Assessing Technical Options for Handling End of Life Solar PV Packaging
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Assessing Technical Options for Handling End of Life Solar PV Packaging
- 1. Assessing Technical Options for Handling Packaging Wastes from Construction of a Solar PV Powerstation: a Case Study from a Remote Site Turlough F. Guerin Received: 28 December 2019 /Accepted: 15 April 2020 # Springer Nature Switzerland AG 2020 Abstract End-of-life packaging materials (EOLPM) present an important challenge from an environmental and financial perspective at utility-scale solar energy (USSE) sites. Reuse on-site represents, in particular for remote sites, a significant contribution to sustainable business practice as it provides a higher value end use when used to develop on-site mulch to enable soil improvement, reducing transport emissions (from the least preferred option of off-site disposal to landfill), reducing costs, and employing local contractors. The objective of the study was to enable on-site reuse, which was primarily achieved through chemical and physico- chemical characterization of EOLPM streams; card- board, and wood. Given the common occurrence of these materials in the rapidly growing renewable energy sector, it represents an important scope of work for the sector internationally. The methods used for characteri- zation of the EOLPM, the first of its type reported, included a range of organic and inorganic chemical analyses, phytotoxicity testing, followed by an environ- mental and high-level (or initial) financial benefit cost analysis. Key scientific findings were that only trace concentrations of chemicals of potential concern (COPC) were detected; the material was not phytotoxic and has potential for soil improvement at the site, and the selected option of on-site reuse (of the materials as a mulch) had a global warming potential of 50 times less than the business as usual option (transport to landfill). The results also demonstrated the broader potential for using EOLPMs from USSE sites for soil improvement at remote locations rather than transporting offsite for disposal or reuse. Structural changes will need to be made to the way in which markets operate to achieve circular economy outcomes for these EOLPMs. Keywords Cost-benefit analysis . Waste . Circular economy . Packaging . Mulch 1 Introduction Solar photovoltaic (PV) installations, while they do not generate significant waste products during operation, their growing installations will mean that there will be increasing PV waste streams in future decades as current facilities reach their end of life (Peeters et al. 2017). All PV technologies contain valuable materials whose recov- ery is likely to become important to sustainable produc- tion of new panels in the future, the most important waste being disused PV panels (Lincot 2009). Understanding the environmental impacts of collecting and processing these solar materials is imperative to informing the rollout of recycling infrastructure (Goe and Gaustad 2016). The rapid increase in the deployment of photovoltaic installations since the beginning of the century has led to Water Air Soil Pollut (2020) 231:250 https://doi.org/10.1007/s11270-020-04604-z Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11270-020-04604-z) contains supplementary material, which is available to authorized users. T. F. Guerin (*) Ag Institute of Australia, c/o 1A Pasley St., Sunbury Victoria 3429, Australia e-mail: chair@aginstitute.com.au e-mail: turlough.guerin@hotmail.com
- 2. the global capacity exceeding 220 GW in 2017. These increasing deployment rates will lead to large volumes of waste photovoltaic modules in the future, and large volumes of decommissioned panels can be expected by the middle of this century. Efficient end-of-life treat- ments will be needed to recover valuable components (Kadro and Hagfeldt 2017). The construction of utility-scale solar electricity (USSE) generation sites also produces an unintended environmental consequence through the production of large volumes of packaging materials which are used to safely transport solar PV panels onto USSE sites. There is only limited information in the published literature as to mechanisms for optimizing the value of EOLPMs at USSE sites (Guerin 2017b). This is particularly the case with remote construction locations where recycling, reuse, and re-purposing options are limited. In the state of New South Wales, Australia, there are more than 30 USSE sites in the planning pipeline, all of which will need to manage the EOLPMs produced. Cardboard and wood are key components of EOLPMs, and with wood, the applications for endues can become complex as previously described in a recent study (Faraca et al. 2019). For a circular economy to work in practice, solu- tions need to be found for ensuring the highest possible value for end-of-life materials in the con- struction of new infrastructure including those in the renewable energy sector (Sica et al. 2018; Winans et al. 2017). While business and industry has em- braced circular economy for several decades (Fiksel and Lal 2018; Geissdoerfer et al. 2018; Korhonen et al. 