INTRODUCTION TO THE ANTIGUA AND BARBUDA ROADMAP
Located between the Caribbean Sea and the Atlantic Ocean, Antigua and Barbuda is an island nation consisting of two land masses with a total area of 443 square kilometres. Apart from the two inhabited islands that are separated by a distance of 43 kilometres, Antigua and Barbuda also includes many smaller islands that are uninhabited (CIA, 2015). According to the World Bank, in 2018 Antigua and Barbuda had a population of 96 286 inhabitants. The Government of Antigua and Barbuda has proposed a target of achieving 100% of its electricity generation
from renewable energy sources by 2030. This target was proposed during the revision process for the Nationally Determined Contributions (NDCs) elaborated under the Paris Agreement. As the energy sector of the country is currently highly dependent on fossil fuels, a transition to 100% renewable power will reduce emissions by more than 90% and will create the necessary environment for 100% adoption of electric vehicles (EVs) in the transport sector.
Roadmap analysis overview
IRENA has been actively supporting islands with their energy transition to a renewable energy future, through the development of detailed renewable energy roadmaps (IRENA, 2017a). Such roadmaps provide clear pathways including technical, economic and policy aspects that can allow large-scale adoption of renewable energy.From the various techno-economic modelling tools available in the market, HOMER Pro was used to develop the roadmap for both the electricity and transport sectors. HOMER is an optimisation tool used to design and technically and financially evaluate options for off-grid and on-grid power systems for remote, stand-alone and distributed generation applications. It allows the user to consider numerous types of technology options to account for energy resource availability and other variables. The model’s ultimate goal is that of simulating and providing the user with the most inexpensive and
viable solution for all possible combinations according to the initial system inputs. Depending on the inputs, HOMER can simulate hundreds or even thousands of viable systems.
The roadmap study consisted of analysing the deployment of renewable energy options for Antigua and Barbuda in the following two sectors/applications: 1.Electricity generation 2.Road transport
The following sections describe the details of both applications including the various options considered for each sector to achieve the 100% renewable energy target.
Electricity generation The analysis for Antigua and Barbuda’s electricity sector was done to perform a detailed optimisation of the current situation as well as for 2030. The first step was to prepare a baseline demand forecast and then to add the planned renewable energy systems for 2030 including additional suggested technologies to achieve 100% renewable electricity. The baseline forecast was prepared using data on the existing generators provided by the Antigua Public Utilities Authority (APUA). The baseline demand forecast is important as it is used for determining the required generation resources.
Road transport For the transport sector of Antigua and Barbuda, the analysis was also done using HOMER Pro by adding the electric vehicle load as a deferrable load (that is, an electrical load that requires a certain amount of energy within a given time period). The EV load was added to the power sector analysis and was performed together.
SCENARIOS The roadmap analysis performed for Antigua and Barbuda’s power system evaluated several scenarios based on the information provided by the Ministry of Health, Wellness and the Environment. In order to simulate the scenarios in HOMER Pro, the model had to first be calibrated. The calibration was done by simulating the current power system of Antigua and Barbuda.
Optimal system The first scenario analysed in this study was the optimal system scenario. This scenario considers the current plans of the Government along with additional renewable energy capacity based on land availability and extra capacity based on the HOMER optimiser, which minimises the system’s net present cost. The reason for selecting this scenario was to show the maximum renewable energy share that can be achieved based on the plans and based on land availability for installing further renewable capacity. The electricity demand for this scenario remained the same as the previous ones at 375 GWh/year. As with the existing plans model, the generators of the Wadadli power plant were not considered in this scenario.
Optimal system + EVs The second scenario analysed in this study was the optimal plus EVs scenario. This scenario was considered to show how the renewable energy share, electricity demand and levelised cost of electricity (LCOE) of the optimal system scenario would be affected by adding electric vehicles. Hence, a deferrable load was added to the optimal scenario to represent the EV demand. A deferrable load can be defined as an electrical load
that requires a certain amount of energy within a given time period. The deferrable load was calculated based on the data received from the Antigua and Barbuda Transport Board and is discussed in detail in chapter3.The HOMER optimiser was used in this scenario to optimise the ideal additional capacity of renewables needed to meet the increased electricity demand due
to the EV load.The optimiser was also used to size the appropriate converter and battery storage needed.
100% RE (no hydrogen) The third scenario considered was the 100% RE without hydrogen scenario. As the name suggests, this scenario represents a 100% renewable energy power system but without considering green hydrogen production. This scenario was selected to show that there is a possibility to achieve the ambitious target set by the Government of Antigua and Barbuda with just solar and wind energy.
