The former Dunedin man is an adjunct senior lecturer in soils at the University of Adelaide and, while in New Zealand on holiday, has been watching the aftermath of the ship stranding off Tauranga.
He believed oil could have been prevented from reaching the shore if a technology he patented was used.
The technology is based on waste clay used in the manufacture of cooking oils.
"They use about 1 million tonnes of clay each year to filter the oil. We are left with a waste that has the cooking oil, or animal fat, attached to it and it's actually thrown away [but] is just as effective [in oil absorption] as synthetically modified spill absorbers," Dr Churchman said.
The clay acted as a "carrier" for the cooking oil or animal fat, which attracted all kinds of oil products.
The clay was turned into a powder, which was put into porous pillow-shaped bags, "spillows", and sewn together into large floating blocks. The spillows were flexible and could "ride on the waves" in any weather, as well as being compostable.
"Soil will deal with oil, given a decent amount of time."
Other absorption methods included using wool and the tips of cotton plants.
Not using absorption technology for the Rena oil spill was "a shame", he said.
"The situation in Tauranga is absolutely classic for this type of technology ... and for a start, you had relatively calm seas. You could have put these things surrounding the boat."
The main aim should have been "to remove the oil before it gets to the shore" and there had been enough "warning" to implement an absorption approach.
The "favoured" oil spill clean-up option was dispersion, "but dispersion is adding another chemical" to the water.
On-water recovery was weather-dependent, and was largely ineffective, while booming was impossible in deep water, with strong currents and wave action.
"I think absorption is another option that should be looked at [and] has the big advantage of actually removing the oil.
"I don't have a financial interest, but I'd really like to see this thing solved. I think it's terrible when this stuff reaches the shore," Dr Churchman said.