2018), governments have been slower to adopt the principles which require systemic changes across the existing economy and the regulatory network. The complexity of implementing the principles of the circular economy, and the barriers that are often in place that limit its adoption (Kirchherr et al. 2018), mean that on-site materials remain in low value applications (Table 1). A USSE site in central New South Wales, with 100 MW installed solar PV generation capacity, was evaluated for its potential to maximize the value from the packaging material generated on-site during con- struction. The broad environmental and community im- pacts of this project have previously been published (Guerin 2017a, 2017b); however, details of the environ- mental fate of packaging materials generated from the site were not evaluated nor published. The current study describes an assessment of the options for managing the EOLPM, focusing on the chemical and physicochemical properties of the packaging materials generated, and applying an en- vironmental and cost-benefit analysis. This site rep- resents an example of the many USSE solar PV sites currently under construction in Australia and which are often remote from services such as waste man- agement handling facilities which, if closer to a major metropolitan center, could orchestrate re- purposing of these wastes. The purpose of this paper is to describe the char- acterization of EOLPMs produced at a remote USSE Table 1 Constraints to implementing the circular economy for materials from remote USSE sites Issue Constraint Transport and logistics Costs of moving EOLPMs from site to other areas to gain higher value (from their end uses) Financial Costs of handling EOLPMs for reusing and moving from site of generation Supply/demand Limited markets in remote locations and/or limited ca- pacity for re-manufacturing, e.g., pallets Quality of materials Unknown quality or variability of materials Regulations Limited consideration for circular economy in current legislation, nor applicable incentives; Barriers to participation high including for on-site reuse and limits to storage Technical Chemical and physical properties of the EOLPMs; Overcome through analytical testing regimes Contractual Lack of planning for and certainty in whose responsibility it is to handle EOLPMs Institutional Resistance to change from suppliers of existing solar PV products and their packaging; Market inertia associated with traditional model of handling EOLPMs is high. 250 Page 2 of 14 Water Air Soil Pollut (2020) 231:250
- 3. electricity generation plant, and to evaluate, in a commercial, social, and environmental way, practi- cal options for returning these materials into the local economy as the construction project was un- derway. These EOLPMs are common to USSE gen- eration plants globally so the challenge and potential application has widespread application to the USSE sector globally. 2 Materials and Methods 2.1 Overview The approach taken follows the case study method based on a recently built USSE facility in a relatively remote location of central New South Wales, Australia, using a combination of laboratory analyses, field assess- ments, and a high-level cost-benefit analysis. 2.2 Site Description The USSE site is remotely located 600 km from the nearest capital city and 200 km from the nearest waste handling facility in central New South Wales, Australia. The facility is constructed on agricultural land previously used for mixed cropping and live- stock and has previously been described (Guerin 2017b). 2.3 Sampling and Analytical Plan A sampling and analytical plan was prepared for the sampling of pallets, cardboard, and mulch on the site (Supplement A) for characterization. A description of the sources, which informed the analytical plan, and quantities of the EOLPMs are detailed in Sup- plement B. The analytical methods were predomi- nantly based on US EPA methods and these are detailed in Rayment and Higginson (1992), as well as selected Australian Standards (Anonymous 1997). In-house methods were used where necessary and analyses were conducted by Leeder Analytical Lab- oratories in Melbourne, Australia. 2.4 Options Analysis A desk top assessment was undertaken of the current commercially available options for managing the EOLPMs on the site, considering environmental, social, and economic impacts. 2.5 Shredder Specifications and Shredding Process Shredding was conducted on-site near the bare areas of soil at the site and next to the stockpiles of EOLPMs. In terms of generating a consistent prod- uct suitable for placement as a groundcover or mulch, a shredder (Komtech Crambo 6000) that removes ferrous metals with an interchangeable screen system, was used. 2.6 Mulch Application After the options assessment and evaluation of the shredded material as a mulch, technical solutions were determined for on-site use. An area of approximately 10 ha was selected for mulch placement. 3 Results and Discussion 3.1 Background Information on the EOLPM The materials to be used as a soil improver (mulch) at the facility are wood from virgin hardwood pallets from Malaysia and kraft cardboard boxes (affixed to these pallets) (Fig. 1). Prior to shredding, the card- board and pallets were used to transport solar PV modules to Australia from Malaysia. 