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Yakutat Biomass Resource Survey

  • Yakutat Biomass Photo 1
  • Yakutat Biomass Photo 2
  • Yakutat Biomass Photo 3

Project Summary

This project is a collaborative research effort between ACEP and the City and Borough of Yakutat, and Yak Tat Kwaan Native Corporation.

The community of Yakutat, located on the Northern coast of the Gulf of Alaska, generates 100% of its electricity and most of its heat from diesel fuel. At a cost of around $6 per gallon, the community is looking at biomass as an alternative heating fuel.

This project is designed to estimate the regrowth rates of Sitka spruce and western hemlock trees in the Tongass National Forest area of Yakutat for the purpose of supplying a biomass energy resource. From the 1950s through the 1990s, the old growth timber in Yakutat was harvested for export. Managing the forest for fast regrowth of high value timber through pre-commercial thinning can benefit both the forest and the community.  By removing smaller-diameter trees (4 to 6 inches), larger trees will have more room to expand, and those small-diameter trees can be used as a fuel for a biomass district heating project.

Project Need

As the community of Yakutat looks to incorporate biomass energy into their renewable energy plan, a big question remains: how much wood is available in Yakutat for a biomass energy project? A study of the available biomass and the sustainable annual harvest was necessary to understand what size and type of biomass unit would be suitable (chip fired, or corwood), and how much heat could be produced.

ACEP led the forest inventory survey in July and August, 2013. By including UAF interns and hiring local Yakutat employees we were able to estimate the forest regrowth rate since the clear cut harvests, and the amount of available biomass through a pre-commercial thinning program for a local biomass fired district heating system.

Project Findings

A survey of 25 200m transects in 25,000 acres found that the 1980s harvest sites (75% of the area) has 8-17 tons per acre available for harvest under a thinning program, whereas the 1970s harvest area (15% of the area) has around 35-69 tons per acre available for harvest by thinning (Table 1). Pre-commercial thinning to around 300 trees per acre will ensure faster growth for possible commercial use for the remaining trees.


Table 1: Average survey area measurements for all transects per cut age

Year Harvested

Mean Biomass/ac (ton)

Acres Per Age Group

Thinning to 300 Stems/ac  (ton/ac)

1952/57

108

2,500

160

1971/79

62

3,750

88

1983/89

15

18,750

26

The 1950s areas are naturally thinning through competition for light, though thinning could help increase the rate of growth, and yield some larger diameter trees (10 to 14 inches) useful as cordwood. The 1970s areas showed a great need for a thinning program as the trees are tightly spaced making it difficult for any trees to grow very large. Many of the 1980s areas have been very slow to grow back, if at all, and while the data shows 8-17 tons per acre, not all areas will benefit from a thinning program.

It is estimated that a harvest of 1000 dry tons of wood harvested annually through a thinning program can be sustainable, and provide enough biomass feedstock for a large chip-fired district heating project.

Next Steps

In order to ensure a viable, cost effective biomass-fired district heating system for Yakutat, a harvest and delivery cost analysis must be performed for a thinning program to determine the most cost effective method to remove up to 1000 dry tons of biomass annually. A study using local workforce labor rates would increase the potential for job creation in Yakutat for multiple local hires, and could eventually create an industry in the small community.

A biomass fired district heating loop in Yakutat could replace tens of thousands of gallons of fossil fuel annually by replacing diesel with wood. Keeping the savings in the community will ensure a strong future for Yakutat.


Photo 1: A student intern from ACEP and field technician from Yakutat measure a Sitka spruce and western hemlock stand 60 years after it was initially harvested. Courtesy of Amanda Byrd ACEP.

Photo 2: ACEP summer intern Henrique Fiche stands in a 1980s harvest site with closley placed trees. Courtesy of Amanda Byrd ACEP.

Photo 3: A 7ft diameter ~500 year old stump left behind in a 1980s harvest area that is slow to grow back. Courtesy of Amanda Byrd ACEP.