Renewable Island Research Articles

Biomethane production through the power to gas concept: A strategy for increasing the renewable sources exploitation and promoting the green energy transition

Direct catalytic methanation of biogas using hydrogen from electrolysis is a promising pathway to store the electricity from renewable power plants according to the Power to Gas concept. This type of methanation offers technical and economic advantages over the methanation of carbon dioxide separated from biogas, since it eliminates the upgrading step.This work is focused on the sizing and performance analysis of a Power to Biomethane plant based on biogas direct catalytic methanation process. The plant consists of two main sections: i) the Renewable Island, in which an anaerobic digestion plant and a renewable power plant (Photovoltaic plant or Wind farm) supply the biogas and the electricity; ii) the Biomethane Production Island, in which the hydrogenation of the carbon dioxide in the biogas, in presence of methane, occurs.This study, by means of an optimization procedure based on a multi-objective approach, aims to evaluate the optimal size of the Power to Biomethane plant that assures the maximum biomethane production and the maximum exploitation of the renewable electricity. Two case studies, referring to the installation of a Photovoltaic plant and a Wind farm as renewable power plants, have been analyzed.Results have highlighted that, for obtaining an annual biomethane production in the range of 2550–3150 kNm3 and by starting from a biogas availability of 500 Nm3/h, the sizes of the renewable power plants must be in the range 15–20 MW and in the range 19–23 MW for the Wind farm and the Photovoltaic plant, respectively. In terms of performance indicators, even if the PV plant has the highest electricity storage factor (up to 69 %), the Wind-based plant has both the highest plant load factor (up to 81%) and the equivalent full load operating hours (up to 6081), so that it is more favorable for the development of the Power to Biomethane concept.

Towards 100% renewable islands in 2040 via generation expansion planning: The case of São Vicente, Cape Verde

In the energy transition context, islands are identified as particularly challenging regions due to their isolation, and energy dependence; while their excellent renewable resource and rapid growth makes them exceptionally interesting test cases. With the growing number of countries targeting 100% renewable penetration during the next decades, it is important to assess not only how to do so, but also whether we should. This paper focuses on the perspective of a generally overlooked set of regions; island developing nations. Their common challenges and energy policies are exemplified with a comprehensive generation and storage expansion planning (GSEP) for the island of São Vicente, Cape Verde. Formulated as an optimisation problem with hourly resolution, the GSEP minimises investment, maintenance, operation and emissions costs over a 20 year horizon from 2021. The extreme seasonal dependence of wind and solar resources is captured along with the operational dynamics of the generation and storage. Three scenarios are defined, one Business As Usual (BAU) keeping the current operational paradigm, another, Green, aligned with the local government goals, targeting 50 and 100% renewable shares in 2030 and 2040, and, lastly, one finding the Optimal. To reduce uncertainty influence, we consider three load growth levels for each scenario, defined based on expectations from national and international sources, corresponding to 1, 3 and 5%. The robust analysis obtained by combining scenarios and load levels provides a thorough view of Cape Verde’s energy system to consider in future energy policy design. Green is the most expensive, BAU represents a 7% cost reduction, while Optimal a 30%, in addition to providing 90% renewable penetration, significant emissions reduction, and enough flexibility to modify the planning course if needed.

Combined multi-objective optimization and agent-based modeling for a 100% renewable island energy system considering power-to-gas technology and extreme weather conditions

Islands are constrained by geographical conditions in terms of energy delivery. Due to weak connections with the mainland and the power grid, the diversity of island energy demand leads to high economic costs and environmental pollution issues. This study proposes a 100% renewable island energy system, which integrates with power-to-gas, combined cooling, heating and power, and desalination technologies to supply electricity, heating, cooling, gas and fresh water to the local residents. A comprehensive approach for energy demand prediction, system design and dispatch optimization, as well as system evaluation is proposed. For energy demand prediction, agent-based modeling is used to simulate the demand of electricity, heating, cooling, gas and fresh water for the case study community on the island. The k-means clustering and scenario tree are further adopted to generate representative stochastic scenarios, which are applied to capture the uncertainty of energy demand. A multi-objective optimization model is developed to optimize the system design and scheduling strategy simultaneously. In order to demonstrate the effectiveness of the proposed approach and to evaluate the obtained optimal solutions for the case study, different objectives and extreme weather conditions are specifically considered. The optimal solution obtained shows that compared to battery storage, a 2.5% annual cost reduction can be achieved by using power-to-gas technology for energy storage. The findings also suggest that extreme weather conditions can be coped with by increasing the capacity of biogas generation, desalination, and energy storage equipment, thereby improving the resilience of the island energy system.

