Fortunately, unfortunately: pathways and barriers to algae biofuels at scale

May 25, 2014 |

fortunatelyThink algae biofuels are real and near? Or, think it’s a promotional scheme for attracting finance for nutraceuticals and academic bridges-to-nowhere?

The barriers might be more, or less, daunting than you think. Let’s look at the recent data.

Fortunately, there’s been much progress on the most important metric in growing algae — the rate of biomass produced.

Back in 2012, Scripps Institute CEO Tony Haymet described the once-elusive target of 25 grams per square meter per day as “now, table stakes, we’ve finished the science on that.”

Unfortunately, that’s based on a lipid content of 25 percent, so it works out to 6.25 grams per square-meter per day for technologies that target production of algae oil.

Fortunately, that’s still a lot of algae biomass. It works out to 22.8 metric tons of algae oil, per hectare, per year, or 9.3 metric tons per acre. In a really good year, you might get get something like 400 pounds of soybean oil per acre per year, by contrast.

Unfortunately, ponds crash.

Fortunately, you can pyro the biomass, and get up to 4X the yield.

Unfortunately, some terrestrial crops get as much as 50 tons per acre per year.

Fortunately, not in full-scale trials, and in the real world the best anyone’s seen is around 10 tons per acre per year of terrestrial biomass.


Unfortunately, there’s the water problem. You either have to get the algae out of the water or the water out of the algae, and that uses energy. Given that algae concentrations max out at, say, 2%, you have to get rid of 50 gallons of water to get to 2 gallons of algae.

Fortunately, biofilms have limited water use by “dipping the algae” into water, keeping it moist but not distributed in low concentrations in a bioreactor or pond.

Unfortunately, you have to rotate the films in and out of the water — e.g. with a paddlewheel, and that chews up electricity.

Fortunately, you can generate power using waste heat from a co-located entity such as an ethanol plant.

Unfortunately, the CO2 is very expensive. At 2.1 pounds of CO2 for every pound of algae, and at a merchant CO2 cost of, say, $30 per metric ton, it’s $63 per ton for the algae inputs even before the cost of water is factored in, or any other cost of production. Why, you can buy complete waste biomass for around $55-$70 per ton in the Midwest, according to companies like POET Biomass. And you can get a tipping fee and free MSW.


Fortunately, you can get free CO2 from a co-located source, such as a power or ethanol plant (in addition to waste process heat or steam). Well, maybe not exactly free, but you can have them a venture partner, and you’ve gone a long ways towards mitigating their carbon and energizing your bottom line.

Unfortunately, the EPA has tossed in a potential roadblock, in its draft proposal that sets guidelines for new power plants to bury their CO2 underground. “Currently the draft does not permit utilities to recycle or reuse their emissions to meet their carbon reduction goals,” according to ABO board chair Margaret McCormick. “Regulators need to understand the opportunity they have to modify the proposal to better promote the use of algae and other utilization technologies. Reusing carbon emissions will be much more cost-effective than CCS, since the wide range of algal products can introduce revenue streams that underground storage cannot.”

Fortunately, you can still obtain CO2 from cement or ethanol plants.

Unfortunately, cement and ethanol plants are not always located in the right areas for optimized algae production, and its prohibitively expensive to transport CO2 over very long distances unless it is liquefied.

Fortunately, the EPA has not issued a final rule in this CO2 regulatory action.

Unfortunately, there’s been less attention paid by senior regulators to CO2 utliziation than capture and storage. “The EPA’s proposal hinders innovation by mandating the use of geologic sequestration and categorically prohibiting reuse technologies,” says McCormick. “In essence, the EPA is picking a “technology winner” instead of leaving it to the market to decide.

Fortunately, there are plenty of places to do projects outside of the EPA’s jurisdiction.


Unfortunately, it is yet another case of a government fostering a technology for domestic use, at huge expense to private investors and the public purse, and then chasing the technology overseas through myopic regulatory action by an unrelated agency.

Fortunately, companies like Algenol have partners outside of the US, for projects in Mexico or India, for example, and are focused on fuels. Their technology is based on directly producing ethanol as a secretion by their modified cyanobacteria, or pyrolyzing algae biomass to generate power and taregt fuels such as diesel or jet fuel.

Unfortunately, many critics are pointing to the huge demands for water that these technologies might place on local resources.

Fortunately, technologies like Sapphire Energy and Algenol utilize brackish or saline water, not suitable for consumption (and they utilize non-arable land). In Algenol’s case, they also don’t use a huge amount of water compared to other fuel or energy technologies. In total, 1 gallon of water, or less, for each gallon of fuel — compared to 2.0-2.5 gallons of water per gallon of gasoline.

Unfortunately, switching to a plug-in electric is no solution for eliminating water use for energy generation. The vast majority of power gen is via thermoelectric units using coal or gas to run steam-driven turbines. It’s a total of 201 billion gallons per day, according to the USGS, which cites an old figure from 2005 that might have improved.

Sapphire Energy Hot 50_5

Fortunately, we can use that figure to work out the gallons of water consumed by electricity generation.

Unfortunately, the numbers aren’t pretty. 42 quads of thermo electric energy production equates to 12.3 trillion Kwh, or about 6 gallons or water per KWh. Given that around 25 percent of power is lost in transmission, and your Nissan Leaf gets 100 miles for 34 Kwh, it takes around 272 gallons of water withdrawals to go 100 miles in an electric car. Using a gas-mileage figure of 25 MPG, you use something like 60 times as much water in an electric.

Fortunately, solar and wind are much, much better.

Unfortunately, both account for just a small percentage of power gen.

Fortunately, all that water is eventually recovered into the ecosystem. It’s not actually lost, it’s just used, and eventually returns as run-off or steam to the environment. That’s why it is called water withdrawal or water use, rather than water consumption.

Unfortunately, every industrial system has pretty much the same story. When we talk about how much water is consumed by agriculture, ultimately it is returned to the water system, either through evaporation, sinking into aquifers, or through the release of water when a food is harvested or consumed. So, water withdrawals are a meaningful topic even if the water is ultimately recycled — but generally only where there are limits on available water, especially where aquifers are low, snow-packs are smaller and rainfall is limited. Such as the US Southwest and California.

Fortunately, we can mitigate water withdrawals through yield improvement — doing more with less, or more with the same.

Unfortunately, some industrial and agricultural sectors are already relatively optimized for water usage — gains are there to be made, but there should be limits on any expectation of transformational changes.

Fortunately, there’s been much progress on the most important metric in growing algae — the rate of biomass produced — or yield, and there is still quite a lot of upside.

Or, did we start there?

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