# Applications of Digital Twin across Industries: A Review
## 5 Power Generation/Energy  
Companies involved in the generation and/or sale of energy from either non-renewable resources, such as oil, gas, and nuclear, or renewable resources, such as wind, solar, and hydro, come under the energy sector [92]. The DT technology in the energy sector is being used from wind farms to nuclear plants. General Electronics (GE) has been successful in creating the DT of an entire wind farm. The DT of a wind turbine increases its energy production, optimizes the strategies for its maintenance, as well as improves its reliability by collecting real-time data such as weather, service, and performance reports, among others. GE provides comprehensive hardware and software solutions to its customers for creating, enhancing, and optimizing their wind farm using their cloud-based software DT platform called Predix [93]. Similarly, DNV GL, a company delivering testing, certification and advisory services to the power and renewable industry, developed a DT analytics tool called WindGEMINI for wind turbines which helps to improve the performance of the wind farm by providing predictive maintenance. Two such cases of predictive maintenance are (1) detection of a crack on the blade of the turbine in 2019, which prevented the loss of USD 5000 [94], and (2) in 2017, a defective component in the gearbox affecting 6% in performance was detected, saving GBP 6000 [95]. Apart from this, it also provides an evaluation of energy production in the long term which includes analysis of the power curve, component failures, and the remaining life. Using WindGEMINI, it was found out that even a small reduction of 2% in the power curve performance can save USD 80,000 over the lifetime of a turbine [96]. Furthermore, the DT of wind turbines can be used in designing and testing them, as well as finding the best position/location to maximize energy generation by taking factors into account such as wind speed, waves, temperature, etc. [97]. The predictive and interrogative features of DTs are being exploited for the next generation of power grids. Siemens developed DTs for the planning, operation, and maintenance of the Finnish power grid by creating a single digital grid. Its advantages, besides improved safety and reliability, include: (i) resource-saving by transforming most of the manual work into the automated one for simulations, (ii) the efficient and improved use of data, (iii) the easier use of data for new applications, and (iv) the improved decision making using big data [98]. [PERSON] et al. [99] implemented and tested their DT on a large-scale grid network model exported from the Chinese national grid energy management system for real-time monitoring. They were successful in tracking the operation state of the power grid with only a sub-second delay. Following Finland, Norway is planning to utilize a DT for optimizing the operations of the power network with the new complexities brought by intermittent renewables and distributed energy resources [100]. The DT will allow operators to predict grid conditions, balance grids, and prevent blackouts. DT technology, when applied to nuclear power plants (NPP), can improve the algorithms for controlling and testing the plant, the diagnosis of plant equipment such as pumps, motor, valves, etc., and the parameter tuning of automatic regulators [101]. France has announced a four-year project led by Electric de France (EDF) to develop DTs for the country's nuclear reactors [102]. EDF operates a fleet of 56 power reactors in France, which is why, instead of creating a DT of a generic rector, EDF focuses on integrating data specific to each plant facility, which includes design data, operating records, and real-time measurements. One of the main applications of these DTs will be training new operators and engineering students. Unlike the real world, the DTs of these nuclear plants will make it possible to fully immerse in a functioning reactor virtually and access all kinds of information on the behavior of its components.