Energy efficiency improvement of dryer section heat recovery systems in paper machines – A case study

Modern paper machines are equipped with heat recovery systems that transfer heat from the humid exhaust air of the paper machine’s dryer section to different process streams. As a result of process changes, the heat recovery systems may operate in conditions far from the original design point, creating a significant potential for energy efficiency improvement. In this paper we demonstrate this potential with a case study of three operating paper machines. Both operational and structural improvement opportunities are examined. Since the existing retrofit methodologies for heat exchanger networks can not be applied to cases with condensing air, we use thermodynamic simulation models presented earlier to assess the effects of possible changes on the existing heat recovery systems. In order to reduce the required processing time of the simulation models, only a limited number of pre-screened retrofit designs are considered. The pre-screening is carried out on the basis of guidelines presented earlier. The analysis in the case mill revealed savings of 110 GWh/a in process heat with profitable investments. According to the follow-up study, the investments carried out have resulted in 12% lower fuel use and 24% lower CO₂ emissions. The results imply that all operating paper machines should be similarly examined.     

Feasibility study for the installation of HVAC for a spa by means of energy recovery from thermal water—Part II: Energy analysis

The use of a low temperature geothermal spring together with the heat energy still contained in waste water from the different therapy systems installed in a spa (shower, jets, bathrooms, jacuzzis, pools, ventilation processes) can significantly reduce the operating and maintenance costs of the installation. This covers part of the air conditioning needs of the building and of the heating of thermal water to the appropriate temperature for therapeutic use.In the first part of the study, an analysis of the spring's situation was made, calculating the thermal water needs and presenting the consumption according to the operation schedule on different types of day. In this way, the contribution the spring was capable of giving was compared and the evolution of the thermal water in the tanks was studied. In the second part, the climatic conditions that the spa should meet are studied, along with the loads that it should support, the energy reclaimed from the different heat focuses and the repercussions on the final solution.     

Energy efficiency in social housing: Opportunities and barriers from a case study in Brazil

This paper investigates the energy efficiency in a segment of the building sector in emerging countries by analyzing and evaluating the energy efficiency of a social housing project in Brazil. Energy efficiency measures and bioclimatic design strategies are developed in order to improve thermal comfort in this social housing project and to reduce the energy consumption and expenses of their residents. The institutional barriers and constraints toward higher efficiency are described. The results of this study show that there is a high potential to increase energy efficiency in social housing in emerging countries like Brazil. The implementation and consideration of the energy efficiency measures and policy recommendations would contribute substantially to the goal to dampen the fast growth of energy demand in these countries. Moreover the improvement of energy efficiency in the social housing sector could be a driver for market transformation towards more sustainability in the whole building sector.     

Impact of European standard EN15251 in the energy certification of services buildings—A Portuguese study case

In Europe, about 40% of the energy is consumed in buildings, more than by industry or transport. However, there is a great potential for energy savings in this field, often at little cost. A new European directive and several European standards, including the comfort standard EN15251, were created to develop comfortable and efficient buildings.     

Development of energy efficiency improvement in the Tunisian hotel sector: a case study

Tunisia expects a very large growth in energy demand but Tunisian' indigenous energy resources are limited. Today Tunisian' energy resources meet the total primary energy demand. In short time Tunisia will become an importer country for primary energy.Energy consumption and conservation in Tunisia has received growing attention in recent years. This paper presents the results and analysis from the data collected during the energy audits of a hotel unit located in the center of Tunis during the years 1987, 1996 and 2002. Two energy conservation measures were carried out to investigate the energy savings after two energy audits. The objective was to obtain a quantified energy saved from the effects of efficient technologies.Based on the findings presented in this paper it is suggested there exists significant energy savings potentials for the Tunisian hotel industry.     

Hybrid solution and pump-storage optimization in water supply system efficiency: A case study

Environmental targets and saving energy have become ones of the world main concerns over the last years and it will increase and become more important in a near future. The world population growth rate is the major factor contributing for the increase in global pollution and energy and water consumption. In 2005, the world population was approximately 6.5 billion and this number is expected to reach 9 billion by 2050 [United Nations, 2008. www.un.org, accessed on July]. Water supply systems use energy for pumping water, so new strategies must be developed and implemented in order to reduce this consumption. In addition, if there is excess of hydraulic energy in a water system, some type of water power generation can be implemented.     

