Consequential analysis of algal biofuels: Benefits to ocean resources

Yizhen Zhang,Alissa Kendall

doi:10.1016/j.jclepro.2019.05.057

Abstract

Ocean resources have been exploited at unprecedented rates, leading to marine biodiversity loss, food web changes, and other alterations of ocean ecosystem functions and structures. The capture of wild fish for human consumption and fishmeal are the primary drivers. Microalgae oil has long been investigated for biofuel production. Its co-product, defatted microalgal biomass, has potential to replace fishmeal from wild fish catch and thus mitigate ocean resource depletion.This study develops a new indicator for assessing consequential impacts on ocean resources in life cycle assessment. The indicator is based on primary production required, a concept previously used in ecological assessments and life cycle assessments to evaluate ecological impacts of fisheries and aquaculture. We estimate the primary production required for fishmeal production from the ocean (166 kg carbon/kg fishmeal), and the potential of defatted microalgae biomass displacing fishmeal. Results show that defatted microalgae biomass can lead to highly variable, but potentially significant, reductions in ocean resource demand. The variability is a function of the potential for replacement, which depends on the cultured fish species considered. As an example of this significance, based on available data for estimating the potential for defatted microalgal biomass to displace fishmeal for cultured tilapia, salmon, shrimp, carp, flounder, yellowtail and cod, by 2020 net primary production demand from the ocean could be reduced by approximately one billion tons of carbon.

Highlights

Human population growth and changing diets across the world have led to increasing demand for food, and for nutrient and protein rich animal products, including fish and shellfish
The results of fishmeal primary production required (PPR) produced in the Americas is shown in table 3, specific PPR stands for PPR using specific transfer efficiency (TE) while general PPR is calculated using the general TE estimate of 10%
Given the high variability between general and specific PPR, fine resolution spatial data of specific TE and trophic level (TL) for different species is desirable for accurately estimating the ocean impacts

Summary

Introduction

Human population growth and changing diets across the world have led to increasing demand for food, and for nutrient and protein rich animal products, including fish and shellfish. Algae avert some of the most challenging problems of terrestrial crops, such as direct and indirect land use change, and in some cases can be grown on low-quality water sources that are unfit for terrestrial crops. Because of these characteristics, along with the potential high productivity, algae has long been investigated as a potential source of biofuel. The typical pathway for algal biofuels assumes that accumulated algal oil is extracted and converted into biodiesel or renewable diesel This process results in a co-product, defatted algae biomass (DAB), which is a potential aquaculture feed.

Methods

Results

Conclusion