Non-recyclable plastic waste (V4)
Hey guys, my name’s Paul and I’m a designer working on PP V4. One of our focuses for V4 is exploring ways to use the non-recyclable plastics (NRP) that we often collect but don’t have a use for.
To be clear, I’m talking about plastics that have no hope of ever being recycled back into useful tools/products/materials. Plastics that have been:
– degraded due to extended sun exposure, saltwater, etc. (common among beach plastics)
– molded with other materials (metal, silicone, etc.) and can’t be separated for recycling
– are simply too dirty to be cleaned effectively for normal recycling
Typically when these materials are collected, they’re sent to the landfill where they waste away eternally, or they’re incinerated to produce energy.
Neither of these options are great… Sending NRP to a landfill means the materials that could be useful will do nothing but take up space in a big pit of waste. And incinerating them releases gases into the atmosphere that contribute to air pollution and climate change.
So.. Our mission is to give hope to the Hopeless. Sounds tricky, but I think we can figure something out. I’ll share progress in this thread. If you’re interested in this issue and would like to contribute thoughts, ideas, and constructive criticisms, they’ll be greatly appreciated
To start out, I’ve collected materials from the ‘Burn’ bin in our workspace – this is our last resort container where we put things that we can’t reuse/recycle properly.
Most of the plastics I found are molded/fused to other materials and can’t be separated (tape, packaging, ink pen, etc). Some are thermosets and can’t be remolded (silicone, rubber hose) and some are simply too dirty/degraded to be used in normal recycling processes.
There are a couple of directions I’m interested in exploring as a starting place.
One direction is Pyrolysis (plastic to oil), which transforms materials (including plastic waste) into oil which can be used for energy. There might be other uses for the oil as well…
The other direction is using NRP for building materials. In this way, the solution would serve as a long-term form of carbon embedment while simultaneously offering an alternative to environmentally harmful materials such as concrete.
Direction 1.0 | Pyrolysis: Waste to oil
Pyrolysis can be used to transform materials into oil which can then be used for energy. It might also be possible to synthesize the oil into a cleaner, more useful material with other applications..
1.1 | Alternative energy source to virgin fossil fuels
Transforming the NRP into oil could offer an alternative to virgin fossil fuels for communities that rely on fossil fuels for energy and don’t have access to renewables. In this way it’d help reduce reliance on virgin fossil fuels and simultaneously give purpose to the abundant material resource of NRP. Using the oil for energy would still emit greenhouse gases, but at least the energy source would be plastic waste that’s useless rather than newly extracted fossil fuels. Along with that, saving money on fuel could enable communities to save enough money to eventually transition to renewable energy sources. In this way, this solution could serve as a sort of stepping stone for some communities.
1.2 | Back into useful material
Once we convert the plastic waste into hydrocarbons (oil), we might be able to synthesize it into a cleaner, more useful material. If so, there’s a variety of purposes that the material could serve that would likely be better than what we’re able to do with it in its current state. Plus it wouldn’t be burned, keeping the carbon and other greenhouse gases embedded in the material rather than emitting them into the atmosphere. Not sure if this is doable, but seems interesting. If anyone has any insights I’d be keen to hear.
I’ve seen Pyrolysis discussed here before and am including a link to the earlier forum as well as some resources I’ve come across in my research so far.
– Earlier forum discussion :https://davehakkens.nl/community/forums/topic/small-scale-pyrolysis-plant-for-making-fuel/#post-132354
– Pyrolysis research article: https://www.researchgate.net/publication/281064326_CONVERSION_OF_PLASTIC_WASTES_INTO_LIQUID_FUELS_-_A_REVIEW
– DIY pyrolysis: https://www.instructables.com/id/Waste-Plastic-to-Fuel/
– Group developing open source pyrolysis unit: https://plasticodyssey.org/technologies/?lang=en
– Plastics-to-Fuel Report by Ocean Recovery Alliance: https://www.oceanrecov.org/about/plastic-to-fuel-report.html
– Plastic to fuel market review 2017: https://www.planning.act.gov.au/__data/assets/pdf_file/0008/1043657/Appendix-G-Review-of-Pyrolysis-Worldwide-RICARDO.pdf
– Intriguing case study, and links shared between @craig89 and @frogfall: https://davehakkens.nl/community/forums/topic/precious-plastic-in-the-scottish-highlands/
– @plaspod ‘s work with Pyrolysis: https://docs.wixstatic.com/ugd/52d1ea_187cf3d94bfc45688ed4ec5ce32afb5f.pdf
– Study on performance and emissions of pyrolysis oil: https://www.sciencedirect.com/science/article/pii/S0378382016307135
Direction 2.0 | Alternative construction material
This direction interests me because it could serve as a long-term method to store NRP in a useful way, rather than letting it simply waste away in a landfill. This direction is also appealing because it could serve as an alternative to ubiquitous, environmentally harmful materials such as concrete.
There are a couple of methods I’m interested in starting to explore that might offer viable solutions.
