The Isle of Struay, 10 km off the west coast of Scotland is home to 200 people and enjoys the climate as described in Table 5.1. The island is not connected to the mainland grid and each household independently generates electrical power using a mixture of diesel generators and small scale renewables. (a) The islanders are investigating their options for electrical generation and connection. The three options for generating and distributing 1000 MWh of electrical energy a year are: i. Option 1. No change. ii. Option 2. Install an island grid with renewables, energy storage and back up generation. iii. Option 3. Install an island grid with a subsea connection to the mainland grid. Table 5.2 shows the costs associated with these three options. Calculate the levelised cost of energy of each option. Which option should they go for? (b) If they go for Option 2, the islanders need to use a mixture of renewable energy technologies. Referring to climate data in Table 5.1, your knowledge of renewable energy technologies and similar Scottish island energy schemes, make and explain your recommendation. (c) A retired power engineer who lives on the island suggests that there are other benefits for connecting to the mainland grid. He lists them as "security of supply", "power system inertia and stability" and "export of power". Explain what these mean and how a grid connection to the mainland would help