Burning Man, Burning Microbe: Biofuels beyond biomass

October 12, 2012 |

Can you have a biofuel without processing an intermediate biomass?

Can post-biomass technologies revolutionize fuel and chemical production?

Fuels and chemicals can make people mighty uneasy, when you think about them.

With fossil fuels, the issues include the uneven distribution of resources and wealth, national security, price and price volatility, and carbon emissions. So along came first-generation biofuels.

Then, along came second-generation biofuels. Using new technologies, non-traditional crops and forest, animal, crop or municipal residues, using land that had fallen out of traditional production – or, in the case of residues, using no additional net land at all.

But there were still issues of an uneven distribution of resources and wealth (e.g. land-grabbing in the hot bioenergy zones), and issues of price and price volatility. Above all, price – the technologies have struggled to beat fossil fuels, or first-gen biofuels, on price.

Which brings us to third-generation biofuels. They are, as a class, post-biomass – and their basis as a biofuel lies not in processing an organic substrate but in the fact that the processing mechanism itself is an organism.

Are they biofuels? We think so – even if they are post-biomass. They do what organisms have done for eons to make biomass in the first place: convert lifeless CO2, sunlight and water and nutrients into a new material.

Today, there are four classes of technologies that directly create a fuel without first making a biomass.

Post-biomass sugar fermentation

In this class of technologies, the organism directly produces a fuel from a sugar and, if the sugar is made via synthetic biology rather than extracted from biomass, it is a post-biomass path. The key step is the creation of a post-biomass sugar – from there, a host of fermentation technologies can make a fuel or chemical. Though some of them, like the technology at Amyris, Solazyme and LS9 is highly versatile and, to an extent, programmable for a wide variety of target fuels, chemicals and biobased products and intermediates.

Post-biomass sugar, that’s what Proterro is working on. Proterro’s microorganism synthesizes sucrose from sunlight, CO2, nutrients and water. They are in the process of training the microorganism to make it fast enough to be a viable technology at industrial scale. If it works – that a post-biomass substrate from which other magic bugs can produce a huge array of fuels and chemicals. Without digging them up from the ground, or using land or sea to grow biomass.

Gas fermentation

In this class of technologies, the microorganism ferments synthesis gas – or syngas, a combination of hydrogen and carbon monoxide – into an alcohol. The syngas can be made by gasifying biomass – but it can also be made directly from, say, methane emissions or natural gas.

There are five technologies that, broadly speaking, have this capability today. Coskata, INEOS Bio, LanzaTech, Siluria and, as a part of its hybrid liquid-gas fermentation process, Zeachem. In the case of Coskata, they are proposing to ferment, primarily, natgas for some time to come, while INEOS Bio has gone the route of gasifying second-gen feedstocks such as MSW and yard waste. LanzaTech has gone the route of acquiring its gases from partnerships with steel companies – that are, in turn, seeking to reduce the blast furnace’s carbon footprint as well as monetize a stream of waste gases. With Siluria’s biocatalysts, metals and metal oxide crystals are grown on biological templates in a technique developed in Angela Belcher’s lab at MIT -allowing unique ways to manipulate the surface of catalysts as they enable the chemical reaction necessary to transform methane.

Solar fuels

In this class of technologies, the microorganism directly produces a target alcohol or alkane – using sunlight, CO2, water and nutrients – and then secretes it into a chamber from which it can be extracted from the liquid medium in which the microorganism lives.

There are two technologies around today that have this broad capability. There’s Algenol and there’s Joule. In Algenol’s case, the microorganism is a strain of algae and it secretes ethanol, which is separated via evaporation from the medium and then collected and purified. In the case of Joule, the microorganism secretes either alcohol, diesel fuel, or other target chemicals inside a capsule unit.

In the case of solar fuels, the yields per acre can be exotic and transformative. Whereas first-gen fuels yield somewhere between 50 and 600 gallons of fuel per acre, Algenol is reaching 7,000 gallons of ethanol per acre in real-world trials, while Joule is reporting ethanol yields as high as 15,000 gallons per acre per year.

Plus, they use saline or brackish water instead of depleting fresh-water.

Electrofuels

In this class of technologies, they are not only post-biomass, they are post-sunlight. Generally speaking, they operate much the same as the solar fuels – excepting that the microorganisms draw energy from electricity instead of from sunlight. The underlying current can, of course, be supplied by a variety of post-biomass sources, including hydro, wind, solar or even natural gas.

This is an experimental class of technologies, for which R&D is being supported by ARPA-E in a multi-year research program that originated in 2010.

Most recently in electrofuels, a team of researchers at UWIsconsin-Madison demonstrated they can use a electricity-and-water based fuel cell to convert acetone into isopropanol, a chemical compound with a wide variety of pharmaceutical and industrial applications, including as a gasoline additive.

The bottom line

Biofuels do not have to be made from biomass, or use arable land, or fresh water. People who cling to those dogmas in their critique of biofuels are just poorly informed, or have an axe to grind.

The extent to which these technologies will dominate, or be viable, in the future is uncertain – they have their own journeys towards commercialization and scale, just as second-gen technologies do. But that is a function of cost, and to some extent is a function of oil prices and the appetite of a given society to accelerate its weaning off the oil dope.

But consider the comparative footprint of, say, corn ethanol vs solar ethanol. Today, the US produces around 13 billion gallons of ethanol from around 24 million (effective) acres. The same land footprint (but, using non-arable land and saline water) could yield up to 360 billion gallons of solar ethanol, using the Joule data that we have – or, around 190 billion gallons of drop-in diesel fuel.

Or, to put it another way, you could produce 240 billion gallons of solar ethanol or 125 billion gallons of solar diesel using the land footprint of the Mojave Desert. That’s twice what the US consumes in diesel fuel – using captured CO2, non-potable water and some nutrients.

Burning Man or Burning Microbe?

Or, in a frenzy of radical self-reliance, you could produce massive amounts of fuel in the Nevada’s Black Rock Desert – which would provide a whole new spin on the Burning Man festival held each year in the Black Rock. Though, in this case, it would probably be Burning Microbe.

That’s apt, for mankind has to kill biomass to make energy for our bodies – while plants can synthesize energy out of lifeless materiel. What could be more biobased than something that makes life from lifelessness, instead of the other way around?

And, in Joule’s case, they say they can produce it for 40 percent less than the cost of a barrel of oil, today, from which refiners have to add cost to make fossil-based diesel fuels. Again, it is early days for the technology – so we are still in the “if, then” phase of analysis. It’s not quite yet time to break out the bubbly.

But, what an “if, then”.

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