Research Team Completes First Milestone of $1.9 Million Grant to Develop Locally Sourced Electricity and Solid Biofuel

D U L U T H,  M I N N. | April 19, 2017 –The Natural Resources Research Institute at the University of Minnesota is Principal Investigator and leader on a $1.9 million Renewable Development Fund grant funded through Xcel Energy to develop a Biofuel Conversion Center at the NRRI Coleraine Lab. The Coalition for Sustainable Rail is one of two industry partners aiding NRRI on the grant; its responsibility includes designing and building a 100 kW steam-electric boiler generator. The other industry partner, SynGas Technology, LLC, is championing development of a proprietary moving bed torrefaction reactor to supply fuel to the boiler generator. This month, the NRRI Development Team completed the first milestone of the Grant: Preliminary Engineering.

“I am excited by the engineering progress seen in the grant work to-date,” explained Don Fosnacht, Ph.D., NRRI Associate Director, CSR Board Member, and the project’s Principal Investigator. “The steam-electric generator the CSR engineering team is designing will be a one-of-a-kind addition to our Biofuel Conversion Center, and it will serve as an important research tool in the development of remote, distributed generation systems.”

NEWS IN BRIEF

• CSR has been awarded a $405,000 portion of a $1.9 million grant from Xcel Energy’s Renewable Development Fund

• CSR is designing and building a modern 100 kW steam-electric boiler generator that runs on torrefied biomass

• This release comes as the NRRI Team completed the first grant milestone

• The boiler generator will build upon the principles of advanced locomotive-style boiler and compound engine

• Zoo train trials also served to provide key biofuel combustion metrics for the boiler generator

The steam-electric generator being developed by CSR will employ an advanced locomotive-style boiler and compound expansion piston steam engine to generate sufficient power to make 100 kW of electricity. The boiler is designed to burn torrefied biomass fuel in a Gas Producer Combustion System and will be able to operate automatically, thanks to an additional $25,000 National Instruments Green Engineering Grant awarded to CSR in support of the RDF project.

“The Xcel grant provides a significant opportunity to push the state-of-the-art in firetube boiler, compound reciprocating steam engine, solid fuel combustion, and distributed generation system design,” said Wolfgang Fengler, MSME, CSR Senior Mechanical Engineer. “Developing an efficient boiler-generator package that can fit into a 20 foot shipping container is no small task, but our experienced team brings a diverse skillset that has translated into an innovative concept which we are eager to fashion into a working prototype.”

The NRRI RDF Grant is broken into multiple milestones, including preliminary engineering, detailed engineering, fabrication, testing, and steady state operation phases. CSR is currently focusing on the detailed engineering and fabrication milestones. Fabrication of boiler, engine, and electrical components is set to begin this summer.

“What the RDF grant has enabled CSR to do is really push boiler and steam piston engine design as can only be achieved through new-build construction,” explained CSR Technical Advisor Hugh Odom, P.E. “I am honored to serve as the Professional Engineer on this project, working with the CSR engineering team in a capacity to verify compliance of the design with ASME and other applicable codes.”

When completed, the boiler generator unit will be installed at NRRI’s Biofuel Conversion in Coleraine, Minnesota, where it will undergo commissioning and steady state operations. That facility is a former Oliver Iron Mining Railroad maintenance complex which has been converted into a one-of-a-kind minerals and biofuel research center by NRRI.
 

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The Biofuel Conversion Center of the Natural Resources Research Institute is housed in the former railroad shops of the Oliver Iron Mining Company in Coleraine, Minnesota. Shown here is the main hall, which serves to house the large torrefaction reactor (center) that can create 14 tons of torrefied material per day. The boiler generator and additional torrefaction reactor will also be housed in this one-of-a-kind reserach facility.

NEW NRRI Paper - Use of Biomass Fuels with a Focus on Biomass Pre-Treatment

This new paper by CSR research collaborator Natural Resources Research Institute was authored by Don Fosnacht, Ph.D (a CSR Board Member) and his colleague David W. Hendrickson. It provides a very in-depth look at the way in which pre-treatment of biomass can be used in steam boilers to make electricity (or, in some cases, propulsion for trains). It is of great importance in serving as a "bridge" fuel to transition from coal to cleaner energy, lowering conversion costs at power plants.

