Future pathways for decarbonization and energy efficiency of ports: Modelling and optimization as sustainable energy hubs

The increasing energy demand in harbour areas, coupled with the need to reduce pollutant emissions, has led to the development of renewable energy-based polygeneration systems to face the carbon footprint of ports and ships at berth. In this way, in the coming years, ports can be converted into modern energy hubs. From this point of view, this paper presents a new dynamic simulation model for assessing and optimizing the energy and economic impact of ports. Here, energy systems and renewable sources can be designed to be connected to national electricity and natural gas grids and can include also alternative fuels (hydrogen, biomethane, etc.) and thermal energy networks, as well as different biomass fluxes (to be exploited for energy aims). Energy availability/demands of near towns and port buildings/infrastructures, as well as on-shore power supply are also included in the dynamic assessments. Hourly weather data and different prices for all the considered energy carriers are taken into account hour by hour. A multi-objective optimization approach is also implemented in the model considering energy and economic indexes to be optimized. The whole model is implemented in a computer tool written in MATLAB. For showing the capability of the developed model, a novel case study referred to the port of Naples (South-Italy) is presented. Here, several renewable energy sources are considered, including an anaerobic biodigester for producing biogas from the organic waste of docked cruise ships. A combined heat and power system (fed by biogas) is implemented in the port energy hub also for supplying absorption chillers. PV panels, and marine power generators are also included. In the conducted analysis, optimization targets are the maximization of system self-consumption and self-sufficiency as well as the minimum simple payback period. The proposed system can effectively contribute to the decarbonization of the port energy demand and reduce harmful pollutant emissions. Results showed that very high rate of renewable energy produced on-site can be exploited (up to 84%) by the considered port facilities, ensuring increasing independency from utility power grid (self-sufficiency index up to 40%). By the obtained results and through the developed simulation/optimization tool, novel design and operating criteria can be achieved for future port energy hubs featured by renewables and bi-directional energy exchange between ships and port

Design and environmental sustainability assessment of energy-independent communities: The case study of a livestock farm in the North of Italy

Abstract This paper investigates the energy and economic performance of several energy schemes that could potentially be applied to agricultural and zootechnical communities contributing to the international objectives of sustainable development. The proposed energy schemes involve integrated energy efficiency technologies and novel system layouts aiming at reaching the zero-energy goal at a community level, by considering collective energy actions with provision of benefits for members and stakeholders. The proposed scenarios include different innovative technologies, such as anaerobic digestion, cogeneration, biogas upgrading, solar, district heating and cooling. These layouts are modelled in TRNSYS simulation environment to perform dynamic simulations and parametric analyses of the pivotal system parameters. Such analyses are conducted to find out the best scenario and the size of its system components which optimize different energy and economic objective functions. To assess the feasibility of all proposed scenarios and energy schemes, as well as to investigate the potential of the developed models, proposed scenarios are studied for an existing community. This existing agricultural community named "La Bellotta", is served through different technologies, including a gas fuelled co-generator and an anaerobic biodigester. Simulation results show that the investigated scenarios allow for achieving very high self consumption ratios of energy produced on-site (from 57 to 100%), high economic performance (measured by the profitability index up to 1.35 for the best investigated scenario) and environmental benefits. The case study provides examples of energy schemes in which citizens and communities have a major benefit to invest in projects including renewables technologies, energy efficiency, and positive energy services

Sustainability and energy self-sufficiency assessment for small islands by adopting dynamic simulation approach

Small islands are usually characterized by high energy demand and no electricity network access with a consequent high fossil fuel energy consumption. This issue could be overcome by increasing the adoption of renewable energy systems and by enhancing the systems’ energy efficiencies. In this framework, the adoption of dynamic simulation and optimization analyses is crucial. For such a reason, in this paper, a novel approach based on dynamic simulation is presented and a suitable case study is conducted. Such an approach is developed with the twofold aim of increasing renewable energy penetration and improving the sustainability of small islands. The convenience in the dynamic simulation adoption is proven by investigating a suitable case study referring to the existing island community of El Hierro. The case study analysis focuses on the feasibility of converting its energy systems into an autonomous one by mixing different renewable-based technologies to traditional ones. The considered polygeneration system includes: i) wind turbines; ii) hydroelectric plants; iii) diesel engines; iv) solar thermal collectors; properly mixed to satisfy the electricity and hot water needs. Furthermore, to identify optimal configurations and maximize the share of renewable energy, a suitable parametric analysis is presented. Also, a hypothetical future scenario characterized by an island population increase is also investigated. Numerical results demonstrate the feasibility of the investigated polygeneration system, as well as the potentiality of the proposed methodology. Specifically, the dynamic simulation approach allows one to determine design criteria and to properly obtain a remarkable increase in terms of renewable energy exploitation and energy independence. In particular, the considered system configuration provides up to 85% of the annual electricity demand and about 82% of the annual thermal energy needs by renewable sources with substantial economic savings