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.     

Energy in subsistence agriculture: A case study of nepal

The paper examines the total energy input requirements and outputs of subsistence agriculture in the rural areas of Nepal with specific emphasis on animate energy inputs for different crops. It analyses the availability of animate energy and the usage pattern and also looks into various issues of energy demands in subsistence agriculture at micro levels and its impact at macro level. The paper attempts to highlight major policy options that are imperative for raising the living standard of the rurals through increased productivity.     

Energy saving and emission reduction: A project of coal-resource integration in Shanxi Province,China

The small or middle coal mines with illegal operations in developing countries or regions can cause bad energy waste and environmental disruption. The project of coal-resource integration in Shanxi Province of China gives a new idea or an approach to energy saving and emission reduction. It is a social- and economic-ecological project. The paper shows the targets of energy saving and emission reduction in Shanxi Province, and analyses the aims, significance, design process and implementation of the integration project. Based on that, the paper discusses the challenges and opportunities the project brings. The analysis shows that the project of coal-resource integration in developing countries or regions can effectively improve mining technologies, collect capital and impel international cooperation and exchange. Finally, the paper analyses the concerns about the future, including the possible problems of implementation period, industrial updating, environmental impact and re-employment. However, the successful integration of coal resources can mitigate energy crisis and climate crisis and promote cleaner production effectively.     

Improving the institutional structures for disseminating energy efficiency in emerging nations: a case study for energy agencies in South Africa

Emerging nations are typically characterised by highenergy intensities despite significant energy efficiency potentials and numerous project oriented efforts to introduce energy-efficient technologies. The paper argues that successful technology dissemination needs appropriate institutional structures to reduce the related transaction cost. While a project-by-project approach risks to evaporate after completion, an energy agency would allow to bundle the know-how and information gained, ease access to funding and thus reduce information search cost and increase availability of efficient technologies. In a case study for South Africa, we examine the appropriateness of this concept for emerging nations. We discuss the underlying incentive problem from a new institutional economics perspective and suggest an approach to the design and implementation of operable energy agencies.     

Energy intensity and greenhouse gases footprint of metallurgical processes: A continuous steelmaking case study

The demand on primary energy resources of three steelmaking technologies has been evaluated using an integrated energy analysis approach that takes into account the energy equivalent of major materials and supplies used in the process, as well as the inefficiency of electricity generation. Two new parameters, Material CO₂ Footprint (MCF) and Process CO₂ Footprint (PCF), are defined to provide unified measures for carbon footprint of the treated materials, and the process respectively. Using these measures, a comparative study of the three processes has been performed. It is demonstrated that a novel steelmaking technology that operates continuously leads to substantial reduction in the overall energy demand, when compared with the conventional batch processes. CO₂ reduction associated with the improvement of the energy efficiency is presented for several scenarios of power generation.     

Key issues in the microchemical systems-based methanol fuel processor: Energy density,thermal integration,and heat loss mechanisms

Microreactor technology is a promising approach in harnessing the high energy density of hydrocarbons and is being used to produce hydrogen-rich gases by reforming of methanol and other liquid hydrocarbons. However, on-demand H₂ generation for miniature proton exchange membrane fuel cell (PEMFC) systems has been a bottleneck problem, which has limited the development and demonstration of the PEMFC for high-performance portable power. A number of crucial challenges exist for the realization of practical portable fuel processors. Among these, the management of heat in a compact format is perhaps the most crucial challenge for portable fuel processors. In this study, a silicon microreactor-based catalytic methanol steam reforming reactor was designed, fabricated, and demonstrated in the context of complete thermal integration to understand this critical issue and develop a knowledge base required to rationally design and integrate the microchemical components of a fuel processor. Detailed thermal and reaction experiments were carried out to demonstrate the potential of microreactor-based on-demand H₂ generation. Based on thermal characterization experiments, the heat loss mechanisms and effective convective heat coefficients from the planar microreactor structure were determined and suggestions were made for scale up and implementation of packaging schemes to reduce different modes of heat losses.     

