Tyro co-founder Andrew Rothwell looking to raise money for carbon capture start up Hydrophis

Tyro Payments co-founder Andrew Rothwell is raising funds to progress trials by his new venture, which is testing tech to sequester carbon dioxide using desalination brine.

Tyro co-founder Andrew Rothwell is chief executive of start up Hydrophis.

Tyro Payments co-founder Andrew Rothwell has turned his sights to saving the planet, raising funds to progress trials by a new venture, Hydrophis, which is testing technology that can sequester carbon dioxide using desalination brine.

The company has completed a trial in collaboration with SA Water and construction giant Acciona, using brine from the Adelaide Desalination Plant.

The process – developed over the past 4½ years – involves capturing and dissolving CO2, then injecting it into saltwater brine where it reacts to make magnesium and calcium comp­ounds than can then be on-sold.

While the chemical reactions at play are not new, Mr Rothwell said the company had been refining the process and was now a leader in the field.

He said the company’s founder, Glenn Leighton, was inspired while reading about sea snakes – hence the company name – on a flight more than four years ago.

“He was also keenly interested in global warming and saw a paragraph about sea snake respiration and how that works,’’ Mr Rothwell said.

It turns out sea snakes use a process called cutaneous respiration to absorb oxygen from seawater and to diffuse CO2 out of their body via the skin.

“We thought if that process could be reversed, could that technology then be implemented at scale in the ocean to draw out carbonate and then use that carbonate in other industries?’’ Mr Rothwell said. He said a lot of research had already been done on the enzymes at play in the process, and while looking to strip CO2 out of ocean water was a valid line of inquiry with a view to moving much faster, the company sought to focus on more concentrated brines.

Hydrophis production manager Ambrose McGrath at the Adelaide desalination plant. Picture: Supplied

“We went straight to the desalination plants because they’re already taking sea water and producing fresh water and then pumping back the rest under the watchful eye of the EPA. We thought there’s some pretty valuable minerals in the brine that’s being pumped back into the ocean.

“You have the ordinary ones like the chlorides and sodium, but you also have calcium and magnesium and strontium and lithium and a bunch of other rare earths that are trace elements and are quite expensive to extract.

“But with some pretty standard chemistry, you can actually pull out the magnesium and the calcium.’’

Hydrophis contacted the Adelaide Desalination Plant’s operator, AdelaideAqua, and with the support of SA Water conducted a 12-week trial at the facility, processing 30 cubic metres of brine a day.

“We had some successes and some failures,’’ Mr Rothwell said. “The end result was that we were producing relatively high-quality magnesium hydroxide, which can be converted into magnesium carbonate, and we’re also producing a reasonable quality of calcium carbonate.’’

Mr Rothwell said the company’s projections were that the process would be “very profitable’’.

Hydrophis is now looking to raise “a few million” to fund the second pilot and provide working capital.

“And then we’re going to need to raise a lot more money like $50m-$60m to actually build the plant and get it operating,’’ Mr Rothwell said.

The company was hoping to have a full-scale plant operating by the end of 2026.

Mr Rothwell said it was invigorating to be involved in a company with a vision to address climate change.

“It wasn’t so much about the financial consideration, alth­ough that’s important,” he said.

“It was more about ‘what can I do to arrest global warming?’

“And this, to me, seemed like a pretty good vehicle to do that.’’