This article is part 2 of an EcoPress series focused on the theme of science and sustainability research at the Natural Resource Ecology Laboratory and the Department of Ecosystem Science & Sustainability. Part 1 can be found here.

By John Field

When I first moved to Colorado almost a decade ago I spent a lot of time recreating on the west side of Rocky Mountain National Park and the Grand Lake area, hiking through the Never Summers or looking for moose along the East Inlet trail.  I was blown away by how isolated and lush the whole area was, despite being only a couple hours’ drive from the developed Front Range.  Within a few years, however, the beautiful deep green hues of Shadow Mountain were marred with large blotches of orange as outbreaks of the mountain pine beetle began appearing thanks to a combination of dry summers stressing the tress and warm winters improving beetle survival.  Before long a majority of the trees you’d see were dead or dying, and news stories about the pine beetle epidemic all started including stock photos taken in the area.  Large swaths of beetle-kill now occur throughout the state, including the Cache la Poudre watershed right in our own backyard.  The low value of the resulting blue-stained wood means that harvesting it for timber usually isn’t profitable, and land managers struggling to maintain well-traveled roads, trails, and campgrounds have limited mitigation options at their disposal.  Roadsides throughout the region are lined with large stacks of wood and slash waiting to be burnt in place come winter.

Having witnessed the progression of the epidemic firsthand, I am excited to now be a part of the brand-new Bioenergy Network Alliance of the Rockies, or BANR.   The goal of the project is to advance the scientific understanding behind using beetle-killed wood as a feedstock for sustainable biofuel production, hopefully improving the economic viability of beetle-affected stand mitigation and “making the best out of a bad situation” in the process.  BANR is led by Dr. Keith Paustian here at CSU, and includes partners from the University of Idaho, University of Montana, Montana State University, University of Wyoming, US Forest Service, National Renewable Energy Laboratory, and Cool Planet Energy Systems.  The consortium is one of seven funded over the last few years by USDA’s National Institute of Food and Agriculture with the goal of laying the groundwork for regionally-appropriate sustainable bioenergy feedstock supply chains around the country.

Biofuel sustainability is a thorny subject that elicits strong passions from both defenders and detractors.  On one hand, biomass is a quintessential renewable resource that was the primary source of energy for humanity for much of history, now widely heralded as an important tool in the fight against climate change.  On the other hand, large-scale biofuel production is almost hopelessly intertwined with the modern global issues of deforestation and land use change, water quality, food prices, and land ownership rights.  Scientists and industry practitioners have been trying to untangle these concerns since ethanol first started receiving widespread attention in the 1970s, and while in many cases assessment science has improved, overall the public perception of bioenergy is decidedly mixed.

My contribution to the BANR project will be to assess the sustainability of biofuel production from beetle-killed timber from the perspective of its net greenhouse gas emission balance.  GHG accounting is a comfortable subject compared to many of the sustainability issues listed above in the sense that it’s relatively tangible and quantitative.  The concept is simple enough– take biomass that would otherwise eventually be mineralized back to CO₂ and use it to meet some of the energy demand that would alternately be met with fossil fuels, thereby reducing overall fossil fuel demand.  In practice this is easier said than done, and there are several ways a project could go wrong:

1. If the process of cultivating, harvesting & converting a feedstock requires so much energy that this new demand outweighs the fossil fuel demand reduction from the biofuel itself.  The existing corn ethanol market is pretty marginal in this sense- the emissions associated with nitrogen fertilizer production, tractor diesel fuel use, fermentation vessel heating, etc. that are ‘embodied’ in the fuel are at least half of those of the gasoline that the ethanol would displace, if not more.  Engineers have been studying biofuel supply chains for over thirty years, and we have a reasonably good handle on such emissions today.
2. If biofuel production diverts feedstock away from other productive uses (e.g., food markets), ‘leakage’ or ‘indirect emissions’ may occur as native landscapes are plowed out elsewhere to fill that unmet demand.  This has been a hot topic for economists for the last five years, and there is some evidence of a biofuel fingerprint on land use changes from the Great Plains to the Amazon, though the uncertainties around such estimates remain extremely large.
3. If biomass harvest disrupts the natural cycling of carbon through the ecosystem to the point that carbon stocks are lost and the land itself becomes a net C-source.  This one falls within the purview of ecologists and has been on the radar for about a decade, though the underlying accounting is still evolving.

For me, the exciting thing about the BANR project is that using beetle-kill as a feedstock largely sidesteps these concerns:

1. Cool Planet makes a modular fast pyrolysis system, theoretically enabling distributed fuel production near the harvest site and requiring minimal pretreatment.  Coupled with the fact that beetle-kill doesn’t require any energy for cultivation, this suggests that this supply chain might have a relatively low energy intensity.
2. Beetle-kill timber currently has minimal economic value, so there’s not much opportunity for indirect emissions from commodity market disruptions.
3. Beetle-affected tree stands are already undergoing extreme disturbance, in many cases transitioning to net C sources on their own.  While disruption of net primary productivity after harvest is highly problematic in most forestry bioenergy systems, here there is some evidence that beetle-kill salvage harvest is neutral or even beneficial for near-term system NPP due to canopy opening.   Additionally, the co-production of biochar may enhance carbon storage in soils, further improving the ecosystem C balance.

In addition to my emissions bean-counting, other ecologists, social scientists, and policy experts on the BANR team will be looking at the sustainability of this system from a variety of different perspectives.  The work is just now starting, but we’ll be checking in with updates as research progresses.  In the meantime, if you’re interested in reading more about general bioenergy technology, sustainability, or policy, check out the blog maintained by the students of the CSU Multidisciplinary Approaches to Sustainable Bioenergy IGERT program:

http://bioenergyigert.wordpress.com/