Related Topics:
Renewable Energy Equipment Businesses-
Electrical equipment energy storage components
The battery is a crucial component within the BESS; it stores the energy ready to be dispatched when needed. The battery comprises a fixed number of lithium cells wired in series and parallelwithin a frame to create a module. The modules are then stacked and combined to form a battery rack. Battery racks can be connected in. Any lithium-based energy storage systemmust have a Battery Management System (BMS). The BMS is the brain of the battery system, with its primary function being to. The battery system within the BESS stores and delivers electricity as Direct Current (DC), while most electrical systems and loads operate on Alternating Current (AC). Due to this, a Power Conversion System (PCS) or Hybrid Inverter is. The HVAC is an integral part of a battery energy storage system; it regulates the internal environment by moving air between the inside and outside of the system's enclosure. With. If the BMS is the brain of the battery system, then the controller is the brain of the entire BESS. It monitors, controls, protects, communicates,.
[PDF Version]
FAQs about Electrical equipment energy storage components
What are the components of a battery energy storage system (BESS)?
This article delves into the key components of a Battery Energy Storage System (BESS), including the Battery Management System (BMS), Power Conversion System (PCS), Controller, SCADA, and Energy Management System (EMS).
Which battery energy storage system components should I use?
We recommend you use these battery energy storage system components: Ideal for cables where entry into a watertight area is needed, typically used in containers for solar energy storage. Designed for superior sealing and strain relief. IP68 rating for excellent protection against the environment. UL94 V-2. Nylon.
What are electrical energy storage systems (EESS)?
Electrical energy storage systems (EESS) for electrical installations are becoming more prevalent. EESS provide storage of electrical energy so that it can be used later. The approach is not new: EESS in the form of battery-backed uninterruptible power supplies (UPS) have been used for many years. EESS are starting to be used for other purposes.
What are the different types of energy storage systems?
Different energy storage systems include thermal and mechanical systems, such as pumped hydro power. Hydroelectric power storage is by far the most common form of stored energy, but harnessing it depends on finding sites with upper and lower pools. That leads us to the most common power storage device: batteries.
What is a battery energy storage system?
Basic AC-coupled, grid-connected, battery energy storage (BESS) system. An inverter is a static semi-conductor device (power converter) which converts DC to AC. Inverters often include additional functionalities, discussed later in this article. A number of types of inverter may be employed within an EESS to permit:
What is a battery energy storage controller?
The controller is an integral part of the Battery Energy Storage System (BESS) and is the centerpiece that manages the entire system's operation. It monitors, controls, protects, communicates, and schedules the BESS's key components (called subsystems).
-
Vietnam uses solar energy equipment for direct sales
The Vietnamese Government has announced a decision to authorize rooftop solar, biomass, and waste-to-energy projects to engage in direct power sales, bypassing the Electricity of Vietnam (EVN).
FAQs about Vietnam uses solar energy equipment for direct sales
What is the solar power industry in Vietnam?
Solar power industry. The potential for solar energy in Vietnam is between 60 and 100 GWh per year for concentrated solar power, while for photovoltaic (PV) systems, it is around 0.8 to 1.2 GWH per year.
What is the cost of solar electricity in Vietnam?
Last year, Vietnam had a solar LCOE (Levelized Cost of Energy) of $0.046 per kWh for solar electricity. The cost in the United States was $0.055 per unit of power, and in Turkey it was $0.064.
What is the potential for solar energy in Vietnam?
The potential for solar energy in Vietnam is between 60 and 100 GWh per year for concentrated solar power, while for photovoltaic (PV) systems, it is around 0.8 to 1.2 GWH per year. With around 1,600 to 2,700 hours of sunlight per year and an average direct normal irradiance (DNI) of 4-5 kWh/m2, the country has huge potential for solar power.
How will Vietnam's solar power market change over the next 5 years?
Mordor Intelligence, a market research and advisory firm, projects that Vietnam's energy demand will increase by 10 percent annually over the next five years, which means the required power capacity will also need to double. Consequently, the solar power market will be crucial in addressing this substantial energy demand.
Why should foreign investors invest in solar energy in Vietnam?
Vietnam's solar energy market, driven by high solar potential and strong government support, plays a key role in the country's “Net Zero” commitment, among other fields of green energy. For foreign investors, this presents a golden opportunity to tap into a rapidly growing sector with sustainable impacts.
