Scrutable

Posted: **Wed Nov 13, 2019 3:43 pm**

I was listening to a podcast which was talking about biofuels, and one thing they mentioned was that any land taken up to grow biofuels has to be replaced in order to grow food for people. I assume the same applies to plant plastics and the like. So when you look at the carbon emissions of the whole endeavour, including having to turn currently unused land into farmland, growing our way out of our fossil fuels dependency doesn't seem like as sensible an idea as it does at first.

Posted: **Wed Nov 13, 2019 3:49 pm**

The idea of using crops like willow is that they can be grown on land that wasn’t previously used for farming food, AIUI. Also in the UK at least, we have an oversupply of farmland.

The observation that bio-derived feedstocks aren’t necessarily carbon neutral is completely valid, of course.

Posted: **Wed Nov 13, 2019 3:54 pm**

I'm not exactly clear on what the point of replacing fossil fuels as a feedstock for plastics etc. really is. If the carbon involved stays in solid form, then it's not contributing to climate change, and the other impacts of waste apply pretty much equally to bio-derived feedstocks.

Obviously there's the question of how much carbon is emitted/energy inputs are used in the two processes, and which is economic with changes in the wider economy, but I don't see that fossil and non-fossil derived plastics are necessarily intrinsically better or worse than the other.

Posted: **Wed Nov 13, 2019 4:06 pm**

Fishnut wrote: ↑
Wed Nov 13, 2019 3:43 pm
I was listening to a podcast which was talking about biofuels, and one thing they mentioned was that any land taken up to grow biofuels has to be replaced in order to grow food for people. I assume the same applies to plant plastics and the like. So when you look at the carbon emissions of the whole endeavour, including having to turn currently unused land into farmland, growing our way out of our fossil fuels dependency doesn't seem like as sensible an idea as it does at first.

Other oft quoted options are things like waste straw from maize, etc. A few academics were surprised to learn that there isn't actually that much 'waste' as such, business generally already doing as much as it can to re-use these sorts of things. What's harder is that the GM processes usually used to convert 'biomass' to 'useful product' are actually quite finicky, and if you've got them optimised for maize straw, you can't suddenly switch them to wood just because you've found some spare.
Alternatives like algae seem quite popular in that you can just grow them in water (ok an issue in some areas) and sunlight - but it's a bigger step to convert industrial processes, which are already used at least in principle to growing things in yeast.

Posted: **Wed Nov 13, 2019 4:53 pm**

The Centre for Sustainable Energy has some good resources relating to renewable energy and energy efficiency in general. If you look under the Reports and Publications section, there is one called Common Concerns about Wind Power that is a useful starting point if you want to explore some of the issues around wind turbines (including impacts on bat and bird populations).

Posted: **Thu Nov 14, 2019 4:39 am**

greyspoke wrote: ↑
Wed Nov 13, 2019 11:17 am
As long as there is a residual demand for oil for some purposes, the whole of the oil will have to be used for something. So that might mean some things (eg petrol for motor-racing, classic cars etc.) remain relatively available as a by-products.

How useful are plant-based products for chemical feedstocks?

Some plant-based products can be used for chemical feedstocks. The problem is that some chemicals (especially medicines) require very specific feedstocks, and the manufacturing process has been optimised for a very refined, mineral-based feedstock. That doesn't mean that some plant-based feedstock couldn't be used, but will it:

a) be cheaper - given that the mineral-based feedstock manufacturing process has already been optimised, re-tooling for a plant-based feedstock process would probably require a significant change in economics to make it cheaper.

b) require a lower carbon footprint - again, the manufacturing process has already been optimised, but this would have to look at the entire feedstock generation cycle (either oil extraction, processing, refining, transportation, etc, or plant growth, water usage, fertiliser manufacture and usage, use of land which could be used for other purposes (oilfields might be subsea), manual interactions, transportation, etc).

c) produce lower emissions - plant-based feedstocks might be less pure than refined, mineral-based feedstocks, so more effluents, solutes, etc.

IABMCTT, so there is no one correct answer to: "How useful are plant-based products for chemical feedstocks?"

