CO₂ sourced in-house gives independence

In summer 2022, many people learned the hard way just how crucial CO₂ is to the brewery. All over the world, the sector suffered from shortages and high prices, and some smaller breweries had to stop production at times. And yet, the problem could have been avoided, at least partially, because the brewing process (fermentation, to be precise) actually generates quite a lot of CO₂ – even more than the brewing and filling processes need. In order to tap just that potential, Steinecker offers proprietary CO₂ recovery systems.

To date, CO₂ recovery has been used almost exclusively by breweries with a large beer output, though there are definite differences, depending on the country and infrastructure concerned. Relatively small operations mostly outsource the gas, which is a by-product of fertiliser and ethanol manufacture. But supply chains had already been disrupted during the Covid-19 pandemic. And in response to soaring prices for energy, especially natural gas, in 2022, fertiliser producers in many regions cut back their energy-intensive manufacturing operations. That resulted in severe supply bottlenecks, which were further exacerbated by periods of hot weather and warmer summers as CO₂ is also used as a coolant and the basic ingredient for dry ice. Moreover, because hot summer days tend to make people reach for a refreshing drink, the beverage industry, too, needed larger amounts of CO₂. Against this background, more and more companies are considering the option of recovering the CO₂ generated in the fermentation tank. “In the past, producers might consider using CO₂ recovery for outputs of several hundred thousand hectolitres or more,” says Peter Gattermeyer, Head of Technology & Engineering at Steinecker. “In view of today’s prices and the resulting supply-chain independence, it definitely makes sense to check out the options for CO₂ recovery from an annual production of about one hundred thousand hectolitres upwards.”

Steinecker has offered CO₂ recovery systems since 2005, with more than 250 already up and running worldwide. The biggest of them planned so far, for an hourly throughput of four tons of raw gas, is currently being built in Spain. The recovery equipment installed at Ustersbacher in Bavaria saves the brewery up to 800 tons of CO₂ per year. These systems are part of Steinecker’s sustainability portfolio, says Peter Gattermeyer: “Our Brewnomic concept consists of three pillars: energy, water, and re-usable materials and substances. The latter include not only spent grains and yeast but also the CO₂ generated during fermentation.” The brewing specialists at Steinecker make sure their recovery solutions are tailored to a brewery’s individual needs, he emphasises: “We don’t sell stand-alone solutions. Instead, our systems are fully integrated into the brewery’s production process and energy concept.”

In view of today’s prices and the resulting supply-chain independence, it definitely makes sense to check out the options for CO₂ recovery from an annual production of about one hundred thousand hectolitres upwards. Erwin Hächl Peter GattermeyerHead of Technology & Engineering at Steinecker

The oxygen displacer

What exactly is CO₂ needed for in a brewery? The smallest part, a mere four to six grams per litre, is used for the beer itself. Without it, a beer won’t taste good, nor would it have bubbles or a head. But quite a bit more CO₂ is required to render the beer shelf-stable. To ensure a lengthy shelf life, the beer must not absorb any oxygen in the process steps after fermentation. CO₂ is ideally suited for removing oxygen from tanks, pipes, valves and bottles before the beer flows in. And the water used for clearing the pipes in the cold section or for pre-rinsing the filler must not contain any oxygen, either, and is therefore purified with CO₂. Many breweries need further amounts of CO₂ for making carbonated beverages like mineral water or fizzy drinks.

But breweries not only consume CO₂, they also generate quite an impressive amount of it in the fermentation tank where yeasts turn malt sugar into alcohol: roughly up to five kilograms of CO₂ per hectolitre of beer.

