Abstract
Overtopping breakwater systems are among the most promising technologies for exploiting wave energy to generate electricity. They consist in water reservoirs, embedded in piers, placed on top of ramps, higher than sea-level. Pushed by wave energy, seawater fills up the reservoirs and produces electricity by flowing back down through low head hydro turbines. Different overtopping breakwater systems have been tested worldwide in recent years. This study focuses on the Overtopping BReakwater for Energy Conversion (OBREC) system that has been implemented and tested in the harbor of Naples (Italy). The Life Cycle Assessment of a single replicable module of OBREC has been performed for analyzing potential environmental impacts, in terms of Greenhouse Gas Emissions, considering construction, installation, maintenance, and the operational phases. The Carbon Footprint (i.e. mass of CO2eq) to build wave energy converters integrated in breakwater systems has been estimated, more specifically the “environmental investment” (i.e. the share of Carbon Footprint due to the integration of wave energy converter) needed to generate renewable electricity has been assessed. The Carbon Intensity of Electricity (i.e. the ratio between the CO2eq emitted and the electricity produced) has been then assessed in order to demonstrate the profitability and the opportunity to foster innovation in the field of blue energy. Considering the impact for implementing an operational OBREC module (Carbon Footprint = 1.08 t CO2eq; Environmental Investment = 0.48 t CO2eq) and the electricity production (12.6 MWh/yr per module), environmental benefits (avoided emissions) would compensate environmental costs (i.e. Carbon Footprint; Environmental Investment) those provided within a range of 25 and 13 months respectively.
Highlights
The International Energy Agency (IEA) estimates that in 2017 global energy demand increased by 2.1% compared to previous years and the 72% of that increase has been met by deploying fossil fuels (International Energy Agency, 2018a)
These results are in line with other Life Cycle Assessment (LCA) evaluations regarding ocean energy technologies (e.g., Dahlsten, 2009; Uihlein, 2016; Thomson et al, 2019) demonstrating that most of their impacts are related to materials even beyond the installation and maintenance of the devices
In order to assess environmental benefits, we considered avoided emissions due to the implementation of Overtopping BReakwater for Energy Conversion (OBREC) based on Carbon Intensity of Electricity (CIE), that corresponds to 0.49 t CO2eq/MWh and 0.54 t CO2eq/MWh per renewable electricity
Summary
The International Energy Agency (IEA) estimates that in 2017 global energy demand increased by 2.1% compared to previous years and the 72% of that increase has been met by deploying fossil fuels (International Energy Agency, 2018a). In order to accomplish the Paris Agreement (United Nations Framework Convention on Climate Change, 2015), the IEA flagship publication, World Energy Outlook 2017, foresees a “Sustainable Development Scenario” (among 240 energy mix scenarios in 2100) according to which a mixture of technologies is considered a prerequisite to meet climate objectives (International Energy Agency, 2017). In this line, the BP Energy Outlook 2018 foresees, in 2040, an extremely diversified world energy mix with a significant increase of renewable energy (BP energy Outlook, 2018). International Renewable Energy Agency (2018) remarked that renewable energy combined with improved energy efficiency are the cornerstone of climate solution and, by 2050 the share of renewable energy in the European Union could grow from about 17% to over 70%
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