The US Department of Energy works with eight regional partner organizations to promote CHP, waste heat recovery and distributed energy technologies around the country. This article summarizes the work of the Northwest Clean Energy Application Center, based in Washington state, and draws upon three of its case study publications.
The Northwest Clean Energy Application Center (NW CEAC) is one of eight regional centres in partnership with the US Department of Energy Industrial Technologies Program (DOE ITP) and also partners with the other regional Clean Energy Application Centers (also known as RACs). The DOE Clean Energy RACs promote CHP, waste heat recovery and distributed energy technologies and practices, and offer regional assistance for specific projects throughout the US.
The NW CEAC covers the states of Alaska, Idaho, Montana, Oregon and Washington. Its headquarters are in Olympia in the state of Washington, and is part of the Washington State University (WSU) Extension Energy Program. A few of the key services the Center offers are policy analysis, project support, and education and outreach. The target markets served are dairies, food processors, pulp and paper mills and forest products.
Target markets are industries that are generally large energy users and/or have the ability and need for process thermal energy (cooling and/or heating). These markets are chosen based on several factors:
- market size and potential
- opportunity fuels within the region or specific states
- technical and economic viability of the resources
- economic, energy, and environmental goals of the state or region.
Each of the eight RACs has target markets they focus on.
|Night-time view of the Simpson Tacoma Kraft forest products facility|
NORTHWEST TARGET MARKETS
The wood/forest products industry produces construction and building materials. Companies in this industry cut timber and pulpwood (mill raw materials) into lumber and building materials, and manufacture finished articles, such as wood panels. A recent trend has been the increase in lumber mills that use biomass boilers for generating electricity in addition to producing steam for mill operators and on-site lumber kilns.
Pulp and Paper Mills
Pulp and paper mills are classic opportunities for clean heat and power. They are energy-intensive and operate within a highly cost-competitive industry. it is critical that they recover as much energy as possible to save money. Wood waste and chemical recovery boilers produce steam to run the mills. Steam turbine power generation is a natural bonus.
Year-round food processors are excellent candidates for CHP and anaerobic digestion. Foods processed in the Northwest include potatoes, sugar beets, onions, fruits and row crops. Food processing requires both steam and power, and has high organic content liquid waste streams suitable for anaerobic digestion.
Dairies, irrigated and dry land agriculture each have distinct energy use profiles and opportunities. For dairies, anaerobic digestion systems replace waste lagoons, and energy efficiency opportunities are found in the milking parlour and crop production. CHP, co-digestion, and nutrient recovery provide a viable and economically valuable alternative to lagoons, providing heat for the digester with an opportunity to sell excess power and nutrients, as well as to receive tipping fees. Dryland and irrigated agriculture also have energy efficiency opportunities.
LOW ENERGY COSTS HINDER CLEAN ENERGY
The Northwest region has had historically low energy costs which have hindered the usage and expansion of energy efficient technologies and practices, such as CHP and waste heat recovery. The low energy costs are due to the high level of hydro-power capacity in the Northwest, specifically within Idaho, Washington and Oregon. However, industries in the region that rely on fossil fuels primarily are the ones most concerned about the increasing costs of fossil fuels.
Potential for CHP/CCHP in the region
Combined cooling, heating and power development in the Northwest has historically been slow to develop in this region due to cheap electric power, poor ‘spark spread,’ and a missing policy-enabling framework. However, it now has tremendous potential as a result of increasing energy rates, policy, receptivity, awareness of its benefits – both economic and environmental – and new environmental regulations for emissions.
In addition, ‘new’ resources not previously utilized and considered waste products, such as forest slash, food processing residue, agricultural residue, and manure products, are now being viewed as valuable resources that can be used to produce energy.
