Montpelier District Energy Montpelier District Energy

Gwendolyn Hallsmith, Director Planning and Community DevelopmentCity of Montpelier, Vermont

History 2001 feasibility study by CANMET for heat Voters passed $250,000 bond in 2003

“for the City's share of the development of the District Heating System involving the State of Vermont's central heating plant in the state complex and the installation of hot water transmission mains from the plant to the City of Montpelier's municipal complex in and around City Hall.”

Energy Town Meeting in 2007 District Energy Team formed 2007 Clean Energy Development Fund Grant

for $25,000 for CHP feasibility study

Feasibility Study Tasks Study the technology required for a combined heat and

power (CHP) plant to optimize power generation and heat using sustainably harvested Vermont forest products.

Prepare a market study and identify buyers and projected prices of the renewable energy credits (RECs), the capacity, and the power.

Develop a financial plan that compares the long-term viability of a CHP as compared to the original heating plant proposals that had been studied in the late 1990s.

Prepare an outreach plan to the end users of both the electricity generated and the heating system to determine what incentives will be necessary to get committed customers of the new system.

Review of Biomass Facilities Duke/St. Paul District Energy facility

European models for biomass generation City of Växjö, Sweden

Grève-in-Chianti, Italy

Canadian technologies Prairie Biogas: Pyrolysis and Synfuels

Organic Power Technologies

Plasco Conversion System

Wood to Energy Alternatives1. Burning wood chips

2. Burning pellets

3. CarbonizationLow temperature, very long residence timeLiquid 30%, Char 35%, Gas 35%

4. Pyrolysis Moderate temperature, short residence time Liquid 75%, Char 12%, Gas 13%

5. GasificationHigh temperature, long residence timeLiquid 5%, Char 10%, Gas 85%

St. Paul Biomass Plant

April 2000 – Waste wood combined heat and power plant that supplies steam to District Energy of St. Paul and 25 MW of electricity to Xcel Energy (Northern States Power)

Wood Burning District Energy Plant

St, Paul, MN

7Confidential and Proprietary

St. Paul Biomass Plant

District Energy St. Paul currently provides heating service to more than 180 buildings and 300 single-family homes, representing over 30.7 million square feet of building space, or 80 percent of St. Paul’s central business district and adjacent areas.

8Confidential and Proprietary

St. Paul Biomass Plant

Service Hot water district heating delivered to customers year-round for

space heating, domestic hot water and industrial process use

Provider District Energy St. Paul Inc., an independent, non-profit company

Distinction It is the largest, most successful hot water district heating system

in North America

Production capacity Combined heat and power plant, four gas/oil-fired boilers, two

coal/gas-fired boilers, backup plant and mobile boiler: total 289 megawatts thermal (987 million Btu per hour); also 860-kilowatt, turbine-driven generator

Växjö, Sweden: Fossil Fuel Free Växjö Since 1993, the city

has reduced carbon emissions by 30% per capita

Results largely due to biomass heating – 90% comes from renewable sources

Recipient of 2007 Sustainable Energy Europe Award

Grève-in-Chianti, Italy

Waste gasification plant

Operating since 1992

6.7 MW electrical power

Product gas for cement kiln

Circulating fluidized bed gasifiers

Organic Power Technologies Carbonization or Fast Pyrolysis System

(Variable gasification)

Moderate Temperature (600 – 800C)

Liquid 12%

Char 23%

Gas 65%

Feedstock

Wood Chips Wood waste Straw Poultry litter Horse bedding Plastics

System Products/Outcomes100 Tons of Wood Per Day 105 MWh electricity from gas

21 tons of charcoal

506 GJ heat

10500 litres of bio-gas

Prairie Biogas

The Process Pretreatment Pyrolysis (syngas & heat) Electricity Generation Heat Production

System Components

1. Shredder

2. Pyromex Induction Heating System

3. Syngas-burning Engine

Feedstocks Wood chips Sewage Sludge Farm Waste Plastic waste Waste from leather and

fur industry Tannery waste Fly ash from power

plants Paper and cardboard

Plastic packaging material

Used oils and hydraulics

Tires Medical & Hospital

waste Natural fiber products Shredder waste Plastic and rubber

Plasco Conversion System

Waste to Syngas Syngas to Electricity

Plasco Plant

One ton of waste…

1. 1400 kWh electricity

2. 55 days of household use

3. 150 kg of vitrified slag (sold as aggregate)

4. 5 kg sulphur (soil enhancement)

5. 1.3 kg heavy metals and filter screenings

6. 300 litres of potable water

7. 5 – 10 kg salt

Questions to Consider

Is waste a renewable resource? Does it qualify for RECs? Which is more sustainable – wood or waste? Will using waste for fuel undermine reduction,

composting, and recycling efforts? How would you structure the public/private

partnerships necessary to manage this kind of plant?