Preface

Today, access to energy is considered for granted for many, while the situation is the opposite for billions of people who still lack energy for basic needs such as cooking and lighting.

Rising energy demand because of economic growth and also population growth will likely lead to higher energy prices, which in turn can exacerbate the situation for a large part of the world population. Moreover, the environmental impact of energy exploitation and use, which to a large extent is based on fossil energy resources, has already reached a level that calls for greater attention. Therefore, the energy and climate issues have gained increasing attention in the political agenda at different levels both nationally and internationally. This has resulted in various forms of policies that are intended to promote sustainability through increased share of alternative energy sources and efficient energy use.

The fact that the world's energy systems for the most part are built on fossil energy resources and that renewable energy alternative must constantly prove competitive means that it will take time to bring about a drastic change in the global energy map. This is a process where the energy system must be improved step by step towards a sustainable direction. The challenges in the area of resources, energy supply security, economic growth and the environment require a joint action in which the development of alternative energy, technology improvement and introduction of relevant policy instruments should go hand in hand in order to achieve sustainable development at all levels.

This book is a collection of six interesting chapters which focus on some specific areas that are vital for the promotion of sustainability in the area of energy and environment. The papers which are included in this book can be generally classified under the following themes: district heating, bioenergy, solar energy, industrial energy auditing and building. The book will provide a general but also some specific insight into the different topics mentioned above.

The first chapter describes the value of district heating and cooling as a means toward efficient utilisation of energy resources. Here, important aspects such as industrial surplus heat utilisation, poly-generation opportunity, biomass fuels utilisation and energy-carrier switching are discussed.

Bioenergy is the main theme in chapter 2 and 3. Chapter 2 gives an extensive literature review on potential and use of bioenergy in ASEAN countries. Moreover, the importance of clean development mechanism (CDM) to boost bioenergy projects in these regions is highlighted. Chapter 3 deals with combustion technology development where local biomass (agricultural residues) can be used for local heat production. This chapter is supported by experiments where the "cigar" firing technology is investigated for combustion of biomass bales.

Chapter 4 deals with the analysis of photovoltaic Maximum Power Point Trackers. This is vital since the output voltage and current from PV modules depend on environmental condition such as solar radiation and temperature. Here, a converter and a tracking algorithm which enables an optimal operation of photovoltaic systems is proposed.

The remaining two chapters focus on industry and residence building with the aim to achieve increased sustainability. In chapter 5 a methodology for industrial energy audit with measurement examples are presented, while the last chapter describes case studies where Building Performance Evaluation is used (here the focus is indoor climate verse energy use).

The search for energy supply security, economic growth and an energy system with minimum impact on the environment underscores the importance of sustainable energy as never before.

The purpose of this book is not to provide answers to how to achieve a sustainable energy system, but rather an effort that leads in that direction by presenting a series of research. The book presents a series of research results ranging from theoretical studies to advanced technological solutions to improve the use of some of the renewable energy sources.

**Alemayehu Gebremedhin**

**Chapter 1**

**District Heating and Cooling Enable Efficient Energy**

Economic development in transition countries, such as China and India, increase global en‐ ergy use. Therefore, the demand for energy carriers grows, which should increase energy prices. Global energy supply is dominated by fossil fuels, such as coal, oil and natural gas, and this situation is likely to remain for many years even if the use of renewable energy sources (e.g., biomass, solar energy and wind energy) is expanding. Higher energy prices make certain changes of the energy system more profitable: use of *free* energy sources, such as sun and wind, efficiency improvements of energy supply, as well as energy conservation

Several policies on various levels now promote increased utilisation of renewable energy sources and reduced energy end-use, for example in buildings. But there are also compre‐ hensive systems that link energy resources with demand for energy. *District heating* is such a concept, which is common in many countries where space heating of buildings is required, for example Iceland, Latvia and Denmark. In a district heating system, heat is distributed through a network of hot-water pipes from heat-supplying plants to heat consumers in a single block or a whole city. The heat is mostly used for space heating and domestic hot wa‐ ter. District-heating systems range from a single development to city-wide networks. *District cooling* works in the corresponding way. *District energy* includes district heating and district cooling. District heating is sometimes called community heating, especially in the UK.

More than one-fourth of the primary energy supply in Europe becomes losses by energy conversion, mainly as heat that is wasted by electricity generation in condensing power plants. These losses are of the same magnitude as the European heat demand [1]. District heating is a means to utilise such losses, which otherwise are wasted, to cover demand for

> © 2012 Henning and Gebremedhin; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Henning and Gebremedhin; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

**Resource Utilisation**

http://dx.doi.org/10.5772/51837

measures, which reduce energy use.

**1. Introduction**

Dag Henning and Alemayehu Gebremedhin

Additional information is available at the end of the chapter

Sustainable energy group Department of Technology, Economy and Management Gjøvik University College Norway
