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What Is Concentrated Solar Power?

2022.08.08     From: helioscsp

What exactly is concentrated solar-thermal power (CSP) and how does it work? Mirrors are used in CSP technologies to reflect and concentrate sunlight onto a receiver. In the receiver, the energy from concentrated sunlight heats a high-temperature fluid.



This heat, also known as thermal energy, can be used to generate electricity by spinning a turbine or powering an engine. Water desalination, increased oil recovery, food processing, chemical production, and mineral processing are just a few of the industrial applications.


Utility-scale projects often employ concentrated solar-thermal power systems. Utility-scale CSP plants can be set up in a variety of methods. Mirrors are arranged around a central tower that serves as the receiver in power tower systems. Linear systems use rows of mirrors to focus sunlight onto parallel tube receivers that are positioned above them.


Smaller CSP systems can be installed just where electricity is needed. Single dish/engine systems, for example, can produce 5 to 25 kilowatts per dish and can be employed in distributed applications.



What does concentrated solar power imply?


CSP (concentrated solar power) is a method of generating electricity in which sunlight is reflected, concentrated, and focused into a single point using mirrors. The concentrated light is transformed into heat, which is then used to produce steam. The steam is then utilized to power a turbine, which produces electricity.


Solar electricity is stored using CSP technology and can be used on overcast days and in the hours after sunset or before sunrise. CSP is still a relatively new method of generating electricity, and it is most typically employed in utility-scale projects as of this writing.


The ability of concentrated solar power (CSP) to store thermal energy has made the renewable energy source particularly attractive in the United States Sun Belt region. Georgia, South Carolina, Alabama, Mississippi, Louisiana, New Mexico, Arizona, Nevada, and Texas are all part of the Sun Belt region, which stretches from California to Florida and includes Georgia, South Carolina, Alabama, Mississippi, Louisiana, New Mexico, Arizona, Nevada, and Texas.


For nearly 15 years, CSP facilities have been reliably functioning in the United States. The Crescent Dunes power plant, for example, was built with US Department of Energy (DoE) money in the 1990s in the Mojave Desert, which stretches through southeast California and southern Nevada. Molten salt is used as a heat transfer fluid and storage medium in the power plant, resulting in increased efficiency and cost-effectiveness.



Key requirements for concentrated solar power


The successful construction of a concentrated solar power system depends on a number of criteria. The following are the most important requirements:


  • Appropriate funding CSP technologies and systems are costly. Obtaining sufficient project funding can be challenging, but it is vital.
  • Water sources – CSP systems require access to a water source for cooling as well as cleaning the collection and mirror surfaces. In order to maximize efficiency in the generation of electricity and water conservation, CSP plants can use wet, dry, or hybrid cooling systems.

  • High solar radiation locations – For optimal concentration of the sun’s energy, the light must be bright and not too spread out. The direct normal intensity (DNI) of the sun’s energy can be used to determine the focus of sunlight. The sun’s DNI is higher in the Sun Belt than anyplace else in the United States, implying that CSP output potential is higher here than anywhere else.

  • While the actual amount of land required by a CSP plant varies depending on the technologies employed, CSP plants typically require five to ten acres per megawatt (MW) of capacity.

  • The area used for CSP must be appropriate for electricity generation as well as provide access to an increasingly stretched and ageing transmission grid. Utility-scale projects will also need high-voltage transmission lines to transport electricity from the CSP system to the end consumer.


Types of concentrated solar power systems


To focus sunlight onto the receiver situated at the focal point of the dish, parabolic dish systems use u-shaped or parabolic mirrored dishes about 10 times the size of a domestic satellite dish. This receiver is built inside a high-efficiency external combustion engine that uses tubes that carry hydrogen or helium gas and open into the four piston cylinders.


The focused sunlight heats the gas in the tubes to severe temperatures, causing the hot gas to expand within the cylinders as it passes through the receiver. This expanding gas drives pistons, which spin a crankshaft, which drives the generator, which generates energy.


In a parabolic dish system, the receiver, engine, and generator are all merged into a single unit that is situated at the mirrored dish’s focal point. The dish system, similar to a tracking array, tracks the sun’s motion across the sky in order to catch the maximum amount of solar energy.


