Gone with the wind: But where?

2009-10-28T22:01:01Z

For a few days, at least until Tuesday's winds came blowing in, the streets of Sacramento’s central city area were looking clean. The colossal mess left by the Oct. 13 storm was taken care of, for the most part. The giant fallen elm trees had been hauled away. Loose piles of branches and Mother Nature’s other castings were nearly all swept up, leaving the question: Where did all that clutter and debris go and where will all this new mess go?

Chances are that the old 100-foot tall elm tree that fell on a home on the 3400 block of J Street two weeks ago, could end up powering someone’s HDTV.

“Typically we recycle all the wood waste, grind it up into woodchips that are then converted into electricity at wood waste plants,” said Michael Root, an analyst at the city’s Urban Forestry Division.

Root, who added that not a day goes by when someone doesn’t point out the obvious relationship between his name and his line of work, said the cost of the cleanup far exceeds the energy savings, but there are other cost-saving benefits to alternatively disposing urban wood-waste.

“The main effect is the lowered cost of recycling the wood-waste, as compared to land-filling it,” Root said.

The cost savings is about half, according to Root. The city could cough up anywhere from $40 to $45 per ton to landfill the waste, as opposed to $20 to $25 per ton to have it handled by wood-waste recyclers.

Woodchips not burned in power plants are also spread around for weed suppression at recreation areas like the American River bike trail, or could be used to fill in the grounds at places like the dog park in Sutter’s Landing, Sacramento’s old landfill on the levee.

Root says approximately 100 to 125 trees went down in the Oct. 13 storm, but the total cost of the cleanup so far has not been determined. By comparison, the last big storm of January 2007 knocked down over 500 public and privately owned trees, costing the city a total of $128,425 for removal and disposal.

With most of the major cleanup of this month’s earlier storm completed by last Friday, Root says the city will move into the next phase: damage assessment.

Luckily, Root said, most of the more mature trees that fell during this year’s storm slowly uprooted and came to rest along buildings sides, rather than cracking and crashing down.

In one such instance near the McGeorge School of Law in Oak Park, a Chinese elm lifted up, then nestled itself along a library building. Buildings and grounds director Paul DeMersseman said the storm looked calamitous but caused no major damage.

“It looked like a tornado came through here,” DeMersseman said. He said that no damage was done to the building other than broken roofing tiles, but some tree branches hit a few parked cars in the area.

So, before fallen elms like the one near McGeorge become the power source to recharge some Californian’s iPhone, they are fated to one of the city’s ulmas purgare — or tree purgatories.

Sitting temporarily in empty lots around the city, these giant bark-covered carcasses await their final destination — either back to the earth or to a tree’s equivalent of cremation at one of the surrounding region’s wood-waste plants.

According to information provided by the California Energy Commission, there are three such facilities in the Sacramento region —one in Woodland and two in Lincoln. Combined, they can generate up to 71 megawatts of power — enough to power about 63,000 homes.

However, these plants don’t serve publicly owned utility companies like the Sacramento Municipal Utility District. According to SMUD officials, Sacramento gets its wood-waste electricity transmitted down from a 55 megawatt plant in Washington.

In the big picture of California’s energy production, urban wood-waste makes up a small portion of the state’s electrical output.

Including anything from old palettes found in landfills to uncontaminated leftover materials from construction sites, urban wood-waste is considered biomass – a renewable energy source that also include agricultural and other solid wastes. In 2006, biomass contributed about 2 percent to California’s electricity mix, according to the CEC.

Given the relatively low output of electricity from wood-waste, Luanne Leineke of the Sacramento Tree Foundation says she thinks all the expired trees from the city’s urban forest would better serve if mulched and returned to the soil.

“Mulch is wonderful,” Leineke said. “It’s organic material, full of organisms that are all great for future things to grow.”

According to Leineke, mulch helps to oxygenate the soil while keeping it impacted. If more mulch were used to replant new trees, Leineke said, they would grow stronger and less susceptible to storm damage.

Dr. Bruce Hartsough, professor at the UC Davis department of biological and agricultural engineering, agreed but said a balance needs to be struck.

“There’s uncertainty on both sides,” Hartsough said. "Fossil fuels are a finite resource - wood can provide an alternative - but there’s a trade off between how much you burn for energy and what you mulch.”

According to Hartsough, using woodchips for mulch is a viable option, but the practice operates in a niche market. “If you tried to take it all and sell it for mulch, you would saturate the market,” he said.

Hartsough, who has researched the potential benefits of forest biomass, says that while energy is currently the lowest-value market for wood products, branches and limbs that are too small for lumber are well suited for energy purposes.

Putting it into perspective, Hartsough added that in the end, California uses some pretty advanced technology to perform a very primitive task: burning wood for heat.

“In less developed countries around the world, about 80 percent of wood is used for heat and cooking,” Hartsough said. “It is a primary source of energy still.”

While researchers and policy-makers further debate about what do to with all the wood-waste, Sacramentans will do like they do every stormy season — continue to pick up the mess.

In the meantime, Root says the Urban Forestry Division is working on updating their tree inventory. He said soon the city will switch to a new Graphic Information System that tracks every public tree, allowing them to instantly determine which trees are public and which are private.

“In the next storm, we’ll immediately know what type of tree it is, and immediately know what type of service to dispatch,” Root said.

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Gone with the wind: But where?