Energy flow analysis in pulp and paper industry

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.     

Optimal waste heat recovery and reuse in industrial zones

Significant energy efficiency gains in zones with concentrated activity from energy intensive industries can often be achieved by recovering and reusing waste heat between processing plants. We present a systematic approach to target waste heat recovery potentials and design optimal reuse options across plants in industrial zones. The approach first establishes available waste heat qualities and reuse feasibilities considering distances between individual plants. A targeting optimization problem is solved to establish the maximum possible waste heat recovery for the industrial zone. Then, a design optimization problem is solved to identify concrete waste heat recovery options considering economic objectives. The paper describes the approach and illustrates its application with a case study.     

Energy optimization in a pulp and paper mill cogeneration facility

Alarmingly low pulp prices in early 2009 left pulp and paper mills across North America desperate for any way to improve thin profit margins. One solution that continues to gain popularity among the industry is improved energy management systems for cogeneration systems, which use steam for two purposes – to provide heat for the pulping process and to generate electricity for sale to regional providers. This paper presents an energy optimization algorithm for use in a pulp and paper mill cogeneration system. The algorithm is applicable to a number of popular mill configurations, power sale contracts, and fuel purchasing scenarios. The method is also extended to address weather-dependent cooling limitations encountered by a mill cogeneration facility, in which case an iterative solution is proposed in order to maintain convexity of the optimization problem. Results are presented in the form of three case studies.     

Integrating waste and renewable energy to reduce the carbon footprint of locally integrated energy sectors

Energy use continues to rise and with it the emissions of CO₂. Energy efficiency methods have been applied across sectors. Efficiency gains and energy use per manufactured unit have fallen, particularly in relation to the processing industry. Residential, work place, leisure, and service sectors still use large amounts of energy and produce large emissions of CO₂ despite efficiency gains. Successful strategies used in the processing industry for integrating energy systems, namely Total Site targeting, have been applied to locally integrated energy sectors. The method shows that it can be successfully applied to integrate renewables into the energy source mix and consequently reduce the carbon footprint of these locally integrated energy sectors.     

New energy strategies in the Swedish pulp and paper industry—The role of national and EU climate and energy policies

The Swedish pulp and paper industry has gone through a strategic change in its approach to electricity production and consumption over the past decade. This paper documents this reorientation, which includes increased on-site electricity production, investments and investment plans for wind power, and new partnerships concerning investments in electricity production assets. We also assess the extent to which these changes can be attributed to key energy and climate policies. Our analysis shows that this strategic reorientation has been driven by changes in the underlying economic conditions for the pulp and paper industry, in particular increases in the price of electricity following the Swedish energy market reform in 1996, and the introduction of the EU ETS. The scheme for tradable renewable electricity certificates, on the other hand, has provided a new source of income. While these market-based signals and responses are the most dominant drivers of strategic change, cognitive changes in the pulp and paper industry have also played a role in the strategic reorientation. The cognitive changes concerning the functioning of the electricity market, i.e. the pricing of electricity and influence of the EU ETS, have been particularly important in this regard.     

Systems analysis of integrating biomass gasification with pulp and paper production - Effects on economic performance, CO2 emissions and energy use

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.     

Energy demand and supply,energy policies,and energy security in the Republic of Korea

The Republic of Korea (ROK) has enjoyed rapid economic growth and development over the last 30 years. Rapid increases in energy use—especially petroleum, natural gas, and electricity, and especially in the industrial and transport sectors—have fueled the ROK's economic growth, but with limited fossil fuel resources of its own, the result has been that the ROK is almost entirely dependent on energy imports. The article that follows summarizes the recent trends in the ROK energy sector, including trends in energy demand and supply, and trends in economic, demographic, and other activities that underlie trends in energy use. The ROK has been experiencing drastic changes in its energy system, mainly induced by industrial, supply security, and environmental concerns, and energy policies in the ROK have evolved over the years to address such challenges through measures such as privatization of energy-sector activities, emphases on enhancing energy security through development of energy efficiency, nuclear power, and renewable energy, and a related focus on reducing greenhouse gas emissions. The assembly of a model for evaluating energy futures in the ROK (ROK2010 LEAP) is described, and results of several policy-based scenarios focused on different levels of nuclear energy utilization are described, and their impacts on of energy supply and demand in the ROK through the year 2030 are explored, along with their implications for national energy security and long-term policy plans. Nuclear power continues to hold a crucial position in the ROK's energy policy, but aggressive expansion of nuclear power alone, even if possible given post-Fukushima global concerns, will not be sufficient to attain the ROK's “green economy” and greenhouse gas emissions reduction goals.     