U-shaped mirrors with oil-filled pipes running along the focus point are used in parabolic trough systems. The mirrors face the sun and concentrate the light onto the pipes, which heats the oil inside to temperatures of up to 750 degrees Fahrenheit. The heated oil is then used to boil water and generate steam, which powers turbines and generators.


Long parallel rows of flat mirrors are used in compact linear Fresnel reflector systems, which are less expensive than curved reflectors in the parabolic trough system. The small linear Fresnel system’s flat mirrors concentrate sun light onto raised receivers with a cluster of tubes filled with flowing water. The concentrated sunlight is utilized to boil water, resulting in steam that can be used to generate electricity.


Many enormous, flat mirrors track the sun and focus the solar energy onto a receiver in power tower systems, also known as central receivers. The receiver in this system sits atop a tall tower and catches sunlight, which is then used to heat fluids like molten salt, which may reach temperatures of up to 1,050F. The heated fluid can either be used right away to generate steam and energy, or it can be stored and conserved for later use.


Benefits of concentrated solar power


One of the key advantages of solar power systems is the decrease of carbon emissions. Other advantages include:


  • Renewable energy sources are domestic, whereas oil and gas supplies are concentrated in certain places. A broad energy supply given by domestic energy sources throughout a country increases energy security and adds to a long-term energy plan that can shield the power supply from market volatility and vulnerabilities. Reduced reliance on imported energy and the replacement of foreign energy with reliable, clean home electricity can boost local economies while also boosting energy security.

  • Long-term dependability – Solar power facilities are designed to last 25 to 30 years on average. The plant’s operator should be aware that the technology and equipment will require maintenance, refurbishment, and replacement over time. Each improvement is projected to be more cost-effective and efficient. As a result, long-term dependability is built because the renewable energy source produces electricity for a long period while improving efficiency.

  • Prices are becoming more competitive – While the cost of gas, fossil fuels, and other energy sources continues to fluctuate between locations, the cost of renewable energy has been steadily declining. The solar business has seen the biggest price decline, with prices plummeting by about 80% in the last seven years. As a result, solar power is a less expensive and more efficient energy source.


History of concentrated solar power


The concept of concentrated solar power was first discovered by Archimedes in 214-212 BC, according to Greek mythology. He devised a defense strategy that involved men utilizing bronze shields to focus sunlight onto invading Roman ships, causing the ships to catch fire. August Mouchout used a parabolic trough system to heat water and make steam in order to run the first solar steam engine in 1866, which was the first documented usage of CSP.


Frank Schuman, a Philadelphia inventor, installed a parabolic trough system in a tiny farming village in Meadi, Egypt, in 1912.


The troughs were used to generate steam, which was then utilized to power massive water pumps that could supply 6,000 gallons of water per minute to broad desert areas.


Professor Giovani Francia established the first operational CSP plant in Sant’Ilario, Italy, in 1968. A power tower system was used at the plant, which was encircled by a field of additional solar energy collectors.


Solar One was founded in 1982 by a group of solar industry organizations and the US Department of Energy. Solar One was a 10 MW power tower system demonstration project that proved the system’s viability and functioning.


In Kramer Junction, California, the world’s largest solar power complex was inaugurated in 1986. The method focused solar light onto a system of pipes and heated the transfer fluid inside using rows of mirrors. The steam generated fueled a turbine, which generated electricity.


Solar Two, a project that was supposed to be an upgrade on the Solar One power tower project, was developed between 1996 and 1999 by the US DOE and a group of solar industry companies.


Future of concentrated solar power and space-based solar power


Concentrated solar power continues to develop in terms of use and accessibility because to advancements and inventions. CSP systems are constantly improved and used, allowing them to run at higher efficiency and power a wide range of utility-scale projects.


The utilization of space-based solar power has been studied since the mid-twentieth century (SBSP). SBSP refers to the idea of capturing solar energy in space and then transferring it to Earth or other planets for use as electricity. SBSP has the potential to solve the global greenhouse effect with low environmental impact.


Using concentrated solar electricity as part of an SBSP system is one option. These SBSP systems use mirrors to focus solar radiation, which heats a liquid and drives a turbine, which generates electricity.


The high expense of procuring and shipping all of the necessary materials is one impediment to extensive development and implementation of space-based solar power systems. SBSP has the potential to offer consistent, clean, and reliable power at lower rates, but it will take many years of development, testing, investment, and successful installations before the system can begin to recoup its original expenditures.


What are the workings of concentrated solar power systems?