How many rooftop solar projects are there in Vietnam?
Vietnam currently has approximately 103,000 rooftop solar power projects across residential, commercial, and industrial buildings, boasting a total installed capacity of over 9,500 MW. By 2030, Vietnam aims to significantly increase its solar capacity, projecting that 50 percent of households will have rooftop solar installations.
-
What equipment is needed to make energy storage batteries
The components of a battery energy storage system generally include a battery system, power conversion system or inverter, battery management system, environmental controls, a controller and safety equipment such as fire suppression, sensors and alarms.
FAQs about What equipment is needed to make energy storage batteries
What are the components of a battery energy storage system?
The components of a battery energy storage system generally include a battery system, power conversion system or inverter, battery management system, environmental controls, a controller and safety equipment such as fire suppression, sensors and alarms. For several reasons, battery storage is vital in the energy mix.
What is a battery energy storage system?
A battery energy storage system (BESS) is an electrochemical device that charges (or collects energy) from the grid or a power plant and then discharges that energy at a later time to provide electricity or other grid services when needed.
How do I choose a lithium-ion-based energy storage system?
Choosing the right supplier when looking at lithium-ion-based energy storage systems is important. EVESCO's battery energy storage systems utilize an intelligent three-level battery management system and are UL 9450 certified for ultimate protection and optimal battery performance.
What is a battery energy storage system (BESS)?
On a more localized level, a BESS allows homes and businesses with solar panels to store excess energy for use when the sun isn't shining. Using a battery energy storage system in this way increases energy independence. It reduces reliance on the grid, reducing emissions associated with energy production and transmission.
How does battery energy storage work?
This blog explains battery energy storage, how it works, and why it's important. At its core, a battery stores electrical energy in the form of chemical energy, which can be released on demand as electricity. The battery charging process involves converting electrical energy into chemical energy, and discharging reverses the process.
What is the power capacity of a battery energy storage system?
As of the end of 2022, the total nameplate power capacity of operational utility-scale battery energy storage systems (BESSs) in the United States was 8,842 MW and the total energy capacity was 11,105 MWh. Most of the BESS power capacity that was operational in 2022 was installed after 2014, and about 4,807 MW was installed in 2022 alone.
-
Energy storage equipment installation site requirements
The site must be located in an outdoor and well-ventilated environment without explosion risks, and must not be a low-lying area. No obstacle shall be above the ESS.
FAQs about Energy storage equipment installation site requirements
Do you need a battery energy storage system?
Battery energy storage systems (BESS) are becoming increasingly popular as a way to store renewable energy, provide backup power, and manage grid demand. But before you can install a BESS, you need to find a suitable location or site. A number of site requirements should be considered when planning a BESS project.
Where should a battery energy storage system be located?
The location of the site for a battery energy storage system should depend on the availability of land, the proximity to transmission lines, and the environmental impact of the site. The land for a BESS project must be large enough to accommodate the system and any associated equipment.
Are energy storage systems safe for commercial buildings?
For all of the technologies listed, as long as appropriate high voltage safety procedures are followed, energy storage systems can be a safe source of power in commercial buildings. For more information on specific technologies, please see the DOE/EPRI Electricity Storage Handbook available at:
Are battery energy storage systems the future of grid stability?
Battery Energy Storage Systems represent the future of grid stability and energy efficiency. However, their successful implementation depends on the careful planning of key site requirements, such as regulatory compliance, fire safety, environmental impact, and system integration.
Who should consider adding energy storage to a commercial building?
This guide is intended for anyone investigating the addition of energy storage to a single or multiple commercial buildings. This could include building energy managers, facility managers, and property managers in a variety of sectors.
Why do energy storage systems need security measures?
Given the scale of energy storage systems and the value of the equipment involved, security is another top concern for BESS installations. These systems are often located in remote or semi-isolated areas, making them vulnerable to theft, vandalism, or sabotage. Therefore, implementing strong physical security measures is essential.
-
Energy storage equipment development is called pcs
PCS Energy storage converters, also known as bidirectional energy storage inverters or PCS (Power Conversion System), are crucial components in AC-coupled energy storage systems such as grid-connected and microgrid energy storage.
FAQs about Energy storage equipment development is called pcs
What is PCs energy storage?
