BTEC webinar explores biomass CHP, district heating
The efficiencies of conventional or central station fossil fuel plants have not changed much in the past half century, according to John Cuttica, director of the Midwest CHP (combined heat and power) Regional Application Center.
“It’s hard to believe, but the efficiencies of these plants have not really increased in over 50 years,” he said. “For every 100 units of fuel that enters these plants, we only get about 30 to 33 units of electricity. The rest of the energy contained in the fuel is released into the atmosphere in the form of heat.”
On the other hand, efficiencies in thermal energy have increased to 80 percent or higher, he said, adding that a baseline to improve upon begins at about 50 to 55 percent efficiency.
Cuttica was one of three presenters during the Biomass Thermal Energy Council’s May 25 webinar on large-scale biomass district energy and CHP.
During his presentation, Cuttica provided an overview of CHP, discussed how it applies to district energy systems and how biomass is used as a fuel in these systems.
When planning to utilize biomass to generate electricity, there are several factors one should give some serious consideration to, according to Cuttica. “The first is to make sure there are adequate resources available,” he said. “This includes long-term procurement contracts at a reasonable price.”
Another factor is the cost of the on-site handling of the fuel, which includes transportation, collection, storage and fuel preparation, depending the type of biomass being used. “Decide on best conversion technology for the biomass, and depending on fuel composition and application, determine what type of prime mover you should be using,” Cuttica said.
Electric utility interfacing is another important project component. “You need to contact the local electric utility early in the [project development] process, and work with them so you don’t get any surprises when you’re ready to hook into their grid,” he said.
Following Cuttica, Nexterra Inc.’s Jonathan Wilkinson discussed the company’s gasification process, several biomass thermal and CHP projects that Nexterra is involved in, some additional tips in implementing projects, as well as some different project financing models.
Right sizing a system is an important project component, Wilkinson said, as well as determining truck traffic to the location and addressing public acceptance. “[Public acceptance] is becoming increasingly significant, particularly in urban applications. The public is increasingly demanding a role, and that their concerns are addressed early in any process that involves energy generation.”
There are three main ways to finance biomass thermal projects, Wilkinson pointed out, one being where a third party finances, owns and operates systems, and then sells the energy to single/multiple users.
Another way is end-user self-financing, which is when the end user uses internal capital to fund the project and then owns and operates the plant. “This is often the simplest and least expensive, but it requires the end user to have the capital available and expertise required [to run the plant],” he said.
Another way to finance a project is through an energy services performance contract, which is an agreement with a private energy service company that will identify and evaluate energy-saving opportunities, and then guarantee a certain savings with the installation and operation of the equipment.
Moving on to an example of a large-scale biomass district heating project, Michael Burns, senior vice president of operations and engineering at District Energy St. Paul’s Ever-Green Energy, discussed the system in downtown St. Paul, and how it is unique and beneficial to the community. Serving 200 commercial buildings and 300 residences, Ever-Green Energy heats more than 80 percent of the downtown St. Paul area, a total of more than 31 million square feet.
“The system is of a significant scale, it’s unique, and it really is a community energy system, as we are a nonprofit utility,” Burns said.
It isn’t any particular technology that has been deployed or any component that makes it unique, according to Burns, but rather it is the way that it has been made into a community asset. “We have the ability to burn and use a variety of fuels,” he said. “Our primary fuel is biomass wood residuals derived from storm damage, tree disease and normal maintenance of urban canopy and municipal parks in the St. Paul area, supplemented with wood residuals from forestry operations.”
Heating buildings with wood fuel on an individual basis would not be possible, Burns pointed out, adding that the system is also capable of consuming other fuels such as natural gas and coal.
The backbone of the system is the hot water distribution, Burns said, which delivers the energy/heat throughout the city. “Many [district energy systems] in the U.S. and North America are baseline steam systems. Hot water systems really make using CHP and biomass effective.”
BTEC will be holding two webinars in June, dates and content of which will soon be announced. For more information, visit www.biomassthermal.org.