Ze-gen's Waste to Energy

Last week we had the chance to talk with Bill Davis, the President of Ze-gen. This three year old company is possibly the furthest along in the race to develop technology to turn waste into fuel – eliminating the need for landfills in the bargain.

Each year, the United States produces about 100 million tons of construction debris, and about 220 million tons of municipal solid waste. Currently nearly all of this waste goes into landfills.


Pouring the foundation at Ze-gen’s pilot
plant in New Bedford, Massachusetts.


What Ze-gen has done in New Bedford, Massachusetts, is set up a demonstration plant to accept up to ten tons per day of construction and demolition residual material. The material is used as the feed stock in a gasification process that utilizes molton bath technology.

The result of this process, which Davis emphasized is not the same as incineration, are “syngas” (primarily carbon monoxide and hydrogen) which can be used to generate electricity, and slag that can be used for construction aggregate.

The reason the New Bedford location was chosen is because it is next to an existing “transfer station” where construction and demolition waste is shredded prior to transfer to landfills. This shredding process yields a mixture of 90% wood, 5% residual metal, and 5% silica (with small amounts of other material) that looks like bark mulch. Having this materials prep already done allows the feedstock to be more easily tested in the 2,700 degree (fahrenheit) furnace.

Davis said that right now they are perfecting the design of the tubes being used to feed the material into the molton bath. This should take a few more months. After settling on a design to move materials from the shredder to the furnace, the next step will be to go into continuous operation and do gas analysis. As Davis put it, “we are looking at the quality and consistency and BTU level and contaminents that are in the stream. That will inform the engineering for the gas cleanup system.”

When asked about possible difficulties prepping construction debris and municipal solid waste, Davis noted “it appears wastestreams over time are surprisingly consistent,” and “we have some proprietary technology to drive the variability out of the feedstock.”

Developing technology to turn municipal solid waste and construction & demolition residue into electricity and construction aggregate is not easy. Davis estimates it will be sometime around 2010 or 2011 before they will have a full scale facility accepting waste and producing electricity. In order for the capital expense to be justified by the revenues over the lifetime of the plant, not only “tipping fees” (payments to accept and process waste streams – replacing the fees charged by landfill operators) are necessary, but also revenues from sales of electricity.

Evidently the prospect of municipalities all over the USA eventually adopting this technology, however, has attracted top tier investment in Ze-gen from Flagship Ventures and Vantage Point Partners – with the most recent round of financing concluded in the Summer of 2007.

And how much energy could converting 100 million tons of construction and demolition residue along with 220 million tons of municipal solid waste generate per year? Based on the generally accepted 2.11 kilowatt-hours of recoverable net energy per pound of waste, the USA could generate 154,000 megawatt-years of electricity per year, which equates to 4.61 quadrillion BTU’s. With the USA currently consuming around 100 quadrillion BTU’s of energy per year, reprocessing 100% of these waste streams would offset about 5% of the energy currently consumed in the United States, along with eliminating the need for landfills.


8 Responses to “Ze-gen's Waste to Energy”
  1. Jeff says:

    How exactly are landfills eliminated when this gasification process only deals with the construction debris?
    Also – author quotes ‘furthest along’ in the race from waste to fuel…These guys self admitted that they haven’t even started the gasification process…let alone the feed mechanism or boiler/turbine/generator phase.
    This article is just an ad for a company that is ‘losing’ the race.

  2. Ed Ring says:

    Jeff – the assumption is that eventually construction debris and municipal solid waste will go into this stream. As we note in the post, there are still several obstacles to proving this technology (1) ensuring the waste stream has a consistent amount of water content, (2) developing and deploying equipment to shred the feedstock into a consistent “mulch,” (3) processing the syngas and removing impurities so it becomes a viable and clean source of power to generate electricity, and finally (4) doing all this and ending up with a plant design that an investor can finance based on a viable internal rate of return from tipping fees and electricity sales.

    Who said this is going to be easy?

    If there is a company who is further along in this process than Ze-gen, please let us know.

  3. Marc says:

    PlascoEnergy Group (http://www.plascoenergygroup.com) is much farther along than ZeGen in the process of waste-to-energy conversion to syngas and electrical power.

    They have a demonstration plant operating on 85TPD in Ottawa, Canada, and signed MOU’s with 2 Canadian cities and 1 Spanish city. They have also completed an equity round of $54M, with another $115M committed for next year, and were one of only 3 companies invited by the Canadian government to the recent conference on climate change held in Bali.

    Plasco’s system converts MSW to syngas, cleans the syngas, makes electricity, and does so at less than 1/3 the pollution of the stiffest North American air regs, with nearly twice the efficiency of other waste-to-energy processes. It has been in development over 20 years, and has nearly 20 patents protecting the technology. Final conversion products are vitrified slag (non-leaching), electricity, salt, and sulfur. Only about 1% of the original MSW goes to landfill.

    While ZeGen’s technology is interesting because of the huge heat reservoir contained in the molten metal, there will be a significant partial pressure of metal in the gas above the melt that must be treated with the Syngas, and a significant amount of slag that must be tapped and float off the bath, just as it would in a blast furnace. The economics of the process and the effect on the environment of the metal in the gas and the slag still must be proven.

    Marc Bacon, P. Eng.

  4. Wouldn’t it be great if this technology were the answer to cleaning up the continent size mass of trash that is whirling about in the Pacific Ocean. Talk about horror stories! All one has to do it show this to the human race so that they can see what their carelessness produces. maybe then they would clean up their act.

  5. How does the Ze-gen technology work? Is it based off of induction melting of the metal components of the waste?

    Also, the article mentioned waste into fuel. Which type of fuel? F-T diesel? Or did they just mean waste-to-syngas?

    I agree with Marc that there are many other gasification companies further along than Ze-gen. Thermoselect, Hitachi/Westinghouse Plasma, and perhaps Plasco in the next few months. (Just to name a few of the many companies with plants in Asia & Europe.)

    Did the article mean ‘further along in the US’ ?

    I wish Ze-gen the best of luck in demonstrating their technology and proving the economics of waste-to-energy or waste-to-liquid fuels.

    By the way, I saw an add for “Natural Capitalism” along the side of this website. For anybody reading this blog, check out that book. It’s a great read and full of optimism for the idea of environmental capitalism.

  6. John Brigham says:

    Range Fuels has yet another technology. The feedstock is gently heated to about 450F to react the internal oxygen. It is then blasted up to 1500 with steam which decomposes the feedstock to syngas. The inorganic material is left as an ash rather than slag and can be recycled as fertilizer or whatever. And they are looking toward catalytically converting the syngas to ethanol.

    Range Fuels, of Broomfield Colorado, is using $200M in venture capitol money to build a plant in Georgia. It is designed to run on wood chips, plentiful in that part of North America.

    Their technology appears simpler and requires less energy input. At any rate, the implications of this technology are immense. . http://www.rangefuels.com

  7. KELLYCO says:

    I wish luck to ZeGen.
    They will also have patent hurdles to deal with.
    The meir mixing of waste streams for an effecient blend is already patented .

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