Making your home-brewing more sustainable

Tips from the Founder of Mash Paddle Brewery


The sustainability of our food and drink is an ever-present issue, and the brewing industry is no different. Brands as large as Guinness to the aptly-named Small Beer Co are finding ways to reduce their inputs, non-brewing outputs and even optimising on packaging. This is an issue dealt with across the industry, but it’s something which can be looked at on the homebrew level as well – here are a few pointers.

Switching to all grain 

Considering more sustainable and viable ingredients for your beer can really reduce the environmental impact your home brew input has. Moving to all grain brewing from extract brewing for example, reduces the additional processing which goes into producing extract. It also doubles up by eliminating the need for manufactured single-use extract packaging – so is a win all round. 

Re-purpose your spent grain

You also need to consider your outputs throughout the process. Grain makes great compost, as we all know, but did you know you can also use it for baking? From amazing sourdough to standard sandwich loaf. You can even jump on the latest Lockdown Trend and make some banana bread with your leftover grain, for a treat after a long day’s brewing.  

Reusing yeast

One of the more expensive parts of homebrewing, aside from the equipment, is buying yeast, and there are few better ways to slash your brewing bill than learning to reuse yeast. There are two ways to do this – reusing fresh washed yeast, or by making a yeast starter. Fresh washed yeast in particular is great if you’re starting your new brew within a week or so. However, you will need to know the specifics about harvesting and washing. 

Harvesting and washing yeast

I find the best way is to start by using a conical fermenter, rather than a flat bottomed one. This means that when you have racked off your brew, the bottom cone will be filled with ‘spent’ yeast. Except it’s not spent – it’s just eaten all the sugars you gave it in your wort. It’s really better thinking of the yeast as sleeping.

The day before you bottle, to speed up the process, boil a litre of water and once cooled, store it in a sealed bottle in the fridge. This will come in handy when you’re harvesting. You’ll also want three mason jars.

After you have finished brewing, firstly sanitise everything you’ll be using. Bring the boiled water down to room temperature. Then take your fermenter with its yeast-cake at the bottom and shake and swirl it up. If the trub isn’t moving, take the boiled water from the fridge, add a bit, swish around and decant into one of the mason jars. Then seal the jar and put in the fridge for an hour. The solution will separate into three layers. The top one is yeast/water. The middle is yeast. The bottom is trub. Carefully pour the top two layers into your other two jars and discard the trub.

Put a loose seal on the jars and leave in the fridge for another hour. These should now just have two layers, yeast/water and yeast. Give the outside a quick spray with sanitiser and tightly cap and put in the fridge – they’re ready for your next brew. On brew day just take the jars out of the fridge – the yeast needs to be at room temp before pitching - carefully pour off the top layer of liquid, and swirl into your wort. 

Chill more efficiently

Water usage during the chilling process before putting your wort into a fermenter can be high, but there are a few ways to reduce this. You’re probably already using a chilling coil (which uses water), but you can also try using freezer packs or even filling plastic bottles with water and freezing. As long as you sanitise these before use you can put them into your wort to chill it as your transfer. I also like to reuse my chiller water by capturing it in a large bucket which you can use to clean your kit afterwards, or even use it to water the garden.

Consider kegging

We all dislike bottling. It’s tedious and slow but it also requires several bottles for a given volume, all of which need to be cleaned and sanitised; and unless you are using swing tops, generate waste in terms of bottle caps. Kegging is better on all of these fronts, and even if you don’t want to sprint for a Corny keg, kegging kits can be purchased for much better prices than even 5 years ago. You can even reuse the pre-filled ones you can buy at any supermarket by replacing the bung at around £1 each. 

Sanitise with Star San (or similar)

No rinse sanitiser not only cuts down the amount of water used, it’s just easier to use all-round. Star San, Chemsan and Puro San are all no-rinse, contact sanitisers which save water in two ways. Firstly – they don’t need rinsed. But less obviously, as they are contact sanitisers they can be sprayed onto all of the surfaces your beer will come into contact with. There is no need to sanitise all of the dead-space in the middle of your fermenter – the beer doesn’t touch this! By mixing up some solution into a spray bottle for cleaning the sides of a fermenter, you can reduce your water use for fermentation by a factor of 30!

Grab that CO2 

And lastly – a personal favourite, simply because it’s overlooked so much. Grab that CO2. Let’s start with what really happens during fermentation: Yeast+ C6 H12 O6 γ 2 C2 H5 OH + 2 CO2. In other words, yeast eats sucrose and turns it into ethanol (C2 H5 OH) and carbon dioxide (CO2). Carbon dioxide is what bubbles out of the top of the airlock. But it’s also what we purchase to purge our kegs. A single fermentation can produce enough CO2 to purge five kegs, bringing savings not only to the environment (from CO2 cartridges) but also to your wallet. To capture CO2 simply put a mylar balloon (the ones typically used for children’s cartoon characters at fairs, rather than your standard birthday balloons), over the end of your airlock during fermentation.

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