Supporting the Sustainable Energy Transition in the Canary Islands: Simulation and Optimization of Multiple Energy System Layouts and Economic Scenarios

The Canary Islands have great potential for the implementation of sustainable energy systems due to its availability of natural resources. The archipelago is not connected to the mainland electricity grid and the current generation system is mainly based on traditional fossil fuel. Therefore, the islands strongly dependent on fuel importations, with high costs due to logistics. Furthermore, due to the inadequate coverage of residential heating and cooling needs, the per capita energy consumption is far below the Spanish national average. This occurrence has inspired an intense debate on the current development model of the Canary Archipelago, which has led to the implementation of actions and measures aimed at achieving greater energy sustainability in the archipelago. Furthermore, at a local scale, an important investment plan has been carried out by the Spanish grid operator to ensure energy supply, to improve the system security and reliability, and to optimize the integration of renewable energies. Future measures and investments will be crucial to ensure a sustainable growth, both from the economic and the environment point of views. In this framework, this paper aims to discuss and compare the energy solutions, based on renewable energy technologies, identified to boost the sustainable transition of the islands. To this aim, multiple configurations of a wind power plant coupled with reversible hydro power/storage system for the distributed and on-site energy production in the island of Gran Canaria were modeled, simulated, and optimized by a TRNSYS/Matlab algorithm suitably developed. Specifically, along with the proposed system layouts, different scenarios related to diverse annual costs growth rate of fuel were investigated. The proposed analysis covers a time horizon of 20 years, up to 2040, and aims at assessing the impact of the investigated solution on energy demand, energy supply, and population incomes. Depending on the considered fuel cost growth rate, the best system configurations allow a primary energy saving in the range of 58.1–68.1%. Based on the system choice, the enterprise will generate significant revenues to the island population. The net present values are estimated in the range 1.50 × 103 ÷ 1.84 × 103 and 0.85 × 103 ÷ 1.27 × 103 M€, respectively for the two considered scenarios (annual costs growth rate of fuel 2 and −2%). The analysis demonstrates the importance of investments targeted at the implementation of renewables. The proposed scenarios indicate that the current energy model has the potential to radical change and to tackle climate change and energy issues while producing substantial economic savings and better life conditions for the population in the next years

A novel dynamic simulation approach for the waste heat energy recovery of modern cruise ships sailing in the Northern sea

In the last years, the International Maritime Organization has been imposing severe and restrictive regulations on pollutant emissions to reduce the environmental impact of modern ships. Thus, the sustainable design of modern cruise ships is crucial to comply with these regulations. In this paper, a novel approach for assessing the potentiality of energy-saving technologies and strategies for ship applications is presented. This approach is based on dynamic simulation, and it is implemented in a suitable tool assembled in TRNSYS environment. Here, the ship-envelope as well as the related ship energy plant systems are modelled and simulated. Also, to consider different ship routes and relative dynamic boundary conditions variations during the cruise, a suitable tool capable of producing customized weather data is developed. To show the effectiveness of the proposed approach, a novel case study is presented. It refers to a modern cruise ship fuelled by liquified natural gas cruising in Norwegian fjords sea. Here, the waste heat of exhaust gases and engine jacket water of LNG engines are exploited to supply different thermally activated devices. Specifically, heat exchangers are adopted for supplying hot water to air-handler units; multi-stage flash distillation systems are adopted for freshwater production whereas steam turbine system, organic Rankine cycle device and molten carbon fuel cells are utilized for electricity production. Suitable control and decision strategies for optimizing the waste heat recovery are implemented. Eight different system layouts are analysed and promising results in terms of primary energy savings (18.1%), avoided pollutants emission (24.4 ktCO2/y, 40.0 tNOx, 90.0 tSOx, 84.0 tPM2.5) and simple payback (0.68 y) are achieved

Dynamic simulation model for the design and optimization of a novel high-vacuum solar thermal collector

This paper focuses on the design of an innovative high-vacuum solar thermal collector, for which a novel dynamic simulation model is developed. As it is well known, standard flat plate solar thermal collectors are affected by thermal losses which significantly reduce their energy performance. Among all thermal losses, convective and radiative account for approximately 80% of the overall. To reduce these losses, a novel innovative flat plate solar thermal collector characterized by a high-vacuum space (i.e. 10-8 mbar) between the glass cover and edge is developed. The vacuum space is made with the aim of insulating the absorber serpentine with a consequent convective thermal loss reduction. In addition, the serpentine absorber system is suitably painted with a solar coating for reducing the radiative thermal loss. Thus, the presented prototype allows store hot water with no need for any additional storage system. In this paper, a mathematical model able to assess the energy performance of the innovative high-vacuum prototype is also presented. The tool is based on a detailed 3D transient finite-difference thermal network and it is validated against the experimental data obtained by different experimental tests