A team of PhD students at Imperial College London has created a carbon neutral beer using eco-friendly processes.

CO_BREW, as the beer and the team behind it are called, will hold tastings and will present the science behind it at Imperial Festival 2018 (28-29 April).

Here, team leader Matt Barker (Research Postgraduate in Mathematics), compiles a list of the least to the most eco-friendly types of beers.

It is well known that the food we consume can have a large environmental impact and that there are various measures that can be taken to reduce that impact, from choosing to eat less meat to shopping for more locally produced food. 

The same can’t be said for the drinks industry. To be honest, until you read this line you probably never thought about the climate impact of the drinks you consume. Neither did I until me and group of Imperial PhD students decided to brew carbon neutral beer - CObrew.

In fact, a 2007 study showed that alcoholic beverages represented 1.5% of the UK’s emissions. Although this figure is old, evidence suggests changes in the amount of alcohol being consumed are minimal

For the size of the industry, this is an important factor in the UK’s emissions and it deserves to be investigated further. But is there anything consumers can do to cut those emissions and drive change in the alcoholic drinks sector?

We’ve put together a ranking of six different types of beer and their environmental impacts, from most to least polluting, to help you make more informed choices.

When comparing the amount of greenhouse gases being produced for each process, we use carbon dioxide equivalent (CO₂e) to measure the total, as all greenhouse gases can be converted to this scale.

1. Internationally produced lager: 759g CO₂e per 500ml

Over 750g of carbon dioxide being produced per pint of lager is a large price to pay. The biggest contributors to this, and for beer production generally, are bottle production and transport (204g), retail electricity use (150g) and malt production and transport (132g).

2. Internationally produced ale: 692g CO₂e per 500ml

With a reduction of almost 70g of CO₂e an internationally produced ale is a better option than any lager, unless you want to brew your own. Where does this saving come from? Well, it’s all down to the serving temperature of the beer. An ale served at room temperature or kept slightly below in a cellar saves 67g of CO₂ compared with a fridge-cooled lager.

3. Locally produced lager: 709g CO₂e per 500ml

The big savings between internationally produced lager and one that has been produced locally are a result of reduced transportation emissions, for example the glass transport reduces the emissions by 35g. Unfortunately, chilling by the end user counteracts any such reduction when compared with an internationally produced ale.

4. Locally produced ale: 642g CO₂e per 500ml

No chilling and a local supply chain gives locally produced ale top marks for CO₂ emissions compared with other commercial beers. It still doesn’t come anywhere near the reductions for home-brewed beer though.

5. Home-brewed lager: 437g CO₂e per 500ml

Brew beer at home and the green rewards come flooding in: Negligible retail emissions, reduced energy requirements for the brewing process, and no artificial carbonation with CO₂ gas. This adds up to more than 300g saving compared with internationally produced lager

6. Home-brewed ale: 370g CO₂e per 500ml

The extra saving here comes from the fact that no chilling is required for the ale. It should be noted that in the home brewing calculations, emissions related to the equipment have not been included. Although these would be high, there are many ways to reduce their impact per bottle: either produce more beer or go second-hand.

7. CO_BREW carbon neutral beer: 0g CO₂e per 500ml

So how did our efforts compare with the ‘normal’ process? One of our biggest savings was through using 100% renewable energy provided by an external supplier. We also sourced locally; walking to the London Beer Lab in Brixton for our equipment and malt supplies and cycling to a farm in Sevenoaks to get the hops.

There were some emissions that we couldn’t account for, such as the intermediate processes related to ingredient production. So to offset those emissions we volunteered with Camden Green Gym to plant some holly bushes, each one taking in approximately 2kg of CO₂ per year.

What can we conclude about alcohol consumption, carbon dioxide emissions and consumer choice? First, as with food shopping, buy local. The impact of locally produced beer is significantly lower than the international ones, you are also supporting the local economy and get to try out a huge variety.

We also need to go back to the ale. There has been a dominance of lager in UK consumption, however with craft beers gaining popularity ale is making a comeback. This trend needs to continue if CO₂ emissions from alcohol consumption are to be brought down.

If you feel brave enough to brew your own beer, then you have even more choice to reduce the carbon footprint of your beer. You can reuse old beer bottles, switch your energy supplier to a renewable tariff, and source ingredients locally.

It’s clear that alternative options are available for reducing energy consumption in beer production and if consumers demand it from the producers then even more change can happen.

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The CO_BREW team will be offering free samples of their carbon neutral beer at Imperial Festival, on Imperial College London’s South Kensington Campus on Saturday 28-Sunday 29 April 2018. The team will be based in the Green Futures Zone (Saturday and Sunday) in the Great Hall.

The team is part of the Science and Solutions for a Changing Planet Doctoral Training Programme (SSCP DTP). Working on outreach projects within a Challenge Team is a fundamental part of the programme.