Posted: **Thu Nov 14, 2019 8:47 am**

Fishnut wrote: ↑
Wed Nov 13, 2019 3:43 pm
I was listening to a podcast which was talking about biofuels, and one thing they mentioned was that any land taken up to grow biofuels has to be replaced in order to grow food for people. I assume the same applies to plant plastics and the like. So when you look at the carbon emissions of the whole endeavour, including having to turn currently unused land into farmland, growing our way out of our fossil fuels dependency doesn't seem like as sensible an idea as it does at first.

Which podcast fishnut? For my own listening ears.

Posted: **Thu Nov 14, 2019 9:16 am**

discovolante wrote: ↑
Thu Nov 14, 2019 8:47 am

Fishnut wrote: ↑
Wed Nov 13, 2019 3:43 pm
I was listening to a podcast which was talking about biofuels, and one thing they mentioned was that any land taken up to grow biofuels has to be replaced in order to grow food for people. I assume the same applies to plant plastics and the like. So when you look at the carbon emissions of the whole endeavour, including having to turn currently unused land into farmland, growing our way out of our fossil fuels dependency doesn't seem like as sensible an idea as it does at first.
Which podcast fishnut? For my own listening ears.

Er, it was actually The West Wing Weekly

The episode was King Corn and they spoke to a reporter about corn biofuels and how things have changed (and haven't) since the episode aired. The stuff about the carbon cost of converting land to replace that used to grow biofuels was based on this Science paper, Land Clearing and the Biofuel Carbon Debt by Fargione et al. (2008).

Posted: **Thu Nov 14, 2019 9:44 am**

Cool, thanks!

Posted: **Thu Nov 14, 2019 10:03 am**

Martin_B wrote: ↑
Thu Nov 14, 2019 4:39 am

greyspoke wrote: ↑
Wed Nov 13, 2019 11:17 am
As long as there is a residual demand for oil for some purposes, the whole of the oil will have to be used for something. So that might mean some things (eg petrol for motor-racing, classic cars etc.) remain relatively available as a by-products.

How useful are plant-based products for chemical feedstocks?
Some plant-based products can be used for chemical feedstocks. The problem is that some chemicals (especially medicines) require very specific feedstocks, and the manufacturing process has been optimised for a very refined, mineral-based feedstock. That doesn't mean that some plant-based feedstock couldn't be used, but will it:

a) be cheaper - given that the mineral-based feedstock manufacturing process has already been optimised, re-tooling for a plant-based feedstock process would probably require a significant change in economics to make it cheaper.

b) require a lower carbon footprint - again, the manufacturing process has already been optimised, but this would have to look at the entire feedstock generation cycle (either oil extraction, processing, refining, transportation, etc, or plant growth, water usage, fertiliser manufacture and usage, use of land which could be used for other purposes (oilfields might be subsea), manual interactions, transportation, etc).

c) produce lower emissions - plant-based feedstocks might be less pure than refined, mineral-based feedstocks, so more effluents, solutes, etc.

IABMCTT, so there is no one correct answer to: "How useful are plant-based products for chemical feedstocks?"

Thanks Martin, that is kind of the thing I expected.

Posted: **Thu Nov 14, 2019 11:17 am**

My gas boiler became enfucked yesterday, prompting a visit from the gas man today.

He told me the hydrogen revolution is imminent. Worcester Bosch are working closely with the govt, and they have already developed a prototype hydrogen-powered domestic boiler. Much of the work you see being done to gas lines isn't repairs, it's upgrading ready for hurtling those tiny little mollycules down to our domestic appliances.

So, you heard it here first. From the gas man.

Posted: **Thu Nov 14, 2019 11:38 am**

GeenDienst wrote: ↑
Thu Nov 14, 2019 11:17 am
My gas boiler became enfucked yesterday, prompting a visit from the gas man today.

He told me the hydrogen revolution is imminent. Worcester Bosch are working closely with the govt, and they have already developed a prototype hydrogen-powered domestic boiler. Much of the work you see being done to gas lines isn't repairs, it's upgrading ready for hurtling those tiny little mollycules down to our domestic appliances.

So, you heard it here first. From the gas man.

Will that be 100% H2 or H2 enrichment of CH4?

