There is a growing interest in reducing energy consumption and the associated greenhouse gas emissions in every sector of the economy. The residential sector is a substantial consumer of energy in every country, and therefore a focus for energy consumption efforts. Since the energy consumption characteristics of the residential sector are complex and inter-related, comprehensive models are needed to assess the technoeconomic impacts of adopting energy efficiency and renewable energy technologies suitable for residential applications. The aim of this paper is to provide an up-to-date review of the various modeling techniques used for modeling residential sector energy consumption. Two distinct approaches are identified: top-down and bottom-up. The top-down approach treats the residential sector as an energy sink and is not concerned with individual end-uses. It utilizes historic aggregate energy values and regresses the energy consumption of the housing stock as a function of top-level variables such as macroeconomic indicators (e.g. gross domestic product, unemployment, and inflation), energy price, and general climate. The bottom-up approach extrapolates the estimated energy consumption of a representative set of individual houses to regional and national levels, and consists of two distinct methodologies: the statistical method and the engineering method. Each technique relies on different levels of input information, different calculation or simulation techniques, and provides results with different applicability. A critical review of each technique, focusing on the strengths, shortcomings and purposes, is provided along with a review of models reported in the literature.

Modeling of end-use energy consumption in the residential sector: A review of modeling techniques

Biodiesel is a renewable transportation fuel consisting of fatty acid methyl esters (FAME), generally produced by transesterification of vegetable oils and animal fats. In this review, the fatty acid (FA) profiles of 12 common biodiesel feedstocks were summarized. Considerable compositional variability exists across the range of feedstocks. For example, coconut, palm and tallow contain high amounts of saturated FA; while corn, rapeseed, safflower, soy, and sunflower are dominated by unsaturated FA. Much less information is available regarding the FA profiles of algal lipids that could serve as biodiesel feedstocks. However, some algal species contain considerably higher levels of poly-unsaturated FA than is typically found in vegetable oils. Differences in chemical and physical properties among biodiesel fuels can be explained largely by the fuels’ FA profiles. Two features that are especially influential are the size distribution and the degree of unsaturation within the FA structures. For the 12 biodiesel types reviewed here, it was shown that several fuel properties – including viscosity, specific gravity, cetane number, iodine value, and low temperature performance metrics – are highly correlated with the average unsaturation of the FAME profiles. Due to opposing effects of certain FAME structural features, it is not possible to define a single composition that is optimum with respect to all important fuel properties. However, to ensure satisfactory in-use performance with respect to low temperature operability and oxidative stability, biodiesel should contain relatively low concentrations of both long-chain saturated FAME and poly-unsaturated FAME.

Review of biodiesel composition, properties, and specifications

As a renewable, sustainable and alternative fuel for compression ignition engines, biodiesel instead of diesel has been increasingly fueled to study its effects on engine performances and emissions in the recent 10 years. But these studies have been rarely reviewed to favor understanding and popularization for biodiesel so far. In this work, reports about biodiesel engine performances and emissions, published by highly rated journals in scientific indexes, were cited preferentially since 2000 year. From these reports, the effect of biodiesel on engine power, economy, durability and emissions including regulated and non-regulated emissions, and the corresponding effect factors are surveyed and analyzed in detail. The use of biodiesel leads to the substantial reduction in PM, HC and CO emissions accompanying with the imperceptible power loss, the increase in fuel consumption and the increase in NOx emission on conventional diesel engines with no or fewer modification. And it favors to reduce carbon deposit and wear of the key engine parts. Therefore, the blends of biodiesel with small content in place of petroleum diesel can help in controlling air pollution and easing the pressure on scarce resources without significantly sacrificing engine power and economy. However, many further researches about optimization and modification on engine, low temperature performances of engine, new instrumentation and methodology for measurements, etc., should be performed when petroleum diesel is substituted completely by biodiesel.

http://www.abe-research.illinois.edu/pubs/T_Grift/EffectOfBiodieselOnEnginePerformancesAndEmissions.pdf