This is where PCS energy storage. What is Power energy storage system converter PCS? PCS Energy storage converters, also known as bidirectional energy storage inverters or PCS (Power Conversion System), are crucial components in AC-coupled energy storage systems such as grid-connected and microgrid energy storage.
What is a power conversion system (PCs) in a battery energy storage system?
2. unctions of Power Conversion Systems (PCS) in a Battery Energy Storage System (BESS) Bidirectional Conversion: The primary role of PCS is to convert the DC power generated or stored in the batteries into AC power that can be fed into the grid. Similarly, during charging, it converts incoming AC power into DC for storage in the batteries.
How does a power conversion system (PCS) improve energy management?
By regulating energy conversion and optimizing storage and release, the PCS plays an essential role in supporting renewable energy usage and ensuring grid stability. In this article, we'll explore how PCS enhances energy management within energy storage systems (ESS). 1. What's power conversion system (PCS)?
What is a power supply system (PCS)?
The PCS is the heart of two-way energy flow between the storage system and the power grid. Its primary functions include controlling the charging and discharging of the battery pack and managing AC/DC conversion. Using a controllable, four-quadrant operating converter, the PCS enables seamless bidirectional energy exchange.
What is a power conditioning system (PCS)?
Power Conditioning Systems (PCS) play a crucial role in energy storage systems, ensuring the safe, efficient, and reliable conversion of electricity from batteries to usable power. With the wide range of PCS energy storage options available, selecting the right one for your specific needs can seem daunting.
What does PCs stand for?
PCS stands for Power Conversion System. In the energy industry, especially in solar and battery energy storage systems (BESS), a PCS is a vital unit that controls the conversion between DC (Direct Current) and AC (Alternating Current). If you've seen terms like pcs meaning or pcs system, it's likely in this context.
-
Botswana Electric Energy Storage Equipment
The World Bank Group has approved plans to develop Botswana's first utility-scale battery energy storage system (BESS) with 50MW output and 200MWh storage capacity.
-
Bahrain Energy Storage Equipment BESS
Search all the ongoing (work-in-progress) battery energy storage system (BESS) projects, bids, RFPs, ICBs, tenders, government contracts, and awards in Bahrain with our comprehensive online database.
FAQs about Bahrain Energy Storage Equipment BESS
What is Bess & how does it work?
Besides providing storage, BESS enables capacity firming, energy arbitrage, frequency regulation, and other ancillary services that improve grid resilience and efficiency.
What is the Bess project?
The BESS project is an addition to the 500 MW Abydos solar PV project under construction. Meanwhile, UAE's EWEC has recommended deploying 300 MW/300 MWh of BESS capacity within the next three years. While the demand for energy storage is growing, the technology has existed in other forms for years.
What are the benefits of Bess?
• Peak Shaving: BESS is instrumental in managing abrupt surges in energy usage, effectively minimizing demand charges by reducing peak energy consumption. • Load Shifting: BESS allows businesses to use stored energy during peak tariff periods, thus substantially reducing electricity costs.
How much does Bess cost?
As of 2024, the price range for residential BESS is typically between R9,500 and R19,000 per kilowatt-hour (kWh). However, the cost per kWh can be more economical for larger installations, benefitting from the economies of scale.
How many gw/40 GWh will a Bess project deliver?
The Saudi Power Procurement Company aims to deploy 10 GW/40 GWh of standalone BESS capacity by 2030 through annual tenders of 2 GW/8 GWh starting in 2024. In the UAE, the Emirates Water and Electricity Company (EWEC) issued a request for proposals for a 400 MW/400 MWh standalone BESS project in mid-2024.
How does Bess contribute to grid stability?
BESS contributes to grid stability by absorbing excess power when production is high and dispatching it when demand is high. This feature enables BESS to significantly reduce the occurrence of power blackouts and ensure a more consistent electricity supply, particularly during extreme weather conditions. 3. Reduced Emissions and Peak Shaving
-
Reasons why hydrogen energy storage equipment has problems
There are several challenges associated with hydrogen storage such as low efficiency, long refueling times, and short life span of the materials used.
FAQs about Reasons why hydrogen energy storage equipment has problems
What are the challenges to hydrogen storage?