Posted: **Thu Nov 14, 2019 12:54 pm**

There are serious issues around embrittlement of metals when in contact with H2 that I can’t see a 100% H2 gas supply a being trivial swap. From memory you can only swap in something like 15% H2 onto a CH4 supply before you start getting problems. You’d also need to swap burner jets as well.

Posted: **Thu Nov 14, 2019 12:58 pm**

Also H2 is a storage medium, not an energy source. You’ve got to make it somehow, which is an inefficient process. In any forseeable future that is going to be from electricity. Depending on what you are doing with the H2, it’s may be far more efficient to use the electricity directly. Eg induction hob, electric boilers.

Posted: **Thu Nov 14, 2019 1:52 pm**

Electric boilers make more sense to me than using hydrogen as a fuel.

Posted: **Thu Nov 14, 2019 2:10 pm**

bjn wrote: ↑
Thu Nov 14, 2019 12:58 pm
Also H2 is a storage medium, not an energy source. You’ve got to make it somehow, which is an inefficient process. In any forseeable future that is going to be from electricity.

I believe the main source of hydrogen at present is steam reforming of natural gas.

Posted: **Thu Nov 14, 2019 3:56 pm**

bjn wrote: ↑
Thu Nov 14, 2019 12:54 pm
There are serious issues around embrittlement of metals when in contact with H2 that I can’t see a 100% H2 gas supply a being trivial swap. From memory you can only swap in something like 15% H2 onto a CH4 supply before you start getting problems. You’d also need to swap burner jets as well.

There are embrittlement problems, but it’s pressure and material dependent and I’m not sure when it starts being a problem. It’s not a problem for stainless steel at 2 bar or so.

Posted: **Thu Nov 14, 2019 3:57 pm**

bolo wrote: ↑
Thu Nov 14, 2019 2:10 pm

bjn wrote: ↑
Thu Nov 14, 2019 12:58 pm
Also H2 is a storage medium, not an energy source. You’ve got to make it somehow, which is an inefficient process. In any forseeable future that is going to be from electricity.
I believe the main source of hydrogen at present is steam reforming of natural gas.

Yes it is. Electrolysis is too slow and expensive.

Posted: **Thu Nov 14, 2019 4:23 pm**

greyspoke wrote: ↑
Thu Nov 14, 2019 10:03 am

Martin_B wrote: ↑
Thu Nov 14, 2019 4:39 am

greyspoke wrote: ↑
Wed Nov 13, 2019 11:17 am
As long as there is a residual demand for oil for some purposes, the whole of the oil will have to be used for something. So that might mean some things (eg petrol for motor-racing, classic cars etc.) remain relatively available as a by-products.

How useful are plant-based products for chemical feedstocks?
Some plant-based products can be used for chemical feedstocks. The problem is that some chemicals (especially medicines) require very specific feedstocks, and the manufacturing process has been optimised for a very refined, mineral-based feedstock. That doesn't mean that some plant-based feedstock couldn't be used, but will it:

a) be cheaper - given that the mineral-based feedstock manufacturing process has already been optimised, re-tooling for a plant-based feedstock process would probably require a significant change in economics to make it cheaper.

b) require a lower carbon footprint - again, the manufacturing process has already been optimised, but this would have to look at the entire feedstock generation cycle (either oil extraction, processing, refining, transportation, etc, or plant growth, water usage, fertiliser manufacture and usage, use of land which could be used for other purposes (oilfields might be subsea), manual interactions, transportation, etc).

c) produce lower emissions - plant-based feedstocks might be less pure than refined, mineral-based feedstocks, so more effluents, solutes, etc.

IABMCTT, so there is no one correct answer to: "How useful are plant-based products for chemical feedstocks?"
Thanks Martin, that is kind of the thing I expected.

The assumption there is that you're replacing like for like, and just changing the source. But it probably makes more sense to look at the final product - rubber/drug/dye etc and see if there's an alternative route to make it, if you're coming from an alternative source. LOTS of money thrown into this at the moment, GMmicro-organism to make x

Posted: **Thu Nov 14, 2019 4:27 pm**

Grumble wrote: ↑
Thu Nov 14, 2019 3:57 pm

bolo wrote: ↑
Thu Nov 14, 2019 2:10 pm

bjn wrote: ↑
Thu Nov 14, 2019 12:58 pm
Also H2 is a storage medium, not an energy source. You’ve got to make it somehow, which is an inefficient process. In any forseeable future that is going to be from electricity.
I believe the main source of hydrogen at present is steam reforming of natural gas.
Yes it is. Electrolysis is too slow and expensive.

