Grass pellet fuel for electricity production

Final Report for FNE11-713

Project Type: Farmer
Funds awarded in 2011: $15,000.00
Projected End Date: 12/31/2011
Region: Northeast
State: New York
Project Leader:
Co-Leaders:
Mary Dolan
Flyingrabbit Farm
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Project Information

Summary:

Our Goal with this project was to determine if it is possible to gasify grass pellets into “producer” or “syn” gas that can be run in an internal combustion engine to make electricity and heat. Our area has acres of unutilized, old worn out pasture and hay land that is growing up to goldenrod and polar saplings. This biomass can be harvested by ordinary haying equipment and be manufactured into grass pellets. We have a local manufacturer of grass pellets here in Wells Bridge NY (enviroenergyny.com). These pellets can be burned in boilers to produce heat. This experiment will be to see if the pellets can be gasified and burned in an internal combustion engine to generate electricity and heat in an experimental combined heat and power (CHP) unit.

Gasifiying the grass pellets worked well and produced a clean burning gas that ran well in a diesel internal combustion engine. The gas contains water vapor and tars that need to be separated prior to entering the engine and we used a water heater exchanger to cool and condense out the water vapor and tried to keep the gasification temperatures above 500 degrees Centigrade to minimize tars. The gas was filtered through a charcoal filter, cooled and then filtered through a shop vac filter before entering the engine intake manifold at less than 90 degrees Farenheit. The 22 hp diesel engine was run at idle speed and consumed approximately 0.4 gallons per hour at 600 RPM. Introduction of syn gas from the gasifier raised the RPMs to 1,200 while the diesel fuel flow remained at 0.4 gallons per hour. At 1200 RPM, the engine turned a 7000watt generator at 1800 RPM through a geared PTO transmission to produce electricity.

The gas did not run well in our John Deere 40. Syn gas will burn without other fuel in a spark ignited engine, however, the low RPM of the JD 40 may not have been the best gasoline engine to try in this test. We tried advancing the ignition timing and got intermittent success with the syn gas but clearly the compression diesel engine resulted in better use of the syn gas in this test.

The use of agricultural biomass provides a fuel that can be gasified for use in internal combustion engines to produce electricity.

Introduction:

In this project we gasified gas pellets and the resulting gas was burned in an internal combustion engine to generate electricity. Our area has a lot of old agricultural feilds that are growing up. Many people brush hog these lands at an expense to keep them open. This marginal land can be put to productive use by harvesting the grass with regular round bale baling equipment and coverted into pellet fuel at a local pellet manufacturer. Many people are using these pellets to burn in boilers for heat. We set out to see if these pellets could be gasified and the resulting gas burned in an internal combustion engine. After several trys and modifications, we successfully gasified the pellets and used the gas to run a 24 hp diesel engine to turn a generator to produce electricity. Our goal is to demonstrate that grass pellets can be used to generate electric power as well as produce heat.

The gasification of biomass is an old technology but the gasification of grass pellets in new. Most gasifiers gasify wood chips. Attached is a manual from the federal goverment that explains how to build a imbert down draft gasifier in a step by step method. Also attached are pictures and an explanation of what we built.

Project Objectives:
  • To determine whether we can gasify grass pellets without disintegration To determine whether the gasification of grass pellets results in a gas that is combustible in an internal combustion engine To determine if a sufficient about of gas can be produced to generate electricity and heat To test both diesel and gasoline internal engines to see how they run on syn gas

Cooperators

Click linked name(s) to expand
  • Mike Miller

Research

Materials and methods:

We used a GEK gasifier manufacturer built by All Power Labs. The gasifer is an Imbert down draft design and essentially burns the pellets in a very low air environment so that combustion is limited and the resulting heat of combustion gasifies the pellets and drives of Hydrogen and Carbon monoxide and some methane gas. We modified the unit in several ways to make it work better on grass pellets. These units are typically used with wood chips as fuels. These gases were then routed through a filter and cooler and put into the intake manifold of regular internal combustion engines. The goal of this experiment is to demonstrate that a useful product can be produced from all the old pastures and hay fields in our area to produce a biofuel that that is capable of producing electricity. We are fortunate to have an established grass pellet maker in our town that can produce pellets out of native grasses.

Research results and discussion:

Our first attempt was to use the gas in a JD 40 23 hp gas tractor. The producer gas was put in to the intake side of the carburator at a ratio of 50% producer gas and 50% air. The engine did not run very well on the gas and we were unable to get a consistent run.