3.2 Reuse Options Identified 3.2.1 Current Disposal Practices and Uses of the EOLPMs The current disposal method for wood generated at the site are reuse options (to a limited extent due to limited demand, and remoteness of the site), is landfilling. Commercial waste management compa- nies offered (for a fee) to pick and store the pallets at licensed facilities; however, none offered defini- tive end-of-life uses for the pallets, other than ongo- ing storage (which was not considered an option in this project). The current disposal methods for card- board generated at the site are recycling options (as bales supplied to a cardboard recycler) via off-site transport, as well as landfilling. The recycling Water Air Soil Pollut (2020) 231:250 Page 3 of 14 250
- 4. options are limited however due to large distances to nearest major metropolitan centers, e.g., 600 km to recycling mills in largest capital city and 200 km from nearest waste transfer facilities. H w P o Hard ware PV m on s dwo eho mod site d ood p use ule duri palle in M box ng t ets a Mala es o he c at su aysia on ha cons uppl a. ardw struc ier’s woo cƟon s d pa n ph allet ase s Sta pr Clo ite arch rior t ose em h h glu to st up o has b ue ap tapli of ha been pplie ing t ardw n the ed to to pa woo erm o ca allet d pa ally rdbo t. allet trea oard sho ated d tra owin d ay ng Sub to h Plas the b-ass hold sƟc e box sem d the shri x an bly e PV nk w d pa is in mo wrap allet sert dule p sep ted i es st para into tead ated the y. from box m xa d b e c f B s P t Bale site Pine tabl ed sh exp e (so es (w hrink ort oŌ w whic k wr wood ch h raps d) pa old plas allet PV m sƟc s fro mod read om d dules dy fo deliv s on or of very pos ff- y of sts) On ca So wi n-sit rdbo oŌ w ith t te ba oard wood able aler d & p d glu es fr for plas uts w om com Ɵc f whic tabl mpac for e h w e su cƟng expo ere uppl g ort o deli ier ff sit vere te ed Ups and Me sho side d bo tal s own) dow x co strap ) is s wn v ombi ppin sent view inat ng (p offs w of h ion plast site f hard tic st for r dwoo trap recy od p s, no ycling palle ot g. etg h i j k l Fig. 1 Packaging materials used for supply of solar PV panels to construction sites. a Hardwood pallets at supplier’s warehouse in Malaysia. b Starch glue applied to cardboard tray prior to stapling to pallet. c Sub-assembly is inserted into the box to hold the PV modules steady. d PV module boxes on hardwood pallets on-site during the construction phase. e Close-up of hardwood pallet showing item has been thermally treated. f Plastic shrink wrap separated from the box and pallet. g Baled shrink wraps plastic ready for off-site export. h On-site baler for compacting cardboard and plastic for export off-site. i Upside down view of hardwood pallet and box combination. j Pine (soft wood) pallets from deliv- ery of tables (which hold PV modules on posts). k Soft wood gluts which were delivered with tables from table supplier. l Metal strapping (plastic straps, not shown) is sent off-site for recycling. 250 Page 4 of 14 Water Air Soil Pollut (2020) 231:250
- 5. 3.2.2 Options Assessment The options assessment explored opportunities to reuse and recycle the various packaging streams. This was a cost-benefit analysis. The project specifically explored end uses for the packaging materials (described in the following sections), some of which have led to alterna- tive uses of minor quantities of the packaging, by ap- plying the waste hierarchy. 3.2.3 Options for Wood The following beneficial outcomes were explored for this material. Firstly, local reuse by providing to the main local social enterprise (The Men’s Shed) was considered. These materials were deemed to be unsuit- able for wood turning process (i.e., on a lathe), or for reuse of the imported hardwood pallets as conventional pallets. After contacting several exporters, and transport companies, it was determined that this was not practical because the pallets from the solar plant site were over- sized and not able to stack onto trucks or commonly used logistics storage systems. Off-site recovery and reuse of non-standard pallets was also assessed, and all of these (that were candidates for returning) have been returned to suppliers (est. 500 units). Finally, reuse through re-manufacturing was explored through an outsourcing company (also a disabled workshop) in a town 400 km away for 1000 pallets (only). 3.2.4 Options for Cardboard Markets for the compacted cardboard (est. quantity is 680 t) were identified including a site 400+ kms away from the site. Approximately 250 bales (or 50 t) of cardboard were exported off-site for recycling on a cost recovery basis. However, due to the relatively slow rate of baling of cardboard (approximately 70–100 bales per week), the project timeline did not allow for enough time to prepare and export all baled cardboard (for off- site sale) prior to construction completion. This meant alternative reuse options were required for most of this material. 