ALLIANCE OF SMALL ISLAND STATES AND ITS ROLE IN SUSTAINABLE ENERGY DEVELOPMENT IN THE SMALL ISLAND DEVELOPING STATES

The small island developing states (SIDS) are among those nations which are the most underdeveloped and vulnerable in the world. The present climate change (CC) situation is at serious juncture. The amount of carbon and other greenhouse gases (GHG) in the atmosphere are way past the industrial levels ascertained by the United Nations Framework Convention for Climate Change (UNFCCC). It is proved that the developed nations like China, United Nations, Russia are responsible for the maximum emissions and the SIDS has little to no contribution in emissions but are the ones who are the worst affected by the negative effects of CC. As such these nations are very pro climate. They are repeatedly voicing their concerns and appealing the world community to wake up and take proper initiative to control the global warming through AOSIS which is an organizational tool for voicing concerns of the SIDS. The clean energy mechanism is one of the initiatives of the AOSIS which is expected to replace the carbon driven energy production and to sustain the states on their own clean energy and this will be the main key finding of this study along with the prospects of the Initiative for Renewable Island Energy (IRIE). The study will be based on a thorough analysis of the published works of climate experts and personal experience and studies as a climate doctoral scholar. A thorough analytical and empirical process of the issue will be adopted in this study to answer the research questions arising in this study and in the conclusion finding a concrete solution to the problems cited will be attempted.

Optimization of tugboat propulsion system configurations: A holistic life cycle assessment case study

The International Maritime Organization has initialized a strategy to reduce 30% and 50% of carbon dioxide emissions from marine activities by 2030 and 2050 respectively. It is extremely challenging to achieve but innovative cleaner technologies are under research and development to help control and reduce maritime carbon emission. One fact is that the usage of tugboats has been increasing in recent years as huge demands of marine offshore activities (construction, installation and maintenance of renewable islands and wind farms); therefore, the performance of tugboats should be well-evaluated which could be a valuable contribution to maritime emission reduction. This paper focuses on investigating a tugboat’s life cycle performance, specifically comparing different configurations of the propulsion system and selecting an optimal system with the lowest emissions release, costs and hazard impacts. A case study was carried out comparing five different engine configurations with the help of commercial and in-house developed life cycle assessment software in order to comprehensively evaluate the ship performance. Three main life phases, three evaluation flows, four emission categories and three criteria, were under consideration in this study. The results indicate LCA method and the in-house software could help to compare and determine optimal configurations and the engine configuration with three medium size engines is the optimal one which generated lowest emissions equivalent to 15.5 million euros, invested 14.2 million euros and occur a risk impact equivalent to 1.01 million euros. This paper not only provides a case study for the tugboat configuration assessment but also recommends LCA methodology as a general evaluation method for emission reduction technologies who have to meet the extreme requirements of emission control in the next few decades.

Steady-state Operation Area of VSC-HVDC Converter Station Connecting Renewable Energy Cluster by Isolated Network

When the large-scale renewable power island is connected to VSC-HVDC transmission system, we should figure out the steady-state operation area of VSC-HVDC converter station. Based on the equivalent model of renewable energy island, the constraints of VSC-HVDC converter station are analyzed, and a fast method for calculating steady-state operation area of converter station is presented in this paper. The influence of equivalent line impedance of renewable energy island, transformer ratio of converter station and voltage setting value of grid-connected point on steady-state operation area of converter station is analyzed. And the three-dimensional view of the steady-state operation area of the converter station under different grid-connected voltage is depicted.

Feasibility analysis of renewable energy options for the union territory of Lakshadweep Islands

The power generation of most islands depends mainly on costly oil. Since the cost of energy is very high so these are the best test place for the implementation of the new technologies. We have considered the case of Lakshadweep Island which is one of a union territory of India. In Lakshadweep electricity is mainly generated from diesel generator sets. In this paper, an investigation has been made to find out total available potential of solar, wind and biomass in five islands of union territory of Lakshadweep. If we start generating up to the available potential then some islands will become renewable islands and this will increase the reliability, employment and decreases the cost of energy generation and pollution. Pearl and Logistic models have been used to find out the growth rate of SPV power generation. Using these models we find out that in how many years we will achieve the total available potential. After this, we have proposed a model of hybrid energy power generation for Kavaratti Island. The simulations and techno-economic evaluations have been done with the help of hybrid optimisation model for electric renewables software. Thousands of simulations have been carried out to achieve an optimal autonomous system configuration, in terms of system net present cost and cost of energy.

