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Is it possible to re sequester gasoline and diesel in the ground

  • 11-03-2015 5:22pm
    #1
    carlowplayer
    Registered Users Posts: 519 ✭✭✭


    Am wondering as I'm doing a project on waste management and I've found that when pyritise sd plastic turns into a liquid similar to diesel. Is it possible to pyrolises plastic and then re sequester the gasoline substance into old oil fields in the desert or in oceans and sequester it permanantly


Comments

  • #2
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    so you want to use a lot of energy to turn a inert solid into a liquid that could seep into ground water ?

    Knowing that that this will mean more fossil fuel will be needed to replace the plastics or the energy they contained ?


    very roughly speaking pyrolysing plastics recovers half the energy in them

    there is also the problem that a lot of cheap plastics have filler, usually powered rock, but some have glass fibre in them and old plastics might have bromine based fire retardants

    and at this stage EU law means that any plastic piece bigger than 100g has to be recyclabe with the ID symbols and stuff , which is by far the best way to utilise the energy originally used to make those plastics

    there's also the pumping energy and the whole "who is going to pay for this ?" especially when we live in a world where are looking at ways to make it cheaper to take stuff back out of the ground , in some cases the EROEI is only about 3.

    So overall the energy balance is , well imagine it 6 units of energy to make the plastic
    pyrolysing would leave 3 units (the 3 go mostly into CO2)

    by pumping them into the ground you loose those 3 units that could have been used to replace fossil fuel, and the 4th unit used to extract that fossil fuel from the most marginal reserves

    If you could recycle the plastic you'd save most of those 6 units of energy.
    to replace them you'd need to extract 8 units of energy (2 because of the low EROEI of the most marginal sites)


    Look at the technologies used here to recover oil from tar sands ,
    http://www.economist.com/news/science-and-technology/21615488-new-technologies-are-being-used-extract-bitumen-oil-sands-steam


  • #3
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    so you want to use a lot of energy to turn a inert solid into a liquid that could seep into ground water ?

    Knowing that that this will mean more fossil fuel will be needed to replace the plastics or the energy they contained ?


    very roughly speaking pyrolysing plastics recovers half the energy in them

    there is also the problem that a lot of cheap plastics have filler, usually powered rock, but some have glass fibre in them and old plastics might have bromine based fire retardants

    and at this stage EU law means that any plastic piece bigger than 100g has to be recyclabe with the ID symbols and stuff , which is by far the best way to utilise the energy originally used to make those plastics

    there's also the pumping energy and the whole "who is going to pay for this ?" especially when we live in a world where are looking at ways to make it cheaper to take stuff back out of the ground , in some cases the EROEI is only about 3.

    So overall the energy balance is , well imagine it 6 units of energy to make the plastic
    pyrolysing would leave 3 units (the 3 go mostly into CO2)

    by pumping them into the ground you loose those 3 units that could have been used to replace fossil fuel, and the 4th unit used to extract that fossil fuel from the most marginal reserves

    If you could recycle the plastic you'd save most of those 6 units of energy.
    to replace them you'd need to extract 8 units of energy (2 because of the low EROEI of the most marginal sites)


    Look at the technologies used here to recover oil from tar sands ,
    http://www.economist.com/news/science-and-technology/21615488-new-technologies-are-being-used-extract-bitumen-oil-sands-steam

    Well I know that algea is a better source of plastics than crude oil


  • #4
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    so you want to use a lot of energy to turn a inert solid into a liquid that could seep into ground water ?

    Knowing that that this will mean more fossil fuel will be needed to replace the plastics or the energy they contained ?


    very roughly speaking pyrolysing plastics recovers half the energy in them

    there is also the problem that a lot of cheap plastics have filler, usually powered rock, but some have glass fibre in them and old plastics might have bromine based fire retardants

    and at this stage EU law means that any plastic piece bigger than 100g has to be recyclabe with the ID symbols and stuff , which is by far the best way to utilise the energy originally used to make those plastics

    there's also the pumping energy and the whole "who is going to pay for this ?" especially when we live in a world where are looking at ways to make it cheaper to take stuff back out of the ground , in some cases the EROEI is only about 3.

    So overall the energy balance is , well imagine it 6 units of energy to make the plastic
    pyrolysing would leave 3 units (the 3 go mostly into CO2)

    by pumping them into the ground you loose those 3 units that could have been used to replace fossil fuel, and the 4th unit used to extract that fossil fuel from the most marginal reserves

    If you could recycle the plastic you'd save most of those 6 units of energy.
    to replace them you'd need to extract 8 units of energy (2 because of the low EROEI of the most marginal sites)


    Look at the technologies used here to recover oil from tar sands ,
    http://www.economist.com/news/science-and-technology/21615488-new-technologies-are-being-used-extract-bitumen-oil-sands-steam

    Well I know that algea is a better source of plastics than crude oil and that recycling plastics usually causes them to be downgraded in lower quailty plastics used only for shoe laces and carpeting


  • #5
    wonski
    Registered Users Posts: 13,687 ✭✭✭✭wonski


    carlowplayer wrote: »
    Well I know that algea is a better source of plastics than crude oil

    Well if you know then it must be true.

    Not saying it is not, but where is the catch?


  • #6
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    wonski wrote: »
    Well if you know then it must be true.