3.2.5 Options for Plastic The project has produced an estimated 30 t of recyclable plastics. This material (i.e., plastic strapping) was recycled off-site through a recycling company (200 km away) (~ 14 t), while the remainder (~ 10 t) was baled (Fig. 1) and shipped off-site to a recycler in a capital city (except for approximately 6 t that was excessively con- taminated with soil) and could not be recycled and was disposed of as landfill. 3.2.6 Optimum Use for the EOLPM The optimum reuse option, identified as reusing the material on-site as a surface mulch (option 3) (Table 2), represented a significant contribution to sus- tainable business practice as it provided a high-value end use for an existing site need to meet project planning requirements for landscaping and rehabilitation, reduced transport emissions (for off-site disposal), and landfill, and employed local contractors. Option 3 (on-site reuse of the mulch) also represented an opportunity cost. This is the value of the next best thing you give up whenever you make a decision. In this case, the economic value of the 1810 t of mulch could potentially have been sold for $50 per m3 for a value of $0.6 M AUD (based on bulk density of mulch of 0.14). Although no off-site customer was able to be secured to purchase any of the mulch produced at the site, the theoretical market value of the mulch produced at site was significant at $50 (AUD) per m3 . 3.3 Physical Characterization of EOLPM 3.3.1 Wood Given that the wood materials were of a highly homogenous nature (Fig. 1), in terms of their source, no chemicals of potential concern (COPCs) were present in the pallets. Approximately 100–150 non- standard pallets, some of which had paint on them, were also analyzed; however, these have been returned to the respective recyclers and are no lon- ger on site and therefore were not shredded and reused on site. It was noted that all the pallets contain nails. The constructor sourced a shredder which used a shred- ding process with an electrically switched, magnetic conveyor component (referred to as a drum diver- sion process) (Fig. 2). These were separately collect- ed and disposed of as a recyclable ferrous material (est. 10–15 t in total). Water Air Soil Pollut (2020) 231:250 Page 5 of 14 250
- 8. a Ferrous materials (mostly nails) collected during shredding b The waste bin containing nails (and accompanying wood wastes) c of the material sent for chemical assays and proposed for re-use as a mulch. d Close up of shredded material sent for chemical assays and proposed for re-use as a mulch. e A small trial area (2-3 m2 ) of shredded EOLPMs applied to dry and poorly f naniar.liosderutcurt ds strong wind events. g A central stockpile representative of the chipped cardboard and HW pallet mixture showing the homogeneity of the final product. 250 Page 8 of 14 Water Air Soil Pollut (2020) 231:250
- 9. 3.3.2 Cardboard This cardboard was used to cushion the solar PV mod- ules from breakage from the manufacturing site in Ma- laysia to the construction site. The total amount of glue and ink present in each box represents an extremely small quantity (estimated at < 1%) on w/w basis. 3.3.3 Shredded Cardboard/Pallet Mix The shredded cardboard/pallet mix is a result of feeding the cardboard and pallets into a shredding machine. The mix represents a 1:1 ratio of box to pallet on a w/w basis. The mulch material produced was relatively consistent in terms of its homogeneity for field application as mulch. Most shredded chip sizes were in the range of 30–40 mm. The particle size fractionation conducted in the laboratory demonstrated that there was only a small quantity of fines produced during the process of shred- ding (the cardboard and pallet feedstock). The mulch has excellent bulking properties (see the “Water Holding Capacity and Bulk Density” section) and is also capable of retaining large quantities of water (due to the hydroscopic properties of the cellulose-rich, kraft card- board). A significant investment was made on-site in ensuring plastic overwrap (and any other plastics) was ƒFig. 2 Photographs of feedstock and produced chipped material. a Ferrous materials (mostly nails) collected during shredding. b The waste bin containing nails (and accompanying wood wastes). c Shredded material representative of most of the material sent for chemical assays and proposed for reuse as a mulch. d Close of shredded material representative of most of the material sent for chemical assays and proposed for reuse as a mulch. e A small trial area (2–3 m2 ) of shredded EOLPMs applied to dry and poorly structured soil. f The same area (as LHS image) after 2 weeks and after approximately 20 mm of rain and strong wind events. g A central stockpile representative of the chipped cardboard and HW pallet mixture showing the homogeneity of the final product. h Cardboard boxes and pallet combinations being chipped with relatively minor dust levels being generated during the process. i Note that the boxes in the background, which are the feedstock for the chipping process, have had plastic overwrap removed prior to chipping h Cardboard boxes and pallet combinaƟons being chipped with relaƟvely minor dust levels being generated during the process i Note the boxes in the background, which are the feedstock for the chipping process, have had plasƟc overwrap removed prior to chipping. Fig. 2 (continued) Water Air Soil Pollut (2020) 231:250 Page 9 of 14 250
