Seeing energy in the trees

Just west of Tree Tunnel Road on Highway 50, there is a dirt turnoff remarkable to most only because it’s the first place tourists can U-turn after missing the tunnel.

Farther up the road, however, where the gravel gives way to red mud, some 4,000 acres hold what could be the first major step toward a sustainable, renewable energy economy on Kaua‘i. And though most of the island has struggled to find a silver lining in winter’s endless clouds, the fact that Bill Cowern’s trees are thriving bodes well for all.

Cowern’s company, Hawaiian Mahogany, recently entered into an agreement with Green Energy Hawaii and the Kaua‘i Island Utility Cooperative to develop the first of four renewable energy projects for KIUC. When all is up and running in 12 to 15 months, Cowern’s trees will provide approximately 7.5 megawatts of electricity a day, one-tenth of Kaua‘i’s current peak load.

“We’re in deep (trouble) as far as energy is concerned,” he said. “It’s really important for our state to get more sustainable, to allow us to continue running our economy.”

The process involves slowly burning Eucalyptus and Albizia wood chips at a Green Energy Hawaii facility. The slow burn releases volatile gasses that, when mixed with oxygen, provides efficient combustion at high temperature.

Scientifically, it’s known as gasification, or thermal oxidation. Environmentally, it’s considered a “clean burn,” with very little waste. Almost all of the wood is converted directly to carbon monoxide and hydrogen. What’s left after that is still not waste.

“The ash content of Albizia combustion is 1.1 percent,” Cowern said. “And the composition of the ash is very similar to fertilizer.”

Reusing the waste as fertilizer is just one part of the “closed-loop system,” to use another environmental buzz phrase.

Some plant species are capable of “nitrogen fixing,” Cowern said. Eucalyptus trees can’t, but Albizia trees, long considered a pest because of their aggressive growth, can.

“Albizia is capable of taking nitrogen from the air and turning it into organic material that can be used by the plant to promote growth,” he said.

Albizia’s conversion rate is “astounding,” Cowern said, and the leaves and other waste from an Albizia tree make for good topsoil for non-nitrogen fixing plants.

To illustrate, Cowern pointed out a small grove of Eucalyptus trees, offset from a much larger grove by a muddy road. The isolated Eucalyptus were puny by comparison.

“They were all planted at the same time,” he said, gesturing at all the trees before settling on the little grove of immature trees. “But we forgot to fill that (area) in with Albizia.”

Because of its nitrogen-rich topsoil, Albizia alleviates the need for commercial fertilizers, which are made from fossil fuels and, as such, are tied to their rising prices. Cowern said Hawaiian Mahogany could save around $200,000 a year on fertilizer costs alone.

“And there are no chemicals in the runoffs to the streams and reefs,” he said.

Albizia trees promote grass growth as well. So much in fact, that Cowern and his two-person staff have to knock it down every three or four months. But nothing is wasted in a closed circuit.

“Grass is 10 percent of what we supply for fuel,” he said. “The ability to harvest it for a product is something we never anticipated.”

Everything on a tree farm is measured in tonnage per acre per year, and Cowern estimated that 20 to 30 tons per acre per year of grass that was once trash will now become fuel.

Though it sounds like they are going to burn everything in sight, Cowern plans to continue his mahogany business, providing the raw materials for high-end furniture and fence posts. But what was once a massive waste producer is now approaching a zero margin.

“Fifty percent of a Eucalyptus harvested for lumber is waste,” he said. “Even more so for smaller trees.”

Now, anything not from the trunks of the best trees — an estimated 3 million to 3.5 million pounds a year — will be sent to the wood chipper and converted into electricity.

Until the trees are 15 years old and ready for a full harvest, Hawaiian Mahogany conducts thinning harvests, removing smaller trees to give the larger, healthier trees room to grow.

In seven or eight years, when the mature trees are ready to be taken, Cowern will fully harvest the weak ones and coppice the healthy ones, cutting them off at the base so they can regenerate.

Because Albizia is viewed as a pest, Cowern said Hawaiian Mahogany will also harvest trees from other people’s lands for a small fee, and send it on to Green Energy Hawaii.

Though not officially associated with the company, Cowern is acting as Green Energy Hawaii’s unofficial spokesperson for the time being. The local investors that make up the company prefer to remain anonymous for now, though Cowern said that is only temporary. Hawaiian Mahogany and Green Energy Hawaii are also exploring other joint ventures, like turbine power to help support the biomass plant, and harvesting palm oil to produce biodiesel fuel.

On a day when oil futures hit $69 a barrel, Cowern lauded the stability of biomass-to-energy production.

“You’re not going to see the dramatic increases in this type of fuel that you’re going to see from oil,” he said.

The biomass production will create an extra 15 to 20 jobs, swelling Hawaiian Mahogany’s staff from three to close to 20 in the next year. Three or four jobs will be available at Green Energy Hawaii’s plant.

A second KIUC contract was recently announced with Barlow Projects, of Fort Collins, Colo., to develop a 3.5 megawatt waste-to-energy facility. Coupled with upcoming announcements of another biomass contract and a wind turbine contract, KIUC hopes to provide almost 200,000 megawatts of electricity annually from renewable energy.

“If all four projects are successful and can be brought online as proposed, they could provide up to 34 percent of the island’s energy needs in 2010, based on forecasted energy requirements,” said KIUC’s Shelley Paik.

“These numbers add up to a very meaningful 27 to 31 megawatts (per day),” said Walt Barnes, a founding director of KIUC. “Thirty megawatts is very significant considering current peak load is only 75 mega-watts and overnight off-peak load is only 30 megawatts.”


Your email address will not be published. Required fields are marked *


By participating in online discussions you acknowledge that you have agreed to the TERMS OF SERVICE. An insightful discussion of ideas and viewpoints is encouraged, but comments must be civil and in good taste, with no personal attacks. If your comments are inappropriate, you may be banned from posting. To report comments that you believe do not follow our guidelines, send us an email.