    Not saying it is not, but where is the catch?
    It's not easy to separate algae from the hydrocarbons they produce. Takes a lot of energy too. In an ideal world we'd use the waste heat and CO2 from fossil fuel power stations to keep the algae cosy. Not sure of the economics though.

    http://www.popularmechanics.com/science/green-tech/a9080/meet-the-high-school-student-making-algae-biofuel-better-15539133/

    And algae don't give the same mix of hydrocarbons as fossil fuel. This can be a good thing if you just want one key product. Otherwise it might not be.


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  • #7
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    It's not easy to separate algae from the hydrocarbons they produce. Takes a lot of energy too. In an ideal world we'd use the waste heat and CO2 from fossil fuel power stations to keep the algae cosy. Not sure of the economics though.

    http://www.popularmechanics.com/science/green-tech/a9080/meet-the-high-school-student-making-algae-biofuel-better-15539133/

    And algae don't give the same mix of hydrocarbons as fossil fuel. This can be a good thing if you just want one key product. Otherwise it might not be.

    http://m.youtube.com/watch?v=V7edf97igcc

    http://m.youtube.com/watch?v=WtrtQVmmOl8


  • #8
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    carlowplayer wrote: »
    http://m.youtube.com/watch?v=V7edf97igcc

    http://m.youtube.com/watch?v=WtrtQVmmOl8
    cba watching PR videos

    methane to plastic eh ?

    Back in the day ICI used to make protein rich food from methane. google pruteen

    It closed down when after the price of fuel went up.
    So I'm completely questioning the economics on that


  • #9
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    cba watching PR videos

    methane to plastic eh ?

    Back in the day ICI used to make protein rich food from methane. google pruteen

    It closed down when after the price of fuel went up.
    So I'm completely questioning the economics on that

    Well the methane can be taken from any sources such as animal waste and organic household waste

    https://m.youtube.com/watch?v=1_3EUohUldE
    I am actually curious is their other applications to gasoline produced by plastic pyrolysis other than a fuel source .can gasoline be recovered into plastics?


  • #10
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    carlowplayer wrote: »
    Well the methane can be taken from any sources such as animal waste and organic household waste

    https://m.youtube.com/watch?v=1_3EUohUldE
    I am actually curious is their other applications to gasoline produced by plastic pyrolysis other than a fuel source .can gasoline be recovered into plastics?
    you can pretty much convert any fossil fuel into another one by cracking or reforming or gasification / water shift reaction. Sulphuric acid can turn sugar into solid carbon or ethanol into ethane.
    all you need is time , huge capital investments and energy.

    If you only have energy you could electrolyse water and add the hydrogen to the gas mains and save a lot of fossil fuel that way.


    Processes that are inefficient economically or energetically will loose out to those that are.

    You are asking if plastic --> petrol --> plastic is possible ?
    that's two major chemical reactions

    instead you could just reprocess the plastic with as little chemical reactions as possible , way more energetically efficient


  • #11
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    you can pretty much convert any fossil fuel into another one by cracking or reforming or gasification / water shift reaction. Sulphuric acid can turn sugar into solid carbon or ethanol into ethane.
    all you need is time , huge capital investments and energy.

    If you only have energy you could electrolyse water and add the hydrogen to the gas mains and save a lot of fossil fuel that way.


    Processes that are inefficient economically or energetically will loose out to those that are.

    You are asking if plastic --> petrol --> plastic is possible ?
    that's two major chemical reactions

    instead you could just reprocess the plastic with as little chemical reactions as possible , way more energetically efficient

    Hmm that reprocessing of plastic sounds good .is that better than the downgrading of plastic that is what happens to plastic that is sent to recycling plants or is actually recycling them?


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  • #12
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    carlowplayer wrote: »
    Hmm that reprocessing of plastic sounds good .is that better than the downgrading of plastic that is what happens to plastic that is sent to recycling plants or is actually recycling them?
    And that is why the EU mandates that any plastic part more than 100g now has to be made of just a single type of plastic and have the type of plastic written on it.


  • #13
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    And that is why the EU mandates that any plastic part more than 100g now has to be made of just a single type of plastic and have the type of plastic written on it.

    But what in the case of different types of plastics that were mixed together couldn't the pyrolosis method be used to convert it to gasoline and then plastic again. Does this reprocessing actually make the plastic ie a bottle into a another plastic bottle or are there only a finite amount of times you could reprocess it before it must be landfilled


  • #14
    Capt'n Midnight
    Moderators, Recreation & Hobbies Moderators, Science, Health & Environment Moderators, Technology & Internet Moderators Posts: 90,657 Mod ✭✭✭✭Capt'n Midnight


    diminishing returns

    it takes energy to do all this, and there are waste products, so figure on loosing up to half the materials if you take the energy from the material you are processing

    so the number of finite times could be as low as two

    pyrolysis is a last resort , it's really for when you want to use the carbon in the plastic as fuel

    It's like storing energy in batteries. Not rechargable ones. Primary batteries that have to be recycled and remanufactured between each charge.


  • #15
    carlowplayer
    Registered Users Posts: 519 ✭✭✭carlowplayer


    Capt'n Midnight wrote: »
    diminishing returns

    it takes energy to do all this, and there are waste products, so figure on loosing up to half the materials if you take the energy from the material you are processing

    so the number of finite times could be as low as two

    pyrolysis is a last resort , it's really for when you want to use the carbon in the plastic as fuel

    It's like storing energy in batteries. Not rechargable ones. Primary batteries that have to be recycled and remanufactured between each charge.

    So that gasoline waste product from the pyrolysis process allows new plastics to be reproduced an infinite number of times?might take energy but then again if you have a pyrolosis waste plant designed you could use the bio oil and syngas extracted from pyroloised organic materials to power converting plastic to gasoline to plastic again


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