Solar Thermal Power Integrated System for Power Generation

In light of fossil fuel consumption’s negative impact on the environment, renewable energy sources have a unique chance at growth and improvement. Solar energy attracts the most attention among renewable energy sources, and several studies have examined how solar energy can be used in the generation of electricity. Researchers have reviewed solar energy technologies to determine the most effective options for electricity generation. Solar thermal power can be used directly or indirectly to generate electricity. The direct method involves the use of PV modules to convert solar irradiation into electricity. Direct methods, such as linear Fresnel collectors and parabolic trough collectors, are used to harvest thermal energy. Indirect methods use concentrated solar power plants (CSP).

Solar Thermal Power- An Overview

An overview of solar thermal technologies such as trough collectors, linear Fresnel collectors, central tower systems, and solar parabolic dishes is presented as well as possible barriers and opportunities. In addition, PV power generation units are compared to solar thermal power plants. In accordance with published studies, PV-based systems are more suitable for small-scale power generation. Comparatively to CSP-based systems, they can also generate more electricity in a given area. CSP plants, however, provide a better economic return due to their economic efficiency.

In other words, Solar thermal power plants use the sun’s energy to heat a fluid to high temperatures in order to generate electricity. Heat is transferred from the fluid to water, which is then converted to superheated steam. In a power plant, steam is used to turn turbines and generate mechanical energy, which is then converted into electricity. Essentially, this is the same as electricity production using fossil fuels, but instead of burning fossil fuels, steam is heated through sunlight.

Passive systems and active systems are two types of systems that collect and store solar radiation. Active systems include solar thermal power plants. Unlike solar power plants, which use only solar energy, most fossil fuel plants use fossil fuels as a means of supplementing output when necessary.

solar thermal power
solar thermal power

Two Types of Solar Thermal Power Integrated Plants

Despite the fact that there are multiple types of solar thermal power plants, they are all similar in that they use mirrors to reflect and concentrate sunlight. Solar energy is now converted to heat energy, which runs a generator and creates steam. This system creates electricity.

Parabolic Troughs

These troughs, also known as line focus collectors, are made out of a long, parabolic-shaped reflector that focuses incident sunlight onto a pipe running down the trough. To ensure maximum solar energy reaches the mirrors, the collectors often track the Sun as it moves from east to west with a single-axis solar tracking system. As the trough focuses the Sun at 30-100 times its typical intensity, the receiver pipe in the centre can reach temperatures of up to 400 degrees Celsius.

The troughs are arranged in rows on a solar field. As it passes through the pipes, the heat transfer fluid in the parabolic trough is heated. Afterwards, the fluid is returned to heat exchangers, where the heat is transferred to water and steam is generated under high pressure. This steam then drives a turbine, which drives a generator, which generates energy. In the end, the heat transfer fluid is cooled and returned to the solar field. These solar collectors can replace a water heater for residential water heating, possibly saving money over time. A large number of these collectors can be assembled in an array and utilised to generate electricity in solar thermal power plants, as well as in-home settings.

Parabolic Dishes

They are enormous parabolic dishes using motors to track the Sun. By doing this, the dishes receive the maximum amount of solar energy, which then is focused on the dish’s focal point. The fluid passing through these dishes may reach temperatures of up to 750°C, which is far higher than that passed through parabolic troughs.

A Stirling engine converts heat to mechanical power in these systems by compressing cold working fluid and enabling the heated fluid to expand outward in a piston or move through a turbine. By using a generator, mechanical energy is then converted to electricity.

Solar Power Towers

Large towers that operate as central receivers for solar energy are known as solar power towers. They are standing, along with a vast array of mirrors, which concentrate the sun’s rays on a single point in the tower. Heliostats are a massive array of flat, sun-tracking mirrors. In the tower, a mounted heat transfer warms the heat exchange fluid. The heat condensed to this point could be 1500 times more intense than incident sunlight. The hot fluid is subsequently turned into steam, which powers a turbine and generator to generate energy. These towers have the disadvantage of having to be extremely large in order to be cost-effective.

Operation of Solar Thermal Power Tower

A solar power tower as briefly mentioned above is one of the key components of a solar power plant. This tower stands in the midst of a dazzling arrangement of mirrors. These mirrors can be curved or flat, but because flat mirrors track the Sun are less expensive than curved mirrors, they are commonly used. These mirrors “capture” the incident sunlight and reflect it back to the solar tower as they track the Sun. A vast number of these mirrors focus a lot of solar radiation onto a small place on the tower called the receiver, which heats up some fluid within. The heat from the sun is transferred to the water via this fluid. Because of their greater heat transfer and energy storage capabilities, contemporary designs use molten salts instead of steam as a heat transfer fluid. Steam is formed when heat is transmitted to water. This steam is then sent to a traditional turbine, which generates power. It’s worth noting that these solar power towers are heat engines, as they convert the energy from being hot in relation to their surroundings into motion. The heat source (the Sun) is apart from the fluid that flows and performs work; hence these solar power towers are external heat engines.

External combustion occurs when sunlight heats a fluid, which is subsequently converted to steam and used to spin a turbine.

Industrial Thermal Demand

The temperature ranges for industrial heating can be divided into three categories. All of these are feasible with solar power.

Everything below 80 degrees Celsius falls into the lowest temperature range. Solar collectors that can withstand these temperatures are currently available on the market. The medium temperature range is between 80 and 250 degrees Celsius. While the number of collectors capable of meeting this degree of heat demand is limited, they do exist and are on the point of being commercially viable.

Many sectors can currently benefit from low and mid-temperature solar thermal collectors that are commercially accessible. They’re especially well-suited to the food, beverage, textiles, paper, and pulp sectors’ heating requirements. Sterilization, pasteurisation, drying, hydrolysing, distillation and evaporation, washing and cleaning, and polymerization are all processes that can benefit from the flat plate and evacuated tube Collectors since they do not require high temperatures.

A Short Look on Advantages and Disadvantages of Solar Power

The conversion of heat energy to electricity is more efficient since these systems can generate steam at such high temperatures. Furthermore, these plants circumvent the problem of inefficiently storing power by storing heat instead. Heat storage is more efficient and cost-effective than electricity storage.

These plants can also provide dispatchable baseload energy, which is essential since it means they can produce a consistent quantity of energy and can be turned on or off as needed to satisfy society’s energy demands.

Furthermore, solar thermal power plants are a sort of electricity-producing technology that is cleaner than using fossil fuels to generate electricity. As a result, these are some of the most environmentally friendly ways to generate electricity. Despite this, these plants have linked environmental implications, as a comprehensive life cycle analysis may reveal all associated carbon dioxide emissions associated with their construction. However, emissions are still significantly lower than those from fossil fuel facilities.

The vast amount of acreage required for these plants to run successfully is one of the disadvantages. Furthermore, the water consumption of these plants can be viewed as a problem, as the creation of sufficient steam necessitates enormous amounts of water. Another possible consequence of the use of huge focusing mirrors is the harm that these plants cause to birds. Birds that fly in the path of the Sun’s focussed rays can be killed. According to some studies, almost one bird dies every two minutes at power facilities like these.

Conclusion

To summarise, solar energy is a widely used electricity generating technology, and various solar power generation technologies can meet the various solar power generation needs of the community and regions. Solar thermal power generation technology, for example, avoids the costly silicon photoelectric conversion process, which can significantly reduce the cost of solar power generation. Simultaneously, the output power of solar-thermal power generation is continuous and stable, with the potential to become baseload power. Among them, the technology of trough Solar-thermal power generation system has matured, making it applicable to the broadest range and essentially commercialised.