By Romy Udanga
Producing oil from algae grown in sewage ponds is close to commercialisation – it can also be used to extract oil from wood.
The February 22 Christchurch earthquake disrupted the production trials of the SCWR MK2, the second upscale version of the super critical water reactor used to extract crude oil from algae, but they are now in full blast, says Solray Energy’s Chris Bathurst.
“We were just getting into production phase when the earthquake hit. The reactor plant was not harmed but the waterways of the algae growth pond were badly damaged because of the faults running through the wastewater ponds where we are,” Mr Bathurst says.
Mr Bathurst is a director at Solvent Rescue Ltd, which has a significant stake in Solray.
Solray is in partnership with National Institute of Water and Atmospheric Research (NIWA) and the Christchurch City Council.
NIWA designed and operate the high-rate pond which treat the wastewater and grow algae. The algae is harvested by gravity sedimentation and is then converted by reactor to Texas-crude equivalent crude oil.
The SCWR technology uses very high temperature water to disrupt the carbohydrate molecules of organic materials, remove the oxygen atoms, and create the range of hydrocarbon molecules commonly found in fossil crude oil.
It is considered to be the same process used by nature to create the fossil crude oil deposits that have supported human society for the last 100 years.
While the ability of high temperature water at around supercritical levels to break down organics has been known for over 40 years, the difficulties of reliability and energy efficiency have proved a barrier to commercialisation until now.
The MK2 is 12 times bigger than the original trial reactor MK1, and can handle five hectares of high-rate algae sewage ponds. It is designed to extract up to two barrels of crude oil daily from 1000kg of algal solids.
“We’ve got this plant and we are running to get good operational data as the basis for the next scale up – the MK3. With the data, we can then go to a commercial operator,” Mr Bathurst says.
The MK3 is expected to be 20 times bigger than the MK2, with an output of about 40 barrels per day.
Christchurch alone has 220 hectares of sewage ponds, a potential source of up to 90 barrels of crude per day.
If all the sewage plants in the country were successfully put under the algae-to-oil scheme, Mr Bathurst estimates the crude oil produced will be equivalent to 15 percent of what New Zealand needs.
Solray aims to find other sources of algae or other feedstock that can be converted to oil once commercial production begins.
“We have tested running minced marine algae or seaweed or kelp through the reactor and that worked as well. That means we don’t need to rely on fresh water. We are also looking at other feed stock not just algae,” he says
Harvesting algae from sewage ponds is more economical than building algae ponds that are not connected to sewage plants because there is value in treating water – and in taking the phosphate byproduct of the extraction process.
But Mr Bathurst says the most exciting aspect is turning wood to oil, which Solvent Rescue, one of the partners in Solray, has discovered.
“We used the same reactor but the wood was prepared differently. The process at this point is a secret, but we have already done it,” Mr Bathurst says.