The potential of emerging bio-based products to reduce environmental impacts

Abstract

The current debate on the sustainability of bio-based products questions the environmental benefits of replacing fossil- by bio-resources. Here, we analyze the environmental trade-offs of 98 emerging bio-based materials compared to their fossil counterparts, reported in 130 studies. Although greenhouse gas life cycle emissions for emerging bio-based products are on average 45% lower (-52 to -37%; 95% confidence interval), we found a large variation between individual bio-based products with none of them reaching net-zero emissions. Grouped in product categories, reductions in greenhouse gas emissions ranged from 19% (-52 to 35%) for bioadhesives to 73% (-84 to -54%) for biorefinery products. In terms of other environmental impacts, we found evidence for an increase in eutrophication (369%; 163 to 737%), indicating that environmental trade-offs should not be overlooked. Our findings imply that the environmental sustainability of bio-based products should be evaluated on an individual product basis and that more radical product developments are required to reach climate-neutral targets.

Fig. 1. Scatterplot displaying all the response ratios as blue dots of the GHG footprints of bio-based products compared to their fossil counterparts, per bio-based product.

Encircled orange dots represent arithmetic average RRs per bio-based product with corresponding 95% CI as opaque orange error-bars. There is no 95% CI for bio-based products with n = 1. Black dashed line at RR = −0.60 is the predicted mean RR based on a random-effects model including product type and study as random effects, accompanied by two black lines as overall 95% CI: −0.74 to −0.47. In the grey area, the GHG footprints of the bio-based products are lower than their fossil counterparts, with a grey line at RR = 0 representing no difference in GHG footprint. See Supplementary Table S. 3 for details.

Fig. 2. Change in GHG footprint response ratios (RR) in relation to key parameters.

a Product category, b feedstock category and b TRL category, meaning the TRL from where the study up scales to a TRL 9. n gives the number of response ratios. Grey bars indicate 95% confidence intervals. Dashed black line at RR = 0 indicates no difference in GHG footprint between bio-based product and its fossil-based alternatives. In (a), biorefinery products refers to biochemicals produced in an integrated biorefinery producing multiple products and energy. For the results in (c), the 13 studies that did not model all the way up to a TRL 9 (but to a lower TRL, e.g. TRL 7) were excluded from the analysis. Plots show the predicted mean RR and 95% CI (error-bars) from single mixed-effects models. The predictions translated to percentages per category (in a–c) can be found in Supplementary Table S. 5.

Fig. 3. Plot showing predicted mean and 95% CI of GHG, eutrophication, acidification, NREU, ozone depletion and photochemical ozone formation impacts.

In percentages, on average the GHG footprint is reduced by 45% (95% CI: −52 to −37%), eutrophication is increased with 369% (95% CI: 163 to 737%), acidification is increased with 41% (95% CI: −9 to 119%), NREU is reduced by 39% (95% CI: −57 to −14%), ozone depletion is reduced with 28% (95% CI: −73 to 88%) and photochemical ozone formation is reduced by 16% (95% CI: −57 to 63%). A plot with the arithmetic averages and 95% CIs can be found in Supplementary Fig. S. 9. A plot with an overview of all environmental impacts with n ≤ 30 and the predicted mean and 95% CI of the RRs across product types and studies can be found in Supplementary Fig. S. 10.