SynGas and the front-end problem of biofuels

April 25, 2012 |

Making good, affordable syngas from municipal solid waste to unlock 9 billion gallons of low-cost fuel? Covanta’s hot new gasification technology makes a big dent in the big challenge.

Just after mealtimes, in the hours after mail delivery, and occasionally when the world’s youth resolve certain unhygienic conditions prevalent in the science experiments known as teenage rooms, we as a species make that materials-or-waste decision known as tossing the garbage.

The MSW opportunity

Here in the US, “Americans generate about 4.3 pounds of municipal solid waste per person per day, or 260 million tons per year nationwide, of which a little over 130 million tons is biogenic” according to Auburn University professor David Bransby. At biofuels conversion rates of 70 gallons per ton, that represents just north of 9 billion gallons of cellulosic biofuels from it every year.

So, why is there not a rush to embrace technologies such as Enerkem, Terrabon, Coskata, Fulcrum Bioenergy or others that convert MSW into liquid fuels?

After all, the sins of waste generally condemn us, if you take Dante’s The Divine Comedy as your guide to the afterlife, to the third circle of Hell. There gluttons and sloths, with their sins of waste, are “forced to lie in a vile slush produced by ceaseless foul, icy rain.” Sounds remarkably like a gig working in an outdoor, dirty Murf (materials recovery facility, where people sort the trash by hand) on a remote island north of the Shetland Islands.

Rough job in the afterlife, eh? So, why are we not more focused on deploying those hot technologies that can save us from a bad fate here on Earth and, apparently, much worse in the hereafter?

The Syngas challenge

The bumps in the road are three. One, the technology is expensive over the generally small radius in which MSW can be profitably aggregated. Two, the technologies themselves are just reaching commercial demonstration scale. Three, they all could use a more affordable stream of optimized syngas.

Generally speaking, enzymatic technologies do not work well with MSW because of the variable mix of waste – basically, there could be anything in there, and magic bugs can be finicky.

So, one of the generally common features of the new generation of technologies coming forward is a front end gasification system. The gasifier produces what is known as a synthesis gas, composed of hydrogen and carbon monoxide, which is what you get when you heat up the biomass at temperatures of between 400 and 1500 degrees under optimal pressure conditions.

Syngas, as its commonly known, can be fermented into biofuels by magic microorganisms (such as the case with Coskata, INEOS Bio) or via catalytic technologies (as in the case of Enerkem, Terrabon or Fulcrum).

But that front end problem – getting the right syngas at the right price. Well, that’s been an area where a lot of companies have been working.

A leap forward from Covanta

Which is why it is big news this week that Covanta Energy Corporation announced at the North American Waste-to-Energy Conference that it has completed commercial demonstration testing on its 300 ton per day modular system, called CLEERGAS (Covanta Low Emissions Energy Recovery Gasification).  The technology has demonstrated the ability to gasify unprocessed post-recycled municipal solid waste (MSW) in a commercial setting, while reducing emissions and increasing energy efficiency.

Covanta’s gasification unit has been processing 350 tons per day of post-recycled municipal solid waste and has demonstrated superior reliability at 95+% availability. Municipal solid waste, which does not have to be pretreated, is subjected to high temperatures and reduced air on the gasification platform, where it undergoes a chemical reaction that creates a synthesis gas, or syngas.  The syngas is then combusted and processed through an established energy recovery system, followed by a state-of-the-art emissions control system.

“We are always working to stay on the cutting edge of technology to convert waste into clean energy,” said Anthony J. Orlando, Covanta’s president and chief executive officer.  “This new gasification technology is truly exciting. Communities interested in emerging technologies can now partner with Covanta’s industry leading team to assure successful project execution.”

“Successfully completing this commercial demonstration was a major step in developing new facilities capable of gasifying unprocessed post-recycled municipal waste,” said John Klett, executive vice president and chief technology officer. “Moving forward, our research and development efforts will continue to improve the syngas quality created in the gasification process.  One day, we anticipate this syngas will be utilized as a fuel in a combined cycle facility and potentially, in the production of liquid fuel.”

The Bottom Line

Now, Covanta’s technology works with post-recycled MSW, which means there is some processing that goes along with the technology. Well, sure, all bio-based technologies need to separate out the refrigerators and the plastics from the biogenic waste. Note that Covanta says that their system does not require pretreatment. That’s interesting. What that means in a commercial setting will be figured out over time.

Syngas, keep an eye on it. We have found more profitable, breakthrough ways to use it, than make it. We will see, over time, the extent to which Covanta has solved “the front end problem” – but the fact that they are releasing a 350-ton per day front end technology, well, that unit should support around 9 million gallons of renewable fuel. String together a couple of them, and you have a very nice size syngas platform for the new fermentation and catalytic technologies coming forward.

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