In recent months, Kaua’i County has attempted to deal with its various solid-waste management problems in a variety of ways.
As was widely reported, the county caused state-owned Conservation District land near Wailua to be used as a dump for abandoned vehicles, starting in early 1996. (It won Board of Land and Natural Resources’ approval to continue this use for 12 more months on March 14, 1997.)
More recently, the county is proposing to increase the height of its Kekaha landfill to an elevation of 60 feet – approximately double the height limit specified in the environmental impact statement prepared for the facility. (The comment period on the draft environmental assessment prepared for this expired on April 7. The county expects a finding of no significant impact to be issued, in which case no further permitting appears needed.)
Finally, Kaua’i Electric has signed an agreement to purchase energy from a company that plans to produce electricity from trash, using a plasma-arc technology. Under the agreement, up to 10 megawatts a day of power is to be delivered for 20 years, starting no later than July 1, 2002.
The company, Coxwell Energy, proposes to build its facility at Port Allen, adjacent to Kaua’i Electric’s main power plant. (Coxwell’s plans were first reported in the June 1996 issue of Environment Hawai’i) Coxwell must still win a bid from the County of Kaua’i to collect the trash it needs to fuel its facility.
Ray Chuan, a Kaua’i resident and consultant with RTK Associates, a firm based in California, has analyzed various aspects of the Coxwell proposal. We reprint his analysis below:
Having watched with interest press reports about the magical system that would solve Kaua’i’s solid waste disposal problem, I became quite intrigued first with the scientific aspects of the proposed Coxwell system and then the fiscal, environmental and operational aspects of this seeming panacea. Aside from drawing on my own experience with basic thermodynamics and power-plant emission control and monitoring, I have also consulted the following persons and agencies:
Rod Yama of the State Department of Health Clean Air Branch; the Office of Environmental Quality Control; the Solid Waste branch of the Kaua’i County Public Works Department; Amy Esaki of the county Attorney’s Office; Wally Rezentes of the county Finance Department; Denny Polosky of Kaua’i Electric; and Brent Stockwell of Coxwell Energy. Out of this, I have come up with some thoughts about the Coxwell project.
Basic Science
The numbers don’t add up. If we were to consider the amount of heat energy in 200 tons per day of good-quality coal (at least 14,000 British thermal units per pound) that was burned efficiently in a power plant (that is, with at least a 30 percent efficiency in converting heat to electric energy), we would be able to produce 20.4 megawatts of electricity, which is pretty close to the output that Coxwell has claimed for its plant. However, solid waste is not good quality coal. I would estimate that our solid waste has probably no more than 5,000 Btu/lb of heat energy. If that is so, the most electric energy that can be generated with 200 tons per day of the stuff would be about 7 megawatts, which would not be enough to provide both the power needed for the plasma arc used to burn the trash and a surplus of 10 megawatts that Coxwell says it will sell to Kaua’i Electric.
Remember, you can’t get something out of nothing. Even if the Coxwell plant could produce synthetic gas to run a turbine, the energy in the gas still has to come out of the heat content of the feed material.
There’s another kicker in the numbers game here. The amount of solid waste the county collects – which would be equal to the amount the county would presumably provide to Coxwell if Coxwell succeeds in its efforts to build the plant – is not 200 tons per day, but closer to 100 tons. Kaua’i does produce more than 100 tons per day of trash, but only this amount is collected by the county. The remainder is hauled off by private commercial collectors who would not be covered by the county’s contract with Coxwell.
Finances
Stockwell has informed me that the plant will cost $52 million to build. Coxwell would like the county to issue revenue bonds, but the county’s capacity to issue such bonds is only about $3.5 million a year – less than 7 percent of the capital cost. Stockwell indicated he would seek additional bonds from the state and, failing that, would seek some sort of tax free bonds on the private market.
All this suggests that the financing for the plant is still highly speculative at this point, with the developer proposing to put little of its own capital at risk.
