Biochar Production System

In the 150 miles that surround the area of the Palouse nearly 2 million tons of waste biomass are accumulated each year. This waste is nearly valueless, taking up valuable space at lumber mills that could be used instead for equipment or inventory. Currently lumber mills try to sell this waste biomass at up to 25 dollars a ton, and in many cases are even having to pay someone to ship it away. The idea is to take this low value waste and turn it into a high value product, biochar, which can be sold for $2000/ton. Along with the problem that the lumber mills are having, the farming industry is struggling with topsoil degradation. Currently the topsoil is becoming less and less nutritious which is creating problems for an industry trying to feed a growing population. As a consequence farmers are needing to use more fertilizer to grow the same number of crops. This causes both economic and environmental problems, as this is a cost intensive solution and reduces the amount of phosphorus available, a key ingredient in fertilizer. All these problems create a business environment with a unique opportunity to allow our product to kick start a brand-new market here in the U.S.

Development and Project Goals
Our team’s mission is to develop and prototype a model of a scalable, practical retrofit for modern, industrial boilers that will produce biochar for sale and heat energy. This design must account for multiple variables and allow control of input and output flow rates amongst other factors. ​

Design Goals
In an attempt to take advantage of biochar’s potential and start a new market in the U.S. the team is designing an attachment that will go on a pre-existing boiler and produce biochar at a continuous rate. This system uses exhaust heat from the boiler system to cook the waste biomass to produce biochar. This means that it will not take any resources the lumber mill already has. It is recycling various aspects of their operation to provide an economically viable solution to the biomass waste that is accumulation. This device will move lumber mills towards a minimal waste operation.

Design Specifications
The needs and constraints designated by the client for the final design include: continuous process​, easily integrated to a boiler system​, scalable industrial design, energy efficient design, dynamic control system​, and function as heat exchanger.

Mechanical Specifications
This section will be completed upon proper specification of materials.

Electrical Specifications
Project designs were requested to use an existing Programmable Logic Controller (PLC) produced by AutomationDirect; the Productivity2000. The PLC was a modular system with room for a power supply, main controller and communication board, and 4 I/O modules.

The PLC makes use of 4 modules; a toggle-switch based digital input, a relay-based digital output, an analog input reading voltage, and a Thermocouple input module. In addition to the modular I/O, a touchscreen control panel is used for user interface and will control motor operation and display temperature and oxygen levels. The project requires the control of 3 motors by use of GS1 Variable Frequency Drives (VFD's) also produced by AutomationDirect. These VFD's use industry standard Modbus protocol over a 2-wire RS-485 connection as their primary control communication. This connection supports addressable operations, thus allowing all three VFD's to communicate over the same connection.

Thermal Specifications
From speaking with our graduate student advisor, Brian Hanson, and various sources online who describe the production of biochar and the requirements of an effective system, our team came to understand the thermal requirements. Temperature is a major component of the resulting material output of a pyrolysis system. Cooked under higher temperatures, biomass tends to release higher amounts of volatile gas and tar-like bio-oils. Alternatively, when cooked under lower temperatures (those around 450°C), pyrolysis tends to lend a higher biochar yield, and a smaller amount of gas and oil.

Due to this understanding of the thermal constraints, our team has conducted testing to determine the quality of biochar cooked in the range of 450°C.

Project Learning
Biochar dates back 2,000 years to a civilization in a remote region of the Amazon Basin where regions of dark, highly fertile soil has been discovered.​ It is theorized that the ancient Amazonians used a process known as “slash and char”, where the biomass (plant material) were cut, ignited and buried to smolder.​ This process allowed the Amazonians to support a diverse agriculture and explains how their population grew to immense numbers.

Biochar is rich in fixed carbon and has an enhanced surface area caused by micro and macro pores that easily absorbed and maintain moisture and nutrients. When it is integrated into soil it works to bring soils from both ends of the spectrum, sandy and clay soils, to a more nutrient rich middle.

Biochar is a very powerful soil enhancer, which makes the soil more fertile, boosts food security, and reduces the need for some chemical fertilizers. Given all of biochar’s qualities it is capable of aiding farmers in meeting the demand of a growing population and reducing the need for more fertilization.

Concept Development
Biochar dates back 2,000 years to a civilization in a remote region of the Amazon Basin where regions of dark, highly fertile soil has been discovered.​ It is theorized that the ancient Amazonians used a process known as “slash and char”, where the biomass (plant material) were cut, ignited and buried to smolder.​ This process allowed the Amazonians to support a diverse agriculture and explains how their population grew to immense numbers.​ Biochar is rich in fixed carbon and has an enhanced surface area caused by micro and macro pores that easily absorbed and maintain moisture and nutrients. When it is integrated into soil it works to bring soils from both ends of the spectrum, sandy and clay soils, to a more nutrient rich middle. Biochar is a very powerful soil enhancer, which makes the soil more fertile, boosts food security, and reduces the need for some chemical fertilizers. Given all of biochar’s qualities it is capable of aiding farmers in meeting the demand of a growing population and reducing the need for more fertilization.

Test Results
Low-quality biochar can be just as harmful as its high-quality counterpart is helpful. A great many backyard gardeners and growers have learned how detrimental poor biochar can be to the soil and garden environment. Poor biochar can be acrid, thus adding unneeded acidity to the garden soil. Poor biochar also isn't very porous, and thus can't retain nutrients or water well.

Preliminary Biochar "Pipe" Quality Tests
As an initial benchmark our team decided that it would be valuable to run some initial tests on biochar production. With some assistance from graduate student Brian Hanson, our team was able to conduct tests on biochar of various materials at different temperatures. The results have helped to guide our team towards some of the thermal requirements before mentioned.

To complete our tests, our team used a testing apparatus consisting of a metal pipe caped and sealed at each end. The metal pipe provided a 0-oxygen environment since after being filled with biomass, the pipe was filled with the inert gas nitrogen and then sealed. This apparatus was then placed inside an oven and "cooked" at various temperatures for varying lengths of time. We cooked a variety of materials to see the differences between the resulting biochar material.

Our team cooked such materials as wood chips, coffee husks, and wood fiber. This was important to our development since although our project primarily deals with wood chips, the other materials could prove to be future biomass sources.

Biochar Reactor Quality Tests
This section will be completed upon completion of construction. When the biochar reactor is functional, then it will be used to test various configurations and determine biochar quality.