- 10. removed from the cardboard and pallets prior to on-site shredding (Fig. 1 and Supplement A). 3.4 Chemical Characterization The analytical plan was developed after consultation with the manufacturers (and their supplied SDSs) (Sup- plement A). The chemicals expected to be present are summarized, along with other general characteristics of the mulch and its feedstock (Supplement B). The results of the laboratory assessment are provided in Table 3 and Supplement C. The elements boron and manganese were present (as totals) at maximum concentrations of 29 and 26 mg/kg, respectively. Lead was also present at 4.2 mg/kg. The leachable concentrations of each of these were well below 1 mg/kg. These were all less than the acceptable concentration thresholds for mulches used in catchment and land rehabilitation applications also set out in New South Wales state guidelines (Dorahy et al. 2008). Formaldehyde, acetaldehyde, and acetone, the only organic COPCs, were present at values close to their limits of detection (up to 5 mg/kg). No other COPCs, including those anticipated to be present due to the presence of inks (in the cardboard), i.e., diethylene glycol (DEG) and monoethanolamine, were detected in any of the samples. Both were present at less than the limits of detection (LOD) of 2 and 1 mg/kg, respec- tively. These solvents, which are inherently biodegrad- able, were present at concentrations that were very low, and therefore do not pose a risk to human health or the environment. No phenols, pesticides, herbicides, or formaldehyde, which are chemicals that could be present in treated wood, were detected above detection limits. These were all below any threshold investigation criteria. In terms of elemental analyses, the pH was neutral, the alkalinity was high, and EC (dS/m) was less than 1. There are benefits presented by the high alkalinity values if this material is added to the soil because of the extensive prior history; the pH is very low at 5.8 pH units due to its previous use in intensive cropping. Total phosphorous was low being detected at the LOD of 0.004% (w/w). In terms of the nutrient nitrogen, ammonium was not detected, and total N was present at 0.15% in one composite only confirming that this nutri- ent will not contribute to the nitrogen pool in the soil it is applied to. Moisture content of the analyzed mulch samples were high, varying in the range 45–67% (w/w), which was due to the recent rain event prior to Table 3 Properties of the mulch and feedstock compared with receiving soil Analyte/measure4 Units PQL Soil1 Mulch Cardboard2 Soil:mulch3 pH4 5.8 7.1 7.3 7.2 EC4 0.01 0.15 0.47 0.19 0.21 Total alkalinity4 mg/kg 10 50 1550 1470 1020 Moisture4 % w/w 0.1 6.1 47 17.2 67 TOC4 % w/w 0.05 < 0.05 44.1 46.2 Total N4 % w/w 0.01 0.19 0.15 < 0.01 0.06 Total P4 % w/w 0.004 0.04 0.005 0.005 0.004 Total S4 % w/w 0.01 0.05 0.03 0.01 0.07 Water evaporation gm/cm2 /h - 0.008 0.006 0.007 0.006 Water filtration (dry rate) mm/h - 400 > 1500 1300 800 Water filtration (wet rate) mm/h - 100 1400 960 160 Bulk density g/mL - 1.2 0.14 0.12 1.2 1 This was receiving soil at the site typical of the soil where mulch was placed 2 Shredded cardboard on its own which is a major component of the mulch in the preceding column 3 The soil mulch mix was from combined samples taken in situ once mulch had been applied 4 The methods are based on those previously published (Anonymous 1997; Rayment and Higginson 1992) 5 Phytotoxicity testing showed that the EOLPM was non-toxic to lettuce seedlings (Anonymous 1984) 250 Page 10 of 14 Water Air Soil Pollut (2020) 231:250
- 11. sampling, as well as its hydroscopic properties. In the composite where the particle size distribution was de- termined at 88.1% of the mulch was retained by a 10- mm sieve, and only 1% was ≤ 1 mm, confirming the low concentrations of fines in this mulch product (and partly explaining the low levels of dust generated during the shredding process). No other references to similar analyses on these types of materials were identified in the literature so this study is the first assessment of this material for reuse as a soil amendment. 3.5 Properties of the EOLPM as a Mulch and its Value from On-site Production Table 3 reports various physical and physicochemical properties of the mulch, cardboard, mulch mixes, and receiving soil, which reflects the value of the mulch as a soil improver. There are relatively few studies that re- port the use of cardboard and wood mixes and their impacts on soil and agronomic properties (Chalker- Scott 2007; Hoitink 2000; Kader et al. 2017; Mucke 1969). Benefits from groundcover mulches generally include improved moisture retention, increased soil flora and fauna, improved soil properties, and a greater sur- face area for capturing and enabling windblown seeds to germinate and establish. 