Pea soup algae ready for processing. Courtesy PNNL.

Scientists at the Pacific Northwest National Laboratory are claiming success in perfecting a method that can transform a pea-soupy solution of algae into crude oil by pressure cooking it for about 30 minutes. The process, called hydrothermal liquefaction, also works on other streams of organic matter, such as municipal sewage. And the crude oil created is lightweight and low in sulfur and can be “dropped in” to refineries that process fossil crudes.

“It’s a bit like using a pressure cooker, only the pressures and temperatures we use are much higher,” said researcher Douglas Elliott in a statement. “In a sense, we are duplicating the process in the Earth that converted algae into oil over the course of millions of years. We’re just doing it much, much faster.”

It only makes sense that scientists should be able to figure out how to turn algae into crude oil. After all, most of the oil that we drill out of the ground was formed by algae and other sea-borne flora that piled up at the bottom of the ocean over millenia, then got compacted and heated over eons and transformed into petroleum.

But figuring out how to do it economically is a challenge. A half-century ago researchers were growing algae on the roof of M.I.T. More recently, ExxonMobil raised the hopes of the algae-to-oil crowd in 2009 when it forged a research venture with Craig Venter’s Synthetic Genomics. If Venter (who was first to decode the human genome) could find or engineer an algae strain adept at naturally creating oils, Exxon would fund development to the tune of $600 million. Unfortunately Venter called off the quest a few years later. Algaes just weren’t oily enough to be commercially viable sources of crude.

A new generation of scientists says that’s hogwash. It’s not about finding a particularly oily algae, it’s about the process of turning any algae into oil, says Jim Oyler, CEO of Genifuel, who has worked closely with Douglas Elliott and other researchers at the PNNL for years and has licensed the technology. “We’ve proven it can be done.”.

A spate of articles in scholarly journals would seem to back him up. In the October issue of Algal Research: Biomass, Biofuels and Bioproducts (a journal published by Elsevier), you can read a couple of pieces by PNNL researchers including one titled “Process development for hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor.” Similar research has also been done at Ohio State and at Denmark’s Aarhus University and the University of Sydney in Australia

Most of these papers are full of geekspeak. Thankfully Oyler was patient enough to walk me through the process. You start with a source of algae mixed up with water. The ideal solution is 20% algae by weight. Then you send it, continuously, down a long tube that holds the algae at 660 degrees Fahrenheit and 3,000 psi for 30 minutes while stirring it. The time in this pressure cooker breaks down the algae (or other feedstock) and reforms it into oil.

Given 100 pounds of algae feedstock, the system will yield 53 pounds of “bio-oil” according to the PNNL studies. The oil is chemically very similar to light, sweet crude, with a complex mixture of light and heavy compounds, aromatics, phenolics, heterocyclics and alkanes in the C15 to C22 range.

The algae feedstock (front) and resulting “bio-crude” behind it. Courtesy PNNL.

Not all the organic matter gets turned into oil. It also yields a stream of carbon dioxide, hydrogen and oxygen, which can readily be turned into a stream of synthetic natural gas and burned to generate heat or electricity.

Also left over is water rich in the plant nutrients (nitrogen, phosphorous and potassium) previously present in the algae. This water can be sold back to the algae ponds as fertilizer.

“Not having to dry the algae is a big win in this process; that cuts the cost a great deal,” said Elliott in a statement. “Then there are bonuses, like being able to extract usable gas from the water and then recycle the remaining water and nutrients to help grow more algae, which further reduces costs.”

The researchers figure that at current algae prices of several hundred dollars a ton they could make algae-based fuel for the gasoline equivalent of less than $5 per gallon.

And algae’s only the most viable oil source. The same tricks can oil-ify all sorts of other organic wastes such as manure, municipal sewage, vegetable compost, even fish heads. Indeed, if the technology can be successfully scaled up to commercial size, says Oyler our stinky streams of human waste alone could provide the feedstock to meet 10% of our worldwide petroleum demand.

First they’ll need to expand their systems beyond the pilot scale — it will cost about $1 million to build a plant that can handle a ton of algae per day.

Yes, I’m skeptical too. But look at what we’ve done with corn in recent years. “Corn ethanol was an amazing accomplishment — to think that we make 15 billion gallons a year using only a small part of the plant,” says Oyler. “But we can all accept that corn is not the right path forward. You can grow algae anywhere and in any water. Compared to corn it’s not very finicky.”

A big criticism of corn ethanol over the years is that the process of growing it requires so much fertilizer, water and other energy inputs that by the time you’ve got it turned into ethanol you’ve lost energy not gained it. If an energy system has a negative net energy balance it is necessarily cannibalizing other energy sources.

This appears to be an inconvenient truth for algae as well. Most methods of cultivating it simply eat more energy than is contained in the algae.

The key will be in figuring out how to make massive quantities of algae cheap. Because then, explains Oyler, the rest will support itself: excluding the energy used in growing the algae (a huge caveat), the hydrothermal extraction process developed at PNNL can create about 9 units of energy for every unit used.

No doubt algae cultivation will improve. Until then the big hope for this technology now may be to pair it with a feedstock that cities otherwise have to pay to get rid of — like sewage. Oyler envisions a distributed system of hydrothermal liquefaction systems set up at regional sewage plants and a fleet of trucks that come to load up on crude oil once a week.

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