Mirrors are used in Concentrating Solar Power (CSP) technologies to focus (focus) the sun’s light energy and convert it to heat, which is then used to drive a turbine that creates electricity.


CSP technology makes advantage of concentrated sunlight. CSP plants generate electricity by concentrating (focusing) the sun’s energy and converting it to high-temperature heat using mirrors. The heat is then transferred to a traditional generator. The plants are divided into two sections: one that absorbs solar energy and converts it to heat, and the other that transforms heat energy to electricity. The Department of Energy’s Solar Energy Technologies Web site has a short video that explains how concentrating solar power works (using a parabolic trough system as an example).


CSP facilities have been operating reliably in the United States for more than 15 years. When used to generate energy at commercial scale, all CSP technical approaches necessitate enormous areas for solar radiation gathering.


Trough systems, power tower systems, and dish/engine systems are three different technological techniques used in CSP.


What’s the difference between solar photovoltaics (PV) and concentrated solar power (CSP)?


  • Photovoltaic (PV) systems use semiconductor-based PV cells to convert sunlight directly to electricity.

  • Using reflecting structures such as troughs or mirror panels, concentrating solar power (CSP) systems focus the sun’s energy to produce heat, which is then utilized to generate electricity.

  • Solar water heating systems have a solar collector facing the sun that either heats water directly or heats a storage tank “The “working fluid” is then utilized to heat water.

  • Solar collectors that have been vaporized, or “The use of solar energy to preheat ventilation air for a structure is known as “solar walls.”


Where does concentrated solar power come into play?


CSP is utilized to assist power an electricity system in utility-scale applications. They can be used in conjunction with energy storage technologies to store thermal energy for use when the sun’s irradiance is low, such as at night or on a cloudy day.


Where does concentrated solar power come into play?


CSP is utilized to assist power an electricity system in utility-scale applications. They can be used in conjunction with energy storage technologies to store thermal energy for use when the sun’s irradiance is low, such as at night or on a cloudy day.


In any case, both CSP and PV contribute to the growth of the solar industry. They are the ones who made solar power conceivable, and they are the ones who will ensure that solar power is here to stay.


The advancement of the technology linked with solar power energy has resulted in a surge in its appeal. After all, once people understood the sun could be utilized to generate power, they would naturally look for ways to do it. So far, there are just two technologies that are currently employed to create solar energy. Concentrated Solar Power (CSP) and Photovoltaic (PV) are two of them (PV).


What are the benefits of solar power that is concentrated?


Due to the utilization of a traditional, rotating turbine that adds inertia to the grid, CSP also provides crucial grid stabilizing qualities. Utilities and independent system operators (ISOs) are responsible for satisfying customer energy requests, and utilities must guarantee that the grid remains stable when energy demands fluctuate rapidly.


Frequency and voltage regulation, short-circuit power, and spinning reserves, which are energy that is already online and synchronized to the grid’s frequency, are all managed by utilities and ISOs to meet these needs. This makes it easy to keep the system running at a high frequency and immediately dispatch additional energy. CSP can provide spinning reserves for immediate demands and non-spinning reserves for near-term needs, offering grid operators more flexibility and control when it comes to assuring grid resilience.


Putting a More Accurate Price Tag on Reliability Benefits


One of the most significant advantages of CSP is its energy source’s dependability and predictable pricing. Unlike traditional fuels, there is no need to harvest, ship, burn, or store waste because sunlight is unlimited and endless. Because the “fuel” is free, the costs of a plant’s operation and maintenance are predictable over time. Furthermore, the first year accounts for more than 60% of the cost of operating a CSP power plant, allowing investors to gain a better long-term understanding of costs and returns.


Is concentrated solar energy beneficial?


The fact that CSP is renewable is perhaps the most obvious advantage. Its supply will never run out and may be used indefinitely, making it a long-term energy source. It also cuts down on carbon emissions. Unlike fossil fuels, which generate carbon dioxide when burned, CSP makes use of the earth’s natural resources, making it more environmentally friendly. It has the potential to enhance air quality while also slowing the rate of climate change.


In comparison to solar photovoltaics (PV) and wind power, which provide intermittent supply, CSP provides a relatively constant source of electricity. The power generated by CSP facilities is predictable and stable because solar energy is stored in the form of molten salts.


