New Biofuel Leans On Slothy Algae With Promiscuous Enzyme
At first glance, the common green microalgae Botryococcus braunii looks like a horrible biofuel candidate. It grows so slowly that it takes a week to accomplish what other species can do in a matter of hours. However, B. braunii has intrigued biofuel researchers for decades, and now a team at Texas A&M has unlocked the genetic mystery behind one of its secrets, a “promiscuous” enzyme that could enable it to spit out gasoline, kerosene, diesel and other fuels.
Biofuel: Not Dead Yet!
Food, land, and water resource issues have been bedeviling the global biofuel industry, but fuel from plants does offer the prospect of carbon neutral fuel production for gasoline, diesel, and jet fuel. After the corn biofuel debacle during the Bush Administration, researchers have been focusing on the oil production capabilities of algae and microalgae, as a non-food crop that could be grown in areas where water scarcity is not an issue.
Biofuel production also offers the potential for some intriguing piggyback operations, such as water desalination and food production, which have the potential to math out as carbon negative.
Here in the US, the Energy Department chopped funding for algae biofuel research in 1995, but it did fold its microbiology efforts into a new national collaboration called the Joint Genome Institute, and by 2010, volatility in the oil market provided the agency with a rationale to pump more dollars directly back into the field.
With an assist from other federal agencies (namely, the US Navy and National Science Foundation), the Energy Department continues to be all over algae biofuel, despite the fossil oil market crash. In February the National Renewable Energy Laboratory modeled a new “whole body” process that could help keep algae biofuel costs competitive against the floundering petroleum market.
In the most recent development, last February, the agency issued the third in a three-year series of multi-million dollar funding rounds for algae biofuel.
Why Botryococcus braunii?
The Joint Genome Institute has been focusing like a laser on Botryococcus braunii. Here’s the official line on the micro-algae’s attractiveness to researchers:
…Botryococcus braunii is found worldwide, but most notably in oil and coal shale deposits. Approximately 40 percent of the B. braunii cells is made up of hydrocarbons, and the oil produced can be easily converted and used for vehicle and jet fuels with more than 90 percent efficiency. B. braunii has been studied for several decades, not just for its potential as a source of biofuel, but for its ability to sequester carbon…
Did you catch that part about oil and coal shale? Oh, the irony!
The Texas A&M AgriLife Biofuel Research
That brings us to the new biofuel study, conducted by researchers at the Texas A&M AgriLife program. While mapping the biochemical pathway that enables B. braunii to produce an oil called lycopadiene, the team nailed down the enzyme that initiates the oil production process, encoded in a “very interesting” gene called lycopaoctaene synthase (LOS), as described by lead researcher Dr. Tim Devarenne:
A closer look at the LOS enzyme revealed that the enzyme is “promiscuous” in that it is capable of mixing several different substances, or substrates, to make different products.
As explained by the research team, promiscuity is a common trait among enzymes, but it is unusual to find this particular combination of hydrocarbon and enzyme. By mixing different substrates, LOS produces longer, more desirable carbon molecules of 35 and 40 carbons long:
…that’s not only different from other enzymes that are similar to LOS, but it’s important because most enzymes like LOS only use a 15-carbon substrate. In terms of fuel, it’s better to start with a higher carbon number molecule.
Don’t expect to fill ‘er up with B. braunii any time soon, though. This is just the “very first” step in the algae fuel production pathway, so there is a lot of gene mapping to be done.
Other challenges involve finding an efficient host organism to express the genes in order to maximize fuel production.
Finding a faster-growing host would also be helpful. According to the research team, B. braunii takes a full week to double its cells, a trick that other algae can accomplish in about six hours.
That seems like a tough row to hoe, but gasoline prices in the US have already begun inching up this year and the global climate is not getting any colder, so the prospects look good for more funding for algae biofuel research.
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Image (cropped): via Texas A&M AgriLife by Kathleen Phillips.
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My old microprinted OED recognizes slothful, slothfully, and even slothly, but not slothy, though it’s a nice coinage.
If you lived inside oil shale rock you wouldn’t reproduce fast either.
Now we know just how lethal is the pollution to be endured during the transition to RE, some of the desperate urgency can hopefully be ameliorated by biofuels. What I fear, however, is that, even though the overall effect is neutral, the combustion will still produce local pollution. How true is this?
It can be true.
