Ze-gen Ramps Up its Waste Gasification Process: Lessons from a Clean-Energy Startup

9/24/09Follow @wroush

Xconomy has been around for 27 months now, long enough to watch quite a few of our fellow Boston-area startups expand, deal with serious challenges, and start to get their technologies out into the world. One of them is Ze-gen, a waste gasification company that I first visited in August 2007. This week I got a chance to take a second tour of the company’s demonstration plant in New Bedford, MA, an hour south of Boston, and to get an update from president and CEO Bill Davis, who founded Ze-gen in 2004.

The tour and the interview turned into a mini-education in the hurdles facing startups in the bustling, bruising cleantech sector. So far Ze-gen has been clearing those hurdles, and if all goes according to plan, the company will have its first commercial gasification plant up and running by the second quarter of 2011. That’s about a year behind the schedule the company originally laid out back in 2004. But considering the state of the economy lately, a year’s slippage isn’t all that bad.

I thought I would try to sum up some of the insights from Ze-gen’s experience in digest form, which I’ve done below. But first, a quick refresher on Ze-gen’s business and technology. The company is developing an industrial-scale system in which organic waste material such as construction and demolition debris (called “C&D,” and composed mostly of wood) is dropped into a vat of molten metal. Under tremendous heat, the waste instantly breaks down into elemental gases—mainly a mix of hydrogen and carbon monoxide that’s known as “syngas.” The syngas can in turn be combusted to run electrical turbines or boilers, or turned into liquid biodiesel fuel. (Unlike incineration, the gasification process produces no carbon dioxide emissions; the name Ze-gen stands for zero-emissions generation.)

The feed hopper in Ze-gen's demonstration plant deposits feedstock (shredded wood waste) onto a conveyor.

The feed hopper in Ze-gen's demonstration plant deposits feedstock (shredded wood waste) onto a conveyor.

Ze-gen’s prototype system takes up a building the size of a large barn—and the commercial version will be even larger. The system was in full, hot, noisy swing during my visit. As the photos scattered through this article illustrate, the process is fairly simple, with shredded C&D waste falling from a hopper onto a conveyor and up an elevator, then falling back down into a furnace half-filled with a molten copper bath that’s maintained at about 2,400 to 2,700 degrees Fahrenheit. Syngas from the furnace flows out into a combustor—where the boiler or turbine would go, in a commercial plant—and leftover gases are scrubbed and vented.

Feedstock eventually drops into the gasification furnace, which is half-filled with molten copper.

Feedstock eventually drops into the gasification furnace, which is half-filled with molten copper.

Lately, Ze-gen has been running the plant for about 12 hours a day, gathering data on its syngas production efficiency using various types of feedstock, and at various bath temperatures. Getting to this point has been a five-year slog. “Any pre-revenue company, in my view, is frustrating, or should be frustrating, because it takes other people’s money in order to get a technology to the point where it’s producing,” says Davis. “For the first few years, at our demonstration plant, it was a lot of episodic testing. You’re not really ready for commercial deployment until you can prove that you can run continuously.” But Ze-gen now has the permits it needs to run 24/7, and as soon as the company can hire enough qualified staff, the gasifier will be running around the clock. “It’s actually quite satisfying, because I can come down here on any given day without making any special plans, and the plant is running,” Davis says.

The company has more than doubled in size since my last visit: it now has 27 staffers, 11 of them in an adminstrative and engineering office in Boston and the rest at the plant, which is conveniently located on the grounds of a solid waste sorting facility in New Bedford. All of that growth takes money, of course, and earlier this year, the company augmented a $4.5 million Series A round from 2007 with a much larger, $25 million round. The main funders include … Next Page »

Wade Roush is Chief Correspondent and Editor At Large at Xconomy. You can subscribe to his Google Group or e-mail him at wroush@xconomy.com. Follow @wroush

Single Page Currently on Page: 1 2 3 4

By posting a comment, you agree to our terms and conditions.

  • http://xconomy.com Bill Ghormley

    Wade,

    Great article — leads to a question:
    Does the energy expended to keep the copper at 2,400-2,700 F, plus the energy required to feed and operate the gassifier, end up being larger than the synfuel energy produced?

  • Pingback: Xconomy's Roush on Ze-gen | Rethink.

