Preface

The idea to prepare this book came from the intention to collect some of the experiences and solutions that are emerging in one of the timely areas of development of the energy systems – green energy. Nowadays there is more attention on the use of technologies and solutions that have low carbon emissions and reduce the presence of hazardous pollutants in the global and local environments. Green energy is a term widely used to group together all these technologies and solutions. A general definition of this term is a sustainable energy source that has zero or minimal environmental and economic impact, and can be obtained from solar, wind, hydro, geothermal, biomass, and other renewable energy sources. Green energy is considered as an important matter for technological, social, and industrial development, as well as to the global energy security. Green energy minimizes the negative effects of global emissions from electricity production and fossil energy resources, reduces the greenhouse effect, thereby offering a great opportunity for satisfying clean energy requirements in residential, industrial, agricultural, and commercial applications.

Significant impacts occur at the local system level, as well as for energy integration in network-based solutions. Remarkable aspects include the evolution of the buildings in to more energy efficient solutions, considering individual or grouped zero-energy buildings supplied by green energy. The increase of green energy use in the future has a positive influence on the economic increase and sustainable evolution of the society. In this case, a key element for the link between society and nature is the sustainability of green energy development and supply. Another important element to raise the life standard of people in a country is the use of low-cost green energy to support technological growth and industrial production. For this reason, researchers all over the world are involved in analysing different global stability scenarios and green energy strategies to promote and intensify the use of green energy sources and their impacts on energy security.

The essential features of the green energy sources include their compatibility with the environment, which makes these sources attractive for widespread utilisation in the context of sustainable development, while also avoiding the growth in carbon emissions and deforestation. A further main reason for wider adoption of green energy sources and technologies with great influence on sustainable development is the flexibility of their utilisation, which can be achieved in combination with appropriate storage solutions in order to mitigate the effects of the green energy source uncertainty. From the social point of view, the utilisation of local resources offers advantageous solutions and benefits to small remote areas that are not connected to the grid. In this way, the traditional paradigm of electrification coming from wide network structures can be revisited by providing electrification from local energy systems supplied with green energy, which can evolve to gridconnected systems through their integration into micro-grids.

Most of the concepts indicated above are addressed in the chapters of this book. The contents are presented by conceptually proceeding from small solutions to large energy systems:


**V**

book chapters.

This book contributes to understanding the development and application of green energy solutions. The editor wishes to thank InTechOpen for the opportunity given to prepare the book, and all the authors for the insightful contents included in their

**PhD Diana Enescu**

Targoviste, Romania

Valahia University of Targoviste,

This book contributes to understanding the development and application of green energy solutions. The editor wishes to thank InTechOpen for the opportunity given to prepare the book, and all the authors for the insightful contents included in their book chapters.

> **PhD Diana Enescu** Valahia University of Targoviste, Targoviste, Romania

**IV**

Most of the concepts indicated above are addressed in the chapters of this book. The contents are presented by conceptually proceeding from small solutions to large

• Green energy harvesting indicates how to extract even small amounts of energy from different physical phenomena and convert them into electrical energy. Chapter 1 addresses the specific case of thermoelectric energy harvesting, which exploits temperature differences through the Seebeck effect to provide

• At the building level, considerable attention is given to reach the situation in which the building design and the contribution from local renewable energy sources will enable the construction of zero-energy buildings. Chapter 2 illustrates various aspects of the development of zero-energy buildings, starting from the definitions and addressing the design criteria for stand-alone or gridconnected solutions, the effects of possible incentives, and the uncertainty on

• The increase in the energy efficiency of the buildings has to be considered together with other objectives, in particular when the buildings are constructed in critical environments such as in seismic areas. Chapter 3 presents an integrated approach to improve the seismic performance and to reduce energy losses

• The mitigation of the effects of uncertainty in renewable energy generation can also be achieved by exploiting storage solutions. Chapter 4 deals with the development of a smart battery management system used in a grid-connected photovoltaic system with storage for residential users. The selection of the best strategy to discharge the batteries, based on the electricity consumption and production forecasts, aims at reducing the peaks of power absorption from the

• The evolution of renewable energy sources and storage technologies is leading the transformation of the consumers into prosumers with potential capabilities to manage their local energy systems. Chapter 5 overviews energy management aspects and standards, and discusses the evolution of local electrical energy systems with their complex interactions addressed through the Internet to ensure energy efficiency, low emissions, power quality, and secure energy

• In the agricultural context, energy sustainability can be improved by the adoption of clean biomass technology. Chapter 6 addresses the usage of biomasses from agricultural wastes to reduce deforestation. The recycling of waste products from the rice industry is discussed under the prospect of contributing to the creation of a circular economy with the production and commercialization

• On the global system side, different climate change policies and incentives have been applied to reduce greenhouse gas emissions. Chapter 7 reports on the experience of the largest Brazilian power trader in the development of voluntary certifications associated with energy trading, which take into account the electrical

energy provided by using only renewable energy sources.

energy systems:

grid.

trading.

of rice husk briquettes.

electricity in small-scale applications.

the local renewable energy production.

of the buildings at the same time.

Chapter 1

Applications

Diana Enescu

Abstract

Thermoelectric Energy

energy harvesting and their low-power applications.

1. Background about energy harvesting

between the two terms are presented in Table 1.

energy required.

1

thermoelectric materials, design, low-power applications

Keywords: thermal energy, Seebeck effect, thermoelectric generator,

Energy harvesting represents the energy derived from ambient sources that is extracted and directly converted into electrical energy. This way to provide energy is further used when another energy source is not available (off-grid use) to supply small- and medium-sized electronic devices, as well as electrical systems, with power from nW to hundreds of mW [1, 2]. Generally, energy harvesting refers to an environment with regular and well-assessed ambient energy sources. Energy harvesting is applied when there is a match between the available energy and the

Another term, energy scavenging, refers to an environment with strong nonuniform and unknown ambient energy sources [3]. Some examples of differences

ent, electromagnetic radiation, light, motion and chemical energy (Figure 1).

The ambient energy sources used for energy harvesting are temperature gradi-

Harvesting: Basic Principles and

Green energy harvesting aims to supply electricity to electric or electronic systems from one or different energy sources present in the environment without grid connection or utilisation of batteries. These energy sources are solar (photovoltaic), movements (kinetic), radio-frequencies and thermal energy (thermoelectricity). The thermoelectric energy harvesting technology exploits the Seebeck effect. This effect describes the conversion of temperature gradient into electric power at the junctions of the thermoelectric elements of a thermoelectric generator (TEG) device. This device is a robust and highly reliable energy converter, which aims to generate electricity in applications in which the heat would be otherwise dissipated. The significant request for thermoelectric energy harvesting is justified by developing new thermoelectric materials and the design of new TEG devices. Moreover, the thermoelectric energy harvesting devices are used for waste heat harvesting in microscale applications. Potential TEG applications as energy harvesting modules are used in medical devices, sensors, buildings and consumer electronics. This chapter presents an overview of the fundamental principles of thermoelectric
