Researchers create biocrude from wet algae in one minute

Engineering researchers at Michigan University believe the process is capable of transforming 65 per cent of green marine micro-alga from the genus Nannochloropsis into biocrude.

‘We’re trying to mimic the process in nature that forms crude oil with marine organisms,’ said Phil Savage, an Arthur F Thurnau professor and a professor of chemical engineering at the university.

The findings will be presented today at the 2012 American Institute of Chemical Engineers Annual Meeting in Pittsburgh.

To make the biocrude, Savage and Julia Faeth, a doctoral student in Savage’s lab, filled a steel pipe connector with 1.5ml of wet algae, capped it and placed it in sand heated at 1,100ºF.

The small volume ensured that the algae was heated through, but with only a minute to warm up, the algae’s temperature will have just reached the 550ºF mark before the team removed the reactor.

Previously, Savage and his team heated the algae for times ranging from 10 to 90 minutes. They are said to have seen their best results, with about half of the algae converted to biocrude, after treating it for 10 to 40 minutes at 570ºF.

Without further experimentation, Savage and Faeth will not be able to clarify why the one-minute method produces better results.

‘My guess is that the reactions that produce biocrude are actually much faster than previously thought,’ Savage said.

Faeth suggested that the fast heating might boost the biocrude by keeping unwanted reactions at bay.

‘For example, the biocrude might decompose into substances that dissolve in water, and the fast heating rates might discourage that reaction,’ she said.

Smaller reactors

The team pointed out in a statement that shorter reaction times mean that the reactors don’t have to be as large.

‘By reducing the reactor volume, the cost of building a biocrude production plant also decreases,’ Faeth said, although both she and Savage cautioned that they cannot be certain if the new method is faster and cheaper until the process is further developed.

Current commercial makers of algae-based fuel first dry the algae and then extract the natural oil, which costs more than $20 (£12) per gallon.

‘Companies know that that approach is not economical, so they are looking at approaches for using wet algae, as are we,’ Savage said.

The wet method is also said to break down proteins and carbohydrates. The minute method did this so successfully that the oil contained about 90 per cent of the energy in the original algae.

‘That result is near the upper bound of what is possible,’ Savage said.

Before biocrude can be fed into the existing refinery system for petroleum, it needs pre-refining to remove extra oxygen and nitrogen. The Savage lab is developing better methods for this leg of biofuel production, breaking the record with a biocrude that was 97 per cent carbon and hydrogen earlier this year.

Once producing biofuel from algae is economical, researchers estimate that an area the size of New Mexico could provide enough oil to match current US petroleum consumption.