Solar Cells theory

Topics: Fossil fuel, Energy development, World energy resources and consumption Pages: 5 (1058 words) Published: December 5, 2013
SOLAR CELLS

Chapter 1. Introduction to solar electricity

Chapter 1.

INTRODUCTION TO
PHOTOVOLTAIC SOLAR ENERGY
Miro Zeman
Delft University of Technology

1.1

Introduction to energy consumption and production

Any change that takes place in the universe is accompanied by a change in a quantity that we name energy. We do not know what energy exactly is, we use this term to describe a capacity of a physical or biological system for movement or change. Energy comes in many forms, such as electrical energy, chemical energy, or mechanical energy, and it can be used to realize many forms of change, such as movement, heating, or chemical change. Any activity, and human activity as well, requires energy. Human beings need it to move their bodies, to cook, to heat and light houses, or to drive vehicles. Human being is a greedy consumer of energy. An active young man needs about 2500 kcal (2.9 kWh) per day to fulfil his daily energy requirements. This means the energy of about 1060 kWh per year. The present global energy consumption is around 19 000 kWh per inhabitant per year. It means that on average a man consumes about 19 times more energy than is needed for his survival and satisfactory health.

The mankind has witnessed an enormous increase in energy consumption during last 100 years. While in 1890 the energy use per inhabitant per year was around 5800 kWh it reached 20200 kWh in 1970. Since 1970 the energy use has dropped to the present level of 19000 kWh per inhabitant per year. The increase in energy use in the 20th century can be - 1.1 -

SOLAR CELLS

Chapter 1. Introduction to solar electricity

related to an evolution process that has started about five centuries ago. The underlying motivation of this process was formulated during the Enlightenment period in the 18th century as the philosophy of human progress. The aim of the process was an examination of the surrounding world and its adaptation to the needs of people whose life would become more secure and comfortable. This process was accompanied by growing industrialization and mass production, which were demanding more and more energy. At the end of the 19th century coal was the main source of energy. In this period electricity was introduced in the industrialized countries as a new and elegant form of energy. This form of energy was quickly applied on a large scale. The widespread growth of electricity use led to construction of hydroelectric plants and hydropower became an important source of energy in the first half of the 20th century.

In the period after the World War II much effort was put into the reconstruction of the society. The emphasis was directed on the growth and efficiency of the mass production. New technologies and new materials, such as plastic, were applied in the production. The energy demand was tremendously growing in this period. Oil and gas started to play an important role as energy sources in the second half of the 20th century. Coal, oil, and gas form today dominant sources of energy. These three energy sources, also known as fossil fuels, are called the traditional energy sources. In this period nuclear energy was introduced as a new source of energy. Increasing and more efficient mass production resulted in the low price of many household products. The consumption of the products grew enormously and therefore it is not surprising that we characterise today society as a consumption society. Nevertheless, it has become evident at the end of the 20th century that the philosophy of human progress that has manifested itself in a huge production and consumption of goods has a negative side too. It has been recognized that a massive consumption of fossil fuels in order to fulfil the present energy demands has a negative impact on the environment. The deterioration of environment is a clear warning that the present realization of human progress has its limitations. The emerging international environmental consciousness...
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