Conservation and solar energy in residential and commercial buildings: The northern industrialized USA

This recently completed study discusses the potential of conservation and solar energy in Michigan. While much of the quantitative analysis is specific to Michigan, the problems and opportunities discussed are largely generic to the northern industrial states in the USA. Technical estimates of energy savings potential are combined with economic analyses and market penetration considerations to provide an overall picture of the potential for conservation and solar energy. Barriers to market penetration are used as a basis for identifying a wide range of economic, informational, and institutional policy options for consideration by government and private sector decisionmakers.     

Selection of metal hydrides-based thermal energy storage: Energy storage efficiency and density targets

Thermo-chemical energy storage based on metal hydrides has gained tremendous interest in solar heat storage applications such as concentrated solar power systems (CSP) and parabolic troughs. In such systems, two metal hydride beds are connected and operating in an alternative way as energy storage or hydrogen storage. However, the selection of metal hydrides is essential for a smooth operation of these CSP systems in terms of energy storage efficiency and density. In this study, thermal energy storage systems using metal hydrides are modeled and analyzed in detail using first law of thermodynamics. For these purpose, four conventional metal hydrides are selected namely LaNi₅, Mg, Mg₂Ni and Mg₂FeH₆. The comparison of performance is made in terms of volumetric energy storage and energy storage efficiency. The effects of operating conditions (temperature, hydrogen pressure and heat transfer fluid mass flow rates) and reactor design on the aforementioned performance metrics are studied and discussed in detail. The preliminary results showed that Mg-based hydrides store energy ranging from 1.3 to 2.4 GJ m^?3 while the energy storage can be as low as 30% due to their slow intrinsic kinetics. On the other hand, coupling Mg-based hydrides with LaNi₅ allow us to recover heat at a useful temperature above 330 K with low energy density ca.500 MJ m^?3 provided suitable operating conditions are selected. The results of this study will be helpful to screen out all potentially viable hydrides materials for heat storage applications.     

Direct heat transfer considerations for improving energy efficiency in pulp and paper Kraft mills

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.     

Energy for sustainable development in Malaysia: Energy policy and alternative energy

Energy is often known as the catalyst for development. Globally, the per capita consumption of energy is often used as a barometer to measure the level of economic development in a particular country. Realizing the importance of energy as a vital component in economic and social development, the government of Malaysia has been continuously reviewing its energy policy to ensure long-term reliability and security of energy supply. Concentrated efforts are being undertaken to ensure the sustainability of energy resources, both depletable and renewable. The aim of this paper is to describe the various energy policies adopted in Malaysia to ensure long-term reliability and security of energy supply. The role of both, non-renewable and renewable sources of energy in the current Five-Fuel Diversification Strategy energy mix will also be discussed. Apart from that, this paper will also describe the various alternative energy and the implementation of energy efficiency program in Malaysia.     

Energy improvement of a conventional dwelling in Argentina through thermal simulation

This paper analyses the design, technology, thermal behaviour, and energy consumption of both a conventional and a refurbished dwelling located in a region with a temperate-cold climate in central Argentina. The thermal behaviour and the energy consumption of the conventional building were monitored during winter. The experimental data were analysed and included in a simulation of the transient thermal behaviour of the house. Measurements and simulation were in agreement, showing a mean deviation below 0.5 °C. To reduce the heating and cooling loads, the dwelling was refurbished and its thermal behaviour was studied through a computer simulation, for the critical seasons (winter and summer) and for two occupancy schedules (with and without inhabitants). The refurbishment included passive solar heating, shading, and an insulated envelope. These successful changes allowed energy savings of 66% and 52% for winter and summer, respectively.     

On the comparison of energy sources: Feasibility of radio frequency and ambient light harvesting

With growing interest in multi source energy harvesting including integrated microchips we propose a comparison of radio frequency (RF) and solar energy sources in a typical city. Harvesting devices for RF and solar energy will be competing for space of a compact micro or nano device as well as for orientation with respect to the energy source. This is why it is essential to investigate importance of every source of energy and make a decision whether it will be worthwhile to include such harvesters. We considered theoretically possible irradiance by RF signal in different situations, typical for the modern urban environment and compared it with ambient solar energy sources available through the night, including moonlight.Our estimations show that solar light energy dominates by far margin practically all the time, even during the night, if there is a full moon in the absence of clouds. At the same time, in the closed compartments or at the new moon RF harvesting can be beneficial as a source of “free” energy.     

