368 - CO₂ is a b(u)y-product | Scoins.net | DJS

368 - CO₂ is a b(u)y-product

Because of the jump in wholesale gas, essay 367, we have a jump in wholesale electricity price, which in turn hits the very big users of energy and of gas. This includes steel mills and large chemical plant. One such is the production of fertiliser; a by-product of fertiliser manufacture is food-quality CO₂. BBC explainer. But we use that CO₂ in volume and all of a sudden we've lost 60% of our supply. This is not merely a UK problem, since the economic arguments— including why one would close a fertiliser plant—apply across Europe and probably wider still. Solutions include subsidising CF Industries, who have closed their fertiliser plant because it's not cost-effective. Supply is dependent on fertiliser demand—emphasis here, the food CO is a by-product (from the production of ammonia and bioethanol) not the target product—and so we might well see that this demand is perhaps going to reduce as a climate change action. 

the drivers of supply are unconnected to the drivers of demand.  [15]

You would think that since CO is the declared problem feature in climate change, that abstracting it for any excuse at all would be a Good Thing. No doubt it is access to the gas in sufficient concentration that makes it cost-effective in the uses being fussed over at the moment.

The production of ammonia does not burn the natural gas; it uses the chemistry. Steam and methane plus oxygen makes N₂H and then ammonia, NH₃, while giving off CO₂ in quantity. Production of ethanol is simple fermentation, in which CO₂ is given off, followed by distillation. CO₂ is a low value product, only £15m a year wholesale; it is difficult and expensive both to store and to transport, which means that the supply chain is short because it cannot be stored long. It is widely used but, in effect, we allow it to be cheap and at all times treat it as a waste product. That is no surprise, but we really should value the quality we demand — or change that demand significantly. The UK is one of the largest users, a fifth of Europe's total and around 600 kilotonnes a year. That 600kt is 60% from fertiliser manufacture (ammonia), 20% from bioethanol and 20% imported.

Yes, there is food grade gas.  99.9% pure for food and beverage.  Source and table. That's FDO (USA) rules and I found it difficult to find the equivalent UK regulation. I think it might be 99% with the (UK) Food Standards Agency.

This shortage of carbon dioxide has happened before, and here is the report, [15].  A surprisingly good read.

I wonder how much the price has to change before small scale fermentation like a brewery finds it cost-effective to capture and re-use its own CO₂.  [15 p12] says that the use of CO within a brewery is far more than they seem to generate, that they are net consumers not net generators. I find that a surprise. The mass use is in the bottling / kegging processes. I suspect that the need here is for local generation close to the point of use, and that it is only when we make a fuss about industrial exhalation that anyone will fund capture.

Given the magnitude of the fuss in 2021, one must wonder how much notice was taken of the 2018 report. One fine point I picked up at the foot of the report referred to Drax power station, switching over from coal to biomass and (mess of reporting sorted out) that the pilot scheme is producing a tonne of CO a day, while the next scale up should raise this to 100t/day , which is 8% of the Billingham plant, 400kt a year. See [16], which suggests full scale capture will be a really large amount of CO captured,10 kt/day.  One wonders what 'capture and store' of CO means; I found application for licence to store it in empty oilwells in the North Sea. 

I observe that we 're not at a point where the gas stays captured yet; we seem to have ways of stealing it from incomplete combustion as in biomass generation at Drax and Ince. Holding this in a tank, given the proven difficulties in any form of long-term storage, is not a solution. “Over the next 5-10 years, there will be lots of developments where clusters of CO producers will have to come together in different locations to provide hubs, which can then take the CO via pipelines to the North Sea for storage in geological features, mainly depleted oil wells.” Prof Chris Rayner, Leeds U Chem Dept, [19]. When it is in a hole in the ground and shown that it is going to stay there, that is 'captured'. Until then, we must continue to add up what that costs. I'm not at all saying we shoudn't do it, but we need to recognise cost in both Joules and currency.

DJS 20210921

top pic is Prof Chris Rayner of the Chem Dept, Leeds University

There's more to discover here in capturing the gas from biomass generation. I need the demand for information to rise, or for proper professional press people to ring up the suppliers and ask. 

Numbering from 15 because I moved this from a Snippets page, once the length became great enough.

[15]   https://www.global-counsel.com/sites/default/files/Falling%2520flat%2520lessons%2520from%2520the%25202018%2520UK%2520CO2%2520shortage.pdf

[16] https://www.drax.com/sustainability/carbon-emissions/towards-carbon-negative/     .....our move away from coal (937 tCO / GWh), to biomass (120 tCO  / GWh) and hydro (0 tCO / GWh).  Drax Power Staton is now the largest single site generator of renewable power in the UK, producing 14.1 TWh in 2020. By 2030 we must: Have two biomass units operating with BECCS running at 90% availability, capturing and storing eight million tonnes of CO a year

[17] https://www.drax.com/press_release/world-first-co2-beccs-ccus/  says they use C-Capture at Drax. I suspect that they have found ways to capture a load of other stuff at the same time, so without processing, the CO is captured but nowhere near food grade in terms of purity. taht doesn't mean no food grade gas is produced. 

[18] Ince Biomass https://bioenergyinfrastructure.co.uk/news-article/ince-biomass-plant-chosen-as-site-for-innovative-carbon-capture-technology-project-at-protos-in-northwest/  are users of C-Capture. No: will be users of....  to capture over 7,000 tonnes of carbon every year. That's not CO₂.

[19] https://www.c-capture.co.uk/wp/wp-content/uploads/energy-industry-times.pdf  

This is [...] a two-step process. The first stage has an absorber column, where a shower of the new amine-free solvent comes down the column while the flue gas is blown upwards. When the solvent comes into contact with the flue gas, it selectively reacts with the CO2, leaving the remaining gases to continue upwards to exit the top of the column free of CO2. Solvent with CO2 attached to it re- mains at the bottom of the column. This is then pumped into a stripper column that operates at a much higher temperature, around 100-120°C, compared to 20-30°C in the first. At this temperature, the bond between the solvent and the CO2 breaks and the CO2 comes out of the stripper column as a pure stream that can be used or sequestered. This stripper column also serves to regenerate the solvent, so that “lean” solvent is ready to capture more CO2.

So quality CO₂ is a likely product. What has not happened is scaling up, neither at Drax nor Ince.

Buried in the detail of [19] is a discussion of energy costs, 1.5-2 GJ/t, where amine processes for CO₂ capture are  around 2.5 GJ/t. It confirms that the pilot project is producing 1 t/day of CO₂.



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