Industrial energy efficiency improvement through cogeneration: A case study of the textile industry in Thailand

Natural gas cogeneration presently appears to be a promising alternative to satisfy the energy utility requirement of the process industries thanks to the favorable energy policy of the Government of Thailand. In this paper, we detail a case study in a textile factory where use of gas-turbine cogeneration with a post-combustion heat recovery system is found to be the most suitable solution. This system has not only the highest thermal efficiency, but it can also provide flexibility in operation. Financial analysis of the most suitable cogeneration configuration provides the net present value (NPV), pay-back period (PBP) and internal rate of return (IRR) with values of 310 million Baht, 5.3 years and 26.6%, respectively. The thermal-matching option is not found to be attractive because the sale price of electricity to the state electric utility is not high enough to absorb the additional investment required for the prime mover. Incorporation of an absorption chiller in the cogeneration system does not bring in any additional advantage as there is no excess waste heat available in this factory.     

Energy efficiency as a preferred resource: evidence from utility resource plans in the Western US and Canada

This article examines the future role of energy efficiency as a resource in the Western US and Canada, as envisioned in the most recent resource plans issued by 16 utilities, representing about 60% of the region’s load. Utility and third-party-administered energy-efficiency programs proposed by 15 utilities over a 10-year horizon would save almost 19,000 GWh annually, about 5.2% of forecast load. There are clear regional trends in the aggressiveness of proposed energy savings. California’s investor-owned utilities (IOUs) had the most aggressive savings targets, followed by IOUs in the Pacific Northwest, and the lowest savings were proposed by utilities in Inland West states and by two public utilities on the West Coast. The adoption of multiple, aggressive policies targeting energy efficiency and climate change appears to produce sizeable energy-efficiency commitments. Certain specific policies, such as mandated energy savings goals for California’s IOUs and energy-efficiency provisions in Nevada’s Renewable Portfolio Standard, had a direct impact on the level of energy savings included in the resource plans. Other policies, such as revenue decoupling and shareholder incentives and voluntary or legislatively mandated greenhouse gas emission reduction policies, may have also impacted utilities’ energy-efficiency commitments, though the effects of these policies are not easily measured. Despite progress among the utilities in our sample, more aggressive energy-efficiency strategies that include high-efficiency standards for additional appliances and equipment, tighter building codes for new construction and renovation, as well as more comprehensive ratepayer-funded energy-efficiency programs are likely to be necessary to achieve a region-wide goal of meeting 20% of electricity demand with efficiency in 2020.

Assessment of the thermal performance and energy conservation opportunities of a cement industry in Indonesia

A simple model is presented to assess the thermal performance of a cement industry with an integrated view to improve the productivity of the plant. The model is developed on the basis of mass, energy and exergy balance and is applied to an existing Portland cement industry in Indonesia. The data obtained from industry show that the burning efficiency and the second law efficiency of the kiln system are 52.07% and 57.07% respectively. Cooler efficiency and heat recovery efficiency are 47.75% and 51.2% respectively. The unaccounted loss at kiln system was found to be 1.85% and that of cooler system was 19%. The high loss at cooler was mainly due to the convection and radiation losses from the uninsulated cooler. Irreversibility of the system was found to be about 20%, which is due to the conversion from chemical to thermal energy. The thermal energy conservation opportunities are identified. This study show that by replacing industrial diesel oil (IDO) with waste heat recovery from kiln and cooler exhaust for drying of raw meal and fuel, and preheating of combustion air, a cement industry in Indonesia can save about 1.264 × 10⁵ US dollars per year.     