Barriers to developing CHP
Cheap electricity rates in this region have been a significant barrier to CHP development. The Northwest has the cheapest utility rates in the country – more than half that of the Eastern US. This is due to the large amount of hydropower electric generation. As a result, industry had little incentive to invest in CHP unless there were strong incentives from their local utility or government. Long payback periods contributed to this disincentive.
Another barrier is policy, and interconnection in particular.
Nevertheless, installed CHP capacity has increased since 2003, when the Northwest Clean Energy Application Center began operations. A large part of this increase had to do with legislation, policy and incentives. In 2009 alone, eight bills favouring CHP passed in the state of Washington.
For more information on the Northwest Clean Energy Application Center and its work, visit: www.northwestcleanenergy.org
Finley Buttes Regional Landfill 4.8 MW landfill gas CHP plant
The Finley Buttes Landfill Gas to Energy facility is 10 miles south of Boardman, Oregon at the Finley Buttes Regional Landfill (FBRL), owned and operated by Waste Connections (WCI). The landfill receives over 500,000 tonnes of municipal solid waste annually.
The landfill gas (LFG) collection and control system has 57 vertical extraction wells and a high-density polyethylene (HDPE) piping network to a blower/flare station. The CHP plant draws methane gas to fuel three internal combustion engines that power electrical generators. The engines also produce two sources of heat: recaptured heat from the engines’ water cooling system and heat from the exhaust stacks. This heat sends water at 112°C to an adjacent onion and garlic dehydration plant.
In 2004 the landfill expanded, entering the BPA’s ‘large’ landfill category, which requires either a gas collection system or proof that emissions are less than 50 mg per year of non-methane organic compounds. WCI chose to install a gas collection system. Finley BioEnergy was formed to manage the Finley Buttes LFG liability by using LFG as an asset.
Main components of the CHP landfill gas system
- three 1.6 MW Caterpillar gensets, (with internal combustion engine). This model can handle dirty gas and can burn low Btu gas.
- three Cain exhaust heat recovery units,
- Three Ameridex flat plate heat exchangers.
- reduced greenhouse gas emissions
- increased renewable energy to the grid
- energy-efficient technology (CHP)
Unique attributes of the project
- overcame utility barriers: location was between two different interconnection points
- new use of technology: interface and heat transfer media (glycol/water solution)
- learned about daily scheduling of power and transmission
- CHP wheeling.
- revenue from electricity sold to PacifiCorp and heat sold to Cascade Specialties
- beneficial use of landfill gas
- potential sale of green tags and carbon credits
- energy savings to Cascade Specialties (purchaser of the supplemental heat). Cascade has reduced its natural gas usage by 25-30% during the eight-month season.
Simpson Tacoma Kraft 60 MW biomass CHP plant
In August 2009, Simpson Tacoma Kraft began commercial operation of a 60 MW biomass CHP plant. The facility, owned and operated by Simpson Investment Company, generates power from a combination of wood-based biomass and wood lignin (black/spent liquor) recovered from the pulping process. The biomass-based fuels are used to generate steam, which spins a turbine, making renewable power while providing process steam to the mill.
Family-owned and operated for more than 120 years, Simpson Investment Company has a long history of investing in its operations to help it stay competitive. As a forest products company, it has diverse manufacturing divisions, with five wood product manufacturing plants, one pulp and paper mill co-located with a sawmill (Simpson Tacoma Kraft) and two door manufacturing plants. The Tacoma Kraft mill is thriving at a time when many pulp and paper mills across the country are closing. The mill manufactures bleached and unbleached kraft pulp and linerboard and employs some of the most advanced paper recycling techniques available. It recycles some 500 tonnes of waste paper and boxes every day.
According to the USA Biomass Power Producers Alliance, the facility is the largest single CHP renewable energy project built in the US in the last 10 years.
Simpson built the CHP plant to maximize energy production from its existing operations that already involve burning sawmill and paper mill by-products, wood-building demolition waste, and logging debris. The ‘surplus’ energy could then be sold. Simpson expects to sell approximately 27,500 MWh/month (yearly average) in surplus energy. The 60 MW power generator will squeeze more energy out of the wood waste the company already burns, so the plant will burn little more wood waste than it did previously.