A lot will depend on how and where the fuel is burned though. Large stationary facilities (power stations, district heating units, industrial process heat boilers) can be equipped with bulky treatment equipment that reduces local air pollution to zero. Literally.
Heavy vehicles like buses and trucks also have very efficient pollution mitigation systems, to the point where a modern diesel truck emits less pollutants in real world conditions than a much smaller diesel passenger car.
If you are going to be fuelling passenger cars or small domestic stoves with diesel-like biofuels, the picture isn’t as pretty. Those are too cheap and too small for truly effective emissions control systems (hence dieselgate).
Thanks;not much cheer for car-clogged city centres then. Taxis and vans would make a big contribution, though.
Why would you want to run cars on algae biofuel anyway?
Electricity is taking over that market, and even if you want to stick to biofuels, ethanol (second generation) scores better than algae-derived biodiesel on every environmental indicator and is a lot cheaper.
Algae fuel would mainly be used for situations where neither electricity or ethanol is a viable drop-in replacement (i.e. aviation biofuel). Its main competitor is biobutanol, which can be made from cheaper feedstocks but is more expensive to produce.
I was just looking at possible stop-gap ways of making the transition but it looks as though there isn’t anything practical.
There is. Ethanol is cheap, the manufacturing process is mature and it can be used in conventional gasoline engines. While it releases some harmful pollutants, it is vastly better than diesel and even somewhat better than gasoline.
It got a bad rep due to its supposed competition with food crops and poor environmental performance, but that is a gross simplification.
Biofuel production is often classified in three generations:
– Gen 1: biofuels from sugary/starchy foodstuffs, which is easy but not always sustainable or ethical.
– Gen 2: biofuels from plant waste (corn stover, straw, black liquor etc) or from crops growing on marginal land not used for food (i.e. Miscanthus or willow).
– Gen 3: biofuels not derived from plants, i.e. from algae or through biochemical CO2-fixing processes.
From the first generation, sugarcane ethanol (widely used in Brazil) has a considerable environmental advantage over fossil fuels and is actually on par with electricity on most grids for carbon emissions. Corn ethanol and biodiesel are a disaster, on the other hand.
All second generation biofuels score well environmentally, and most are affordable. Generation 3 does about as well environmentally but loses heavily on cost.
So, if old diesel users like me doing 3-4000 miles annually fork out a bit more for the biodiesel option we needn’t feel too guilty soldiering on for the time being?
Depends. Biodiesel (which is completely different from ethanol, just to be clear!) is a much better choice than fossil fuels in terms of carbon emissions, but almost as bad as diesel in terms of air pollution.
If you live in a city, get rid of the diesel car. If you mostly drive in a rural area, the air pollution problem is limited anyway and it might make sense to keep your car.
Thanks, I’ll keep it a while as I live at the seaside in Spain which is still in the dark ages on RE and EVs sadly.
It also depends on what you burn. You can make Oxymethylenether (OME) from Methanol which burns a lot cleaner than Diesel.
And on how you burn it. In a hybrid truck while range driving or in the city.
Thanks. Are there any drawbacks ?
It’s an expensive conversion of an expensive feedstock.
Companies making the stuff (i.e. Exxon Mobil, Sasol and Shell) have been bragging about how it burns cleanly and is a drop-in fuel for diesel engines for decades.
However, it has the same problem hydrogen has: if made from a renewable feedstock, it’s incredibly expensive. If it’s made from fossil fuels, it’s an environmental disaster.
“Biofuel production also offers the potential for some intriguing piggyback operations, such as water desalination and food production,”
I didn’t see a relation.
Some of the algae’s nutrients (notably nitrogen) could be provided through wastewater, in which case the algae would help in water treatment. This concept is already widely used in the form of algae treatment ponds. How you get to water desalination is not clear to me either.
What is left of algae (or plants) after extracting oil is a dry, protein rich cake that is excellent animal feed and thus an indirect food source.
Thanks, in the past I have bought Spirulina at the health food store
to mix with my power shakes.
F*’ing hippy 😉
*Pedant mode on*
Spirulina are not algae, they’re bacteria. Producers often market them as algae because bacteria have a bad rep among consumers, but it’s a misnomer.
Biofuels, from algae,? all for it, anything to stop farmers wasting food crops to produce biofuel, but biofuel should only be used where the EV alternative is presently unavailable, IE aviation.
Algae biofuel could be useful for jet fuel