Some of the common challenges to opportunities of hydrogen storage are highlighted below. 1. Low Energy Density by Volume: Hydrogen has a low energy density per unit volume, leading to the need for efficient storage technologies to store an economically viable amount of energy.
Does hydrogen storage have a safety problem?
Improved Safety: Safety is a major problem with hydrogen storage, as it is with any energy storage system. Improvements in safety precautions, such as the creation of safer storage materials and better hydrogen infrastructure, might result from ongoing research and development initiatives.
Why is a risk assessment of the whole hydrogen energy system important?
A risk assessment of the whole hydrogen energy system is necessary to develop hydrogen utilization further. Here, we concentrate on the most important hydrogen storage technologies, especially high-pressure storage, liquid hydrogen in cryogenic tanks, methanol storage, and salt cavern storage.
Can a hydrogen storage system reduce operational costs?
The findings demonstrate that incorporating an energy storage system (ESS) can cut operational costs by 18 %. However, the utilization of a hydrogen storage system can further slash costs, achieving reductions of up to 26 % for energy suppliers and up to 40 % for both energy and reserve suppliers.
What are the environmental benefits of hydrogen storage technologies?
The environmental benefits of hydrogen storage technologies heavily depend on the method of hydrogen production. Green hydrogen, produced using renewable energy sources like wind or solar power through electrolysis, is considered environmentally friendly as it avoids carbon emissions associated with traditional production methods.
Why do we need a safe and reliable hydrogen storage method?
Frequent cycling process may lead to the degradation of hydrogen storage, therefore safe and reliable storage is pivotal in maximizing hydrogen energy. Although, hydrogen is clean energy the methods employed for production and storage of hydrogen are not environmentally friendly.
-
New energy battery equipment is divided into several types
For new energy vehicles, the battery is the most critical component and one of the hot areas of investment in the industry chain in recent years. According to the different cathode materials, the. 3.1 Comprehensive financial analysis and valuation methods for the industry Figure Comprehensive financial analysis of the industry Valuation methods: Lithium battery industry valuation. 2.1 Lithium battery industry chain and value chain Power battery four major upstream raw materials: diaphragm (Enjie shares, star source material), cathode (DangSheng technology), negative electrode (PuTaiLai),. China is the world's largest producer and consumer of new energy vehicles, and also occupies an important position in the global new energy battery market, which creates good conditions for the development of new.
FAQs about New energy battery equipment is divided into several types
What types of batteries are used in energy storage systems?
This comprehensive article examines and ion batteries, lead-acid batteries, flow batteries, and sodium-ion batteries. energy storage needs. The article also includes a comparative analysis with discharge rates, temperature sensitivity, and cost. By exploring the latest regarding the adoption of battery technologies in energy storage systems.
What are the different types of batteries?
Batteries are mature energy storage devices with high energy densities and high voltages. Various types exist including lithium-ion (Li-ion), sodium-sulphur (NaS), nickel-cadmium (NiCd), lead acid (Pb-acid), lead-carbon batteries, as well as zebra batteries (Na-NiCl 2) and flow batteries.
What are the different types of energy storage?
Note that other categorizations of energy storage types have also been used such as electrical energy storage vs thermal energy storage, and chemical vs mechanical energy storage types, including pumped hydro, flywheel and compressed air energy storage. Fig. 10. A classification of energy storage types. 3. Applications of energy storage
How are chemical energy storage systems classified?
Chemical energy storage systems are sometimes classified according to the energy they consume, e.g., as electrochemical energy storage when they consume electrical energy, and as thermochemical energy storage when they consume thermal energy.
Should batteries be integrated with supercapacitors?
Batteries are often compared to supercapacitors for various storage applications and it is expected that exploiting their features (i.e., frequent energy storage capability without sacrificing their cycle) by integration could help address future electrical energy storage challenges.
Can car batteries be used for grid energy storage?
Their results show that it is unlikely for vehicle owners to receive sufficient incentives from electricity arbitrage to motivate large scale use of car batteries for grid energy storage in any of the three cities.
