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Scenario 1 - Constant Population
Currently 163 residents live on the island. The first scenario to be simulated will keep the number of residents constant until 2030 in order to measure the potential of the island as it is, creating a baseline scenario on which to build upon and stretch the aim of the project. Scenario 2 - Population Increase
The population will rise from 163 to 200, as well as the number of dwellings from 76 to 94. The islands population has been slowly growing since the community buyout, we assume this trend to continue to the maximum accommodatable population as a realistic scenario to build upon Scenario 1. It will allow us to investigate the relationship of population to energy demand on the island. The maximum population was estimated from the GREL’s director to be no more than 180 people by 2030. Thus, we used a population of 200 with the rationale that if the system can support 200 inhabitants, then it can also support less. To estimate the number of dwellings required for 37 new residents, the average household size of Argyll & Bute council was used, which is 2.06 residents per households [1], thus 18 new dwellings were added in the model. Scenario 3 – Population and Tourism Increase
The current tourism capacity is 110 people, on opening 16 new accommodation businesses this can reach the maximum accommodatable tourism capacity for the island, which would be 210 people. This scenario was chosen as the tourism industry is growing in the Scottish Hebrides year on year and we know the Isle of Gigha is keen to follow this trend. For the generation of this scenario contact was established with the hospitality businesses on the island in order to collect data for the maximum number of tourists that the island can support currently, as well as the apportionment of tourists during the year. Adding the increased tourism to the increased population will really stretch the aim especially due to the resultant peak demand in the Summer months. Scenario 4 – Net Energy Positive
Our GREL contact showed a keen interest in energy autonomy. As we are keeping the grid connection in each scenario we decided on a scenario that will be net energy positive meaning that there will be no imports via the grid only exports sold back to the grid. This represents the most aggressive scenario were Gigha generates all energy required in order to meet the demand from renewable supply sources on the island. In this scenario the generation of energy on the island will rapidly increase in order to eliminate the imports from the grid, with the demand of various sectors being kept the same as in Scenario 1. |
Common Features
The common features refer to the changes that could happen until 2030 in regards of dwellings, vehicles efficiency and the condition of the grid connection as well as the carbon intensity of the grid imports. The features will be the same for all of the scenarios assuming that the Strategy Energy Scotland’s plan is going to be implemented in the future.
The common features refer to the changes that could happen until 2030 in regards of dwellings, vehicles efficiency and the condition of the grid connection as well as the carbon intensity of the grid imports. The features will be the same for all of the scenarios assuming that the Strategy Energy Scotland’s plan is going to be implemented in the future.
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Domestic Retrofitting
The majority of dwellings on the island were retrofitted after the community buyout. In order to achieve the U.K standard of the new ‘Energy Performance Certificate’ Regulations for 2030 [4], further retrofitting will be required on a number of these dwellings to reach an EPC rating of at least a 'C'. This has been applied to said dwellings through the demand profile of each scenario. |
Storage
Tesla lithium-ion batteries, were applied, of different capacities depending on the scenario. Storage will be an important aspect of the renewable future of the U.K due to the dispatchability of renewables. For Gigha, minimising the use of the back-up diesel generator was a very important aspect hence applying storage. Once again, helping to lower the carbon footprint of the island. |
Grid CO2 Levels
U.K grid carbon emissions will decrease towards 2030. UK government predictions [5] were used as a guideline, with a more conservative estimation applied incase the national uptake in renewables is not as large as predicted. The predictions have been applied to each scenario to ensure the carbon footprint is accurately calculated dependant on grid imports required. |
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Electric Vehicles
90% of vehicles on the island will be electric by 2030. There is not a calculation involved with this, the scenarios are pushing a renewable and low carbon future for 2030 and not 2050 (U.K targets) so with this in mind electric vehicles will be part of the islands actions within each scenario to reach the aim of the project. |
Electrification of Heat
Heat pumps will be applied to all dwellings, increasing electrical demand but reducing overall demand for each of the profiles. This will play a very important role in the carbon emissions reduction and helping to achieve the aim of the project. |
Grid Connection
The subsea grid connection that already exists on the island will be kept, with its 1MW export limit. The island may acquire an upgraded cable before 2030, but as there is a long waiting list, it is uncertain when or if Gigha will receive a new cable. |