Application of Green Technology for Energy Conservation and Sustainable Development

E. P. APARNA¹’ and K. S. DEVAKY²

'Research Scholar, School of Chemical Sciences,

Mahatma Gandhi University, Kottayam, Kerala, India

²Professor, School of Chemical Sciences, Mahatma Gandhi University, Kottayam, Kerala, India

'Corresponding author. E-mail: This email address is being protected from spam bots, you need Javascript enabled to view it

ABSTRACT

In the modem era of technology, energy conservation and environmental protection is the most burning global issue, and it has a major role in our everyday life. Minimal use of fossil energy can be attained through energy preservation and the novel ideas and practical use of renewable energy like sunlight, wind, water, tides, geothermal heat, and so on. As Einstein said, “Neither energy can be created nor destroyed, rather we can alternate.” The present chapter discusses the potentials of green technology to solve problems related to conventional energy sources in the environment.

INTRODUCTION

The demand for power has been increasing globally though utilization is faster than its production. For instance, the most common energy resources are coal, oil, natural gas, and so on, and are being formed through thousands of years of natural process.¹-² Most of these energy resources are limited and could not be reused or renewed. A proper conception of energy helps to decrease its requirement, and thereby saving one unit of energy is equivalent to the creation of two units. In fact, every energy production, one way or another, adversely affects the nature; hence, the reduced production helps to save our environment.^3,4

Energy preservation is a best exercise to lessen energy usage resourcefully or by reducing the utilization of energy sendee. It is the process that reduces pollution by utilizing natural energy. It also reduces energy cost and saves the conventional energy resources by using renewable resources.^4-6 Renewable resources are natural resources which are refilled by natural production or other frequent processes in a fine time frame. Energy can be preserved either by decreasing the wastage and loss or by improving the effectiveness through advanced technologies, operation, and maintenance.^{7 8} The current chapter descr ibes the different dimensions of energy conservation.

USE OF ENERGY FROM RENEWABLE RESOURCES

12.2.1 SUN: AS A SOURCE OF ENERGY

Sunlight is an important renewable energy source. There are two groups of light energy: active and passive. Photovoltaic cell is used in active technology, while harvesting solar light in passive energy systems.⁹ The amount of energy obtained from all the nonrenewable resources such as coal, oil, natural gas, and so on is about half the amount of solar energy reaching the surface.¹⁰ Electricity-generating photovoltaic cell displaces all other energy sources and reduces the release of potentially harmful emissions and toxic substances into the environment. The first photovoltaic cell. Si-based, was produced in 1970s.⁸ These cells were produced using doping technology.

An efficiency of 32% is shown by silicon photovoltaic cells in terms of total energy conversion. They can only take up energy from sunlight. Tlrin- film cells are the second-generation solar cells. They contain thin films of various semiconductor materials placed onto substrates, yielding more efficient, thinner, and flexible cells. Amorphous silicon, cadmium telluride, and copper indium gallium selenide are the key materials used in commercial thin-fihn photovoltaic cells.¹¹

The third-generation solar cells are more efficient, safer, and cheaper to produce. Examples include perovskite solar cells based on hybrid perovskite structured crystals such as methylammonium lead iodide and other compound halides.¹² These materials can be produced at lower temperatures and absorb light well. These are also cost-effective since they are made from commonly available industrial chemicals. Gallium arsenide is another material used to improve solar cell efficiency. Gallium arsenide solar panels are primarily used on spacecraft.

