Keeping their cool

When Greg Hutchings and his team at SELECT Member firm Lotus Electrical were faced with the problem of how to power a plant producing freezing dry ice, they rose to the challenge and created a smart solution that’s already proving to be a big success

The UK’s supply of CO2 has been precarious for some time. It’s a vital gas that’s used across industry in everything from food storage to fizzy drinks and keeping nuclear power plants cool.

It’s also the raw ingredient used by Dry Ice Scotland, which, as its name suggests, makes dry ice and supplies it to large pharmaceutical and frozen food delivery firms across the UK – including COVID-19 vaccine maker Pfizer which needs sub-zero temperatures to safely store the life-saving drug.

Keen to have a guaranteed supply of CO2, director Richard Nimmons and his colleagues at Dry Ice Scotland – including his brother Ed – spotted the opportunity to set up their own production site next to an existing anaerobic digestion plant in Dumfries and Galloway.

But there was a problem – it would not be possible to draw enough power for both plants from the existing site supply.

Fortunately, SELECT Member firm Lotus Electrical, which is based in the same area, was able to come up with the answer.

Prioritised

Greg Hutchings, managing director of Lotus, explained: “As well as sourcing sufficient power, one of the tasks we were set was to make sure that the existing anaerobic digestion plant should always be prioritised.

“We carried out a lot of research, looking at options such as solar power and a larger grid connection. Many of these we had to discount because of costs or other reasons. We came up with a solution that the equipment that Richard would use in his CO2 plant must be able to sustain a hard trip if necessary.”

Greg and his team designed a control system and Richard secured a guarantee that the fixtures and fittings he bought could be switched off at the drop of a hat should the power demand exceed the connection agreement, thus potentially compromising the site’s power. Greg added: “Complicating matters, the existing site was running almost entirely off-grid through a combined heat and power (CHP) plant. As people may know, CHP plants don’t like their electricity being switched off very quickly.”

To avoid that possibility, the team utilised a 200 kilowatt bank of heaters and a tripping system that would help the CHP slow down in a controlled fashion.

Getting connected

As well as using a huge amount of power, for safety reasons the dry ice plant had to be 170 metres away from the anaerobic digestion plant.

“We had a large infrastructure job to do to allow those massive cables to be connected,” said Greg. “The same goes for the control system, which required many multicore cables so that each side could speak to one another.”

Separately, the Lotus team had to take into account potential welfare issues at Dry Ice Scotland should the power drop out. The installation had to be carefully designed so that the essential plant – including lighting and fire alarm circuits – could keep running, thereby not compromising on health and safety. The system has now been in place for six months and, according to Greg, the emergency fallback has only been activated once, when an engineer servicing the CHP generation switched off while the dry ice plant was in full production. “Our system coped with it well,” said Greg, “and the reset was seamless.” This project is the latest unusual challenge faced by Lotus, which has a special interest in tasks that bring environmental benefits. We told two years ago how the firm had made a successful move into the renewables market.

Greg explained: “These are the sort of jobs we come across regularly. We’ve become known as problem solvers. It keeps my grey matter ticking over and does the same for my team.

“Being based in Dumfries, the big difficulty we have is recruitment. We have talented people, but not enough of them. I’m always on the lookout for skilled engineers.”

Skilled tradespeople might be in short supply, but the work done by Lotus and Dry Ice Scotland is helping to increase the country’s stock of an essential raw material.

Self-supporting plant takes pressure off taxpayer

The UK experienced a severe shortage of CO2 in September last year.

As well as creating some worrying headlines, the crisis forced the UK Government to step in and start paying a US firm whose site in Billingham, County Durham, supplies around 60% of the country’s needs.

Richard Nimmons, of Dry Ice Scotland, explained: “Until now, the way the UK has sourced feedstock CO2 is by taking it as a byproduct of the burning of hydrocarbons.

“That’s what happens at Billingham, where the main purpose is to manufacture ammonia.

“However, increasing gas prices have made that operation unprofitable.

“Therefore, the UK Government has had to subsidise continuing production so that we could continue to get CO2.

Richard believes that costly arrangement for the UK taxpayer illustrates why it’s vital to have other sources of CO2, like the one Dry Ice Scotland has put in place.

“We have created Scotland’s only source of CO2 and, in particular, food grade CO2,” he said. “We take the gas from an anaerobic digestion point, which makes it commercially sustainable, self-supportive, and environmentally friendly.

“What’s more, we have a wide range of important clients, including the drugs company, Pfizer.

“Among other benefits, this new plant means we’re able to play our part in guaranteeing the supply of essential COVID-19 vaccines.”

The challenge facing Lotus Electrical Services

The task: Add a new dry ice plant with a 780kw load to an existing set up at a anaerobic digestion gas production site. This existing site has a base load of 740kw served by a 1000kva connect agreement from the DNO and a 600kw CHP generator. At all times the anaerobic digestion plant must be prioritised.

The solution: Gain a deep understanding of the site and diversity possibilities and introduce a tripping system that allows the dry ice plant to power down if the supply from the CHP unit is interrupted.