Main components of the CHP biomass system:
- steam boiler: Riley 2.57 tonnes/minute 60 bar
- recovery boiler: Combustion Engineering fire-tube type, 4.12 tonnes/minute 60 bar
- steam turbine: Dresser Rand triple-extraction condensing type, rated capacity of 60 MW
- generator: Brush, rated capacity of 60 MW.
Steam enters the turbine at 60 bar and is then extracted at three different pressures: for driving the steam turbines to supply the boiler soot blowers; for drying the pulp and paper and heating the digester; and for the liquid evaporators, boiler feed water heating, and miscellaneous process heating.
Simpson currently uses black liquor (60%), hog fuel (36%), fossil fuel (<2%), and municipal wastewater sludge (2%) to power their biomass plant.
These fuels are available year-round but, because the housing slowdown has reduced the normal supply of scrap wood from local lumber mills, Simpson had to plan ahead and stockpile material for combustion later. As a forest products company with four other subsidiaries, Simpson has better access to biomass than most pulp and paper mills. It receives about 700 dry tonnes/day of biomass in various shapes and sizes. It arrives by truck, is put in a storage pile and sent to the reclaim system.
Flexibility of fuels
The mill can use a variety of fuels, including those listed above, plus wastewater sludge, sawmill and forest residuals, demolition debris, and other miscellaneous woody-type waste streams.
The mill installed an improved over-fire air combustion system for the purpose of reducing carbon dioxide (CO2) and NOx. Carbon dioxide emissions are 300,000 tonnes/yr lower than if the mill had generated the same amount of power from separate heat and power facilities.
- additional revenue streams from green power sales and green energy credits
- reduced carbon dioxide emissions
- more efficient technology
- reduced odours
- helps Simpson stay competitive when many pulp and paper mills have shut down.
The total installed cost of the 60 MW biomass plant was $90 million, which Simpson financed. Simpson also owns the plant. The electrical output is sold to Iberdrola Renewables. Simpson has two revenue streams: green power sales and green energy credits. Expected simple payback is approximately five to eight years.
Simpson sells approximately 27,500 MWh/month. The length of the power purchase agreement is 10 years.
Rough and Ready 1.5 MW wood-fired CHP plant
In February 2008, Rough and Ready Lumber, in Josephine County, Oregon, began commercial operation of a 1.5 MW wood-fired CHP plant that dries lumber in 12 kilns. The firm sells all the power – over 10 GWh a year – to the utility, PacifiCorp, and buys what it needs to run its plant.
Until recently, Rough and Ready air-dried lumber on schedules that created gaps in sawmill production. To stay competitive, the firm went from a three shift, two-mill operation to a one-mill, single-shift operation with a focus on high-quality, low-production specialty items.
Drying more lumber required greater boiler capacity and the firm replaced a 30-year-old boiler. Increased thinning of national forests meant the federal government would supply a lot more wood than the firm could burn in its existing plant.
Main components of the CHP systems:
- steam boiler: Wellons 0.3 tonnes/minute 21 bar water tube
- turbine: Coppus Murray 1.5 MW backpressure
- genset: Kato Reliance generator
The CHP system has a 0.3 tonnes/minute wood-fired 21 bar water-tube boiler that feeds saturated steam into the 1.5 MW backpressure steam turbine. The turbine is harnessed to a Kato Reliance generator. Dis-charge steam is reduc-ed to 1.4 bar and heats 12 double-track dry kilns. Kiln condensation is then returned to the boiler to be reheated.
Rough and Ready could not afford the CHP plant until the US Congress created incentives for power from burning biomass. Leaders in the timber industry realize this can help finance thinning forest to combat wildfires and insect infestations. Reducing dependence on fossil fuels is an added benefit.