Nanomaterial-based solar technologies are also developing. Based on the particle size, the bandgap of nanoparticle can be changed, which greatly affects the properties of solar cells. Examples of these semiconductor materials are cadmium sulfide, cadmium selenide, lead sulfide, and others. Conversion of infrared radiation into visible light can be achieved by upconverting phosphor nanoparticles doped with rare-earth elements. Transparent bifacial cells, tandem cells, and solar thermophotovoltaic devices are emerging technologies to boost the efficiency of photovoltaic cells.¹¹

12.2.2 WIND ENERGY

Electricity can be produced by using wind. Turbines are driven by the wind and thereby ensure the proper working of generator that produces electricity, which is considered as a dependable source of energy, and it has less adverse effect on the environment. The wind is an intermittent energy source which cannot release on demand. It varies with time, climate, and so on. As the quantity of wind power in a region increases, more conservative power sources are needed to back it up. Power management methods like releasable power sources, importing and exporting power to neighboring areas, hydroelectric power, energy storage, or reducing demand when wind production is low can in many cases overcome these problems.^13-16

Wind power does not need fuels and fuel costs. The price of wind power is much more stable than the prices of fossil fuel sources. The marginal cost required for the construction of wind station can be reduced by improved turbine technology. The length and weight of the turbine blade improve the performance and increase the production of power in a lesser capital investment and maintenance. Using fossil fuels release toxic elements into the environment on a larger scale compared to wind energy. Habitat disturbances by the turbine generator sound are the available, reported disadvantage of wind energy.¹⁷

12.2.3 HYDRO ENERGY

Hydro energy is also called hydroelectric power, which is produced from water. According to statistical calculations, the amount of electricity generated by hydropower is expected to grow about 3.1% by each year for the next 25 years.¹⁸¹⁹ This method of producing electricity is relatively cheap compared to gas or coal plants. Depending on changing energy demands, the dam and reservoir help to produce the required amount of electricity by using the stored water; by this way, the flexibility of electricity production can be achieved. Here the start-up time of turbines is lesser than any other electricity plant.

The mam benefit of the conventional plant is to store water at a cheaper rate for release later as electricity. Hydroelectric stations have long economic lives. Operating labor cost is frequently low. Since hydroelectric dams do not require fuel, power generation does not produce any toxic gases. The same amount of electricity produced by hydroelectric projects and through this 3 billion tons of C0₂ emissions instead of making electricity through fossil file Is. The low greenhouse gas impact of hydroelectricity is found chiefly in temperate climates. These hydroelectric power stations work by using the potential energy of water stored in a specific height; hence, they do not require fuels and chemicals, and they do not release any kind of toxic elements into the environment, thus reducing the emission of CO,, methane, and any other kind of greenhouse gases. Environmental impact of hydr oelectric stations is lesser than any other electric plants.²⁰

The major disadvantages associated with hydroelectric projects are as follows: ecosystem damage and loss of land, water loss by evaporation, siltation and flow shortage, methane emissions, and relocation of the people living where the reservoirs are placed. The construction of hydroelectric power stations requires large areas of land but nuclear stations required a small area. The main disadvantage of the hydroelectric station is that the dam may act as a water bomb which cannot be controlled, whereas the nuclear power station failure can reduce quickly; meanwhile, the cost difference varies on a larger scale. Hydroelectricity along with other sources can achieve an adequate amount of electricity in all seasons. The failure of a hydroelectric power station is much danger than the failure of a nuclear power station. However, nuclear power can reduce its output reasonably quickly. Since the cost of nuclear power is higher due to high infrastructure costs, the cost per unit energy goes up significantly with low production. But hydroelectricity can supply power at a much lower cost. Thus, hydroelectricity is a complement to other sources of energy. Compared with wind power, the easily regulated character of hydroelectricity is used to compensate for the intermittent nature of wind power. In some cases, wind power can be used as additional to water for later use in diy seasons.²¹-²²

12.2.4 TIDAL ENERGY

Tidal power is produced by the conversion of energy from tides to electricity. Among various types of renewable energy, tidal energy has a comparatively high cost and limited availability of sites with adequately high tidal ranges. By new technologies, the availability of tidal power could be increased, and economic and environmental costs are decreased. The energy associated with the tidal flow can be easily converted into electricity with the aid of a tidal generator. The selection of a site for tidal power generation mainly depends on the tidal variation and tidal current velocities present at that particular place.