  • Wade Roush

    Good question, Bill. The short answer is no — the synfuel contains much more energy than is required to keep the gasifier up to temperature. In a commercial plant (the way Bill Davis explained it to me) part of the synfuel generated, about 30 percent, would be cycled back into running the furnace. But the way I understand it, once the furnace is hot, a large part of the energy that keeps the metal in its molten state is actually generated by the gasification process itself, which is exothermic.

  • http://www.ze-gen.com Cara

    Hi Bill,

    That is a great question! Ze-gen’s liquid metal gasification system processes carbon-rich waste material, like wood waste, and converts those materials to usable renewable fuel in the form of synags. When applied at commercial scale, the process is exothermic, meaning that the chemical conversion process will produce more total energy than is required to operate the facility, enough to keep the bath at optimal operating temperature as well as to produce syngas to make steam and/or electricity. Currently, Ze-gen is operating its pilot-scale test facility that is designed to test efficiency and operability. At this sub-optimal scale, the pilot plant does require incremental natural gas to keep the gasifier’s liquid metal bath at optimal temperature, using more input energy than the plant outputs, however at full scale, this will not be the case.

  • Tom

    Clearly this is the same technology that MMT worked on for many person-years in Fall River. That is a matter of record that cannot be disputed (c.f. USDOE technical reports – and others). The issue there, as noted, is expiration of patents – some have expired, some have not.

    I don’t think MMT/QC would go away quickly – so it is reasonable to surmise that the Sept. 18th settlement and the pending “new partner” announcement are closely related.

  • ghali hasan

    good job/ would like more info on cost a for new a unit thank’s

  • John

    What about a toxic release that injured several NB workers at the landfill. Was this related? Is the state investigating, or are they killing it because of Ian Bowles past ties to Zegen?

  • http://www.ze-gen.com/rethink Cara

    Hi John,
    The toxic release was not related to Ze-gen’s pilot facility. It occurred at the facility next door.

  • rob

    Hi, would this the process and the plant support the burning of tyres and copper,chrome,arsenic coated organic material ,if so what additional emmissions and impact do you foresee this employing on the environment?

  • http://www.ze-gen.com/rethink Cara

    Hi Rob,

    We are currently testing materials now in New Bedford. The emissions will vary by material, but we expect to put in full-scale emissions control on the commercial facility. The commercial facility will comply with any and all federal, state and local regulations regarding air emissions. You can check out more information about our plant by watching our video: http://ze-gen.com/rethink/transforming-the-way-we-view-waste

  • Ani

    would this work in municipal waste with high moisture content and low calorific value,where things like paper plastic etc have already been picked buy rag pickers ,what is the minimum BTU required ?

  • http://ze-gen.com/rethink/ Cara

    Hi Ani,

    An ideal feedstock for Ze-gen’s technology contains a relatively low moisture content and high caloric value, which is generally higher than municipal solid waste. However, we expect to blend feedstock materials that range in moisture content and BTU value, in order balance these materials with feedstocks that have more ideal moisture and energy contents.

  • Roy

    What happens to the small amounts of toxic chemicals extracted, such as arsenic? Is it captured and disposed of separately, or diluted in the syngas?

  • Tom

    The issues and questions raised by Ani and now Roy are not new, they have been addressed in the earlier MMT work, including patents and government research reports (public stuff). Maybe Cara(?) can provide these for reference, now with the settlement final as reported.

  • http://ze-gen.com/rethink/ Cara

    Hi Roy,

    Thanks for your question. The toxic chemicals are captured in the plant’s emissions control system (including a baghouse). The contents of the baghouse are periodically hauled off site by a licensed contractor.

  • rob

    hi Cara

    thank you fror your reply,could you please forward your contact details as i would like to discuss ze-gens plant and application capabilities.
    regards
    rob

  • Roy

    Thanks for your replies, Tom and Cara. I would be interested in reading some of the MMT research reports and public documents. If either of you could point me to the references, I’d appreciate it. Cara, I’d like your contact info as well. Thanks, Roy.

  • http://ze-gen.com/rethink/ Cara

    Hi Rob and Roy,
    Please feel free to contact me at cgiudice(at) ze-gen(dot)com

  • shaik

    hai Cara.. can u give me more info ….i like to develop your technology in my country,can we use wood waste only? also the cost ?

  • Cara

    Hi Shaik,

    Please visit our website: http://www.ze-gen.com for more information. Also, feel free to email me at cgiudice (at) ze-gen (dot) com.