3.5.1 Water Infiltration, Evaporation Reduction, and Water Retention The EOLPM reduced the water evaporation rates from the bare (unamended) soil from 0.008 to 0.006–0.007 g/ cm2 /h, illustrating the value of the mulch to enhancing the agronomic properties of the receiving soil. Also the mulch quantitatively improved the infiltration rates of water into the soil compared with receiving soil only. Water infiltration, evaporation reduction and water re- tention properties are all enhanced by soil mulches as has been reported in an extensive review of the literature (Chalker-Scott 2007). 3.5.2 Water Holding Capacity and Bulk Density The mean bulk density of the shredded materials was 0.14 g/mL compared with 1.2 g/mL for the receiving soil (Table 3). Although the bulk density of the soil:shredded mixture was 1.2 g/mL, it is expected that the overall effect of the EOLPM will be to enhance the bulking properties of the soil, i.e., more towards the value of 0.14 of the mulch. The mulch has bulking properties and is therefore also capable of retaining large quantities of water (due to the hydroscopic properties of the cellulose-rich, kraft cardboard) with moisture con- tents up to more than 60%, which reflects the high water holding capacity or water retention of the mulch, and the cardboard that makes up a significant proportion of the mulch. 3.5.3 Yield Enhancement Although in the current study no direct measurements we made of increased crop yield, it can be expected that improvements to the soil from the added mulch will enhance the productivity of the site soil. There are many factors that affect crop yield. Added soil mulches and amendments, just one of these, impact on yield through the various mechanisms that have previously been published. These include from en- hanced soil moisture properties as well as increased cation exchange, improved physical properties, and soil structure. Considerable focus is now evident from the literature regarding the use of synthetic mulches to increase crop yields and profits (Ma et al. 2018). Crop yields have also been increased by at least 5% as a result of higher soil-water storage from traditional organic, crop residue mulches (Freebairn et al. 1986). Other studies have shown that crop residue mulch, at 4–6 t/ ha, prevents raindrop impact, reduces velocity and shearing strength of flowing runoff and blowing wind, and effectively reduces rate and magnitude of accelerat- ed erosion (Lal 2008). The impacts of mulch can be long-term, not been seen until at least 2–3 years from placement. Future predictions of crop yield growth in the next 20 years, which is limited by water-related factors, suggest that 0.8–1% year on year improvements are possible in broadacre wheat are possible in Australia compared with the current rate of progress at 0.5%. This higher yield growth will come from a combination of genetic and agronomic factors including mulching and residue management (Robertson et al. 2016). 3.5.4 Dust Suppression A further benefit from mulches applied to soil is dust suppression. This has been important given the high clay content of the soil at the site and its susceptibility Water Air Soil Pollut (2020) 231:250 Page 11 of 14 250
- 12. to wind blown soil erosion and dust storms from pre- vailing winds. The particle size analysis showed that only 1% of the mulch was present in the ≤ 1-mm frac- tion. This indicates that the amount of fines in the mulch is very low, and therefore so is its potential to generate dust. Although the generation of dust has decreased as the project moved from the construction phase to oper- ations, through the application of wood and cardboard chips onto the bare areas across the site, the mulch is expected to help reduce the necessity to apply large quantities of water and dust suppression chemicals (e.g., calcium lignosulfonate) for ongoing dust suppres- sion at the site. 3.5.5 Avoided Transport Emissions Although not a mulch property, the on-site production of mulch has avoided the need to bring mulch materials onto site. As part of the rehabilitation project at the site, surface mulches would have needed to be delivered to site, incurring further carbon emissions from transport as well as the need for suitable wood chips to provide the required mulch. The estimated quantity of such wood chips would be in the vicinity of 1800 t to provide a depth of 150 mm of mulch across the 10 ha of the proposed rehabilitation area. 3.5.6 Broader Economic Value of EOLPM as a Mulch There are agronomic improvements, agricultural pro- ductivity from mulch application to agricultural opera- tions, both intensive operations and extensive broadacre production. These will be realized through the mecha- nisms described it the previous subsections above. If other USSE solar PV sites produce these packaging materials, they could produce mulches using the same processes discussed in this paper. The value of the type of mulch produced is estimated at $50 (AUD) per m3 based on local market testing. Therefore, the value of the mulch has potential for generating revenues from the construction phase of a USSE solar PV project. Furthermore, the consequence of not enabling the availability of mulches produced from these types of packaging materials are lost benefits to agricultural cus- tomers who could purchase and apply the materials