Garbage or green energy: a look at the issues around RDF

What do the Hennepin County garbage-burner and the windmill fields of southwestern Minnesota have in common? Last year, the Minnesota legislature defined them both as renewable energy sources. Legally defining garbage as a renewable energy source makes more public subsidies available for garbage-burning plants. New garbage-burning plants in Minnesota can now compete with cornfields and windmills and solar energy panels for renewable energy funding.

In St. Paul, the Rock-Tenn company needs a major new energy source, and garbage is the leading candidate. According to Rock-Tenn executives, “We don’t have any models that are without RDF [refuse-derived fuel].”

The Burning Question: coal, garbage, biomass and sustainable energy

We invite YOU to weigh in with questions, comments, corrections and opinions at Your Burning Questions—readers and writers talk back, a space for dialogue and feedback for concerned citizens AND involved parties. Friday: Re-fueling Rock Tenn: environmental and economic challenges Saturday: Who’s on First? Keeping track of the players Sunday: Following the money: who pays and who profits Monday: Garbage or green energy: a look at the issues around RDF

Ramsey and Washington counties are also interested in seeing Rock-Tenn use RDF. According to Ramey County Environmental Health Director Zack Hansen, “Besides wanting to preserve the recycling asset that Rock-Tenn is, the counties have a potential role in working with RRT to provide fuel, should they decide RDF is the fuel they want to use.”

While Rock-Tenn and local government bodies express enthusiasm for burning RDF, some environmental and community groups disagree. The trouble with RDF, they say, is that it is not clean enough or green enough. When garbage is burned—whether in a mass burn facility like Hennepin County or after conversion to RDF—some hazardous wastes remain in the fuel source. If scrubbers take these particulates out of the air, they remain in the ash. The ash is usually buried in landfills, but sometimes it is used for manufacturing cement or roadbeds. A resolution approved by Eureka Recycling in November states, in part, “Eureka Recycling does not encourage the burning of garbage as it results in waste in the form of toxic ash and hazardous emissions that are damaging to the health of our community and the environment.”

Other critics focus on the public money funneled into RDF subsidies. A 2005 Fed Gazette article calls incineration “a legacy technology and a financial burden on the municipalities that bought into it.” In the larger policy picture, strategies of reduction, reuse and recycling all outrank landfilling and incineration as desirable strategies for dealing with municipal solid waste. Could the millions spent in subsidies to produce RDF be better used to increase waste reduction, reuse and recycling programs?

For the past twenty years, Ramsey and Washington counties have contracted with a plant in Newport (operated first by NSP, then by NRG, and now by RRT—Resource Recovery Technologies) to turn their municipal solid waste into RDF. The facility processes about 420,000 tons of solid waste annually, turning MSW into RDF and then shipping it to Xcel to be used as fuel. The Newport plant is subsidized by Ramsey and Washington counties. When the agreement between the counties and the RDF plant expired at the end of 2006, it was renewed for a six-year term.

Back in 1994, the Minnesota legislature mandated development of biomass fuels and specifically excluded waste from the definition of biomass, focusing instead on farm-grown biomass. In a series of changes driven by individual companies or proposals, the legislature classified first waste wood, then poultry litter, and finally RDF, as biomass fuels.

“Refuse-derived fuel” sounds better than garbage, and its proponents are quick to point out that the new generation of RDF plants are not like the Hennepin County garbage-burner. Hennepin County uses mass burn incineration, which basically incinerates unsorted Municipal Solid Waste (MSW). In contrast, RDF systems first remove recyclable and non-combustible materials by shredding and screening incoming MSW. This results in a cleaner burn, a higher heating value, and a lower content of moisture and ash.

Converting municipal solid waste to fuel is expensive. Landfilling garbage costs less than processing it to make fuel. Garbage haulers pay a lower “tipping fee” to dump their loads in landfills than to dump them at the RDF processing facility. Public subsidies from Ramsey and Washington counties, paid to the Newport plant, allow it to charge a low enough tipping fee to acquire garbage.

In addition to expense, another looming obstacle to using RDF is supply. Rock-Tenn’s RDF fuel needs are estimated at nearly 400,000 tons per year. The Newport facility has produced an average of 330,000 tons of RDF per year, and has delivered this output to Xcel plants in Mankato and Red Wing. According to the Foth & VanDyke report prepared for Ramsey and Washington counties, meeting the needs of Rock-Tenn and the two existing users would require the Newport plant to process about 170 percent of the total amount of MSW generated in Ramsey and Washington counties each year.

One way to get fuel to Rock-Tenn would be to terminate the RRT contracts with Xcel Energy, and to deliver all of the Newport plant’s production to Rock-Tenn. Another option is to build additional processing lines at the Newport plant, and to acquire more MSW from the broader metro area.

Another potential source of fuel is waste wood. Some waste wood comes from tree trimming and disposal of trees, shrubs and woody waste in the metropolitan area. Other wood fuel comes from construction and demolition waste (C&D). District Energy, which provides district heating and cooling for downtown St. Paul, already claims most of the waste wood available in Ramsey County. C&D wastes require significant processing, which could be done at the landfills where these wastes are now delivered for burial. That would require building and running some kind of processing plant(s). A study due to be completed in July will address the broader question of C&D wastes.

Either on the market or under development are a wide range of biomass fuels, from switch grass to turkey manure to crop residues (e.g. corn stalks and cobs). The Green Institute, which is studying the availability and feasibility of various biomass fuels for Rock-Tenn, will report on the economic and environmental

A Green Institute study due later in March will focus on biomass alternatives to RDF. We will report on that study, and we invite you to participate in the on-going discussion at Your Burning Questions—readers and writers talk back, a space for dialogue and feedback for concerned citizens AND involved parties.