Environmental Issues
The OEQC has informed me that any kind of financial obligation incurred by the county or state, including the issuance of revenue bonds, would trigger Chapter 343 of Hawai’i Revised Statutes. Judging from my conversation with Stockwell, he is not aware of this.
But he is aware of the need for a permit from the Department of Health Clean Air Branch. So even if the plant is financed entirely with private funds it will still have to meet clean-air standards. The problem here will be dioxins.
Since our typical solid waste contains large amounts of plastics, dioxins will be inevitably produced when this waste is burned, especially if the combustion temperature is very high – as the Japanese found out 15 to 20 years ago when they thought they had solved the problem of getting rid of plastics with high-temperature incinerators. Note here that an incinerator by any other name is still an incinerator, the use of an electric arc as a heat source notwithstanding.
Coxwell has stated that at the temperatures it proposes to use 15,000 degrees Fahrenheit – everything breaks down into molecules or even atoms. This is true, but these atoms don’t stay at that temperature very long. As soon as they leave the arc, they start recombining in all sorts of complicated chemical ways.
Presumably some of the chemistry can be manipulated to yield synthesis gas, as Coxwell proposes. But what about the dioxins? There is one known method of inhibiting the formation of dioxins. The rights to this method – DIT, for dioxin inhibition technology – are held by Dow Chemical. It is not easily accomplished and requires sophisticated control and monitoring. DIT is not used frequently in the United States, where large-scale incinerators are as rare as new nuclear power plants. The only place DIT is in wide use is Japan, mainly because the country has thousands of incinerators and strict standards for dioxin emissions.
Another serious environmental problem arises with the storage of the feed stock. There is no way to maintain a steady flow of solid waste from the dispersed sources around the island to the incinerator, so storage must be provided. The good thing about a landfill is that as soon as the waste arrives, it is buried, leaving little exposed. The storage area needed for the Coxwell plant could be quite substantial, especially considering that the plant will have down times. Since the type of plant envisioned by Coxwell does not now exist -Kaua’i’s will be the first one there will assuredly be plenty of down time, during which waste continues to flow in.
It is not unreasonable to contemplate a storage area being large enough to hold a month’s accumulation of waste. How to store and prevent serious environmental, health, and sanitation problems during this time is a daunting challenge. The obvious solution is to have a standby landfill. This, however, brings us back to Square One.
Contracting Uncertain ties
How will the county evaluate the financial status of Coxwell, both in terms of its bid for collecting solid waste and in considering whether to issue revenue bonds for the plant? Presumably, the county is ready to go out for bids now, but can Coxwell famish sufficient credible assurance that it can perform on time so that the county can decide what to do – or not do – about a new landfill?
In view of the technical uncertainties, can Coxwell even offer a credible start date for collecting the waste? Where does that leave the county with respect to alternate schemes for waste disposal. especially in view of the long lead time required by any alternative? A conventional performance bond will not buy the county anything because, for one thing, by the time it is established beyond question that Coxwell cannot perform, it will be too late to switch to any alternate scheme, no matter how generous the performance bond is (assuming also that it is collectible).
Conclusion
It is clear that none of the many questions raised above has been answered satisfactorily. Even if Coxwell had full private financing today, how can it prove it will deliver on time and that it can get the required air permit and any other DOH permits that may be needed?
I don’t know how the financial and legal questions will be resolved. But I can tell you what won’t work as far as emissions control is concerned. The almost universal solution offered is a scrubber, which is basically a big water spray in the exhaust stack. But a scrubber will always produce a haze, consisting of very small particles left over from the evaporation of the water spray which invariably contain dissolved and suspended material (unless one uses fresh distilled water to form the spray) These haze particles – 50 of them lined up end to end are no wider than a human hair – are too small to be caught by any practical method.
The concept offered by Coxwell is superficially appealing. But the reality is that the concept has never been carried out in a working system. Kaua’i cannot afford to be the guinea pig for proving the practicability of an unproven idea.
Volume 7, Number 12 June 1997
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