Company develops algae/wood-to-methane system

By Anna Austin
Posted September 9, 2010 at 3:42 p.m.

A Whitefish, Mont.-based company is working to further develop a greenhouse-based algae growth/anaerobic biodigester system that transforms algae and wood waste into methane for heat and power production, as well as an organic fertilizer.

Algae Aqua-Culture Technology was formed about two years ago, according to CEO Michael Smith, with initial research focusing on growing algae in geothermal water. After discovering the amount of geothermal water available was not sufficient for the size of the project, it was moved to Columbia Falls, Mont., to Stoltze Lumber Company mill. "They had a boiler problem-very old boilers that they needed to replace-and we had this algae project, so we thought we could help them by capturing their waste heat and CO2 as they upgrade their boiler system and pipe it into our system to supply the heat and energy needed for these algae ponds," Smith said. "We thought we could generate enough electricity to power our facility and the mill at the same time, and as we began looking at the outputs we realized that the anaerobically digested algae and biomass coming out of the system was producing a very high quality organic fertilizer. Because we're controlling the inputs-we're not using sewage, landfill waste or anything-we can get the material certified as organic. One thing that people involved in algae and bioenergy are doing is focusing on its ability to fix nitrogen."

Currently, the fertilizer is worth about 10 times more than the electricity produced, Smith said. "That's because the price of electricity is still relatively cheap up here. It's scheduled to go up, but it's fairly low right now."

Dubbed "Green Power House," the complete system consists of multiple components. "The reason it's a green house to begin with is because it takes warmth year-round to grow algae so we needed a covering for it," Smith explained. "Our photobioreactors in which the algae are grown are basically flat, horizontal pond systems that are covered with a plastic material so we can enclose that CO2 that comes in from the outside. We take the waste CO2 and heat from the existing boiler stack from the mill-they generate steam for the kilns to dry the timber-and send them to the algae as feedstock."

The other main component of the system is an anaerobic bioreactor/digester, which is a specially- designed two-stage digester that Smith describes as a pipeline. "We separate the bacteria using precise temperature controls, during the asthmogenic and methanogenic phases of the bioreactors, and we use computers to control those temperatures," he said.

After hydrolysis begins, the algae are pumped into the first stage of the bioreactor, where it is held at about 70 degrees Fahrenheit. "It's more of a fermentation stage," Smith said. "Once that stage is done-it takes five days-we start raising the heat up to the temperature of the methanogenic phase, and drop that down into another tank. The nice thing about the way this system works is that it uses computing-a lot of parallelism and pipelining in order to get better throughput."

After other various stages, methane is pulled off and sent through a microturbine to generate electricity to operate the process, some of which is sent back to the mill. The CO2 released from the microturbine is sent back to the algae tanks as feedstock to grow more algae, demonstrating a closed-loop system. Though right now the power produced is just enough the fully power the Algae Aqua-Culture Technology facility and process, and also a little extra for the mill, Smith said in following stages that amount will increase. "This is the first stage, and we have up to two acres we can grow in. This covers about 1/8 of an acre so as this project proves out to be successful, we'll expand," he said.

While the idea right now is to use these systems on-site at small and medium scales, Smith said it could be economical on a large scale. "We've had discussions with coal-fired power plants and oil refineries and have concluded that it could very well work," he said. "There's certainly a lot of excess heat and CO2, it's just a matter of balancing the amount of each available, as well as nutrients, so that we can keep the process running continuously. "

Now armed with a $350,000 grant awarded by the Montana Department of Environmental Quality, Smith said his company has enough capital to complete one Green Power House. In order to make the technology fly economically, however, between three and five units must be built. Financing has been the biggest challenge, he added, as everything until now has been financed out-of-pocket.

Following capital costs, Smith said the most difficult part in developing the system hasn't been advancing the technology, rather it has been integrating the many components of the system. "We're not genetically modifying algae or doing rocket science, as the science behind these technologies has been around for 100 years," he said. "The idea is for each one of these components to be autonomous and controlled by an autonomous agent, and matching inputs to outputs isn't trivial."

Smith, who has an extensive background in software engineering, helped design the character physics for the football video game Madden NFL, in which each character required hundreds of inputs to demonstrate that it is doing something humanistic. "If we can do that in a gaming technology, there's no reason we can't come up with processes and controllers that can regulate the amount of CO2 and heat that are available through the diurnal cycle. All of those parameters should be very easily controlled."