New Alaska handbook provides how-to on heated greenhouses

Cold-climate greenhouses have long been an option for increasing the limited growing season in Alaska, where fresh produce is a rarity in a harsh environment. But for many remote communities that rely on costly imported diesel fuel for their power source, they're too expensive to operate.
Now, the state has released a handbook that shows schools and community groups how to build greenhouses heated with a plentiful local resource: wood.
The 98-page guide comes as greenhouses gain popularity in the vast state for several reasons, including improved technology and heightened awareness, according to officials who worked on the handbook.
Thousands of schools in the continental US have gardens and some have greenhouses where students learn to grow food.

But Alaska's situation is unique given the lack of fresh produce from local sources in remote parts of the state.
"There's nobody that comes close," says Bob Deering, renewable energy coordinator for the Alaska region of the US Forest Service, the handbook's main funding source.

In villages off the state's limited road system, for instance, goods must be flown up or barged in. Steeply priced vegetables can be more than a week in transit and past their prime by the time they arrive at stores.
The new handbook covers a range of subjects from community planning and funding options to types of greenhouses and management of plant nutrients aimed at putting more locally grown food in Alaska kitchens and school cafeterias.

It also contains curriculum and case studies of projects by several schools, including the one in the small Prince of Wales Island community of Thorne Bay, in southeast Alaska, which installed a 750-square-foot (70-square-meter) aquaponics greenhouse three years ago.
The school was able to cheaply heat its greenhouse year- round with cord wood cut by students. Wood and variations such as cord wood, wood chips and pellets are known in the industry as biomass.
"They could never have afforded a greenhouse if they were heating their school with diesel heat," said Devany Plentovich, manager of the Alaska Energy Authority's biomass program.

A year in the making, the guide was funded by federal and state grants totaling $150,000. It involved input from multiple entities, including those with successful projects such as Thorne Bay, whose heating system was funded through the state biomass program.
Inefficient wood-burning stoves and outdoor boilers have created a huge pollution problem in Fairbanks. The boilers used in the greenhouses, however, are far more efficient, burning most of the pollution that otherwise would go into the atmosphere, thanks to a second combustion chamber absent in less sophisticated systems, officials say.