CCS has a bit of an image problem, part of which is due to it being very hard to visualise – no-one but a geologist can easily imagine what a CO₂ store over a kilometre below the seabed might look like, so mental images can range from giant caverns in the rock to CO₂ gas bubbling just below the sand. So often when I’m talking about CCS – to politicians, civil servants, NGOs etc – I start with a brief explainer of how it works. And what better way to explain something than with a tasty treat?
One of my favourite parts of my job is using chocolate to demonstrate how CO₂ storage works. Very few people don’t welcome a bit of chocolate, and I’m no psychologist, but I imagine it must cause a positive correlation in the brain: chocolate is good, therefore CCS must be good too. Plus taking part in the demo looks a little bit silly, but not too silly, which is always good for a twitter photo op.
In summary, a Penguin bar has layers of biscuit that are porous and permeable – like the sandstone rocks used for subsurface CO₂ storage – and layers of chocolate and fondant that are neither porous nor permeable – like the cap rock in a CO₂ store. Using the Penguin like a straw, it’s possible to suck milk through the biscuit, mimicking the movement of CO₂ through rock.
The demo was originally thought up by CO2CRC, but I’ve added my own caffeine-addict twist – cold brew coffee, instead of milk. This was after a bit of trial and error – hot coffee means the ‘cap rock’ melts, undermining messages about its ability to keep the CO₂ securely in place.
The full version of the demo includes a Wispa (porous but not permeable) and a Dairy Milk (not porous, impermeable), but three chocolate bars in one meeting seems a bit extravagant, so I tend to just describe those.
However, I have found one item that covers all these bases: the Wispa Biscuit, which has a layer of Wispa, a layer of biscuit and a solid chocolate coating. The only drawback is that it is circular and about the same diameter as a mug, so even harder to use as a straw than a Penguin (memo to the makers of Penguin: please can you make a double-length bar? It would make my job so much easier if it could reach the bottom of a cup).
A minimal amount of research for this post (flicking through the 2005 book A Nice Cup of Tea and a Sit Down) reveals that Penguin biscuits originated in Glasgow in 1932, which is a nice extra bit of Scottish trivia.
Sadly, the Covid-19 pandemic has put paid to in-person meetings, so I’m left with a quandary: what is the etiquette around asking people I’m meeting to supply their own biscuit? Do I need to post out chocolate biscuits far enough in advance that they can be quarantined before opening? Or do I - worst case scenario - have to stop doing the Penguin demo altogether?
Cake is another option for demonstrating how CO₂ storage works – this trial run in 2019 was meant to prepare us for our 15th birthday cake this year, but unfortunately Covid-19 put paid to that, too.