2.1 | Compression to form bricks
With this method, the NRP would be shredded and compressed into forms which could then be used to build long-lasting structures. This could be especially useful in communities where construction materials are limited, but plastic waste is abundant such as coastal communities and towns rebuilding after a natural disaster.
The tricky thing with this direction is that the materials being used will be mixed, so we’ll have to find a way to bind them reliably across all sorts of different mixture ratios.
One way that might work is ensuring that there’s a certain amount of PE in the mix (lowest melting point of common plastics), then heating the mixture to PE’s melting temp and using the molten PE to bind everything together. Or maybe there’s another binding agent or cold-compression method we could use… Again, any experience and insights are greatly appreciated
2.2 | Alternative to conventional concrete aggregate
Concrete, one of the most commonly used commodities in the world consists of cement and aggregate (or filler). Generally, the aggregate is a mixture of sand and rock, which is typically mined. Mining these resources inflicts serious damage on our planet (google ‘concrete mine’).
Using NRP as an alternative aggregate could reduce demand for these environmentally damaging materials and provide a method of storing NRP in a useful, long-lasting manner without releasing its carbon/toxic gases into the atmosphere.
The thing we’d want to be careful of is ensuring that the NRP concrete is used for static applications with low friction that won’t cause the plastic to slowly rub off and emit microplastics into the atmosphere. Buildings and furniture seem like they could be good uses. From what I understand, using the material in applications such as pavement, etc. could lead to problems down the road (hehe) with microplastics rubbing off and being dispersed into the environment, which is something we definitely want to avoid.
One concern that some V4 teammates have voiced while sharing the idea around the workspace is that mixing the plastic with cement might complicate the problem by adding a new material into the mix. My thoughts are that the NRP we’re using is already an unsortable mixture of plastics, metals, rubbers, etc. (part of why it’s non-recyclable) so adding cement would only marginally reduce the NRP mixture’s “purity”. Granted, it would add some complexity in terms of what exactly the concrete is made of, but as I understand it, once concrete reaches the end of its life, its best use is to be ground and used again as an aggregate base for new concrete, so it seems like having the NRP would be okay from my view. Keen to hear others’ thoughts.
Below are some resources I’ve found in my research so far:
Alternative construction resources
– Earlier forum discussion: https://davehakkens.nl/community/forums/topic/help-on-a-earthquake-rebuilding-project/
– Plastic waste compression molded into bricks: https://www.byfusion.com/the-blocker/
– Henry Miller’s research into using NRP as concrete aggregate: https://inhabitat.com/plastic-concrete-repurposes-landfill-waste-into-building-bricks/
– Article about NRP as concrete aggregate: http://useofcement.cembureau.eu/2018/04/09/cements-solution-to-plastic-waste/
– Plastic legos construction concept: https://www.youtube.com/watch?v=SR2N_USfFzE&feature=youtu.be
– Cement life cycle overview: http://www.designlife-cycle.com/new-page-40/
Seems there have been some weird things happening with this forum topic… apologies to all tagged if you’ve been receiving sporadic and/or broken emails referring to this post. I think we got it worked out… tagging those I saw throughout the forums who might be interested one last time to be sure
Glad to see you guys are looking into this.
This article has some interesting figures about adding pyrolysis products into building materials. The author focuses much on wood charcoal, but I suspect solids from the plastic pyroysis (aka carbon black) could have a role in improving concrete and plastic composites. Energy in the form of heat or liquid fuel could be extracted from the plastics prior to tying up the remaining carbon in building materials.
We run our heavy pyloysis oils through a babington style burner we modded from a conventional oil heater. We’ve also used these oils as an asphalt binder (tarmac) – our sample isn’t much to show for, but it’s held up for over 3 years outside now. I suspect raw plastic oils could be used in a similar process. Though I doubt we’ll be able to find a contractor that would let us use their equipment and scale up…
I hear alot about people saying they COULD make diesel/gasoline from plastic pyrolysis oils, but I don’t see much of it actually being done on small scale.
Precious Plastic has created a unique model that allows plastic to be re-purposed on scales that are beneficial to both society and ecology. That fact is an important driver!
The collective aim here should be to bolster and enhance that model with the addition of beneficial technologies (micro-scaled) that can support and sustain the development of social enterprise at community scales.
The images that follow have been taken from a ‘work in progress’ document. This document details the levels of energy used to collect and recycle certain types of plastic via current industrial processes (UK model). It also details an alternative community-based model, built around PP machines and Plas-Pod. This model does not include the production and use of pyrolysis oils and still achieves zero-waste.
We have determined the value of the waste to the community in terms of energy generated from non-recyclable plastics. We will endeavour to determine the carbon footprint of this model for comparison but would be confident to suggest that it will be more efficient than the industrial status quo.
Determining value to the community via the production of products will be more challenging. Selling high-grade plastic on to recycling companies has been included here as one option: other options, including manufacturing products that can embedded into the community will be added as the work progresses. The opportunity to develop a cashless economy is exciting but requires careful planning.