for their own beneficial use. The rigidity of the current market-based waste han- dling and disposal system (in regional areas) has to date limited the reuse of materials such as the mulch produced on remote sites. This needs to be overcome if a circular economy is to be implemented. Planning requirements could specify circular economy outcomes for all materials (on the supply side for project devel- opers and/or constructors), and incentives could be pro- vided to potential off-takers (e.g., farmers, land users, waste handlers) on the demand side to procure such EOLPMs. Such requirements would help to drive the supply of goods to a construction site that does not require disposal options at the end of their useful life. 3.6 Mulch Application Rate The material, shredded wood and cardboard, used as a mulch, was applied at a rate that targeted approximately 0.14 m3 /m2 (or equivalent to 360 t/ha). It was proposed that the material will be of benefit in helping the soil retain moisture in the rehabilitation (bare soil) areas (Table 2). The targeted application rates were equivalent to a layer of mulch of approximately 125–150 mm. Given that the total quantity of mulch was 1810 t, the actual depth of mulch was less than that targeted at < 125 mm. 3.7 Monitoring Post-Application Feedback to EOLPM Producer The manufacturing team (responsible for packaging) has been advised of the reuse, recycling, and disposal challenges presented using the current packaging materials for delivering the constructor’s PV modules to the site. Further interaction with the constructor’s global manufacturing group fo- cused on providing feedback on the design of packaging so that the used packaging materials can be readily reused in the logistics supply chain or other high order uses found compared with disposal. Ongoing on-site monitoring Other studies report the use of paper and cardboard on their own as material that have been incorporated into farming soil (Alvarez et al. 2009; Kaufmann 1991; Yabannavar and Bartha 1993). These have been shown to be effective in improving agronomic outcomes. The mulch in this study, as placed, will be monitored on an annual basis and will be reviewed in detail in a future publication, as well as an in-depth ecological impact assessment of the applied EOLPMs at the site to provide further assurance to USSE solar PV constructors that on-site soil amendment and mulching is a viable option. 250 Page 12 of 14 Water Air Soil Pollut (2020) 231:250
- 13. 4 Conclusion An environmental, social, and high-level financial cost- benefit analysis drew upon a laboratory assessment of EOLPMs and other site information on potential end uses. The meaningful results from this study was that EOLPMs, generated at a USSE site, which was a remote location in Central New South Wales in Australia, could be reused on-site to enhance the properties of the receiv- ing soil, which covered an area of 10 ha. Alternative options would have led to higher greenhouse gas emis- sions (3145 compared with 58 t CO2e) attributable to transport and landfilling. Furthermore, there was also some limited off-site reuse of the EOLPM which en- hanced the value of the packaging materials by provid- ing these materials to social enterprises. This is the first study to demonstrate that EOLPMs for USSE projects can be mulched on site. The mulch product was relatively clean (free of COPCs), visually appealing, possessed positive water retention properties, and had other attributes suitable for soil improvement. The production of mulch on site (from EOLPMs) has applicability to other USSE sites globally, where there is a requirement to assist soil stabilization and generally improve soils prone to erosion. There are however limitations of the current study. These include (1) it does not negate the need for further detailed materials characterizations on a site-by-site ba- sis, and (2) a full life cycle assessment was not conduct- ed on the EOLPMs. While these were identified limita- tions, the results presented have general application to managing these types of end-of-life materials across the global USSE sector. Future research could include (1) the conduct of a full lifecycle assessment of the EOLPMs to further illuminate why the USSE sector needs to take care in managing these materials, (2) an assessment of the success or otherwise, of the application of mulch to the soil to demonstrate the long-term efficacy of the approach put forward in this paper, (3) an integrated method to undertaking a more comprehensive cost-benefit analysis to assess the optimum approaches for managing EOLPMs at remote USSE sites, including facilitating the input from local communities, universities (researchers), landholders, and businesses, in- cluding social cost of carbon, and (4) an assessment of planning policies to identify what changes can now be made to government policy and regulations in order to accelerate a transition to a circular economy in this grow- ing sector of the economy. References Alvarez, J. V. L., Larrucea, M. A., Bermúdez, P. A., & Chicote, B. L. (2009). Biodegradation of paper waste under controlled composting conditions. Waste Management, 