Ecosourcing raw carbon dioxideFood-grade CO₂ from waste gas

As a greenhouse gas, carbon dioxide does not have the best of reputations. But with all the bad press about harmful emissions and climate change, we often forget what an important role liquid carbon dioxide (LCO₂) plays in the food and beverages industry – freezing pizzas, making soft drinks sparkle and keeping packaged foods fresh. The CO₂ used in food and drinks is ultra-pure, safe and hardly falls under the harmful or unwanted emissions banner. It is, however, recovered from the unwanted off-gas streams emitted in particular by fertiliser and plastics factories as a result of chemical synthesis. As a by-product, it is captured, purified and then usually liquefied. “We currently obtain most of our liquid carbon dioxide from these sources,” reveals Matthew Onions, Product Manager at BOC, the UK’s largest gas supplier. “But this often results in bottlenecks, as production is not always stable.”

These bottlenecks have previously had a significant impact on BOC, since the company does not have its own LCO₂ production plant and has been totally dependent on suppliers. Now, though, an interesting opportunity has opened up in Manchester. There, an US food company produces large amounts of alcohol for use in food, beverages, pharmaceuticals and cosmetics. This involves fermenting renewable resources, a process which generates carbon dioxide as a by-product – and it is this gas stream that BOC will be using as feedstock from now on.

This is where Linde’s synergised strengths come into play. Experts from the company’s Gases and Engineering divisions are now working together to plan and construct a turnkey CO₂ purification and liquefaction plant for BOC in Manchester. This bundled know-how is highly unusual for projects of this scale – and a key advantage for BOC. This type of plant typically involves several different companies. Collaboration, communication and the workflow need to be coordinated and this increases project complexity and the risk of error. “By contrast, this interplay works to perfection across Linde, as has been demonstrated by many successful projects”, underlines Andreas Lodig, Sales Manager at Linde. “This way, BOC can look forward to a fully operational and customised plant – on time.” This synergised know-how also simplifies operation and maintenance as Linde’s operational experience is also constantly being channelled into plant engineering.

The majority of the process plant will be engineered remotely – in the form of large individual modules, which will then be hooked up on site. Linde subcontractors in Germany’s Dresden area will provide the gas purification and liquefaction process units, for instance. Meanwhile, a Turkish supplier was responsible for ensuring the precast storage tanks were fully insulated before loading them onto trucks and shipping them.

Once the various components engineered at the different sites are ready, they are transported by land and sea to the Manchester location. “This approach accelerates on-site assembly activities, substantially speeding up delivery overall. It also means the plant can be easily relocated at a future point in time – and that makes this modular design unique”, enthuses Andreas Lodig. BOC also sees the value of this approach: “At the end of the day, all we need to do is lay the foundations here in Manchester – and as soon as all the components are delivered, the entire plant will be up and running in just a few months”, confirms Matthew Onions. Once the facility goes on stream, it is designed to yield 100 tonnes of carbon dioxide per day at full capacity. That works out at 36,000 tonnes per year.

In addition to securing its own independent LCO₂ supply, BOC is particularly keen to maximise efficiencies. The aim is for every single CO₂ molecule generated by the alcoholic fermentation process to find its way into the storage tanks in future. Part of this efficiency drive includes seamless handover of plant operations to BOC. The Linde experts who will initially take the plant on stream will train the BOC team in parallel, ensuring no time or resources are wasted right from day one. As an industrial hub, Manchester is also home to many prospective buyers for the purified carbon dioxide. This will ensure short supply routes – whether the LCO₂ is ultimately used to flash-freeze fresh produce, create a modified atmosphere for meat packing or put the fizz into soft drinks.

Some of the prefabricated modules like the tank platforms are from Germany.