-
What are the solar energy environmental protection equipment manufacturers
Business Capabilities: Manufacturer, Supplier, Exporter Location: Zhejiang, China Main Markets: Globally. Year Of Establishment: 2011 Certificates: ISO certification BENY Electric is a well-known manufacturer of solar system protective components all around the world. It was founded in 2011 in Zhejiang, China. Their. Business Capabilities: Manufacturer, Supplier, Exporter Location: Oklahoma Main Markets: America, Europe, and the Middle East. Year Of Establishment: 2012 Certificates: ISO certification Okie Solar, based in Yukon,. Business Capabilities: Manufacturer, Supplier, Exporter Location: USA Main Markets: America, Europe, and the Middle East. Years Of Experience: 27 years Certificates: ISO certification SEPCO Company develops. Business Capabilities: Manufacturer, Supplier, Exporter Location: Toronto, Canada Main Markets: America, Europe, and the Middle East. Year Of Establishment: 2005. Business Capabilities: Manufacturer, Supplier, Exporter Location: Canada Main Markets: America, Europe, and the Middle East. Years Of Experience: 30 years Certificates: ISO.
[PDF Version]
-
What equipment does the DC side of the energy storage include
DC-Coupled system ties the PV array and battery storage system together on the DC-side of the inverter, requiring all assets to be appropriately and similarly sized in order for optimized energy storage and power flow.
FAQs about What equipment does the DC side of the energy storage include
How does a battery energy storage system (BESS) work?
3) The battery energy storage system (BESS) is integrated into the secure (protected by the DU) dc link at the receiving-end station, with only dc current going through during its normal operation, thereby extending lifetime and reducing losses; 4)
How does a battery energy storage system work?
The two assets are coupled together on the alternating current (AC) side of their inverters - before the power reaches the grid connection. Battery energy storage either charges or discharges electricity in direct current (DC). This is also how a lot of renewable generation works - including solar.
Why do we need energy storage systems?
1. Introduction Development of energy storage systems (ESSs) is desirable for power system operation and control given the increasing penetration of renewable energy sources, .
What is DC-coupled and AC-coupled PV & energy storage?
This document examines DC-Coupled and AC-Coupled PV and energy storage solutions and provides best practices for their deployment. In a PV system with AC-Coupled storage, the PV array and the battery storage system each have their own inverter, with the two tied together on the AC side.
Why is massive energy storage important in bulk power systems?
Abstract Massive energy storage capability is tending to be included into bulk power systems especially in renewable generation applications, in order to balance active power and maintain system security.
What is a pvs-500 DC-coupled energy storage system?
The PVS-500 DC-Coupled energy storage system is ideal for new projects that include PV that are looking to maximize energy yield, minimize interconnection costs, and take advantage of the federal Investment Tax Credit (ITC). control how much reactive power is generated or absorbed by the inverters and can be used to help regulate system voltage.
-
Are power equipment and batteries considered energy storage
Energy storage solutions for electricity generation include pumped-hydro storage, batteries, flywheels, compressed-air energy storage, hydrogen storage and thermal energy storage components.
FAQs about Are power equipment and batteries considered energy storage
What is a power battery?
Unlike energy batteries, which prioritize long-term energy storage, power batteries are optimized for high power discharge when needed, especially in applications like electric vehicles, power tools, and systems requiring quick acceleration or heavy loads. Primary functions: Supply rapid bursts of energy.
What is a battery energy storage system?
A battery energy storage system (BESS) is an electrochemical storage system that allows electricity to be stored as chemical energy and released when it is needed. Common types include lead-acid and lithium-ion batteries, while newer technologies include solid-state or flow batteries.
What is the difference between Power Battery and energy storage battery?
1. The difference between the capacity of power battery and energy storage battery In the case of all new batteries, the battery capacity is tested by a discharge meter. Generally, the capacity of power lithium battery is about 1000-1500mAh; the capacity of energy storage lithium battery pack is above 2000mAh, and some can reach 3400mAh. 2.
What is an energy battery?
An energy battery, also known as a high-energy battery, is a rechargeable battery designed to store and release energy over an extended period. These batteries are optimized to provide sustained power output, making them ideal for applications requiring long-lasting energy storage and usage. Primary functions: Store energy for extended periods.
What is energy storage?
Energy storage is the capturing and holding of energy in reserve for later use. Energy storage solutions for electricity generation include pumped-hydro storage, batteries, flywheels, compressed-air energy storage, hydrogen storage and thermal energy storage components.
How do energy storage batteries work?
In the energy storage system, the energy storage lithium battery only interacts with the energy storage converter at high voltage, and the converter takes electricity from the AC grid to charge the battery pack; or the battery pack supplies power to the converter, and the electrical energy is supplied by the converter.