29, 1514–1519. Anonymous. (1984). OECD guidelines for testing chemicals - terrestrial plants growth test. France, OECD: Paris. Anonymous. (1997). AS 4454-2012 composts, soil conditioners and mulches (p. 80). Sydney: Standards Australia. Anonymous (2005). ‘GHG Protocol - Mobile Guide (Version 1.3)’, World Resources Institute and World Business Council for Sustainable Development, p. 116. Anonymous. (2018). National Greenhouse Accounts Factors (p. 81). Australian Commonwealth Government: Department of the Environment and Energy. Chalker-Scott, L. (2007). Impact of mulches on landscape plants and the environment - a review. Journal of Environmental Horticulture, 25, 239–249. Dorahy, C. G., Pirie, A. D., Pengelly, P., Muirhead, L. M., Chan, K. Y., Jackson, M., Smith, A., & Emery, T. (2008). Guidelines for using compost in land rehabilitation and catchment management (p. 48). Sydney: NSW EPA. Faraca, G., Boldrin, A., & Astrup, T. (2019). Resource quality of wood waste: The importance of physical and chemical im- purities in wood waste for recycling. Waste Management, 87, 135–147. Fiksel, J., & Lal, R. (2018). Transforming waste into resources for the Indian economy. Environmental Development, 26, 123– 128. Freebairn, D. M., Wockner, G. H. & Silburn, D. M.: 1986, ‘Effects of catchment management on runoff, water quality and yield potential from vertisols’, 12, 1–19. Geissdoerfer, M., Morioka, S. N., de Carvalho, M. M., & Evans, S. (2018). Business models and supply chains for the circular economy. Journal of Cleaner Production, 190, 712–721. Goe, M. & Gaustad, G.: 2016, ‘Estimating direct climate impacts of end-of-life solar photovoltaic recovery’. Solar Energy Materials and Solar Cells, 156, 27–36. Guerin, T. F. (2017a). A case study identifying and mitigating the environmental and community impacts from construction of a utility-scale solar photovoltaic power plant in eastern Australia. Solar Energy, 146, 94–104. Guerin, T. F. (2017b). Evaluating expected and comparing with observed risks on a large-scale solar photovoltaic construc- tion project: A case for reducing the regulatory burden. Renewable and Sustainable Energy Reviews, 74, 333–348. Hoitink, H. A. J. (2000). ‘Trends in treatment and utilization of solid wastes through composting in the United States’, Proceedings of The International Composting Symposium (Ics’99), Vols 1 and 2, pp. 1-13. Kader, M. A., Senge, M., Mojid, M. A., & Ito, K. (2017). Recent advances in mulching materials and methods for modifying soil environment. Soil and Tillage Research, 168, 155–166. Kadro, J. M., & Hagfeldt, A. (2017). The end-of-life of perovskite PV. Joule, 1, 29–46. Kaufmann, D. A. (1991). ‘Bio-degradable mulching material’, United States Patent, pp. 7. Kirchherr, J., Piscicelli, L., Bour, R., Kostense-Smit, E., Muller, J., Huibrechtse-Truijens, A., & Hekkert, M. (2018). Barriers to Water Air Soil Pollut (2020) 231:250 Page 13 of 14 250
- 14. the circular economy: Evidence from the European Union (EU). Ecological Economics, 150, 264–272. Korhonen, J., Nuur, C., Feldmann, A., & Birkie, S. E. (2018). Circular economy as an essentially contested concept. Journal of Cleaner Production, 175, 544–552. Lal, R. (2008). Crop residues as soil amendments and feedstock for bioethanol production. Waste Management, 28, 747–758. Lincot, D. (2009). ‘Synthesis summary environmental, health and safety aspects of first solar photovoltaic systems containing cadmium telluride’, Paris, France, CNRS (the National Center for Scientific Research), p. 3. Ma, D., Chen, L., Qu, H., Wang, Y., Misselbrook, T., & Jiang, R. (2018). Impacts of plastic film mulching on crop yields, soil water, nitrate, and organic carbon in Northwestern China: A meta-analysis. Agricultural Water Management, 202, 166– 173. Mucke, K. H. (1969). Are paper and cardboard good soil amend- ments and organic fertilizers? [Sind papier und pappe gute bodenverbesserungs-und humusdungemittel?]. Papier, 23, 907–910. Peeters, J. R., Altamirano, D., Dewulf, W., & Duflou, J. R. (2017). Forecasting the composition of emerging waste streams with sensitivity analysis: A case study for photovoltaic (PV) panels in Flanders. Resources, Conservation and Recycling, 120, 14–26. Rayment, G. E., & Higginson, F. R. (1992). Australian laboratory handbook of soil and water chemical methods. Port Melbourne Inkata: Press. Robertson, M., Kirkegaard, J., Rebetzke, G., Llewellyn, R., & Wark, T. (2016). Prospects for yield improvement in the Australian wheat industry: A perspective. Food and Energy Security, 5, 107–122. Sica, D., Malandrino, O., Supino, S., Testa, M., & Lucchetti, M. C. (2018). Management of end-of-life photovoltaic panels as a step towards a circular economy. Renewable and Sustainable Energy Reviews, 82, 2934–2945. Winans, K., Kendall, A. & Deng, H.: 2017, ‘The history and current applications of the circular economy concept’, renew- able and sustainable energy reviews 68, Part 1, 825–833. Yabannavar, A., & Bartha, R. (1993). Biodegradability of some food packaging materials in soil. Soil Biology & Biochemistry, 25, 1469–1475. Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. 250 Page 14 of 14 Water Air Soil Pollut (2020) 231:250