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Energy Recovery from Non-Recyclable Packaging

This topic contains 24 replies, has 4 voices, and was last updated by  Richard Edwards 5 days ago.

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Richard Edwards plaspod

Energy Recovery from Non-Recyclable Packaging

03/08/2018 at 15:45

Hello,

We have spent the past 15 months designing, testing and proving a micro-scaled ‘refinery’ which produces heat and power from non-recyclable plastic waste.  Technology is described at http://www.plas-pod.com.

Ambition is to marry this refinery to Precious Plastic machines to develop national (Wales, UK) network of community-based projects to deal with plastic to benefit society.  Ambition is to establish 50-100 projects over next 3-5 years.  Lot of support from Govt, NGOs and private business.

Would be keen to support and work with others if there is interest.  Unable to free-source the refinery build until we can be sure that others have capability to build – could be dangerous if operated incorrectly.

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helper
03/08/2018 at 22:03
1

Very interesting project.  Diolch !

helper
05/08/2018 at 17:54
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Hi @plaspod – I would be interested in your comments on this topic, about waste plastic on the island of Eigg.

Maybe situations where communities are not already integrated into existing fuel supply systems (grid gas, or local heating fuel road tanker networks) might be most keen to try out your plastic waste heat recovery technology.

starter
05/08/2018 at 19:34
1

Plas-Pod can process beach-plastic into heat and power.   There would need to be some minor processing to convert that plastic into a feedstock that will allow consistent operation: cutting waste into manageable pieces (20-60cm).  Similarly, it might be possible to produce pellets from the Precious Plastic extrusion machine – which we will research in the future.

Plas-Pod was not designed to process large volumes of waste plastic because we don’t want it to take the focus away from the more important process of upcycling plastic into products that permanently embed the carbon.

Most plastics carry a high calorific value, which means that that you don’t have to process much to generate a lot of heat and power.  The current version will process between between 4-8kg of plastic, which will generate up to 10kWhe and up to 60kWh for heat.

An ideal use would be to use that power to run the Precious Plastic machines!

Because Plas-Pod is mobile, the unit can, in theory be moved from building to building.  In theory, with the appropriate battery-storage system in place, Plas-Pod could generate up to 80kWhe a day.  The best way to store the heat would be to utilise an efficient system built round large-volume buffer tanks – pic below.

If you know the cost of power and heat already being paid then a business could be developed from providing replacements from plastic waste, but that should not replace energy from renewable sources that may already exist.

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helper
06/08/2018 at 23:01
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Thanks.  I’m guessing that the plas-pod is a batch operation device – that you charge up with waste polymers and charcoal (torrified wood) and then “set off”.  Is that so? What would be the ratio of charcoal to plastic?

Is 60 kWh of heat a typical batch output? Over what time period would a full charge release its heat?  If this is how it works, then I can certainly understand the need for a heat store of some kind.  Similarly for any electrical output – it’s going to need a battery bank in most off-grid situations.  But of course if someone is already using a combination of wind and PV, they are likely to have the battery bank anyway.

I’d be interested in learning more about your machine.  I can see there might be a few legislative hurdles to overcome in operating a high temperature, high pressure reaction vessel in a domestic situation (especially in the UK), but I’m sure that is something to which you have given a fair amount of thought 😉

I’ll email seperatly.  Cheers.

helper
06/08/2018 at 23:33
1

@plaspod
Nice Work, Bravo! I love the scale.
Am I right – You’re mixing plastic and torrefied wood in a downdraft gasifier?
Care to share how you currently process beach plastic to fuel pellets?

@frogfall
I too would be curious on plastic/wood ratios.
In the US we don’t call it a boiler if it’s open to atmospheric pressure… Legally, things change a lot when it’s called a boiler.

helper
07/08/2018 at 00:16
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I don’t think @plaspod has worked with beach plastic yet. He was just answering my question about the possibility of processing it (linked to the posts about Eigg).