High penetration renewable generation within Australian isolated and remote power systems

Remote communities increasingly integrate renewable source generation to reduce the environmental and economic impact of diesel generation. Despite benefits scaling proportionally with the level of renewable penetration, most systems restrict renewable utilisation to below 30% of annual production. Identifying system complexity as a key barrier to renewable uptake, this paper investigates methodologies to simplify integration of high renewable penetrations. Three approaches are considered, via three Australian case studies; King Island, Tasmania (approach one), Flinders Island, Tasmania (approach two), and Rottnest Island, Western Australia (approach three). Approach one details a methodology for wind plus storage integration. Approach two details a methodology for wind, solar PV, plus storage integration. Approach three details a methodology for wind and solar PV integration, without storage. All approaches facilitate high renewable penetrations, with each island majority renewable supplied. Approach one benchmarks system performance, with King Island one of the worlds’ earliest high penetration renewable islands. Approach two explores benefit via renewable diversification. Approach three investigates rationalisation of energy storage via low load diesel and demand management technology substitution. For approach three a 32% reduction in capital cost was observed, identifying commercial justification for the approach via deferral of energy storage integration.

Funding Boost for Ferry Fuel Project

Hydrogen diesel injection system to run on renewable island energy

Techno-economic assessment of a renewable bio-jet-fuel production using power-to-gas

A techno-economic assessment of a novel biorefinery concept is carried out. It combines the hydrotreatment of vegetable oils (HEFA) with a power-to-gas (PTG) unit that provides the required hydrogen. Several scenarios are examined: the electricity supply for the PTG unit is varied from a grid-based supply to a renewable island solution; the hydrogen supply is varied from a PTG unit to conventional steam reforming; the utilised vegetable oil is varied from jatropha to rapeseed, palm and used cooking oil; the main product is varied from jet fuel to diesel.The HEFA-plant is assumed to process 500 kt of vegetable oil annually. In the reference scenario, jatropha oil is used as feedstock producing 227 kt a−1 of jet fuel. Per ton of processed oil, 1910 kWhel are used to produce 35.7 kg of hydrogen required for its treatment. By using different vegetable oils, both hydrogen demand and fuel output vary in a range of about ±10%. The overall energetic efficiency towards jet fuel is 41.6%.With a bandwidth between 1295 and 1800 EUR t−1 of jet fuel, the specific production costs are three to four times higher than the market price for fossil jet fuel. Operating the refinery in diesel-mode could lower the production costs by ca. 30%. More high-value, long-chained fuels are produced this way due to a lower cracking rate compared to the jet-mode.Investments of around 132million EUR are required for the HEFA-plant in all scenarios. Investments for the PTG-plant lie around 82million EUR if there is a constant electricity supply from the grid. They reach 246million EUR if electricity is supplied in an island-solution based on fluctuating renewables demanding much higher hydrogen production and storage capacities. Total investments in the biorefinery reach 378millionEUR in this case. Despite high capital costs, the largest cost item is vegetable oil – similarly to a conventional HEFA plant. Supporting policy instruments such as subsidies or quotas for renewable jet fuel seem indispensable for an introduction of the PTG-HEFA technology in the short to medium term.

Toward a 100% renewable island: A case study of Ometepe's energy mix

Abstract Despite generally having significant renewable energy potential, islands tend to depend on imported fossil fuels with volatile prices. This paper aims to provide technical inputs for reorganizing the energy planning for Ometepe Island. The result of the wind and solar resource assessments indicates wind power densities of 147 W/m2 and 178 W/m2 at elevations of 80 m and 120 m, respectively, and an irradiation level of 5.3 kWh/m2/day. The estimated wind LCOEs are significantly lower than current diesel plant operating prices. Photovoltaic systems will probably become cost-effective 15 years from now for all non-subsidized end customers. However, it would be necessary to store energy to phase out diesel generation, and analyses were conducted to determine the possibility of a pumped-storage hydro plant. The annual biogas potential was estimated as ∼550,000 Nm3, and in conjunction with electric stoves, it could be used to replace other fuels for cooking. Electric buses are an option for replacing the current diesel-run public buses, but advantageous financial conditions and reorganization of the bus schedules would be required. Also, a street lighting program was found to be cost-effective. The renewable energy transformation of the island might act as a role model for energy transition in Nicaragua.

