Abstract
The expansion of photovoltaic solar energy in the world is significant. However, its contribution to decreases in greenhouse gases (GHG) is not an absolute guarantee. In this context, it is necessary to evaluate its benefits in advance, considering the structure of the electric energy supply matrix of the country producing the photovoltaic solar system, as well as the country where the technology will be implemented. This study evaluates the adoption of renewable sources for electric power generation in a country with a high share of renewable energy. A life-cycle assessment (LCA) of a set of multi-Si photovoltaic (PV) systems installed in the Brazilian northeast (NE), was carried out. The actual generation data of 10 plants totaling 1.1 MWp installed capacity were evaluated during two years of operation. Energy payback time (EPBT), greenhouse gas emission rate (GHGe-rate), and emission payback time were calculated. The great influence of the electric matrix characteristics of the country manufacturing PV systems was evidenced in the results. The interconnected Brazilian electrical system had a 2020 projected GHGe-rate of 63.9 g CO2/kWh, while the results of 70% of the photovoltaic solar power plants (PSPS) assessed herein exhibit higher GHGe-rates. Thus, in countries where the electric matrix comprises a high share of renewable sources, such as Brazil, the incentive to use PV systems manufactured in nations whose electric matrix registers high emission factors should be well evaluated in terms of the impacts of GHG concentrations and the promotion of sustainable development, in order to avoid indirect import of significant amounts of carbon embedded in the systems.
Highlights
Humanity, at the very beginning of its existence, continuously faced climatic changes, fundamentally characterized by climate variability in cyclic regimes before the rupture caused by the use of productive technological machinery marked by the industrial revolution
In countries where the electric matrix comprises a high share of renewable sources, such as Brazil, the incentive to use PV systems manufactured in nations whose electric matrix registers high emission factors should be well evaluated in terms of the impacts of greenhouse gas (GHG) concentrations and the promotion of sustainable development, in order to avoid indirect import of significant amounts of carbon embedded in the systems
The Energy payback time (EPBT) results were, on average, 1.5 years above the average standards presented by other authors in previous studies [42,68,69,70,71,72,73,74,75], as the primary energy saved by the use of PV systems is lower when installed in Brazil, a country with a grid efficiency factor of 0.625
Summary
At the very beginning of its existence, continuously faced climatic changes, fundamentally characterized by climate variability in cyclic regimes before the rupture caused by the use of productive technological machinery marked by the industrial revolution. Energies 2018, 11, 2806 greenhouse gas (GHG) emissions, according to projected scenarios, are the main cause of the rise in average earth temperature from the middle of the 20th century, and the main variable responsible for the current environmental imbalance [1]. From 2000 to 2010, annual anthropogenic GHG emissions grew at a rate of 2.2% per year, leading to a total increase of 10 Gt CO2-eq. This increase was directly driven by energy supply (47%), industry (30%), transport (11%), and buildings (3%). Electricity and heat generation accounted for 25% of total direct emissions in 2010 [2]
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