We need to ensure that the energy that we generate from non-recyclable plastic is used wisely (restricting waste). We can do this by producing electricity that we need to run the PP machines and we can generate the energy needed to heat the workplace over winter using the same process. This makes sense because it is the most efficient way to produce and utilise energy – at the point of use. Theoretically, this plastic becomes embedded into the community as well.
Added to this, we have made the Plas-Pod mobile, hoping that we can take it to various locations within the community to generate energy that can be fed straight into existing water heating systems: this would work well in schools, where reasonable volumes of waste plastic are generated. Reducing the energy costs for the community offers benefits to everyone in that community.
Key for us has been to develop smarter methods of heating and storing water. We are currently working with a team of engineers from Romania (where it can get very cold!) to develop a low-cost boiler which can run directly from the Plas-Pod machine. We don’t want to reveal the entire design until we are confident that it meets expectations, but you can see the test here –https://youtu.be/IHlxDLldnzw
The reason that we have tested to steam-point is because we have been working with a company in Holland (Green Turbine) to develop a unit that can produce super-heated steam to drive their micro-turbine to produce between 1.5 – 15kWhe.
We have more than 20yrs experience of producing pyrolysis oils, both as a primary product, via the Biogreen Technology (http://www.biogreen-energy.com) and as a co-product via several other methods of pyrolysis. As Dan suggests, we are also yet to see anyone making anything useful from these oils.
Our experience would be to steer others away from pyro-oils to focus purely on more efficient conversions to energy from non-recyclable plastic.
Respectfully – @plaspod
2.2 | Alternative to conventional concrete aggregate
Firstly thank you for tagging me into this conversation,
To contribute a little I completely support this direction and would like to make some points from my time in Eco Architecture.
This solution (2.2) is the easiest to implement from my experience compared to creating solid plastic blocks mainly because it utilizes basic technology that most countries understand fully, and are trained to work in (Concrete work). Concrete is based on ratios to acquire different strengths and those mixes can be edited to use different aggregates (no extra tools required). If clever we could also come up with a mix to make hollow blocks, using standard hollow block machinery.
Have you by any chance investigated Biocrete? (Hemp Crete, Coco Crete, or Rice Crete?) all substitute the 3/4″ gravel aggregate to utilize a waste fiber or material. In some cases, lime is also added, this allows the material to hold moisture. So that in tropical climates moisture is collected at night and evaporates during the day to create naturally ventilated buildings through evaporative cooling.
The fiber or waste also tends to provide a certain level of tensile strength, not found in standard concrete. This could be a good selling point when pitching the idea of inserting plastic into standard concrete to communities. Cheaper & Better….always a good pitch.
My only comment about plastic in this method of construction is that we would need to ensure that it is not exposed to the sun. Solar degradation will cause the surface layers to decay, and create a fine plastic dust. This can be avoided by plastering the surface layer.
While we are on the topic of utilizing waste materials, the island I am currently running our project on doesn’t have any glass recycling. Could we not take this one step further, Cement, fine glass (Sand), Plastic (Aggregate)?
Another method is Eco Brick, they use a standard bottle and pack it with NRP, however, this is very labor intensive, and most developing countries will stick to traditional methods with a limited adaptation of the method.
Keep up the great work, if you have any questions I’ll be happy to help.
PS. We are building a few walls in a recycling center in a few months, it would be great to pilot these methods if we get the facts straight. Then we can create an instruction video?!
Thank you for your thorough responses. Your input will be super helpful moving forward.
@lwfbiochar The article you shared about incorporating pyrolysis by-products into building materials is super interesting… the Biochar Journal as well as other resources that it led to are proving to be helpful for research as well. I’m very keen to explore the other applications that pyrolysis might be used for beyond energy production.
@plas-pod Couldn’t agree more – Precious Plastic’s micro-scale is a key part of what makes it so valuable. Our goal in exploring uses for NRP is to develop ways that we can make use of the mixed, dirty, non-recyclable waste that we currently have no use for. As I understand it, a lot of communities simply burn the waste with no filtration system as a way of getting rid of it. Finding a solution that’s more useful than burning will help mitigate the negative environmental and personal health impacts for those living in the communities where this occurs. @mattia-io and I were chatting this afternoon and he mentioned that you guys have spoken previously about pyrolysis. I’d love to learn more about your experience and particularly what sort of plans you have moving forward with Plas-Pod.
@rorydickens I agree with you that the simplicity of the concrete aggregate application would make it easy for communities to implement – in fact I’ve already seen some doing it. I haven’t looked into biocrete much, but am keen to check it out. Adding plaster to the surface of plastic-concrete to avoid solar degradation is a good thought. I’ve seen the Eco-Brick before and find it interesting. Aside from its labor intensity, it seems like a good use for this material. I wonder if there’s a way that we could streamline the process to make it more efficient…
Thanks again for your input and support.. More to come 🙂
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