A Preliminary Life Cycle Analysis of Bioethanol Production Using Seawater in a Coastal Biorefinery Setting

Claudia E. Carter,Fanran Meng,Christopher E. French,Abdelrahman S. Zaky

doi:10.3390/pr9081399

Abstract

Bioethanol has many environmental and practical benefits as a transportation fuel. It is one of the best alternatives to replace fossil fuels due to its liquid nature, which is similar to the gasoline and diesel fuels traditionally used in transportation. In addition, bioethanol production technology has the capacity for negative carbon emissions, which is vital for solving the current global warming dilemma. However, conventional bioethanol production takes place based on an inland site and relies on freshwater and edible crops (or land suitable for edible crop production) for production, which has led to the food vs. fuel debate. Establishing a coastal marine biorefinery (CMB) system for bioethanol production that is based on coastal sites and relies on marine resources (seawater, marine biomass and marine yeast) could be the ultimate solution. In this paper, we aim to evaluate the environmental impact of using seawater for bioethanol production at coastal locations as a step toward the evaluation of a CMB system. Hence, a life cycle assessment for bioethanol production was conducted using the proposed scenario, named Coastal Seawater, and compared to the conventional scenario, named Inland Freshwater (IF). The impact of each scenario in relation to climate change, water depletion, land use and fossil depletion was studied for comparison. The Coastal Seawater scenario demonstrated an improvement upon the conventional scenario in all the selected impact categories. In particular, the use of seawater in the process had a significant effect on water depletion, showing an impact reduction of 31.2%. Furthermore, reductions were demonstrated in natural land transformation, climate change and fossil depletion of 5.5%, 3.5% and 4.2%, respectively. This indicates the positive impact of using seawater and coastal locations for bioethanol production and encourages research to investigate the CMB system.

Highlights

Growing concern regarding the effect of anthropogenic activity on climate change has given the impetus to research greener energy sources
Fossil depletion and climate change are areas in which bioethanol production has already reduced the impacts compared with the use of fossil fuels, and so they were included to ascertain whether they could be further improved with the Coastal Seawater scenario
The impact assessment showed that the Coastal Seawater scenario had 31.2% less impact on water depletion than the Inland Freshwater scenario (Figure 3)

Summary

Introduction

Growing concern regarding the effect of anthropogenic activity on climate change has given the impetus to research greener energy sources. To reach these goals, it is essential to base infrastructure on a framework of sustainable technology to reduce emissions, and to mitigate the environmental changes already generated, such as long-lived carbon dioxide (CO2 ) emissions. Transportation is a major contributor to climate change, accounting for about 24% of global CO2 emissions and 21% of the total GHG emissions; three quarters of these emissions are generated by road vehicles [2,3]. These emissions, along with other greenhouse gases (GHGs), are released from the production and combustion of fossil fuels, mainly coal, gasoline and diesel. Fossil fuels are a dwindling finite resource

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