I still think some kind of pyrolysis holds the key to small scale processing of plastic into less problematic forms.  Although if heat recovery is one of the aims, then high temperature incineration could conceivably be simpler – unless it is too difficult to maintain high enough temperatures in anything smaller than a municipal scale continuous process plant.

starter
08/08/2018 at 08:46
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Plas-Pod was designed under contract from FEMA.  The design remit was for a flexi-fuel system (plastic, biomass, food waste, animal and human poo!) that would accommodate rapid-deployment in disaster and war-zones.

The prototype was built on a pull-cart frame so that it could be moved between buildings that required heat and energy – hospitals and crisis command buildings, etc.  A batch-load system was seen to be the best solution for that requirement.  Larger, static generators are used in other buildings that demand constant heat and power.

The prototype was designed to operate on charcoal, because charcoal was seen to be widely available and easy to produce.  The later models have been tested with torrefied biomass because the mass-balance is more favourable, less wasteful and less polluting than charcoal production.

We are currently preparing drawings so that we can free-source the torrefaction reactor, which will run most efficiently when challenging plastics (beach and non-recyclable) are used, via Plas-Pod, to provide the energy needed to manufacture torrefied biomass.

The carbon cost of producing torrefied biomass is off-set when that biomass is harvested from short-rotation energy crops or from woodlands where coppice management regimes exist.  Similarly, waste-wood that cannot be upcycled can be used, though in Europe there is legislation relating to the contamination that such waste could carry.

The ratio of plastic to torrefied fuel fluctuates with the type of plastic used and how that plastic is loaded into the chamber.  As a rule of thumb 2-3kg of torrefied will process between 4-8kg of plastic.  As suggested previously, if we can produce pellets from the Precious Plastic extrusion machine (which DH has detailed in one of his videos) then this would allow us to increase the volume of plastic (as a guess) to more than 10kg.  The only issue with pellets is that we may need to add a method of agitation to ensure that all pellets are processed – this is all theoretical at the moment.

Plastics carry an average calorific value of 35Mj/kg, which equates to 9720kWh per tonne (wood pellets are about 4600kWh per tonne).  It takes 11.6kWh to heat 1000litres of water by 10degrees.  You can play with those figures to produce your own conclusions and models.

Plas-Pod is being described as ‘an improved pyrolytic gasification unit.’  The current model has 2 chambers: one to hold and burn the torrefied fuel and the other to hold the plastic.  We had to change the design because FEMA would not allow us to use their patent (which they paid us to develop) – we knew this would happen so designed accordingly.

New process, which we are still very protective of, takes place under conditions well above incineration at 1000C in an oxygen-deprived environment, which means that toxic dioxins and furans do not form.  Resulting gas (flue gas) is rich in hydrogen and carbon monoxide (40-45%).  We work with Babcock & Wilcox Volund (Prof Sven Andersson) to ensure that entire process exceeds all legislation relating to emissions.  Emissions are lower than 95% of all biomass/wood burning appliances.  That can only be achieved when technology is built at human/appropriate-scale!

Trials have been undertaken using beach plastic and PETE, HDPE, LDPE, PP & PS.  All produce good syngas for power production via ITC engines and converted NGas generators.

With regard to legislation: this from EU in BrusselsPlease note that Directive 2000/76/EC has been replaced by Directive 2010/75/EU (Industrial Emissions Directive – IED). This Directive regulates waste incineration plants of all throughput. In its Article 42 it lists certain exclusions from the scope of its provisions on waste incineration.

In particular in Article 42(2) it states:This Chapter shall not apply to the following plants:

(b) experimental plants used for research, development and testing in order to improve the incineration process and which treat less than 50 tonnes of waste per year

Therefore, in this regard plants satisfying simultaneously the following two conditions are excluded:

they are used used for research, development and testing in order to improve the incineration process, andthey treat less than 50 tonnes of waste per year.In view of this, once commercialised, your solution would no longer fall under the first condition and therefore it would be subject to the provisions of the IED chapter IV.

