How much does my home brew actually cost to make?

Despite being a brewer now by profession, I still brew beer at home because it’s fun and it helps me get to know different ingredients better. But how much does it actually cost.

First there is the cost of ingredients. I aim to produce 10 litres of beer each time. The amount of malt I use for this varies depending on the sort of beer I’m going for but my last brew used about 2.15kg of malt. My homebrew shop charges €2.21 for this. I use 4g of gypsum at €9/kg, and 2g of calcium chloride at €8/kg to harden my brewing water (5.2c). I use 1g brewtan in the mash and 1g in the boil at €34/kg (6.8c). I use 1g of kettle finings at 5c/g (5c). I use 1pk of yeast at around €3/pk. And I use about 50g of hops at €40/kg (€2). Altogether that comes to €7.38

Now let us calculate the costs of the process. I give my time for free. I also charge nothing for the “quality control” that comes later!

We pay 15.87 cents + VAT at 13.5% = €0.1801245 per kWh for electricity. I will neglect the standing charge because we pay that whether or not I brew beer at home.

We pay 4.61 cents + VAT at 13.5% = €0.0523235 per kWh for gas. likewise neglecting standing charge.

I draw hot water from the tap at 55˚C. The temperature of our incoming water feed is 16˚C at this time of year so our condensing boiler has done the first part of heating for me. I don’t know how efficient my condensing boiler is, but according to wikipedia a typical rating would be 90%.

I used 5.375 litres of water to mash in (2.5:1 liquor to grist ratio). Assuming 1 litre weighs 1kg and that water has a specific heat capacity of 4.2kJ/kgC, then my condensing boiler has to put in (55-16)x 5.375 x 4.2 /90% = 978.25 kJ or 0.2717361kWh work = €0.014

 

I heat my mash water on the gas stove. According to this link, stove top heating is about 70% efficient. The water is heated from 55˚C to a strike water temperature of 75˚C for mashing in. (5.375kg x 4.2kJ/kgC x 20˚C /0.7% = 645kJ =€0.0094

I boil the jug three times and add it to my mashtun and swish it around to heat it up before adding the hardened brewing water. 1.5 litres x 3, heated from 16˚C to 100˚C in an electric kettle which is 100% efficient is: 4.5kg x 4.2kJ/kgC x 84˚C = 1587.6kJ =0.441kWh = €0.08.

I aim for 15 litres of wort in the kettle, and I assume 1 litre of water will be absorbed by the malt, so I need 15 + 2.15 = 17.15 litres of water altogether and I’ve already heated 5.375 litres so I need to heat another 11.775 from 16˚C first to 55˚C in the condensing boiler and then to 80˚C on the stove. This comes to 3909.3kJ = €0.057.

During my last brew, I boiled the 15litres of wort down to 9 litres in my electric boiler. This was a bit over kill. I was aiming for a post-boil volume of 12 litres. Here I’m trying to find a compromise between giving the hops enough time to isomerise, which needs a minimum of a 30 minute boil, and getting enough evaporation to drive off smelly sulphur vapours. The latent heat of evaporation of steam is 2260kJ/kgC. I’m going to assume my electric brew kettle is 100% efficient too because I keep the elements clean and they are submerged directly in the wort. The 15 litres were collected at a temperature of 70˚C so I first had to heat them up to boiling point. So I used 6kg steam x 2260kJ/kgC + 15kg wort x 4.2kJ/kgC x 30C = 15450kJ = 4.29kWh = €0.77

We don’t pay for water, but Dot doesn’t like me wasting water so I freeze plastic drink bottles full of water and add them to the wort to cool it down. I use about a kg of this. The latent heat of fusion for water is 333.55kJ/kgC so 333.55kJ. (Plus at this time of year, my incoming water temperature is so high (16˚C) that it would take forever to cool the wort down to 18˚C. Heat exchangers work best when the difference in temperature is great. I still do use a heat exchanger to cool my wort, but I don’t try to cool it all the way to pitching temperature this way). I’m not sure how efficient my freezer is. If it was 100% efficient, creating 1kg ice from 1 kg 16˚C tap water would be 1kg x 4.2kJ/kgC x 16˚C + 333.55 = 400.75kJ, or €0.02.

I don’t use any temperature control on my fermentations because I don’t have the set up for that yet. So fermentation is free!

 

TOTAL COST for 10L of beer = €8.33

How could I save money? Although the electric boil only costs 77c, it’s easily the biggest process cost. Gas is much cheaper than electricity, so I should swap to doing all my heating with gas, even though it is less efficient. I would need a bigger pot for the stove to be able to boil sufficient quantities without it spilling over and making a mess. I could put the hops in a separate pot on the stove and boil them in 2kg of water for an hour and add it back in at the end. This would give me better hop utilisation because tap water has a higher pH than wort. It would also help my precipitate protein in the boil, because hops are a natural antifoam (no hops means more foaming). But I’m not sure the result would be worth the extra trouble, because the kind of hop bitterness produced by boiling hops at a higher pH is supposed to be harsh and astringent. Still, I could perhaps reduce the amount of bittering hops I needed by about half. And I’d save on the costs of boiling because I’d not need to boil the full mass of wort for as long. Maybe I’d only require 55-60% of the heating requirements and be able to meet some of that requirement using a cheaper form of fuel. It would also allow me to shorten the brewday somewhat, because I could overlap the boiling of the hops with the mashing, so when it came to the proper boil later it would be a shorter time.

The raw material costs are the biggest component by far, notably yeast. I can’t avoid this cost, because one of the things I am particularly interested in is trying out lots of different yeast strains. But being able to drop the cost of yeast would reduce costs significantly.

Also, hops are an expensive component. I can’t really avoid this cost either despite the fact that I actually have some hops growing in the back yard, because as before experimenting with different hop varieties is part of the point.

 

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