100% RE (with hydrogen) The fourth scenario considered for the roadmap analysis was the 100% RE scenario with hydrogen. This scenario estimated the ideal renewable energy capacity needed to achieve the target of the Government to cover all the electricity demand from solely renewables by 2030 In order to achieve the 100% share of renewable energy, any fossil fuel generation had to be removed from the model, hence this scenario did not consider any of the current power plants that run on heavy fuel oil. Together with the solar and wind capacity of the previous scenario, additional capacity for both solar and wind was estimated using the HOMER optimiser. Furthermore, in order to achieve the 100% share, green hydrogen production from renewables was considered.
100% RE (hydrogen + EVs) The last scenario considered in the analysis was the 100% RE scenario with hydrogen plus EVs. This scenario was considered in order to show how much additional renewable energy capacity will be needed to cover the demand for hydrogen as well as the demand for charging electric vehicles. For this scenario, the demand for the EVs was added as a deferrable load in HOMER Pro. This load was added together with the current electric demand of 375 GWh/year, hence increasing the demand and concurrently the enewable energy capacity. Similar to the previous scenario, a hydrogen tank, electrolyser and fuel cell were added into HOMER to perform an optimisation for their ideal size. The HOMER optimiser was also used to estimate the size of the storage and converter, and any additional PV and wind capacity needed to meet the new electric demand.
This chapter discusses the various assumptions that were considered when performing the HOMER modelling. It covers the key assumptions considered when estimating the baseline electricity demand for 2019 and the assumptions for the main components and the project
economics in the HOMER model. It also encompasses the assumptions considered for the power sector, and for the transport sector when estimating the EV deferrable load.
Demand analysis The 2019 annual load profile for Antigua and Barbuda was estimated using the hourly load demand for 2012. The following section details the data provided by APUA
on the electricity generation and the methodology used to estimate the hourly load for 2019, which served as the baseline year for the roadmap analysis.
2019 baseline electricity demand To estimate the load for Antigua and Barbuda, data were needed on the energy production from the existing generators. APUA provided IRENA with data on the generation of each power plant for four consecutive years: 2016, 2017, 2018 and 2019.
Power sector assumptions Antigua and Barbuda’s power sector relies heavily on conventional fossil fuel generation to supply electricity. Currently, the country has a total of three main power plants consisting of heavy fuel oil generators of various capacities. The APC Power Plant is the largest on the island with three generators of 14.4 MW and one of 17.1 MW. The Blackpine Power Plant consists of a total of four generators, two of them with 6.6 MW of capacity, and the other two with 8.6 MW.
which was decommissioned on 15 September 2020, is the Wadadli Power Plant, with six generators of 6 MW each all powered by heavy fuel oil. Table 2 details the generation capacity for each power plant presently in Antigua and Barbuda.
General techno-economic assumptions Together with the main components in the HOMER
model, assumptions were also made for the economic and financial parameters. These assumptions were essential in order to achieve more detailed and precise results for the financial part of the project. The key assumptions include a nominal discount rate of 7%, an
expected inflation rate of 1.9%, a real discount rate of 5%, a value of lost load of USD 20/kWh and a project lifetime of 25 years. The system fixed capital cost and system fixed O&M cost were both assumed to be zero.
Transport sector assumptions As mentioned previously, Antigua and Barbuda’s transport sector is dominated by fossil fuels. The data provided by the Antigua and Barbuda Transport Board show that at present, there are 54 891 road transport vehicles in the country, with more than 97% of them fuelled by gasoline and the remaining 2.7% running on diesel.
To estimate the total EV deferrable load to input in HOMER, a contemporaneity factor of 0.30 was used.
RESULTS This chapter elaborates the main results obtained from the various HOMER models for each scenario considered. The results and outcomes from the modelling are discussed in detail and key figures and charts are provided, showing how the Government of Antigua and
Barbuda can achieve the ambitious target set of 100% renewable energy generation in the power sector by 2030 and in the transport sector by 2040.
Current power system The results of the optimisation performed for the current power system of Antigua and Barbuda have confirmed that today’s power system is highly dominated by fossil fuels with merely 3.55% of the electricity share coming from renewables. Hence, there is a lot of potential to increase the share of renewables and concurrently reduce fossil fuel generation. With an electricity demand of 375 GWh/year, the results have shown that there is no excess electricity. The country currently consumes a total of 65.8 million litres of heavy fuel oil, with average fuel use per day of 180 305 litres and average fuel use per hour of 7 513 litres. The optimisation of the current power system shows high emission values of 197 629 tonnes of carbon dioxide per year.