It appears from the existence on your website of a sales brochure, that the product is already on sale. In view of this, the exclusion under Article 42(2) would not apply. However, Article 42(1) also contains an exclusion which states:

This Chapter shall not apply to gasification or pyrolysis plants, if the gases resulting from this thermal treatment of waste are purified to such an extent that they are no longer a waste prior to their incineration and they can cause emissions no higher than those resulting from the burning of natural gas.

In view of this, you should consult with the relevant Competent Authority to assess how your product would need to be permitted.

 

helper
08/08/2018 at 21:39
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Thanks for the extra details.

This Chapter shall not apply to gasification or pyrolysis plants, if the gases resulting from this thermal treatment of waste are purified to such an extent that they are no longer a waste prior to their incineration and they can cause emissions no higher than those resulting from the burning of natural gas.

I can see, then, that selling a gasifier appears to be OK – as long as the subsequent use of that gas has comparatively low emissions.  Tricky, as emissions from burning “natural” methane/butane/propane are pretty low too.

So, how “pure” are the gases from the unit – and could they be stored? (maybe in an old fashioned gasometer)

starter
09/08/2018 at 11:41
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There are possibly 150-200 biomass-based gasifiers (Spanner, Entrade, Ankur, etc) in operation throughout the UK, producing between 25 – 750kWhe.  They all pass EU regs relating to emissions.Plas-Pod produces a rich syngas with a composition (variable) of 20% H2 (Hydrogen), 20% CO (Carbon monoxide) and 5% CH4 (Methan).  Inert gases are 47% N2 (Nitrogen), 8% CO2 (Carbon dioxide).Emissions from the generator or water boiler are below those for biomass and are being improved all the time.  We are currently utilising waste  Palladium shavings from a company in Netherlands that build catalytic converters for cars which are effective at catching particulates below <2.5PPM – the ones that are killing us all.

helper
09/08/2018 at 13:54
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We are currently utilising waste  Palladium shavings from a company in Netherlands that build catalytic converters for cars which are effective at catching particulates below <2.5PPM – the ones that are killing us all.

Erm…  Some of the particulates killing us are Palladium.  See Determination of platinum, rhodium and palladium in car exhaust fumes. 😉

I’d rather trust a proper wet scrubber to capture particulates (having used them way back in my nuclear engineering days).

starter
09/08/2018 at 14:08
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Did look into this beforehand.  Palladium in CAT are usually placed into pretty-poor filters, which do release palladium particles.  We use the big old shavings, which are stable and work really well.

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helper
09/08/2018 at 22:46
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Crikey. Palladium isn’t exactly cheap. What is the scale on the photgraph?

starter
10/08/2018 at 11:06
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Works out at about 100Euros per Plas-Pod, which is a price worth paying given the improvements.  We have been paying 300Euros per Kg, but that may change when the lunatics have their way with Brexit….

We have options to manufacture products in EU countries if Brexit fails, as most expect.

helper
11/08/2018 at 23:04
2

Thinking about the “one shot” heating concept reminded me of this article from Low Tech Magazine on Oven Stove Heaters.
I understand that the Plas-Pod transfers the bulk of its heat output to water (as shown in a previous reply).  Is there an option for a dry ceramic/brick/stone heat storage method?

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dedicated
12/08/2018 at 03:57
1

@frogfall , @plaspod
Low Tech Magazine Rocks! and a great article as well.

starter
12/08/2018 at 15:07
1

Something that we have been working on for some time (put it on the back-burner while developing Plas-Pod).  First effort was to improve the basic rocket stove, which work fine for 15minutes on Youtube videos.  We took the basic concept, improved the combustion process, patented a process that avoids the sticks being burned to a point and then spent a long time fitting it all into EU directives.  Image attached is STICK STOVE.

