Life cycle assessment of nutrient remediation and bioenergy production potential from the harvest of hydrilla ( Hydrilla verticillata)

• Published in: Journal of environmental management Vol. 91; no. 12; pp. 2626 - 2631
• Main Authors: Evans, Jason M., Wilkie, Ann C.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.12.2010; Elsevier; Academic Press Ltd
• Subjects: Anaerobic digestion; Animal, plant and microbial ecology; Applied ecology; Aquatic plant harvest; Aquatic plants; Bioenergy; Biofuels - economics; Biogas; Biological and medical sciences; Biomass; Biomass energy; Compost; Composting; Conservation, protection and management of environment and wildlife; Cost-effectiveness; Economics; Environmental Restoration and Remediation - economics; Environmental Restoration and Remediation - methods; Fertilizers; Flora; Fundamental and applied biological sciences. Psychology; General aspects; Harvest; Harvesting; Herbicides; Hydrilla; Hydrilla ( Hydrilla verticillata); Hydrilla verticillata; Hydrocharitaceae; Life cycle assessment; Life cycle assessment (LCA); Life cycle engineering; Management; Marine resources; Mathematical analysis; Nutrient remediation; Nutrients; Remediation; Waste utilization; Water management; Compost; Life cycle assessment (LCA); Waste utilization; Hydrilla ( Hydrilla verticillata); Biogas; Nutrient remediation; Bioenergy; Anaerobic digestion; Aquatic plant harvest; Monocotyledones; Ecobalance; Hydrocharitaceae; Environmental management; Hydrilla (Hydrilla verticillata); Angiospermae; Nutrient; Spermatophyta; Aquatic plant
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2010.07.040

Hydrilla ( Hydrilla verticillata) is one of the world’s most problematic invasive aquatic plants. Although management of hydrilla overgrowth has often been based on use of chemical herbicides, issues such as the emergence of herbicide-resistant hydrilla biotypes and the need for in situ nutrient remediation strategies have together raised interest in the use of harvester machines as an alternative management approach. Using a life cycle assessment (LCA) approach, we calculated a range of net energy and economic benefits associated with hydrilla harvests and the utilization of biomass for biogas and compost production. Base case scenarios that used moderate data assumptions showed net energy benefit ratios (NEBRs) of 1.54 for biogas production and 1.32 for compost production pathways. NEBRs for these respective pathways rose to 2.11 and 2.68 when labor was excluded as a fossil fuel input. Base case biogas and compost production scenarios respectively showed a monetary benefit cost ratio (BCR) of 1.79 and 1.83. Moreover, very high NEBRs (3.94 for biogas; 6.37 for compost) and BCRs (>11 for both biogas and compost) were found for optimistic scenarios in which waterways were assumed to have high hydrilla biomass density, high nutrient content in biomass, and high priority for nutrient remediation. Energy and economic returns were largely decoupled, with biogas and fertilizer providing the bulk of output energy, while nutrient remediation and herbicide avoidance dominated the economic output calculations. Based on these results, we conclude that hydrilla harvest is likely a suitable and cost-effective management program for many nutrient-impaired waters. Additional research is needed to determine how hydrilla harvesting programs may be most effectively implemented in conjunction with fish and wildlife enhancement objectives.