Our second attempt was to run the producer gas into a 24 hp 3 cylinder Kubota diesel engine. Diesel engines cannot run solely on producer gas so the engine was run on diesel at idle power and producer gas was introduced to the intake manifold. Some straight filtered air was metered in in order to make the producer gas burn. The diesel at idle ran at about 700 rpm and the introduction of the producer gas brought the RPM to 1200 which was needed to turn the generator at the required 1800 RPM (the Kubota has a three speed PTO).

The Kubota diesel ran extremely well on the syn gas and did not produce any visible exhaust.

Research conclusions:

We successfully produced electricity by gasifying locally produced grass pellets. This biomass harvested by local farmers using standard hay equipment was converted into gas which successfully burned in a Kubota 3 cylinder diesel engine which turned a 7000 watt PTO operated generator. By expanding the use of grass pellets into multiple products rather than just a heating fuel, we can hopefully expand the use of locally produced biofuels so that farmers have an outlet for low quality hay and waste agricultural products. Corn stover, soybean stubble, and canola stubble have all been pelletized by Enviroenergy and all could run in a gasifier.

Many people helped with the project including Sandy Alles, Mike and Bob Miller, Mike McCormick, the Catskill Grass energy group and others. Dr. Jerry Cherney at Cornell has also helped many people strive to use local biomass energy out of otherwise unused product.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

We have been very involved in the use of grass pellets as a heating fuel and now as a fuel that can be used for the co-generation of electricy and heat. We have been to several meetings of the Catskill Grass Energy Committee, which is run by Cornell Cooperative Extension and have been to two conferences to discuss the project including the Carbon Farming conference held near New York City at the Pfeiffer Center and at the Northeast Biofuels conference in Saratoga New York. In addition, several interested farmers have looked at the machine running. We will continue to be involved and share our experience in the grass and agricultural waste energy field.

We made videos that demonstrate how the apparatus is put together on a running tractor. Go to

Part I
http://www.youtube.com/watch?v=CmA22wn2VNM

Part II
http://www.youtube.com/watch?v=0L89MgfgTPA

Part III
http://www.youtube.com/watch?v=R8pa7KahRy4

Project Outcomes

Assessment of Project Approach and Areas of Further Study:

Potential Contributions

The use of biomass as a fuel can help to reduce our use of foreign oil. We are located in the Marcellus Shale that has a tremendous amount of natural gas. However, many people are opposed to the extraction of this gas because of potential environmental problems. By promoting the efforts of locally pelleted biomass fuels, we are working to provide an alternative to fossil fuels. While there are few boilers and furnaces designed exclusively to use grass pellets as a fuel, or to gasify grass pellets into a combustible gas, many people are working on the problem. Dr Jerry Cherney at Cornell has been promoting and studying grass energy for several years and is currently studying the emissions from burning grass. Our experience in successfully gasifying grass and using the syn gas will help in the development of the use of grass and agricultural waste as a fuel.

The development and expansion of agricultural biomass fuels could help local farmers and business. By avoiding the conversion of biomass into liquid fuel, such as ethanol, we are saving energy and utilizing low quality lands rather than using productive food growing land. Additional work and study concerning the energy balance of biomass fuels needs to be undertaken. However, it appears clear, that minimally processing local waste agricultural products is more energy efficient that intensively processing biomass into liquid fuels. While liquid fuels are convenient, compact and transportable, a local energy system can be designed to use solid biomass fuels.

Just driving along the interstate it is clear that there are hundreds of acres of open land growing weeds and small brush,(including the lands within the highway right of way that are mowed at great expense)that could be used for locally produced biomass. There remains the need to continue to develop efficient boilers and gasifiers. Gasifiers could prove to be an efficient and clean way to maximize the conversion of this local biomass into heat and electrical power.

Future Recommendations

The gasification of grass pellets and other pelletized agricultural wastes is very promising based on our experience. One of the benefits of gasification is that rather than ash as the byproduct, the result is char that can be used as a soil amendment and as a means of sequestering carbon in the soil. We will continue to work to develop a system that can provide heat for our greenhouse while producing electrical power and making char as a by product. New york state has a small scale cogeneration statute that provides for net metering of electric power produced through small scale cogeneration. We would like to continue to work toward developing a small scale unit (less than 10KW)that could be a grid tied co-genertion plant which runs on locally produced grass pellets.

Additional research and projects:

A better cooling and filtering system is needed to make sure that tars are not entering the engine and causing problems. Additional research is needed on using the byproducts of grass pellet gasification and burning as a soil amendment. Emmisions testing of the exhaust should also be explored to see the composition of exhaust gas and to make sure they are within limits.

Information Products

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.