 

Been aware of thermal mass stoves and principles for many years.  Turned our attention to developing smarter (and more affordable) thermal mass stoves about 4 years ago – TM1 attached.  Got to move Plas-Pod concept forward before returning to these 2 stoves, which sit among the most efficient ever built.

 

 

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starter
12/08/2018 at 15:10
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Problem with ‘Rocket Stoves’ vertical sticks burn to a point – patent developed to overcome that

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starter
12/08/2018 at 15:12
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World’s first pellet-based thermal-mass stove:

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helper
12/08/2018 at 16:33
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Yeah, rocket mass stoves are a problem when it comes to satisfying safety regulations – but for some very good reasons.  Keeping the flue gas temperature high, to ensure no back flow (and gases escaping into the room), makes the traditional rocket mass stove concept illegal.  And that’s also one of the reasons that ordinary EU certified wood stoves are so damned inefficient.

I’ve occasionally given some thought to how the various designs could be improved – although I’ve not had the time to build any experimental models myself yet (one of the dozens of projects I’ve been putting off until I can eventually retire!).  So at the moment I have to be satisfied with the occasional bit of thermodynamic theory and mathematical modeling 😉

I like the concept of using cullet as a heat storage medium.  (Pity about the unit errors in the advert text, though 😉

starter
12/08/2018 at 18:08
0

Pity about the unit errors in the advert text, though

???

helper
12/08/2018 at 21:54
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Ah.  Ok.  Please don’t take this the wrong way, but…

The advert says “It takes 1000 kilowatts of electricity to recycle 1 tonne of glass.” However kilowatts, as a unit, is a measure of the rate of heat transfer (i.e. kilojoules per second) not an amount of heat (energy).

This source gives the heat required to melt cullet (broken bottles) at 3.74e6 Btu/ton(US), which converts to 994 kilowatt-hours per (metric) tonne, or 3.58 gigajoules per tonne.

Hence, leaving aside the fact that full recycling takes more energy than just melting the waste glass, the phrase should have said “1000 kilowatt-hours”. Unfortunately the same “units error” also crops up in the statement about the steel used in construction.

Of course they could just have been typos, but the fact that they weren’t picked up at proof-reading stage would certainly lead some people to cast doubt on the competence of the company advertising the product.

What makes things worse is the phrase about releasing heat at “1.2 KWh per hour” which is really just a rate of 1.2 kilowatts (i.e. the hours cancel each other). Whilst not technically incorrect, when taken with the above errors, it helps to make the entire advert look either like a product of muddled thinking or a poor attempt to baffle potential customers with bullshit.

This is a shame – because the heater itself sounds like it could be quite interesting…

starter
12/08/2018 at 23:18
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Cool – that flyer was produced by a community group nearby who were going to manufacture the stove under licence.  The brochure has not been proof-read (until now) and should’not have been posted (should have checked!).  Will take it down.

That should not detract from what is still a very good stove designed by very good engineers.

helper
13/08/2018 at 15:26
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@plaspod – thanks for sharing details
We operate a series of Adam style retorts for biochar (ag. charcoal) production in north carolina, USA.  We capture and store excess heat in 18K gallon water storage.  Our process is started a simple downdraft wood chip gasifier, and becomes self sustaining after just an hour or so.   Seems we’re doing something similar, though maybe on just a slightly larger scale.  Would love to talk to you more about your work.
I’ll admit our heat exchange has been a bit dissapointing – only about 2M Btus stored / 1200 lbs of sawmill waste.    Our big project now is using gas/process heat as it’s made – prior to storage – for drying tasks and large plastic compression moulding work.
Care to talk privately? We’re leading a workshop for our community on our work (so far) with plastics recycling – I’d be honored if you or someone else in your group wanted to share your work in plastic pyrolysis via skype with our group.

starter
13/08/2018 at 19:13
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Hi Dan,

drop us an email at [email protected] and we’ll respond.

Regards

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