Integration of renewable energy and demand response technologies in interconnected energy systems

Sustainable island energy systems have been a subject of academic research for some time. Real-life examples of highly renewable and sustainable island energy systems can be found all over the World. Islands on small geographic proximity provide the potential for the development of 100% renewable island energy systems by exploiting their grid interconnections. This paper proposes that interconnections of a group of islands can be used to integrate the production from locally available renewable energy sources. Besides interconnection, electric vehicles were used as a demand response technology to provide storage for electrical energy from variable sources. Electric vehicles were connected to the grid using smart charging systems (vehicle-to-grid). In addition, stationary batteries were explored in sub-scenarios for the year 2035. This enabled to analyse the influence of the battery location through two main different scenarios, i.e. one big central battery and several smaller distributed batteries. Scenarios with different integration dynamic of variable renewable energy sources and electrical vehicles were modelled with EnergyPLAN model, while the interconnection analysis was carried out with the MultiNode tool expansion. The results showed that the interconnections increased the share of energy from renewable energy sources in the final energy consumption and declined the total critical excess electricity production, while vehicle to grid technology enabled exploitation of synergies between sectors.

Initial perspective on a 100% renewable electricity supply for Prince Edward Island

Prince Edward Island, already with the highest wind energy penetration of any province in Canada, aims to increase its renewable energy generation. A challenge is realizing better matching of intermittent wind and solar power with on-island electricity demand. This paper provides an initial perspective by considering the case of a 100% renewable island electricity system. Using time-series power data of wind, solar, and electricity demand for the province, varying capacities of wind and solar power along with battery energy storage and biomass are considered to model 100% renewable electrical energy scenarios. Wind, solar, and storage combinations without curtailment show how complementary supply combinations can reduce seasonal variations. Scenarios including curtailment demonstrate significantly reduced storage requirements. Scenarios that include biomass suggest little benefit in combining biomass and storage. Least-cost solar, wind, and storage capacities are estimated. Potential storage cost reductions appear to be transformative in enabling greater renewable energy integration.

Possibility of Zeroing CO<sub>2</sub> Emissions Due to Energy Use in Gavdos Island, Greece

The possibility of transforming Gavdos Island located south of Crete, Greece to a 100% renewable energies island has been investigated. Gavdos Island has few inhabitants but it hosts a large number of tourists during the summer. Due to the small size of the island the use of vehicles is limited. It has abundant local energy resources, mainly solar and wind energy, which are currently underutilized. Electricity is locally generated with diesel oil and its electric grid is not interconnected with the grid of Crete. Energy demand in the island has been estimated as well as the availability of various renewable energy resources. The most reliable and cost effective of them, including solar thermal, solar and wind power, solid biomass burning and high efficiency heat pumps have been indicated for achieving a 100% renewable island. Electric vehicles must also replace conventional vehicles in order to zero carbon emissions in transport. Since the power grid in the island is isolated, electricity storage is required and it could be obtained either with electric batteries or with a small hydro-pump storage system. The nominal power of the required solar-PV system for covering all the electricity needs in Gavdos island has been estimated at 848 KWp and the required electricity storage capacity was at 19.2 MWh.

Cook Islands: 100% Renewable Energy in Different Guises

Abstract In its approach to delivering a 100% renewable energy target across 12 islands by 2020, the Cook Islands presents a rare insight into how planning requirements of high penetration renewable island systems vary with scale. To support this ambitious plan the Asian Development Bank and the European Union fund the Cook Islands Renewable Energy Sector Project, which will construct up to six solar photovoltaic (PV) power plants with a total installed capacity of about 3 megawatts-peak coupled with battery to store electricity from solar energy. The first three islands have small, standardized, centralized solutions (solar PV coupled with battery with existing diesel backup). An order of magnitude larger, Aitutaki will be implemented as a centralized solution in two stages, allowing detailed data collection and capacity building. An order of magnitude larger again, Rarotonga requires progressive planning and implementation including distributed generation, advanced control and integration, and sophisticated commercial structures.

