Physics of solar energy and its applications - Solar Energy Sciences and Engineering Applications - page 3

are also expected to contribute a bigger part of the increase of energy demand. The
rapid demand for conventional energy sources has created a geopolitical energy tension
due to the sizable amount of energy supply from major energy producing countries and
regions instead. It is expected that the Middle East and Russia will play a major role
as global energy producers.
The increase of greenhouse gas emissions is attributed to the increase of carbon-
based energy consumption. With rapid demand for coal for power plants and oil
and gas for transportation and other sectors, greenhouse gas emissions are increasing.
The report of the Intergovernmental Panel on Climate Change (IPCC) shows that the
increase of the global temperature is caused by the increase of greenhouse gas emissions
(IPCC). As global warming and climate change have tremendous and complex effects,
they will have greater significance for human survival. Therefore, minimization of
greenhouse gas emissions without stifling the demand for progress and human comfort
is crucial.
The reduction of greenhouse gas emissions is possible through reduction of the con-
sumption of conventional energy resources. The reduction of the use of conventional
energy resources is achievable by the means of energy efficiency, energy conservation
and utilization of renewable energy sources. Existing processes, devices and opera-
tions can be energy efficient through application and development of new and novel
technologies with the aid of basic sciences. The energy conservation measures are pos-
sible through the combined application of the passive (natural) and active (artificial)
methods, of which in previous and present times active methods have dominated.
Utilization of renewable energy sources, particularly solar energy which is available
in most parts of the planet, can be advanced through investigation of the existing
equipment, processes and sources of energy and energy requirements which can be
alternatively sourced from solar energy. In this scenario, demand for and consumption
of conventional energy sources or carbon-based energy sources will gradually decrease,
resulting in the reduction of greenhouse gas emissions.
1.3 SOLAR ENERGY UTILIZATIONS
In the modern world, cities and other modern facilities are operated using electrical
energy. This is because of easy and simple transmission and storage of electrical energy
in different forms. In this situation it is expected that demand for electrical energy will
increase in future generations.
Electricity production through solar energy is being achieved in two major
processes - solar thermal and solar-photovoltaic. Solar thermal power plants employ
concentrating solar collectors to produce high temperatures by focusing solar energy
in order to produce steam for power plants. Solar-photovoltaic power plants employ
semiconductor materials to convert radiant energy photons to electrons to produce
electricity. The two technologies have both advantages and disadvantages depending
on the point of view of the user. However, as solar energy is free and clean, the uti-
lization of solar energy for electricity production is compelling and offers both energy
security and environmental benefits.
There are many biological processes in which thermal energy is a requirement
and which are called endothermic processes. In endothermic processes, the thermal