Final Report: Energy Generation through Gasification of Optimized Rice Hull Biomass

EPA Grant Number: SU836790
Title: Energy Generation through Gasification of Optimized Rice Hull Biomass
Investigators: Dahlgren, John
Institution: Butte College
EPA Project Officer: Page, Angela
Phase: I
Project Period: November 1, 2016 through October 31, 2017
Project Amount: $15,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet (2016) RFA Text |  Recipients Lists
Research Category: Sustainable and Healthy Communities , P3 Awards , P3 Challenge Area - Air Quality


The objective of this research was defined in the Phase I grant proposal as follows: “This proposed EPA-P3 Phase I project addresses a growing challenge of utilizing large quantities of agricultural biomass residues (waste) as a renewable, carbon-negative energy source in California.”

In the problem definition and justification for the proposed research of our the Phase I proposal we identified the primary reason for the decline in the use of the large quantities of available biomass residues (waste) for energy generation in California, as the lack of economic viability of large scale biomass power plants in the state due to inability to compete with natural gas in power generation. The transportation and handling cost of biomass residues makes them uneconomical for use as fuel in large power plants.

Our proposed solution to this problem was the following: “A potential solution is a new approach in the use of agricultural biomass residues (waste) for energy generation is gasification (pyrolysis) of the biomass combined with biochar production directly on-the-farm. This approach offers a carbon negative source of energy through carbon sequestration in the soil with added benefits of increased agricultural production.”

The objective of the proposed research in Phase II will continue as the sustainable and environmentally beneficial conversion of biomass residues (waste) into biochar. However, the emphasis will be on maximizing carbon sequestration in the soil for improving water retention and agricultural productivity. Energy generation in the form of usable heating or cooling will be a secondary objective.

We will be focusing our efforts toward working with the local agricultural industry and certain fire-hazard threatened communities in Northern California to convert the large amounts agricultural and forest biomass residues into biochar on-the-farm and onsite in the forest.

Summary/Accomplishments (Outputs/Outcomes):

After 8 months of our Phase I effort, we are convinced that our proposed approach of on-the-farm gasification (pyrolysis) of biomass residues for biochar production and its application for soils improvement is the right solution to the challenge of sustainable and economically viable use of agricultural biomass residues (waste) in California.

In addition, we also have identified the need for studying and developing “conservation burn” as an onsite biochar production method to dispose and utilize large volumes of woody biomass from orchards and forest residues (waste) in a sustainable and economic manner with reduced air pollution and greenhouse gas emissions.

Furthermore, we have adopted analytical methods of testing and classifying biochar by the establishment of a biochar laboratory at Butte College for this purpose, operated by our student interns based on the Basic Biomass Metrics (BBM) procedures developed by Dr. Hugh McLaughlin, PE, the CTO of Next/Char (Ref.1. Baseline Biochar Metrics. Ver. X. Nov. 18, 2016). Dr. McLaughlin provided a full day of hands-on training on the BBM procedures to our EPA-P3 project student interns and lectured on Basic Biochar Science at Butte College and at CSU-Chico last December.

We cited in the Phase I proposal recent advancements in the development of small scale gasification equipment such as the PP20 Power Pallet manufactured by All Power Lab of Berkeley, CA (Ref. 2. http://www.all”, and the BioMax 100 unit by Community Power Corporation of Denver, Co. (Ref. 3. We stated that we believe these small gasification units are the most suitable for on-the-farm applications with the flexibility of electrical and thermal energy output combined with biochar production. In the course of the Phase I effort, we have identified other suitable equipment that may be used for this purpose. A list of these technologies is provided in Appendix A of the full final report.

We further stated that the progress in the use of biomass residues for energy generation represented by on-the-farm gasification equipment is a promising effort to reverse the decline in biomass power generation in California over the past 20 years (Ref. 4. Cal. Energy Commission). However, we also cited a major obstacle in the use of rice hulls in these type of gasifiers due to so called “slagging” of the rice hulls during the pyrolysis process. The problem is due to the high silica content of rice hulls that causes them to fuse together and clog up the flow of biochar through the gasifier.

Thus we proposed that, “The specific objective of the proposed EPA-P3 project will be to research and develop methods to solve the rice hulls slagging problem during gasification. This will be done by mixing the rice hulls with other biomass, such as walnut shells and or wood chips (orchard tree cuttings).” We further proposed that, “Gasification experiments will be performed using the existing Olivier gasifier units at BGCCD. The resulting mixes of biochar will be evaluated and classified as to their effectiveness in benefiting plant growth by conducting laboratory scale agricultural testing…”

In the course of the EPA-P3 Phase I project, we did carry out the proposed gasification experiments using mixed biomass fuels in our Olivier gasifier units. However, we could not reproduce the “slagging problem” reported in commercial gasifiers. We believe the reason for this is the relatively low temperature of the pyrolysis process in the Olivier gasifiers.