Sustainability of remote communities: 100% renewable island of Hvar

Island communities require in-detail mapping of resources available for exploitation for energy purposes, since infrastructure and connections to the mainland present, in most cases, a weak point of the island energy supply. As the present energy supply on Croatian islands relies mostly on fossil fuels and electricity from the mainland, it becomes obvious that exploitation of renewable energy sources is the only solution that leads towards self-sufficiency and sustainable development. In order to design a self-sufficient and sustainable island, three major technological changes are needed: integration of renewable energy sources alongside with energy savings and improvements in energy efficiency in the energy production. Analyses for several other Croatian islands have been performed using Renewislands/ADEG methodology in order to assess all possible outcomes. The scenarios in these cases have shown that islands can become self-sufficient through combining renewable technologies and energy storage systems. Energy storage systems will be crucial for achieving desired objectives in terms of energy independence from the mainland and in general import of fossil fuels. The analysis conducted for the island of Hvar will result in creation of several scenarios which will clearly point out the favorable solutions for improvement of both security of energy supply and covering the majority of energy demand with renewable energy sources and storage technologies. Also, when talking about implementation of renewable technologies on island of Hvar, an optimal mix of technologies must be applied in order to avoid excess costs and to achieve minimal impact on environment in terms of visual pollution.

How to achieve a 100% RES electricity supply for Portugal?

Portugal is a country with an energy system highly dependent on oil and gas imports. Imports of oil and gas accounted for 85% of the country’s requirements in 2005 and 86% in 2006. Meanwhile, the share of renewable energy sources (RES) in the total primary energy consumption was only 14% in 2006. When focusing only on electricity production, the situation is somewhat better. The share of RES in gross electricity production varies between 20% and 35% and is dependent on the hydropower production in wet and dry years. This paper presents, on a national scale, Portugal’s energy system planning and technical solutions for achieving 100% RES electricity production. Planning was based on hourly energy balance and use of H 2RES software. The H 2RES model provides the ability to integrate various types of storages into energy systems in order to increase penetration of the intermittent renewable energy sources or to achieve a 100% renewable island, region or country. The paper also represents a stepping-stone for studies offering wider possibilities in matching and satisfying electricity supply in Portugal with potential renewable energy sources. Special attention has been given to intermittent sources such as wind, solar and ocean waves that can be coupled to appropriate energy storage systems charged with surplus amounts of produced electricity. The storage systems also decrease installed power requirements for generating units. Consequently, these storages will assist in avoiding unnecessary rejection of renewable potential and reaching a sufficient security of energy supply.

H2RES, Energy planning tool for island energy systems – The case of the Island of Mljet☆

When it comes to the energy planning, computer programs like H2RES are becoming valuable tools. H2RES has been designed as support for simulation of different scenarios devised by RenewIsland methodology with specific purpose to increase integration of renewable sources and hydrogen into island energy systems. The model can use wind, solar, hydro, biomass, geothermal as renewable energy sources and fossil fuel blocks and grid connection with mainland as back up. The load in the model can be represented by hourly and deferrable electricity loads of the power system, by hourly heat load, by hydrogen load for transport and by water load depending on water consumption. The H2RES model also has ability to integrate different storages into island energy system in order to increase the penetration of intermittent renewable energy sources or to achieve a 100% renewable island. Energy storages could vary from hydrogen loop (fuel cell, electrolyser and hydrogen storage) to reversible hydro or batteries for smaller energy systems. The H2RES model was tested on the power system of the Island of Porto Santo – Madeira, the islands of Corvo, Graciosa, and Terrciera – Azores, Sal Island – Cape Verde, Portugal, the Island of Mljet, Croatia and on the energy system of the Malta. Beside energy planning of the islands, H2RES model could be successfully applied for simulation of other energy systems like villages in mountain regions or for simulation of different individual energy producers or consumers.

A renewable island life: Electricity from renewables on small islands

Individually, islands may not be very important energy markets with sensible critical mass, but taken together, they represent quite a big niche market in the world for renewable energies (RE). In fact, at present, the largest percentage of RE in the energy mix can be found on islands. Indradip Mitra reports.

Ireland's renewable island

Ireland's largest island, Achill, could supply all its energy needs from renewable sources. This paper discusses the energy analysis performed for Achill and the examination of Achill's renewable energy potential. In order to meet electrical demand, wind (offshore and onshore) and tidal energy were examined. However, the weakness of the electrical grid was found to be a prohibiting factor for wind generation. A planned upgrade of the network from one 10 kV feeder to two 20 kV feeders is likely to commence in 2003. The investigation of tidal power at Bull's Mouth is discussed.