The following executive summary provides a good overview of the paper, which can be downloaded in its entirety here.

The desire to fire biomass for electric power generation has recently been amplified by President Obama’s new Clean Power Plan with a call for a 32% cut in power plant emissions by 2030 from 2005 levels.

With carbon-capture and sequestration technology still developing, many coal plants are looking for alternative ways to reduce the CO2 from larger scale fossil fueled power plants. Some utilities have started mixing their coal with a cheap material such as woody biomass that could help them meet the expected EPA targets. Co-firing with wood and coal is becoming a viable ‘bridge strategy’ for increasing the use of renewable resources while reducing atmospheric CO2. Worldwide, over 200 test burns have been completed for co-firing wood with coal at large-scale coal fired power plants to show the feasibility of this technique to reduce CO2 in plant emissions.

Compared with fossil fuels, biomass has not been widely utilized in the electric power generation industry due to its relatively low energy density. Biomass pre-treatment technologies have therefore been developed to densify biomass into forms that can be stored and handled in a manner consistent with coal usage at power generation operations.(2) The biomass industry is currently focusing on biomass pretreatment technologies for either pelletizing raw biomass fuels or pelletizing torrefied biomass fuels. The wood pelletizing process for production of wood fuel pellets is a well-developed technology worldwide. The torrefied wood industry, however, is in a ‘development stage’ in that many torrefaction processes are being researched and refined, with no one technology perfected or preferred as yet.

The global electric power industry is thus seeking ‘refined’ renewable fuel products to partially or fully replace coal as its fuel source in order to reduce carbon and other significant emissions. ‘Refining’ is a generic term for different fuel processing technologies including steam explosion, torrefaction, and hydrothermal carbonization (HTC) (also called wet torrefaction). Through the use of torrefaction ‘mild pyrolysis process,’ a significant improvement in the suitability of biomass for co-firing in coal fired power plants is produced while providing the potential to enable higher co-firing percentages of biomass versus using untreated wood pellets. The quality of the torrefaction process depends on the balance between temperature and residence time to preserve a maximum of energy density to achieve certain fuel properties like grindability and hydrophobicity.(3) While the lignin content in wood is usually enough to bind pellets, other forms of biomass require special conditioning to strengthen them. Sometimes binders such as starch, sugars, paraffin oils, or lignin must be added to make the pelletized biomass more durable.(4) Pelletizing into a highly water repellent pellet or briquette is required for the torrefied wood industry to produce an acceptable coal replacement product that can be shipped in bulk in open containers and stored in a manner similar to coal. As of 2015, emerging biomass torrefaction companies have significantly improved their ability to produce high quality products with pellets of comparable durability to conventional wood pellets. Key areas of work remain, and these include: densification with and without binders to enhance the bulk density of the produced fuels, development of moisture resistance regimes to allow avoidance of indoor storage, optimization of the shape and size of the fuel products, and the degree of pretreatment required to reduce ash content and to achieve the desired fuel values in the products.

Southern Company, at its Gulf Power subsidiary, successfully tested the use of ‘white pellets’ that had undergone torrefaction in a mobile torrefaction facility. Even though the produced materials were not of ideal physical quality, the company showed that up to 100% coal substitution could be achieved. The company concluded that the use of torrefied materials was a straightforward path to substitution of increasing amounts of coal in power generation. Ontario Power in Canada has converted two plants in Western Ontario to completely use biomass materials. In one case, they modified the power plant to utilize white pellets, and the capital costs for this modification were estimated to be C$170,000,000. In the second case, the power plant decided to use advanced wood pellets produced from steam explosion processing methods (Zilkha or Arbaflame), and the capital costs to allow the materials to be used was only C$5,000,000. The capital cost reduction illustrated that the advanced wood pellets could be used like coal in that second plant example. Finally, a European economic analysis indicates that considering all aspects of potential fuel use, advanced wood pellets compared to ‘white pellets’ have a significant economic advantage when logistics and actual cost of use at the power plant is considered.