Page - 285 - in Freshwater Microplastics - Emerging Environmental Contaminants?

benefits of plastic. Plastics make food last longer [84], offer more durable and lightweightpackagingfortransportationofgoods,maintaincleanpipesfordrinking waterdistribution,and facilitate low-cost sterile supplies forhospitals, eachhaving degreesof efficiencyover alternativematerials in termsofwastegeneration,water usage, andCO2 emissions, like lightweighting carswith plastic resulting in lower fuel consumption [85]. For example, an industry analysis comparing the impacts of transportation, production,wastemanagement, andmaterial/energy recovery on the environment concludedthat theupstreamproductionandtransportationphasesof thevaluechain forplasticsaccountedfor87%oftotalcosts [78], leaving13%ofthe impactsonthe environmentcauseddownstreambyhowwaste ismanaged.Plasticproducershave suggested that some of these upstream production impacts could be furthermiti- gated by sourcing low-carbon electricity that by doubling the current use of alternate energy for production could cut the plastics sector’s owngreenhouse gas emissions by 15% [78].Mitigating the problems ofmicroplastics requires under- standing not only where waste is generated but also where other environmental harms canbe avoided at all points along the value chain. TheCase forBridgeTechnologies While large-scale incinerators are criticized for cost, waste quotas, emissions, and the effect of undermining zerowaste strat- egies, is thereacasefor the temporaryuseofsmall-scalewaste toenergyuntilmore efficient systemsofmaterialmanagement evolve? While theH-Powerplant inOahu,Hawaii hasbeencriticized, alternativeshave been proposed. One firm recently proposed gasification (high heat conversion of waste toasyntheticgas),submittingevidencethat theinitialcostof infrastructure is far less than theH-Powerplant,pays for itself in1.4yearswithcurrentwaste input, is three timesmore efficient than incineration in terms of energy conversion, and has no long-termwaste quota, allowing zerowaste strategies to alleviate existing waste streams. The system could then be relocated to other waste hot spots to manage waste or reducewaste volumes in exposed landfills (Sierra Energy, per- sonal communication). Althoughvolumesofwaste reducedon landbecomevolumeofwaste increased in the air (conservation ofmass), any formof combustion (pyrolysis, gasification, incineration) to create energy results in greenhouse gas (GHG) emissions, a prin- ciple concernof any formofwaste incineration. A study ofwaste incineration and greenhouse gas (GHG) emissions found that once itcametoenergyrecovery,“thecontentof fossilcarboninthe inputwaste, for example, as plastic, was found to be critical for the overall level of the GHG emissions, but also the energy conversion efficiencies were essential” [86]. Increasedplastic in thewastestreammeant increasedoverallGHGemissions. Reliance on energy recovery fromwaste in the linear economicmodelwill have a net balance of more GHG than upstream mitigation strategies in the circular economicmodel, though the linear vs. circular economymaynot be so black and white.A combination ofmultiple end-of-life strategies could collectivelymanage the diversity ofwaste in both efficiency and economy. Microplastic:WhatAre theSolutions? 285