Recovery concept – the details

The starting point for CO₂ recovery is the fermentation tank’s exhaust air. The recovery process begins when fermentation is in full swing and the exhaust air contains at least 95 per cent CO₂:

First, the CO₂ collects in the buffer balloon.
Before the raw CO₂ gas is compressed, a rain of water washes out any unwanted constituents like sugar or beer residues.
For the next stage, Steinecker offers an additional aerosol separator as an optional extra, to make sure that all liquid residue is removed. That prevents deposits forming in the compressors, reduces wear and tear and substantially upgrades the compressors’ efficiency.
The following step requires meticulous care: Activated carbons are used to remove any remaining aroma compounds from the CO₂. That is because, depending on the type of beer (e.g. top-fermented) and the brewing process used (like high-gravity), various fermentation by-products are formed, including pungent-smelling, sulphurous substances. If the CO₂ recovered is intended for mineral water or dealcoholised beer, for example, it is absolutely essential that such unwanted aroma compounds be reliably and completely removed. That is why, in addition to its activated carbon filters, Steinecker also offers an optional filter for removing hydrogen sulphide. The system is specifically designed to meet all of the brewery’s needs, so as to make sure the quality of the CO₂ recovered is perfectly suited for the intended application.
The CO₂ is dried and once again purified, and then stripped of all the remaining oxygen by means of the countercurrent gas flow method. The 99.998 per cent pure CO₂ thus produced is cooled down to an extremely low temperature in a refrigeration system specifically designed for this purpose in order to liquefy it, after which it is stored in a well insulated accumulator tank.
An evaporator warms up the CO₂ to return it to gaseous state, so it can be passed into the piping leading to the consumers in the brewery.

06 - Image with Hotspots 39482 — Integrating a Steinecker CO₂ recovery system in a brewery’s operations

Whatever the quality of the raw gas, our filters will remove all unwanted aroma compounds from the recovered CO₂, to make sure it can be used for any application, even for highly taste-sensitive products like mineral water. Erwin Hächl Peter GattermeyerHead of Technology & Engineering at Steinecker

Highly flexible in all respects

Quite a lot of energy is needed for the CO₂ recovery process, mainly for liquefaction and evaporation. To this end, Steinecker examines the energy concept of the entire brewery, says Peter Gattermeyer: “A brewery has many sources of thermal or cooling energy. So you no longer need any primary energy from the heat supply system in order to evaporate the CO₂. We take a close look to find out how the CO₂ recovery system best fits into the production process and into the energy circuit, and dimension its capacities for a perfect match.” The coolant needed in a brewery’s various cooling processes, such as glycol, is run in a closed loop. It absorbs a sufficient amount of thermal energy at the beer production’s chillers in order to return the CO₂ to gaseous state. And conversely, as heat is released during CO₂ evaporation, the glycol’s temperature is reduced so much that it can again be used as a coolant, hence easing the load on the brewery’s main refrigeration system. This exchange of thermal and cooling energy not only provides savings in primary thermal energy, it also significantly helps cut power consumption for refrigeration. On request, Steinecker can also produce a refrigeration system for CO₂ liquefaction that uses the eco-friendly coolant CO₂.

Flexibility is a key priority not only in Steinecker’s specification of cooling and heating capacities to make sure these are perfectly tailored to a company’s overall energy concept. The CO₂ recovery system itself is not a one-piece entity, either, but consists of individual units that can be installed in a flexible configuration. That makes is relatively easy to fit it into the space available in each case. Flexibility is also provided in terms of the methods offered for treating the CO₂ recovered, as Peter Gattermeyer explains: “Whatever the quality of the raw gas, we offer suitable filter concepts for any possible application, right through to use for highly taste-sensitive products like mineral water.”

Self-sufficiency is no vision, it can be done

Can CO₂ recovery render a brewery completely self-sufficient? “If it makes only beer, yes,” says Peter Gattermeyer. “Roughly 2.5 kilograms of CO₂ can currently be recovered per hectolitre of beer. Of that, 500 grams are bound in the beer itself, and the rest is enough to supply all of the brewing and filling processes. In most cases, CO₂ sourced in-house will be insufficient only if the brewery also produces further carbonated beverages.” So that offers plenty of development potential if the ambitious sustainability targets set for Steinecker’s product portfolio are to be reached in this field as well.