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Gene-Editing Algae Doubles Biofuel Output Potential – Another leap forward for sustainable biofuels

Scientists have created a strain of algae that produces twice as much lipid as its wild parent, a substance that can be processed into a biofuel.

By using a combination of gene editing tools, including the famed CRISPR-Cas9 technique, they identified and switched off genes that limited the production of lipids. Creating an alga that can pump out commercial amounts of sustainably obtained biofuels.

“We are focused on understanding how to maximize the efficiency of [lipid production] algae and at the same time maximise the amount of CO2 converted to lipids in the cells, which is the component processed into biodiesel,” Eric Moellering, lead researcher from company Synthetic Genomics Inc, told ScienceAlert.

Scientists have been trying to make the concept of using phototropic algae to produce bio-diesel a reality since the 1970s. In the past, it has been said that a new energy sector based on algal biofuels could guarantee transport fuel and food security far into the future.

Despite years of research, the best attempts until now have been limited to industrial strains which, although they have a really high lipid conversion rate, do not make sufficient amounts of lipid to make it commercially viable – limited by the fact it can’t grow very fast.

“Early in the [study] we posed the basic question, can we engineer an alga to produce more lipids while sustaining growth? This publication provides the proof of concept answer to that question is yes,” said Moellering.

In this new research, the team used CRISPR-Cas9, among other editing techniques, and identified 20 transition factors that regulated lipid production. By knocking out 18 of these, the team were able to double the lipid output compared to the non-modified algae.

But here’s the important bit: they were able to do so without stunting the alga’s growth rate. It grew at the same rate as the unmodified type.

The genetically modified algae produced up to 5 grams of lipid per metre per day, about twice as much as in the wild.

Another important metric is the total carbon to lipid conversion. This tells us how efficient the algae is at converting CO2 to lipids. In wild, unmodified alga the conversation rate is about 20 percent, but in the engineered alga it converted 40 to 55 percent of carbon to lipids.

It’s worth pointing out that this study was only performed at the laboratory scale but one of the researchers, Imad Ajjawi, also from Synthetic Genomics, told ScienceAlert that while they consider this a ‘proof of concept’, “they represent a significant milestone in establishing the foundation for a path that leads to eventual commercialisation of algal biofuels.”

Should this research graduate from the lab, bio-fuel production would no longer be reliant on sugars produced by land-grown crops like sugar cane and maize. Studies on the use of crop based biodiesel has shown that it could prove to be incredibly costly and damage our food security.

This research is another win for gene editing and the researchers have shown that new genetic editing tools sit at the centre of talking some of the world’s biggest problems.

“We have also developed the necessary genomic and genetic tools that will enable future breakthroughs to advance this field,” said Ajjawi.

The study has been published in Nature Biotechnology.

Fuel from sewage is the future – and it’s closer than you think

Technology converts human waste into bio-based fuel

Sludge from Metro Vancouver’s wastewater treatment plant has been dewatered prior to conversion to biocrude oil at Pacific Northwest National Laboratory. Courtesy of WE&RF

Sludge from Metro Vancouver’s wastewater treatment plant has been dewatered prior to conversion to biocrude oil at Pacific Northwest National Laboratory.
Courtesy of WE&RF

Biocrude oil, produced from wastewater treatment plant sludge, looks and performs virtually like fossil petroleum. Courtesy of WE&RF

Biocrude oil, produced from wastewater treatment plant sludge, looks and performs virtually like fossil petroleum.
Courtesy of WE&RF

RICHLAND, Wash. – It may sound like science fiction, but wastewater treatment plants across the United States may one day turn ordinary sewage into biocrude oil, thanks to new research at the Department of Energy’s Pacific Northwest national Laboratory.

The technology, hydrothermal liquefaction, mimics the geological conditions the Earth uses to create crude oil, using high pressure and temperature to achieve in minutes something that takes Mother Nature millions of years. The resulting material is similar to petroleum pumped out of the ground, with a small amount of water and oxygen mixed in. This biocrude can then be refined using conventional petroleum refining operations.

Wastewater treatment plants across the U.S. treat approximately 34 billion gallons of sewage every day. That amount could produce the equivalent of up to approximately 30 million barrels of oil per year. PNNL estimates that a single person could generate two to three gallons of biocrude per year.

Sewage, or more specifically sewage sludge, has long been viewed as a poor ingredient for producing biofuel because it’s too wet. The approach being studied by PNNL eliminates the need for drying required in a majority of current thermal technologies which historically has made wastewater to fuel conversion too energy intensive and expensive. HTL may also be used to make fuel from other types of wet organic feedstock, such as agricultural waste.

What we flush can be converted into a biocrude oil with properties very similar to fossil fuels. PNNL researchers have worked out a process that does not require that sewage be dried before transforming it under heat and pressure to biocrude. Metro Vancouver in Canada hopes to build a demonstration plant.

Using hydrothermal liquefaction, organic matter such as human waste can be broken down to simpler chemical compounds. The material is pressurized to 3,000 pounds per square inch — nearly one hundred times that of a car tire. Pressurized sludge then goes into a reactor system operating at about 660 degrees Fahrenheit. The heat and pressure cause the cells of the waste material to break down into different fractions — biocrude and an aqueous liquid phase.

“There is plenty of carbon in municipal waste water sludge and interestingly, there are also fats,” said Corinne Drennan, who is responsible for bioenergy technologies research at PNNL. “The fats or lipids appear to facilitate the conversion of other materials in the wastewater such as toilet paper, keep the sludge moving through the reactor, and produce a very high quality biocrude that, when refined, yields fuels such as gasoline, diesel and jet fuels.”

In addition to producing useful fuel, HTL could give local governments significant cost savings by virtually eliminating the need for sewage residuals processing, transport and disposal.

Simple and efficient

“The best thing about this process is how simple it is,” said Drennan. “The reactor is literally a hot, pressurized tube. We’ve really accelerated hydrothermal conversion technology over the last six years to create a continuous, and scalable process which allows the use of wet wastes like sewage sludge.”

An independent assessment for the Water Environment & Reuse Foundation calls HTL a highly disruptive technology that has potential for treating wastewater solids.

WE&RF investigators noted the process has high carbon conversion efficiency with nearly 60 percent of available carbon in primary sludge becoming bio-crude. The report calls for further demonstration, which may soon be in the works.

Demonstration Facility in the Works

PNNL has licensed its HTL technology to Utah-based Genifuel Corporation, which is now working with Metro Vancouver, a partnership of 23 local authorities in British Columbia, Canada, to build a demonstration plant.

“Metro Vancouver hopes to be the first wastewater treatment utility in North America to host hydrothermal liquefaction at one of its treatment plants,” said Darrell Mussatto, chair of Metro Vancouver’s Utilities Committee. “The pilot project will cost between $8 to $9 million (Canadian) with Metro Vancouver providing nearly one-half of the cost directly and the remaining balance subject to external funding.”

Once funding is in place, Metro Vancouver plans to move to the design phase in 2017, followed by equipment fabrication, with start-up occurring in 2018.

“If this emerging technology is a success, a future production facility could lead the way for Metro Vancouver’s wastewater operation to meet its sustainability objectives of zero net energy, zero odours and zero residuals,” Mussatto added.

Nothing left behind

In addition to the biocrude, the liquid phase can be treated with a catalyst to create other fuels and chemical products. A small amount of solid material is also generated, which contains important nutrients. For example, early efforts have demonstrated the ability to recover phosphorus, which can replace phosphorus ore used in fertilizer production.

Development of the HTL process was funded by DOE’s Bioenergy Technologies Office.