The following are the main challenges of tidal power. Tidal power affects the marine life. The turbines may adversely affect the swimming life in the sea. The advanced application like switching off the turbine immediately after detecting any animals entering the turbine causes energy loss. To ensure the security of marine animals is essential while placing the tidal generator in water. The breeding stream of migrating fishes is also disturbed by the tidal energy generator. The same acoustic concerns apply to tidal barrages. Environmental concerns are the damages by the turbine blade to marine animals and its sound, which are limited to a small area and do not affect the entire bay.²³

Another challenge is the corrosion of metal parts due to saltwater. Nickel alloys, titanium, and stainless steel materials prevent corrosion. Mechanical fluids such as lubricants can be leak out into the sea, which is harmful to the marine life. Proper maintenance can minimize the leakage of harmful chemicals. Tidal energy is not used as a popular source of energy due to its initial setting up cost. Researches are going on to reduce the price of tidal energy. One such approach is the application of the orthogonal turbine, a simplified design that offers considerable cost savings. The water is 800 times denser than air, and the unsurprising and regular nature of tides makes a predominantly striking source of energy. Regular screening is the key step for reducing the cost.

12.2.5 GEOTHERMAL ENERGY

The power obtained from geothermal energy is known as geothermal power. Major technologies involved in geothermal energy production are flash steam power stations, diy steam power stations, and binary cycle power stations. The heat extraction in geothermal energy production is small compared with the heat produced from earth and thus considered as a sustainable and reusable form of energy. Geothermal electric stations emit lesser greenhouse gases compared with conventional coal-fired plants. These power stations are analogous to other thermal power stations as heat is used for heating water or another working fluid. The steam produced from the working fluid turns the turbine of a generator, thereby producing electricity. The various types of geothermal power stations include diy steam stations, flash steam stations, binary cycle power stations, and so on.

Dry-steam stations'. Diy steam stations are the simplest and oldest. A large amount of diy steam is required for the proper working of this type of power station. Therefore, diy steam station is not found veiy often. Such power stations are simple but very resourceful. Geothermal steam (temperature > 150 °C) is the main fuel in such power stations. After rotating the turbine, the steam is emitted to a condenser. The steam then is reformed as liquid form and chills the water. Then the cold water carries condensate into deep wells through the pipe.

Flash steam stations: Highly pressured, well heated, water injects into the tank with lower pressure which helps to drive the turbines. The tempera- hire of fluid is around 180 °C. Flash steam stations use groundwater having temperatures greater than 182 °C. This high temperature is sufficient to generate adequate pressure required for the upward flow of water through the wells. The upward flow reduces the pressure, and a certain amount of steam is produced by hot water. The steam is used for power generation. Both existing water and compressed steam sent back to the reservoir, completing the circle sustainably.

Binary cycle power stations: Binary cycle power stations are recently developed. The fluid used here has a low temperature of about 57 °C. The secondary fluid vaporized by this fluid drives the turbines. These kinds of power stations are existing commonly. Both organic Rankine and Kalina cycles are used in binary cycle power stations.²⁴ An efficiency of 10-13% is shown by this type of power station.

The main environmental impacts of geothermal power are as follows: The deep earth fluids contain certain gases like carbon dioxide, methane, hydrogen sulfide, radon, and ammonia. The release of those gases might cause global wanning and acid rain. From a theoretical point of view, the geothermal stations release back these gases into earth’s atmosphere by C capture and storage. In addition to these gases, hot water from geothermal sources may contain toxic chemicals like boron, mercury, arsenic, antimony, and so on. Release of these can cause environmental damage. Geothermal station building can harmfully affect land stability. Geothermal stations can generate earthquakes due to water injection. Minimum use of land and water is the major advantage of geotheimal stations. It does not require fuel. The capital cost of the geotheimal station is high.²⁵