If we are sourcing it from CH4 for straightforward energy, why not use the CH4 instead and avoid the cost of conversion. H2 as a storage medium only makes sense in the world of abundant cheap electricity.

Posted: **Thu Nov 14, 2019 4:28 pm**

Grumble wrote: ↑
Thu Nov 14, 2019 3:56 pm

bjn wrote: ↑
Thu Nov 14, 2019 12:54 pm
There are serious issues around embrittlement of metals when in contact with H2 that I can’t see a 100% H2 gas supply a being trivial swap. From memory you can only swap in something like 15% H2 onto a CH4 supply before you start getting problems. You’d also need to swap burner jets as well.
There are embrittlement problems, but it’s pressure and material dependent and I’m not sure when it starts being a problem. It’s not a problem for stainless steel at 2 bar or so.

How much of our CH4 distribution infrastructure is known to be able to handle pure H2.

Posted: **Thu Nov 14, 2019 4:31 pm**

science_fox wrote: ↑
Thu Nov 14, 2019 4:23 pm

greyspoke wrote: ↑
Thu Nov 14, 2019 10:03 am
...

Thanks Martin, that is kind of the thing I expected.
The assumption there is that you're replacing like for like, and just changing the source. But it probably makes more sense to look at the final product - rubber/drug/dye etc and see if there's an alternative route to make it, if you're coming from an alternative source. LOTS of money thrown into this at the moment, GMmicro-organism to make x

And also look at if there are alternative things to make that are more easily makeable from planty sources I guess.

Posted: **Thu Nov 14, 2019 4:47 pm**

I've noticed that UK "unleaded" petrol is now openly being sold as E5 - with 5% ethanol - however, I understand that the energy content is lower than 100% petrol, so fuel consumption increases.

France is going quite big for E10 petrol, which some older vehicles have problems with as hoses and seals aren't designed to be tolerant of that much ethanol.

Given that the land (and fertilisers etc) used to grow the feedstock for the ethanol could be used for food production, I think this is not a good move, even if it gives governments a 'green' glow.

Posted: **Thu Nov 14, 2019 5:18 pm**

There is a research project for looking at the effects of H2 in the UK national grid, which was due to start around now
https://www.smarternetworks.org/project ... /documents
which has the objective of:
"The UK has committed to be net zero by 2050 and as a result National Grid Gas Transmission (NGGT) is committed to understand and trial
the impact of hydrogen within the National Transmission System (NTS). The impact of natural gas is well understood, however there is little
understanding of the impact of a natural gas blend with a significantly increased hydrogen content (up to 100%) on the assets we own and
operate and the impact to our direct customers."

I believe there are also people looking at Wind-to-Hydrogen for using wind turbines to produce H2 e.g.
https://www.nrel.gov/hydrogen/wind-to-hydrogen.html

Posted: **Thu Nov 14, 2019 6:47 pm**

bjn wrote: ↑
Thu Nov 14, 2019 4:28 pm

Grumble wrote: ↑
Thu Nov 14, 2019 3:56 pm

bjn wrote: ↑
Thu Nov 14, 2019 12:54 pm
There are serious issues around embrittlement of metals when in contact with H2 that I can’t see a 100% H2 gas supply a being trivial swap. From memory you can only swap in something like 15% H2 onto a CH4 supply before you start getting problems. You’d also need to swap burner jets as well.
There are embrittlement problems, but it’s pressure and material dependent and I’m not sure when it starts being a problem. It’s not a problem for stainless steel at 2 bar or so.
How much of our CH4 distribution infrastructure is known to be able to handle pure H2.

Absolutely no idea. I’d be more worried about regulators and anything with a diaphragm in it, hydrogen definitely embrittles polymers. The life of a hydrogen regulator is about 5 years maximum. Those are fairly easily replaced though, unlike buried pipes.

This is an analogous problem to ethanol in petrol.

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