[bouldercouncilhotline] Hotline: Waste-to-Energy

[kohls at bouldercolorado.gov]

Sender: Appelbaum, Matt

Colleagues,

As you know from our study session on waste management, I've been doing a bit of research on waste-to-energy (WTE), where the part of the wastestream headed for the landfill is instead used to generate electricity (and heat).  While this is obviously quite a long-shot approach for Boulder, I'm delighted that we gave staff the go-ahead to at least take a very, very preliminary look at the WTE concept.  I've provided staff with my NREL contact, and will also give them contact info for some folks at the Montgomery County WTE facility and waste management division.  Montgomery County (MC), Maryland, has a very aggressive recycling/composting program, shares many environmental concerns with Boulder, and has been operating a WTE facility for many years, and is likely to construct another one soon.

I thought it might be useful if I provided some of the notes I took while talking with the NREL and MC staff, who were all extremely helpful.  Obviously these were rather high-level discussions, and any confusion or misrepresentation is entirely my fault alone, as are the comments on several of the items.


 *   Montgomery County has mandatory recycling for some products.  Their overall recycling (including composting, I think, but perhaps not) rate is 44%, and they believe they are capturing 70% or more of recyclables from single family residential and commercial, but only 33% from multi-family.
 *   MC also collects hazardous waste, and has a comprehensive program for waste reduction.
 *   C&D recycling is done by a private company, and that is apparently not working so well.  It is not, however, a priority for the county.
 *   Food waste recycling is not mandatory and is about 10 - 12% of the waste stream.
 *   Not surprisingly, the main WTE facility costs more to run than it generates in revenue (by about $7M/year, I think), and that doesn't include the capital costs.
 *   Their WTE facilities use advanced combustion (mass burn).  There are 86 such WTE facilities in the US, and a large number in Europe.
 *   Emerging technologies (like gasification) are not yet viable for municipal waste (but might work for construction or industrial waste).  MC's recent study for a new WTE plant determined that advanced combustion is currently the best approach.  (Note that LA County currently has RFPs out for WTE plants using emerging technologies; whether they will get any bids that are acceptable isn't yet clear.)
 *   WTE facilities are very expensive and typically need to be fairly large, on the order of 400,000 tons/year (on a site that's 13 - 15 acres).  However, they have a much smaller facility as well and it works fine, but it isn't as cost-effective.  The WTE authority actually isn't a part of MC's government but a quasi-governmental agency that works with several counties.
 *   Their recent study took a comprehensive look at the total 30-year costs of building and running a WTE facility vs. landfilling the waste -- and determined that WTE was less expensive.  Of course, this is heavily dependent on numerous local characteristics: cost of landfilling, building/land costs, electricity revenue (deregulated in Maryland), etc.
 *   They also studied GHG emissions, using an EPA model, finding that WTE was better than landfilling.  This too is heavily dependent on local conditions (and whether the model is accurate!), such as the alternative source of electricity.
 *   A huge additional savings (not counted in the analysis, I think) was that their sewage treatment plant did not need to spend $20M+ on digesters, since they simply send the sewage sludge to the WTE and burn it!
 *   At the WTE, they screen only for radioactive materials, and don't worry about toxics.  They burn only household/commercial waste, not industrial or C&D waste.
 *   Their WTEs meet/exceed all EPA air quality standards.  They do continuous air monitoring, and even put hourly results on their web site.
 *   Of course, ash is produced by the WTE, amounting to 30% by weight or 10% by volume (more important) of the waste input.  This is used as a daily landfill cover and used in road construction.
 *   As they do in Sweden, it would obviously be significantly more effective (both in terms of costs and GHG reduction) if the waste heat generated by the WTE were used.  In Sweden, they have district heating, something hard to find here (although I think the CU main campus essentially used that when they ran their on-campus power plant).  Users of generated steam or hot water would, in theory, need to be within 3 miles of the WTE.
 *   Obviously the WTE needs to be located somewhere that provides good access for the waste stream, and in MC their main unit is on a rail line.  (I'd note, at the great risk of being skewered, that a WTE at the Xcel Valmont site has rail access, an electric substation, and is close enough to our wastewater treatment plant to access the sludge.)
 *   NREL is currently exploring emerging technologies for WTE and believes that some of them will be cost-effective, even for smaller facilities.  NREL is working with CU on these issues and might be interested in exploring whether Boulder could be some sort of test case.  NREL also can do a quick analysis that might help us determine whether WTE has any potential for handling Boulder's waste stream.

Which leaves the critical question: why not just get to zero waste and not bother with a WTE?  MC is indeed quite aggressive with recycling, and they expect to continue to decrease the waste stream.  But as a practical matter they simply don't believe that they'll get anywhere near zero-waste in the foreseeable future, even with more regulations and expense.  In Sweden -- which may or may not be a good model in this realm -- they shoot for 45% recycling, 45% WTE, and 10% landfilling, and consider that to yield 90% recycling of the waste stream (and don't understand why we put so much effort and money into increasing recycling rates when we can just use WTE).



--Matt