Industrial processes consume huge amounts of heat and steam. These may be generated by burning fossil fuels or using expensive liquid or solid fuels – all at a frequency that fluctuates considerably depending on business demand and manufacturing capability. These approaches’ sheer cost and ecological impact have led many industrial organizations to consider alternative methods for generating heat, steam, or power for their operations. Electric power generation is one option, but it is rarely used because of its high capital cost, associated maintenance costs, and low availability.
Solar Energy Applications
1. Power Generation – Solar Thermal Power Generation
The process of generating power from sunlight is known as ‘solar thermal energy’ and is similar to the process of ‘solar photovoltaic energy. STE and SPV are two forms of energy conversion: converting sunlight into electrical power. The electrical power can be stored in batteries or stored for use at a later time. Solar thermal, which involves using concentrated solar radiation, can generate up to 50-100 times more electrical power than solar photovoltaics. STE is increasingly considered an economically viable alternative to conventional fossil fuel power generation.
SPV electricity generation also has many applications for backup energy during peak hours or in cases of emergency and for remote locations not connected to the utility grid. It is also a great on-site energy source for small islands and off-the-grid communities.
2. Water Purification
Solar Water Disinfection and Purification Methods:
Various water disinfection technologies are available, involving sunlight’s ability to destroy microorganisms, such as bacteria and viruses. In the case of water purification, sunlight’s ability to create steam and disinfection chemicals can be used to eliminate harmful microbes from drinking water.
3. Distillation – Solar Distillation
Removing dissolved gases from liquids can be done using solar energy. Still, it is less efficient than other technologies, and this form of energy recovery is generally used only as a secondary method in combination with other methods. One example is the solar distillation of hydrogen gas which uses the principle of heat transfer by radiation, one of the most efficient methods for converting solar energy into useful work, especially in hydrogen production. Solar distillation is mainly used in wastewater treatment plants where water heating is a major cost factor.
4. Electrolysis – Solar Electrolysis
Electrolysis is a method for separating water into two components; oxygen and hydrogen. This process involves using electricity to break the chemical bonds of water molecules and is the opposite of electrolysis which is used to produce hydrogen from water using heat. The production of hydrogen by electrolysis involves passing an electric current through water that has been heated by sunlight.
5. Ozone Generation
Ozone Generation by Photo-Oxidation Method:
The electrolysis process can also generate ozone, a diatomic form of oxygen. This can be done either in the atmosphere’s presence or absence of oxygen. Ozone can be considered a disinfectant and has been used for many years, especially in municipal water treatment plants.
Although there are many applications for STE and SPV power generation, it is never a direct replacement for fossil fuel power, although it may assist in reducing greenhouse gas emissions. It is also important to note that although solar technology is commonly believed to be an environmentally friendly solution to our energy needs, it can also have adverse environmental impacts if not closely regulated. For example, mining raw materials such as silicon to build solar cells may cause environmental damage by using toxic chemicals and releasing particulates into the atmosphere. STE technologies also require much clean water to produce steam, and sufficient water is becoming increasingly scarce.
6. Heat and Steam Generation- Solar Heating and Cooling:
Solar heating systems, known as ‘solar thermal collectors,’ can capture and store thermal energy later in heating water or rooms. A solar thermal collector is generally a system that absorbs incident solar radiation and converts it into heat. A heat transfer medium must be used to transfer the heat from the solar collector to the liquid, air, or water that is to be heated. The HTM could be as simple as an open water tank or a more complex system of pipes containing running fluids. Solar hot water collectors heat either ‘open’ or pressurized water at high temperatures, up to 200 °C.
SWH systems are often used for residential heating and hot water. In these applications, the heat generated by the collector is transferred directly to the water using a circulating loop of piping. While SWH systems are inexpensive to build and operate, they require large amounts of clean water.
7. GeoThermal – Geothermal Energy:
Geothermal energy refers to using underground processes (in the earth’s core) to generate thermal energy that can be turned into electrical energy in a geothermal power plant. Geothermal power plants have few environmental concerns; they simply utilize natural processes in the ground as sources for their power production. The earth constantly replenishes geothermal power plants. One significant environmental concern is that, in rare circumstances, a geothermal system could be located in an area with natural methane gas deposits. These deposits may spontaneously combust when exposed to air.
8. Ocean Energy – Ocean Thermal Energy Conversion:
OTEC involves converting thermal energy present in warm ocean water into usable energy. This is done through a three-step process:
In this way, OTEC can be considered a type of solar energy since it draws heat from the sun-warmed water and turns it into mechanical work for electricity generation or desalination.
A. Operation of OTEC:
The OTEC plants are operated as closed-cycle systems with the heat produced by the solar concentrator reactor. A cold water supply and a steam turbine, which drives a generator, are used to transfer energy to the power grid. The cold water supply pumps the warm ocean water from the deep ocean to a submerged storage tank called a “false bottom.” The warm water flows from this storage tank through tubing into adjacent “solar collector” tubes, absorbing heat from incoming sunlight. Through steam pipes, its heat is transferred to both a heat exchanger and two turbine generators (one for each leg of the system).
B. Energy Use:
In recent years, several OTEC projects have been built. In the small-scale test generators, the radiation from the solar concentrator is sufficient to drive a small turbine. Heliostats focus solar radiation on the water storage tank in the larger test generators. The concentrated sunlight can raise its temperature by approximately 50 °C. This heat is used to steam boil water in a heat exchanger, and it is also used to generate electricity using two turbine generators. Both units are rated at approximately 750/kW.
C. Environmental Impact:
The environmental impact of OTEC systems has been studied extensively by academics and other researchers. Many of the environmental concerns are similar to those for solar energy.
The thermal energy from OTEC systems can be used for industrial applications. The first use of OTEC was for ocean thermal desalination. Ocean Thermal Energy Conversion is a renewable energy source that can produce power from ocean temperatures. It is energy that can be harnessed from the natural ocean processes and used in many different industries, such as seawater desalination, water remediation, direct heat exchange, and chemical production, including hydrogen.
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