Existing plans as of 2020 The results of the existing plans as of 2020 modelled into HOMER have showed that according to these Government plans, by decommissioning the Wadadli
power plant and by adding the additional wind capacity of 4.13 MW and additional distributed solar capacity of 5 MW, the renewable energy share will increase from 3.55% to around 8.8%. The results show that although the renewable energy share will increase significantly, it is still far from the ambitious target set by the Government of Antigua and Barbuda. Hence, there is still a long way to go to achieve 100% electricity generation exclusively from renewables.
Optimal system The first scenario of this study, the optimal system cenario, analysed the current plans of the Government along with additional renewable energy capacity based on
land availability and extra capacity based on the HOMER optimiser. The optimal system is the least-cost scenario based on net present cost. It considers solar, wind, and storage, and does not consider hydrogen. The results of the optimisation show that by adding a further 90 MW
of rooftop PV, 100 MW of ground-mounted PV, 13.5 MW of additional wind capacity and an extra wind capacity of 40 MW, the renewable energy share will markedly increase to almost 89.5%. The battery inverter and storage were optimised to 62 MW and 593 MWh respectively.
Optimal system plus EVs After the optimal system scenario, the second scenario modelled in this study includes the deployment of electric vehicles to the optimal system.
100% RE (no hydrogen) The first option considered in this roadmap for Antigua and Barbuda to achieve 100% of its generation from solely renewables was the 100% RE (no hydrogen)
scenario. This scenario was considered to show that it is possible to achieve the target set by the Government without adding green hydrogen production and by increasing the solar PV, wind and battery storage capacity. The results of the HOMER modelling showed that by adding further PV capacity of 173 MW to the previously estimated 199 MW, and by deploying further wind turbine capacity of 93 MW, the renewable energy share can increase to 100%. However, it must be noted that a large battery capacity would be needed to achieve this share, and the optimisation results have estimated that a 1.4 GWh battery storage system would be required.
When observing the cost results of the optimisation, it is clear that this scenario has the highest costs when compared to the other scenarios considered in this study. The initial capital cost needed to deploy the above-mentioned renewable energy systems would be around USD 783 million. The LCOE has also increased as opposed to previous scenarios, to USD 0.184/kWh.
The net present cost and operating cost for this specific scenario were optimised to be USD 985 million and USD 14.2 million/year respectively. The reasoning behind such high costs is the large battery storage system of 1.4 GWh. Having such a large capacity storage leads to very high capital, replacement and O&M costs.
100% RE (with hydrogen) In order to achieve a 100% renewable energy share by 2030, the Government of Antigua and Barbuda would need to decommission all the current power plants running on fossil fuels and deploy only renewable energy. This scenario considered the production of green hydrogen from renewables to help achieve the goal set by the Government. The results of the optimisation showed that by doing so, the renewable share will indeed reach the 100% target set by the Government. However, to reach this target, the Government would need to install an extra 3 MW of solar PV capacity on top of the current plans for the 100 MW of ground-mounted PV and the 90 MW of rooftop PV. Therefore, a total of 202 MW of solar PV would be needed. Furthermore, an additional wind power capacity of 83 MW would be needed to meet the new electrical demand. Through HOMER, it has been evaluated that if this 83 MW of wind power cannot be deployed, then an additional solar PV capacity of 514 MW would be needed instead.
100% RE (with hydrogen plus EVs) The last scenario that was modelled in HOMER was the
100% renewable energy with hydrogen plus EVs scenario. This scenario consisted of the 100% renewable energy (with hydrogen) scenario, but in addition it also explored the possibility of replacing all vehicles with EVs by 2040. Hence, together with the electricity demand a deferrable load was also added. The deferrable load in HOMER had a scaled annual average of 310650 kWh/day, a storage capacity of 770 700 kWh and a peak load of 61020 kW. The EV load, together with the hydrogen production, increased the total electrical load to 722 GWh/year. Thisscenario also showed the lowest excess electricity with 62 GWh/year and a capacity shortage of 3.5 MWh/year. No unmet electric load was calculated.
illustrates the hourly dispatch graph for the main components of the system during 1-2 January. The total load (light-blue line) includes also the EV deferrable load. During the early morning hours of 1 January, most of the total load is covered from stored electricity in the battery storage system. Around 4 a.m., however, renewables (mainly wind), commence to cover the entire electricity demand. Between 6 a.m. and 9 a.m., some excess electricity is generated by the wind turbines, after which the total load is covered with renewables until 5 a.m. the next day.
BARBUDA This chapter provides an overview on Barbuda and the analysis performed for the island’s power system. It also encompasses the results obtained by the HOMER optimisation, which was based on the design suggested in the Green Barbuda Study conducted in 2018. The
optimisation performed for Barbuda also consists of additional solar PV and battery storage capacity, which has been explored to achieve the target set by the Government of Antigua and Barbuda.
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