Sustainability: Power Generation from Forest Biomass

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Salt River Project will be doing a test burn of forest biomass to produce electricity at the Coronado Generating Station in St. Johns. SRP water supply director Bruce Hallin will tell us more about the effort to produce power from forest waste.

TED: Tonight's edition of Arizona Sustainability looks at how Salt River Project will be doing a test burn of forest biomass to produce electricity at the Coronado Generating Station in far Eastern Arizona. Here now is SRP Water Supply Director Bruce Hallin. Thanks for joining us.

Using forest debris as supplemental fuel… explain, please.

BRUCE HALLIN: Well we have a challenge here in the state of Arizona to get our forests thinned. Not only in Arizona but throughout the Western United States, our forests are overgrown and we've seen these large catastrophic wildfires. The impact that it's having upon the Salt River Project is on our watershed. We have a 13,000 square mile watershed that most of the water originates from in the reservoirs, where we collect that water. Most of that comes from snow melt in those forested lands, and so from our perspective, we need a healthy forest to ensure a healthy watershed. These catastrophic wildfires have an impact on sedimentation--sediment loadings into our reservoirs--and an impact on water quality, and then there are obvious damages just to the ecosystems and the local communities.

So in order to get these forests thinned, and restored, we need forest products industry. We need someone to come in and thin those forests. Well unfortunately, there's a significant amount of material within those forests that is low-value biomass material. It doesn't have a large market for it.

If you look at an acre of forested land in Arizona, where you should have maybe 20 to 30 trees per acre, if it was more of a natural forest, now we have over a thousand trees per acre, and of those thousand trees, three-quarters of them are small trees where there's not a market. And so what we're evaluating is the opportunity to take this low-value material and process it and chip it and do a test burn at our Coronado Generating Station and actually burn some biomass.

TED: So when you say forest debris, what does that entail? When I think of forest debris, I think of things you kick around as you're hiking.

BRUCE: It's limbs, it's pine needles, it's the smaller stems… it's all that smaller material. The estimate is that there's about 25 tons of material per acre and of that 25 tons of woody material, 12 tons per acre is that low-value biomass.

TED: And the idea now is to burn this biomass, use it as fuel at a coal-fired plant. Not to -- to replace coal to a certain degree, but to help with the process, correct?

BRUCE: Exactly, it's really just to help with the process, to help with accelerating the treatments within the forested land and within the watershed. What we're looking at now is a test burn, no greater than 5% of the total fuel load within the power plant itself.

TED: How long would that test burn go on?

BRUCE: 20 days, 10 days at 2% of the fuel load and another 10 days at about 5%. We're gonna be monitoring impacts on the facility itself and also monitoring air quality, and so we want to get a real understanding of is this doable and is it something that we could move forward with.

TED: I was going to say, the impact on the machinery would be interesting to find out, because it could perhaps harm some machinery, could it not?

BRUCE: It could, and it's very important. Those coal fire plants are critical to our power resources. We need those coal fire plants to meet demand here in the valley for our power customers, so we don't want to put that plant at risk. But what we do want to do is evaluate and see if there is an opportunity at a low level to utilize some of this biomass and help accelerate treatments, because we also have a stewardship obligation on the watershed too.

TED: I know that there is concern as well that producing and burning the biomass for fuel may be not quite as efficient as other ways of getting fuel in there, correct?

BRUCE: It isn't a fuel of choice, no. It's more expensive than coal and more expensive than natural gas and other fuels, and the BTUs aren't as high as coal. So it's gonna take a little bit more material to burn when it comes to the actual weight of that material versus coal.

TED: Is that why we haven't seen much of this in the past?

BRUCE: Part of it. I think one of the reason's you haven't seen much of this in the past is that we have had alternative fuel sources. Secondly, no one has really evaluated this--at least within Arizona--the opportunity to co-fire such a small quantity of biomass within a coal-fire plant. This is really a first, at least within Arizona, at a large plant such as Coronado Generating Station.

TED: And the debris, in the past, what became of this stuff? Was it just burned? Did it actually do harm to the atmosphere?

BRUCE: You know, at this point, if we don't get those forests thinned, essentially all of that material will burn. It's not a matter of if; it's a matter of when because of the significance of the fuel load within that forest. Then that releases all of that carbon and other material in the atmosphere, and we're also concerned that if we don't find alternative uses for this biomass… the last thing we want to do is start piling up all of this biomass within the forest and then burning it.

TED: Right.

BRUCE: At least at the coal fire plant we have some air quality equipment there.

TED: Let's talk cost here. We've heard about forest restoration efforts in the past, and it's always been a great idea to find someone and pay them to take the stuff out and it can be used for x, y, z. Unfortunately, as you mentioned, the stuff they take out is low-value, and in some cases almost no value. So with that in mind, who pays for something like this?

BRUCE: At this point, we're working together to get a better understanding of what are the actual costs associated with this material. Some of the estimates are anywhere from $30 to $40 per ton to actually move this biomass. So transportation costs are a significant amount of the actual cost associated with moving this material.

Ultimately, from our perspective, there are a variety of organizations and agencies that benefit from forest restoration and to ensure those forests are healthy and so we're -- we're looking to partner with a variety of agencies and other organizations as part of -- following this test burn, to help, hopefully, fund and, hopefully, partner together to get this biomass out of the forest.

TED: It sounds to me like the cost would suggest that the federal government will probably have to get involved in some way, shape or form.

BRUCE: I think ultimately, the federal government will have to get involved when it comes to restoration. Initially, as you mentioned, the thought was the private sector. The private sector can step up and move this material. But I think what we're finding over the last few years, the economics are such that we're going to have to get support from the federal government and other agencies.

TED: I know environmentalists are concerned, they worry about those trucks and vehicles making -- paving new roads, making new paths and disrupting the environment. A concern?

BRUCE: Well, that's why they have this collaborative, this forest restoration initiative collaborative. The environmental groups are represented there, they put together prescriptions and they have programs and shall we say, treatments and limits on what they can and can't do in the forest, and so we have what I would say is full support from a variety of organizations and agencies that historically have battles when it comes to thinning forests.

TED: Well the whole idea sounds fascinating and encouraging, good to have you here.

BRUCE: Thank you very much.

Bruce Hallin: SRP(Salt River Project) water supply director

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