We recognized that we could not pursue this line of research with our existing equipment, the Olivier gasifiers, and we had no funding under the Phase I project to acquire suitable equipment, a commercial gasifier such as the PP20 Power Pallet, which cost $30,000. Therefore, we decided to pursue a different course of action, focusing on working with the local agricultural industry to promote and advance on-the-farm conversion of agricultural biomass residues to biochar and its application for carbon sequestration in the soil for the purposes of moisture retention and agricultural productivity improvements. This effort will result in the installation of a prototype “on-the-farm” biomass production unit by Next/Char at the Carriere Farm in Glenn, California during this summer. At least one or two of our EPA-P3 Phase I student interns will be employed during the installation and start-up operation of this equipment.

We have developed close ties with the California Biochar Association (CBA). CBA is a newly formed organization promoting the conversion of agricultural and forestry biomass residues to produce biochar. CBA’s approach reflects the realities of the use of biomass in energy generation and focuses on conversion of the biomass to biochar for its value as a means of carbon sequestration and potentially beneficial uses in agriculture and forestry. CBA believes that increased production and application biochar offers the potential for the development of a new industry based on improving agricultural production and forest rejuvenation through the use of biochar by improving soil moisture retention and soil health.

Through our contacts with CBA, we benefitted from the valuable contribution to our project by two well-known biochar research experts, Dr. Hugh McLaughlin CTO of Next/Char and Dr. Milt McGiffen, a Soils Science Professor at UC Riverside. Both of them visited Butte College last fall, personally instructing our EPA-P3 project student interns in biochar production, analysis, and applications.

Dr. McLaughlin gave a presentation at Butte College and also at CSU Chico in December on Basic Biochar Science and has introduced our student interns to his Basic Biochar Metrics (BBM) procedures for analyzing and characterizing biochars. Based on his advice, we have established a biochar analysis laboratory at Butte College operated by our student interns under the EPA-P3 Phase I project. We propose to expand the biochar laboratory at Butte College during the next school year, which will serve the local agricultural industry in analyzing and characterizing various biochars.

Preliminary results using the BBM procedures on several different biochar samples produced by our own Olivier gasifiers and onsite produced biochar at Berkeley Olive Grove are presented in the following section with more detailed discussions.

Dr. McGiffen provided us with detailed procedures and recommendations for conducting soil water retention testing in laboratory and field settings to study the effects of biochar on moisture retention in soil. Laboratory scale testing, based on his methods, currently is being performed at Butte College and results will be presented by our students this May at the EPA-P3 Exhibit in Washington DC. Field experiments based on Dr. McGiffen’s input will be carried out at Carriere Farms, in Glenn, California, at our local agricultural partner’s operations during this summer. Final planning and preparations for these field experiments currently are in progress. We anticipate preliminary results to be available by late summer and they will be reported in our Phase I Final Report this fall.

We are expecting further visits by Dr. McLaughlin and Dr. McGiffen in early May, prior to our trip to Washington DC, for further instructions and hands on advice in our project.

We also are collaborating with another EPA-P3 project conducted at CSUC studying water filtration, including the effects of the use of biochar as a filtration medium. We donated approximately 20 kilograms of rice hull biochars produced by our Olivier Gasifiers at Butte College for this purpose. We have visited the Soils Laboratory at CSUC where the water filtrations are being conducted by student interns under the direction of Dr. Sandrine Matiasek.


We have learned at Butte College during the performance of two EPA-P3 Phase I and one EPA-P3 Phase II projects since 2012, that the real value of the EPA-P3 program from the standpoint of the participating students is not technical discoveries or breakthroughs, but the experience of participating in hands-on, applied research projects working with fellow students under the guidance of a highly qualified and motivated faculty advisor and with the technical direction of a well experienced professional mentor with 55 years of worldwide experience. Nowhere is this more significant and important than at a community college level, where a meaningful experience of this type can be so important in the guiding of first generation college students in their career choices and future academic and professional lives.

We believe that it was this consideration that resulted in the award of our current EPA-P3 Phase I grant as expressed in the review comments: “The key strength of this proposal is an approach that effectively integrates a proven record of student engagement, a locally-relevant challenge, and a sound work plan that is appropriate to the time and budget allotted… Although the impact might not be as great as one might expect, the results/outcomes of carrying out the proposed work would certainly have an impact upon the overall mindset, as to energy and sustainability. There is a reasonable probability that success would result in benefits to the concept of energy and sustainability, at various levels.”

We intend to continue focusing on these values from the standpoints of our students in the completion of the current EPA-P3 Phase I project and in the proposed Phase II project.

Supplemental Keywords:

Biochar, biomass conversion to biochar, carbon-negative energy generation, biochar for soils heath, carbon sequestration through biochar

P3 Phase II:

Conversion of Agricultural and Forestry Biomass Residues to Biochar for Carbon Sequestration and Soils Improvement Applications  | 2018 Progress Report  | 2019 Progress Report