Energy and cost evaluation in total treatment system of sewage and waste

This paper discusses a total treatment system which is designed not only to treat waste and sewage discharged in a new town but also to use energy which is recovered from these waste materials as effectively as possible. Various alternative systems are planned by taking realization possibilities of new technologies and environmental impact into consideration, and their energy efficiencies and economy are investigated comprehensively. From the investigation, the following system is selected as the optimal one: In the sewage treatment system, an activation method using an ultradeep aeration tank is adopted as the aeration method, a method using hypochlorite as that for disinfection, and an anaerobic digestion system as that for sludge treatment. In the waste disposal system, a combined heat and power system with a pyrolysis furnace of rotary kiln type is adopted. In this total treatment system, the waste disposal system uses both the recovered gas and residues of sludge after methane fermentation in the sewage treatment process, and the sewage treatment process gets both steam and electricity which are generated by using the pyrolysis gas obtained in the pyrolysis furnace. As a result, it was made clear that the proposed total treatment system makes it possible not only to be operated by steam and electricity produced within the system itself, but also to transmit surplus power to the outside of the system.     

From fluid milk to milk powder: Energy use and energy efficiency in the European dairy industry

In this paper, we conduct a cross-country analysis of energy consumption and energy efficiency for the dairy industry in four European countries. Changes in energy efficiency were monitored in two different ways. One way is to look at the energy use by tonne of milk processed by dairies (EE_Ip1$\mathit{EE}{I}_{p1}$). Another way is by comparing the actual energy use with the energy that would have been used if no changes in energy efficiency would have taken place (EE_Ip2$\mathit{EE}{I}_{p2}$). A characteristic of EE_Ip2$\mathit{EE}{I}_{p2}$ is that it corrects for differences in product mix among countries and in time. We found that changes in production mix are important in three of the four countries studied and that EE_Ip2$\mathit{EE}{I}_{p2}$ should be preferred when comparing levels of energy efficiency among countries or when there are significant changes in product mix. Once changes in product mix have been taken into account, our results show that France, Germany, the Netherlands and the United Kingdom have reduced their values in EE_Ip2$\mathit{EE}{I}_{p2}$, respectively by −0.4%, −2.1%, −1.2% and −3.8% per annum. The results also show that the British, German and Dutch dairy industries have converged towards similar (lower) values in their energy efficiency indicators and that the French dairy industry would save 30% if were to converge to similar values of EE_Ip$\mathit{EE}{I}_p$ as the ones obtained for Germany or the United Kingdom.     

Policies to reduce energy use and carbon emissions in the UK

The UK differs from may other industrialized nations in that its carbon dioxide (CO₂) emissions from energy use have declined in recent years despite relatively rapid economic growth. In all sectors but transport, substantial reductions have already occurred in the level of carbon emissions per unit of GDP output. At the same time, a number of official and unofficial studies have pointed out that the UK has one of the largest remaining potentials amongst comparable industrialized countries for achieving further CO₂ reductions through the implementation of cost-effective energy efficiency and fuel switching measures. This paper discusses past and present patterns of energy use and carbons emissions in the UK. The analysis then examines historical trends in UK energy policy and presents policy options for further reducing the UK's energy-use and carbon emissions in the future.     

Solar and wind energy potential and utilization in Pakistan

Pakistan needs substantial amount of energy to develop its industry and to increase the agricultural productivity. The available indigenous energy resources are limited. The only option which the country has to pursue is renewable energy. This paper identifies the potentials of solar and wind energy. The prime sites for wind are coastal area, arid zone and hill terrains. Solar energy is abundant over most part of the country, maximum being received over Quetta valley.     

Simulated energy and exergy analyses of the charging of an oil-pebble bed thermal energy storage system for a solar cooker

Energy balance equations are used to model the solar energy capture (SEC) system and the thermal energy storage (TES) system of a proposed indirect solar cooker. An oil-pebble bed is used as the TES material. Energy and exergy analyses are carried out using two different charging methods to predict the performance of the TES system. The first method charges the TES system at a constant flowrate. In the second method, the flowrate is made variable to maintain a constant charging temperature. A Simulink block model is developed to solve the energy balance equations and to perform energy and exergy analyses. Simulation results using the two methods indicate a greater degree of thermal stratification and energy stored when using constant-temperature charging than when using constant-flowrate charging. There are greater initial energy and exergy rates for the constant-flowrate method when the solar radiation is low. Energy efficiencies using both methods are comparable whilst the constant-temperature method results in greater exergy efficiency at higher levels of the solar radiation. Parametric results showing the effect of each charging method on the energy and exergy efficiencies are also presented.     

Opportunities for the integration of absorption heat pumps in the pulp and paper process

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.     

Energy, economics and environmental impacts of renewable energy systems

The renewable based electricity generation technologies were assessed against a range of sustainability indicators using data obtained from the literature. These indicators are cost of electricity generation, greenhouse gas emissions and energy pay-back time. All the three parameters were found to have a very wide range for each technology. For grading different renewable energy sources a new figure of merit has been proposed, linking greenhouse gas emissions, energy pay-back time and cost of electricity generated by these renewable energy sources. It has been found out that wind and small hydro are the most sustainable source for the electricity generation.