-
New Energy Storage Modern Equipment Industrial Park
The park is reported to include an Energy Storage Technology Research Institute, an energy storage module production line, a 100MW/400MWH large-scale energy storage demonstration station, a 110kV substation, and an energy storage station operations headquarters.
FAQs about New Energy Storage Modern Equipment Industrial Park
What are common energy storage technologies in industrial parks?
Common energy storage technology in industrial parks. Schematic diagram of power-power hybrid energy storage. Typical framework of cooling-heating-power hybrid energy storage system . Schematic diagram of a power-cooling/heating-gas hybrid storage system. Typical framework of a hybrid power-gas storage system .
What are hybrid energy storage mechanisms in industrial parks?
For hybrid energy storage mechanisms in industrial parks, the primary focus is on comprehensively coordinating power-type energy storage, energy-type energy storage, heating energy storage and cooling energy storage operational methods, to realize the rational allocation of cooling, heating and electric loads for different energy storage methods.
Can energy storage be used in industrial parks?
Energy storage has been widely used in industrial parks, but the role of a single energy storage technology in such industrial parks' is limited and cannot meet the full needs of energy storage .
Are electricity storage technologies a good idea?
Electricity storage technologies have high energy quality and can convert stored electricity into various types of energy. Their application potential is vast. However, these technologies still have some shortcomings, such as low energy density, high unit cost, and inherent security risks.
What is gas storage technology in industrial parks?
Gas storage technology in industrial parks includes gas storage tanks, liquefied gas, pipelines, hydrates, compressed gas, and other gas storage methods [87, 88]. Pipeline gas storage uses the pressure and volume variation at the user end to store natural gas.
What is a Hydrogen Energy Park?
The park – relying on the institutional innovations of Lin-gang and the advantages of the hydrogen energy scene – is committed to promoting the development of the entire industrial supply chain of hydrogen energy production, storage, transportation and use.
-
What is the prospect of energy storage professional energy
The development of energy storage technology (EST) has become an important guarantee for solving the volatility of renewable energy (RE) generation and promoting the transformation of the power system. Ho. ••Reviews the evolution of various types of energy storage technologies••. With the rapid development of the global economy, energy shortages and environmental issues are becoming increasingly prominent. To overcome the current challenge. 2.1. Research status of ESTEnergy storage is not a new technology. The earliest gravity-based pumped storage system was developed in Switzerland in 1907 and has sin. 3.1. Research frameworkFig. 3 shows the EST development framework based on multidimensional analysis.3.2. Sample and. 4.1. Analysis and comparison based on the technology type dimensionComparative of the number and percentage of publications in different types of energy storage technolo.
[PDF Version]
FAQs about What is the prospect of energy storage professional energy
What are energy storage technologies?
Energy storage technologies, which are based on natural principles and developed via rigorous academic study, are essential for sustainable energy solutions. Mechanical systems such as flywheel, pumped hydro, and compressed air storage rely on inertia and gravitational potential to store and release energy.
Why is energy storage important?
With the large-scale generation of RE, energy storage technologies have become increasingly important. Any energy storage deployed in the five subsystems of the power system (generation, transmission, substations, distribution, and consumption) can help balance the supply and demand of electricity .
Why should we invest in energy storage technologies?
Investing in research and development for better energy storage technologies is essential to reduce our reliance on fossil fuels, reduce emissions, and create a more resilient energy system. Energy storage technologies will be crucial in building a safe energy future if the correct investments are made.
Who are the authors of a comprehensive review on energy storage systems?
E. Hossain, M.R.F. Hossain, M.S.H. Sunny, N. Mohammad, N. Nawar, A comprehensive review on energy storage systems: types, comparison, current scenario, applications, barriers, and potential solutions, policies, and future prospects.
Why should we study energy storage technology?
It enhances our understanding, from a macro perspective, of the development and evolution patterns of different specific energy storage technologies, predicts potential technological breakthroughs and innovations in the future, and provides more comprehensive and detailed basis for stakeholders in their technological innovation strategies.
What are the benefits of energy storage technologies?
Renewable energy integration and decarbonization of world energy systems are made possible by the use of energy storage technologies. As a result, it provides significant benefits with regard to ancillary power services, quality, stability, and supply reliability.