Energy efficiency,security of supply and the environment in South Africa: Moving beyond the strategy documents

Energy efficiency is one of the most potent and cost effective ways of meeting the demands of sustainable development. It has in fact been referred to as the best energy resource. Way back in 2005 the South African Department of Minerals and Energy (DME) published its Energy Efficiency Strategy in support of some of the objectives enlisted in the 1998 White Paper on Energy Policy. The Strategy set a national target for energy efficiency improvement of 12% by 2015 against the baseline year 2000. The document further predicted that, with a business as usual model of energy usage, at the projected rate of national economic development, there would be a need to invest in new power generating capacity by around 2007. Despite the policy foresight and seemingly enthusiastic efforts, though, the dawn of 2008 saw the country gripped in an electric power crisis, with a capacity shortfall of over 10%. This paper looks at what could have gone wrong, examines energy efficiency policies and measures in other countries and how these lessons could be adopted to the South African context.     

Energy efficiency and the cost of GHG abatement: A comparison of bottom-up and hybrid models for the US

A highly influential report by the McKinsey consulting firm suggests that a large potential for profitable energy efficiency exists in the US, and that substantial greenhouse gas emissions reductions can therefore be achieved at a low cost. This result is consistent with other studies conducted using a bottom-up methodology that dates back to the work of Lovins beginning in the 1970s. Research over the past two decades, however, has identified shortcomings with the conventional bottom-up approach, and this has led to the development of new analytical frameworks that are referred to as hybrid energy–economy models. Using the CIMS hybrid model, we conducted simulations for comparison with the McKinsey results. These exercises suggest a more modest potential to reduce greenhouse gas emissions at a given marginal cost, as well as a smaller contribution from energy efficiency relative to other abatement opportunities such as fuel switching and carbon capture and storage. Hybrid models incorporate parameters reflecting risk and quality into their estimates of technology costs, and our analysis suggests that these play a significant role in explaining differences in the results.     

Comparative study of different insulating materials for reducing the heat losses in steam pipes: a technical study

An efficiency loss such as heat loss across bare pipe surfaces reduces the available energy to end-uses and increases the burden on boilers to meet the demand. Energy losses create additional stress on the system that accelerates wear and leads to overloading on the system for which it is not originally designed. In the present study, calculations for heat loss and cost of different insulating materials for varied thicknesses were performed for typical location in Jammu and Kashmir, India. The detailed analysis of the heat loss from bare steam pipes was performed with a view to suggest suitable type of insulation to lower the heat loss to acceptable limits, thereby reducing the cost of fuel. The present work provides the detailed study on the heat conduction analysis of steam pipes for different diameters. This analysis includes the heat loss from steam pipes and cost of insulation for different thicknesses of mineral wool, cement and lead, which can be used as the insulating material. The economics of each insulation type is studied, and the analysis indicates that there is an appreciable fuel saving in terms of thermal units.     

Use of material flow accounting for assessment of energy savings: A case of biomass in Slovakia and the Czech Republic

Anthropogenic material and energy flows are considered to be the major cause of many environmental problems humans face today. In order to measure material and energy flows, and to mitigate related problems, the technique of material flow and energy flow analysis has been conceived. The aim of this article is to use material and energy flow accounting approaches to quantify the amount of biomass that is available, but that so far has not been used for energy purposes in Slovakia and the Czech Republic and to calculate how much consumed fossil fuels and corresponding CO₂ emissions can be saved by utilising this biomass. Based on the findings presented, 3544 kt/yr of the total unused biomass in Slovakia could replace 53 PJ/yr of energy from fossil fuels and 6294 kt/yr of the total unused biomass in the Czech Republic could replace 91 PJ/yr of energy. Such replacement could contribute to a decrease in total CO₂ emissions by 9.2% in Slovakia and by 5.4% in the Czech Republic and thus contribute to an environmental improvement with respect to climate change.     

Energy intensity and structural change in eastern europe: Methodology and case study of Hungary

Historical energy use in the industrial and transport sectors of the Hungarian economy is investigated using Divisia analysis to separate changes in aggregate energy intensity into components such as structural shift and process efficiency change. It has been found that the effect of structural change, commonly thought to be a source of reducing energy intensity in such economies has, for Hungary, generally been a less significant influence than efficiency improvements and has mostly acted to increase energy use. Major improvements in the efficiency of industrial fuel use in the last ten years are identified. Within the transport sector, efficiency has improved considerably, but the effects have been partly balanced by a trend to more energy-intensive modes. Comparison is made of the results with those reported in the literature for other developed and developing countries.