing the operating strategy of the existing equipment units. It is also apparent that the percentage of recycled fibres strongly influences possible savings.

Catalytic co-pyrolysis of biomass and plastics (HDPE (high density polyethylene), PP (polypropylene) and PET (polyethylene terephthalate)) has been performed in a fixed-bed reactor in presence of cobalt based alumina, ceria and ceria-alumina catalysts to analyze the product distribution and selectivity. Catalysts are synthesized using co-precipitation method and characterized by BET (Brunauer-Emmett-Teller) surface area and XRD analysis. The effect of catalytic co-pyrolysis at different temperature with product distribution has been evaluated. The results have clearly shown the synergistic effect between biomass and plastics, the liquid products gradually increases forming with rise in the plastic content in the blend. Gaseous products have yielded most during pyrolysis of blend having biomass/plastics ratio of 5:1 with the presence of 40% Co/30% CeO2/30% Al2O3 catalyst with hydrogen gas production touched its peak of 47 vol%. Catalytic performance enhanced with increase with the cobalt loading, with best performance attributing to 40% Co/30% CeO2/30% Al2O3 catalyst. (C) 2016 Elsevier Ltd. All rights reserved.

Large kraft paper industries could economically generate 40% more electricity than the present demand by using steam-turbine cogeneration technology. A computer-based model has been used for the economic analysis. A systems approach, referred to as rational-use-of-energy, is proposed to overcome barriers to cogeneration.