Abstract
AbstractClimate change and energy security promote using renewable sources of energy such as biofuels. High woody biomass production achieved from short‐rotation intensive plantations is a strategy that is increasing in many parts of the world. However, broad expansion of bioenergy feedstock production may have significant environmental consequences. This study investigates the watershed‐scale hydrological impacts of Eucalyptus (E. grandis) plantations for energy production in a humid subtropical watershed in Entre Rios province, Argentina. A Soil and Water Assessment Tool (SWAT) model was calibrated and validated for streamflow, leaf area index (LAI), and biomass production cycles. The model was used to simulate various Eucalyptus plantation scenarios that followed physically based rules for land use conversion (in various extents and locations in the watershed) to study hydrological effects, biomass production, and the green water footprint of energy production. SWAT simulations indicated that the most limiting factor for plant growth was shallow soils causing seasonal water stress. This resulted in a wide range of biomass productivity throughout the watershed. An optimization algorithm was developed to find the best location for Eucalyptus development regarding highest productivity with least water impact. E. grandis plantations had higher evapotranspiration rates compared to existing terrestrial land cover classes; therefore, intensive land use conversion to E. grandis caused a decline in streamflow, with January through March being the most affected months. October was the least‐affected month hydrologically, since high rainfall rates overcame the canopy interception and higher ET rates of E. grandis in this month. Results indicate that, on average, producing 1 kg of biomass in this region uses 0.8 m3 of water, and the green water footprint of producing 1 m3 fuel is approximately 2150 m3 water, or 57 m3 water per GJ of energy, which is lower than reported values for wood‐based ethanol, sugar cane ethanol, and soybean biodiesel.
Highlights
Using sources of renewable energy, such as biofuels, may result in cleaner, cost-competitive alternatives to fossil fuels (Sekoai et al, 2019; Winjobi et al, 2018)
When 434 mm/year of irrigation of E. grandis was added to the intensive scenario, the number of water stress days decreased by 85% and the cumulative biomass production of the watershed increased to 12.3 × 106 ton, an increase in 36% over the non-irrigated intensive scenario
The main objectives of this work were to predict the hydrological impacts and evaluate the water-b iomass tradeoffs associated with the development of E. grandis plantations for bioenergy production
Summary
Using sources of renewable energy, such as biofuels, may result in cleaner, cost-competitive alternatives to fossil fuels (Sekoai et al, 2019; Winjobi et al, 2018). Cellulosic crops, crop residues, and woody biomass are promising bioenergy sources because they have shown to produce similar fuel yields per feedstock mass as first-g eneration biofuels such as corn-based ethanol (Lynd et al, 1991; Tilman et al, 2009). Many parts of the world are experiencing a rapid increase in Eucalyptus plantations for biofuel (Gonzalez et al, 2011). There are several bioenergy products from Eucalyptus, including cellulosic biodiesel and ethanol (Gonzalez et al, 2011), as well as wood pellets for direct heating or electricity generation (Pirraglia et al, 2010)
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