Existing steam-based power facilities can readily be converted to CSP. CSP systems can be employed in vehicles that run on fossil fuels. Because operations and maintenance are simpler, CSP plants have lower operating costs than nuclear and hydrocarbon-based plants.


Concentrated solar power can be used with other energy sources to create a more reliable energy grid. CSP can assist satisfy future electricity demand if it is included in the energy mix. It can also help with oil recovery by concentrating heavy oil so it’s easier to pump with the steam it produces.


It also has the potential to be used as a portable energy source. For example, the renewable energy consultancy Ecofys issued a research to evaluate the potential of CSP as a technology for producing cost-effective hydrogen that may be used to power transportation.


What are some of the drawbacks of concentrated solar energy?


The term “solar thermal” has been applied to two distinct types of systems. One is where solar panels collect heat for use as home or process hot water, space heating, or, in some circumstances, air conditioning. Solar heating and cooling (SHC), the most fundamental kind of solar energy consumption, was discussed in a previous post.


The other form of solar thermal system uses concentrating solar collectors to focus sunlight and increase its intensity to generate extremely high temperatures that can be converted to steam and used to power a traditional thermal power plant or heat engine. This is known as concentrating solar power (CSP), and it’s what we’ll talk about today.


There are three major types of CSP systems, according to the National Renewable Energy Laboratory (NREL): linear concentrator, dish/engine, and power tower systems.


Curved panels reflect and focus the sun’s rays onto a tube that runs the length of the panel in linear concentrators. A fluid is contained in the tube, which heats up and produces steam, which is used to power a turbine. The parabolic trough type, in which the tube runs down the focal line, and the linear fresnel type, in which Fresnel lenses collimate the reflected beam so that one receiver tube can be positioned over numerous mirrors, are the two primary types. This type offers more flexibility in tracking the sun while also being less expensive.


Dish engine systems range in size from 3 to 25 kW, which is smaller than linear concentrators. They are made up of a circular parabolic disk mirror that tracks the sun’s position and focuses its rays onto a power conversion unit that is situated along an axis extending outward from the disk’s center at the required focusing distance, which is determined by the disk’s curvature. A thermal receiver and a heat engine make up the power conversion unit. The heat reflected from the mirror is absorbed by the thermal receivers and transferred to the heat engine. The Stirling engine is the most widely utilized heat engine. Stirling engines, unlike internal combustion engines, are heated from the outside and do not require the internal explosions that are typical of today’s automobile engines. They are significantly cleaner and potentially cheaper to operate than fossil fuel fueled engines since they can be heated by a variety of energy sources, including concentrated sun. The fact that they are slow to respond to changes is their major flaw, rendering them unsuitable for vehicle use (except perhaps in a hybrid system where they might be used to recharge a battery).


Finally, there are the power towers, which are possibly the most spectacular and scalable systems. Power towers, also known as point-focus central receiver systems, are similar to dish/engine systems with the exception that there is a single central engine surrounded by several dishes that all focus on it. The heated receiver generates steam, which is utilized to power a traditional turbine generator. In the 1990s, two 10-megawatt plants were successfully tested in the United States. Spain has also installed multiple 20MW units, the most current of which uses molten salt for energy storage and transfer. eSolar launched a 5MW power tower installation with 24,000 mirrors in 2009. For power tower technology, the DOE is currently constructing a 200-megawatt molten-salt solar receiver panel. In the United States, BrightSource Energy’s 392MW Ivanpah facility on the California-Nevada border and SolarReserve’s 110MW Crescent Dunes facility northwest of Las Vegas are both expected to be completed next year.


There will be more in the future. Saudi Arabia recently announced intentions to invest $109 billion in solar power, with the goal of generating 41 gigawatts (GW), or about a third of the country’s estimated consumption by 2030. The specifics are unknown at this time, although it will very certainly entail power tower facilities.


Unlike solar PV and solar heating and cooling, which both take advantage of the fact that the sun shines everywhere and use an inherently distributed model, CSP follows the more traditional centralized utility model, in which power is transmitted over long distances from a capital-intensive central utility and sold to ratepayers.


CSP has the promise of a clean energy source that can be produced at scales equivalent to coal or nuclear under the right conditions, despite the fact that it is expensive and far from simple. Improved thermal energy storage technologies, while still vulnerable to intermittency, have been recommended as a key to CSP’s long-term viability.

 

By  The UtilitySmarts Team


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