Effect of biodiesel on engine performances and emissions

Biodiesel production from waste cooking oils

Energy is vital for sustainable development of any nation – be it social, economic or environment. In the past decade energy consumption has increased exponentially globally. Energy management is crucial for the future economic prosperity and environmental security. Energy is linked to industrial production, agricultural output, health, access to water, population, education, quality of life, etc. Energy demand management is required for proper allocation of the available resources. During the last decade several new techniques are being used for energy demand management to accurately predict the future energy needs. In this paper an attempt is made to review the various energy demand forecasting models. Traditional methods such as time series, regression, econometric, ARIMA as well as soft computing techniques such as fuzzy logic, genetic algorithm, and neural networks are being extensively used for demand side management. Support vector regression, ant colony and particle swarm optimization are new techniques being adopted for energy demand forecasting. Bottom up models such as MARKAL and LEAP are also being used at the national and regional level for energy demand management.

Energy models for demand forecasting—A review

The effect of biodiesel fuel obtained from waste frying oil on direct injection diesel engine performance and exhaust emissions

https://harmanatsoroako.files.wordpress.com/2012/09/energy-and-exergy-analyses-of-a-raw-mill-in-a-cement-production.pdf

Energy and exergy analyses of a raw mill in a cement production

In recent years, there has been an increasing interest in applying energy and exergy analysis modeling techniques for energy-utilization assessments in order to attain energy saving. In this regard, various approaches have been used to perform the exergy analyses of countries. The main objective of the present study is to evaluate and analyze the energy utilization efficiencies of countries by reviewing the studies conducted on various countries or societies, to which different approaches have been applied. Thermodynamic relations used to perform energy and exergy analyses of countries are given first. The classification of studies conducted and the approaches applied are then investigated in terms of subsectors, such as utility, industrial, residential-commercial, and transportation sectors. Next, the countries considered are evaluated in terms of energy and exergy utilization efficiencies. Finally, the results obtained are discussed. It is expected that the review presented here will provide the investigators with knowledge about how much effective and efficient a country uses its natural resources. This knowledge is also needed for identifying energy efficiency and/or energy conservation opportunities as well as for dictating the energy strategies of a country or a society.

A review on analyzing and evaluating the energy utilization efficiency of countries

Exergy has been seen a key component for a sustainable society, and in the recent years exergy analysis has been widely used in the design, simulation and performance evaluation of thermal and thermo chemical systems. A particular thermo dynamical system is the society of a country, while the energy utilization of a country can be assessed using exergy analysis to gain insights into its efficiency and potential for improvements. Energy and exergy utilization efficiencies in the Turkish industrial sector (TIS) over the period from 1990 to 2003 are reviewed and evaluated in this study. Energy and exergy analyses are performed for eight industrial modes, namely iron–steel, chemical–petrochemical, petrochemical–feedstock, cement, fertilizer, sugar, non-metal industry, other industry, while in the analysis the actual data are used. Sectoral energy and exergy analyses are conducted to study the variations of energy and exergy efficiencies for each subsector throughout the years studied, and these heating and overall energy and exergy efficiencies are compared for the eight subsectors. The chemical and petrochemical subsector, and the iron and steel subsector appear to be the most energy and exergy efficient sectors, respectively. The energy utilization efficiencies for the Turkish overall industrial sector range from 63.45% to 70.11%, while the exergy utilization efficiencies vary from 29.72% to 33.23% in the analyzed years. Exergetic improvement potential for this sector is also determined to be 681 PJ in 2003, with an average increase rate of 9.5% annually for the analyzed years. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral and subsectoral energy and exergy utilization to determine how efficient energy and exergy are used in the sector studied. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.

Zafer Utlu

Papers

The effect of biodiesel fuel obtained from waste frying oil on direct injection diesel engine performance and exhaust emissions

Energy and exergy analyses of a raw mill in a cement production

A review on analyzing and evaluating the energy utilization efficiency of countries

A review and assessment of the energy utilization efficiency in the Turkish industrial sector using energy and exergy analysis method

Residential-commercial energy input estimation based on genetic algorithm (GA) approaches: an application of Turkey