Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA 01069.
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543.
Proc Natl Acad Sci U S A. 2021 Nov 16;118(46). doi: 10.1073/pnas.2107250118.
Collecting and removing ocean plastics can mitigate their environmental impacts; however, ocean cleanup will be a complex and energy-intensive operation that has not been fully evaluated. This work examines the thermodynamic feasibility and subsequent implications of hydrothermally converting this waste into a fuel to enable self-powered cleanup. A comprehensive probabilistic exergy analysis demonstrates that hydrothermal liquefaction has potential to generate sufficient energy to power both the process and the ship performing the cleanup. Self-powered cleanup reduces the number of roundtrips to port of a waste-laden ship, eliminating the need for fossil fuel use for most plastic concentrations. Several cleanup scenarios are modeled for the Great Pacific Garbage Patch (GPGP), corresponding to 230 t to 11,500 t of plastic removed yearly; the range corresponds to uncertainty in the surface concentration of plastics in the GPGP. Estimated cleanup times depends mainly on the number of booms that can be deployed in the GPGP without sacrificing collection efficiency. Self-powered cleanup may be a viable approach for removal of plastics from the ocean, and gaps in our understanding of GPGP characteristics should be addressed to reduce uncertainty.
收集和清除海洋塑料可以减轻其对环境的影响；然而，海洋清理将是一项复杂且能源密集型的作业，尚未得到充分评估。这项工作研究了将这种废物通过热液转化为燃料以实现自供电清理的热力学可行性及其后续影响。全面的概率分析表明，热液液化具有产生足够能量的潜力，为清理过程和执行清理的船只提供动力。自供电清理减少了满载废物船只返回港口的次数，从而减少了对大多数塑料浓度所需的化石燃料的使用。针对大太平洋垃圾带（GPGP）模拟了几种清理方案，每年清理的塑料量为 230 至 11500 吨；该范围对应于 GPGP 中塑料表面浓度的不确定性。估计的清理时间主要取决于在不牺牲收集效率的情况下可以在 GPGP 中部署的浮标数量。自供电清理可能是从海洋中清除塑料的一种可行方法，应解决我们对 GPGP 特征理解的差距，以降低不确定性。
