By Paul Davis, January 15, 2008
This document responds to Brent Racher's affidavit and response to the “Fuel-Wood Estimate for the Proposed WWP Biomass Plant near Estancia, New Mexico” developed by Paul Davis, Bud Latven, and Bill Fogleman and submitted to the NM Energy Secretary dated October 25, 2007.
A biomass plant near Estancia, NM is being proposed solely because of the New Mexico Renewable Energy Act (REA). The REA was passed to encourage the development of clean, renewable energy. With its allowance of higher rates for consumers and tax credits funded by consumers, the act seeks to move New Mexico toward permanent, clean energy sources. Spent wisely, an investment of our tax dollars at this time could provide continuous energy supplies for all time.
Energy sources such as solar and wind are clearly renewable. The sun will continue to shine and fortunately or unfortunately the wind will continue to blow in New Mexico. However, the use of biomass requires an analysis to determine if the rate of energy generation (in this case, tree growth) will meet the energy demand for all time. In addition, proof must be provided to demonstrate that biomass is available to the biomass owners. Available means contractually available, legally available, and available without harm to the environment.
In this light, two estimates of available biomass for the proposed Estancia plant have been developed. One was produced by the Native Community Development Corporation in July of 2005 under contract to the Public Service Company of New Mexico that estimated the total available fuel within a 50 mile radius without regard to renewability and with little regard for availability. Specifically, the issue of renewability (is the rate of energy generation (growth) equal to or greater than the rate of energy use) was not addressed at all. With regard to availability a very limited number of constraints were employed. Essentially this was an estimate of how much wood could be clear cut within a 50 mile radius of the proposed plant.
WWP has been touting this estimate for several years now saying it proves that three times the amount of wood the plant needs is available. However, they have never demonstrated that they have access to this wood or that clear cutting of all forests would be allowed.
A group of concerns citizens then took it upon themselves to evaluate the original PNM estimate. Because PNM would not provide all of the technical details of their estimate to these citizens or to the public at large, this group of citizens produced their own estimate independent of the PNM estimate.
Next comes Mr. Racher, WWP’s thinning contractor, with a criticism of our analysis. Unfortunately, Mr. Racher’s focus on criticizing our work did nothing to reduce the uncertainty about how much wood is renewable and available. That is, the shortcomings of the original PNM estimate were not addressed in Mr. Racher’s criticism of our work.
The fact that Mr. Racher did not clarify the hidden parts of the PNM estimate and the fact that Mr. Racher’s criticisms of our work did nothing the elucidate the amount of renewable and available biomass raises our first and perhaps the most serious concern. Three groups now (PNM, our work, and Mr. Racher’s criticism) have come up with different estimates of the amount of renewable and available biomas. Therefore there is an obvious need for the Energy Department to perform their own analysis. We support and encourage such an analysis with the requirement that any such analysis must address the key issues of renewability and availability.
Our second general response to the criticisms of WWP’s thinning contractor is that WWP has still not proven they have access to sufficient sustainable wood to fire the biomass plant for 20 or 30 years (or whatever their current number is). Mr. Racher attempts and fails to argue that the growth rate is sufficient to renewably provide fuel to the biomass plant and in doing so also fails to address whether or not such fuel is available to the owners of the biomass plant. When all is said and done we are left in the same position, WWP has not proven access to a renewable fuel source for their proposed plant.
The following is a response to specific criticisms raised by WWP’s thinning contractor.
Response to Specific Criticisms
1. ‘Bone dry’ versus ‘green’ tons.
WWP’s thinning contractor argues that we used the weight of green wood that the plant would consume, 55 tons per hour, and should have used the equivalent weight of dry wood, about 30.25 tons per hours. Such a difference would change our estimate of the lifetime of the plant from 3.2 to 5.3 years. If this is indeed a mistake, our calculation for the lifetime supply of renewable and available wood for the biomass plant would change to 5.8 to 9.6 years still far short of renewable and far short of the amount of wood needed to supply the biomass plant for its first 20 years of operation.
While this may seem like a simple straight forward mistake, it is not. Recognize first that the trees being proposed for use in the biomass plant are alive today and green. Therefore some conversion from green, wet wood weight to bone dry weight is required. In addition, wood is never ‘bone dry.’ We understand that wood will be allowed to dry out at the biomass plant prior to burning and will achieve an equilibrium moisture content which is related to the moisture content of the air but this wood will not be bone dry.
The original PNM estimate uses the term ‘bone dry’ but has refused to provide us with the data used in converting green wood weight to bone dry wood weight.
In addition, the basic concept of ‘bone dry’ is not defined. Sounds simple, but it isn’t. In the attachment entitled “Physical Properties and Moisture Relations of Wood.” Moisture content is defined as the ratio of the weight of water contained in the wood to the weight of oven dry wood. Since the density of water is greater than the density of wood, the article points out that, depending on the specific gravity of wood, the maximum moisture content can range from 267% to 40%. Most important, the moisture content does not vary from 0% (‘bone dry’) to 100% as most would expect and as the attached reference points out.
Conceptually, the moisture content at which only the cell walls are completely saturated (all bound water) and where no water exists in cell lumens is called the fiber saturation point. While a useful concept, the term fiber saturation point is not very precise. In concept, it distinguishes between the two ways water is held in wood. In fact, it is possible for all cell lumens to be empty and have partially dried cell walls in one part of a piece of wood, while in another part of the same piece, cell walls may be saturated and lumens partially or completely filled with water. It is even probable that a cell wall will begin to dry before all the water has left the lumen of that same cell. The fiber saturation point of wood averages about 30% moisture content, but in individual species and individual pieces of wood it can vary by several percentage points from that value. The fiber saturation point also is often considered as that moisture content below which the physical and mechanical properties of wood begin to change as a function of moisture content. During drying, the outer parts of a board can be less than fiber saturation while the inner parts are still greater than fiber saturation.
So what does all this mean? It means there is no simple concept of ‘bone dry.’ Bone dry could mean oven dried, it could mean no unbound water, or it could mean a fiber saturation of 30% or even 45%. Yes, bone dry could mean 45% moisture content. But this is not an unsolvable problem. If PNM would simply provide the public with the details of their analysis we would all know the meaning of ‘bone dry.’
Using the definition of moisture content above, it turns out that Mr. Racher calculation is wrong. Mr. Racher assumes that since the wood to be burned has a 45% moisture content he can multiply the total wood demand of 481,800 tons of wet wood by 0.55 and obtain the estimate of 24,990 tons of equivalent dry wood. Using the above definition the correct calculation is:
Weight of water/weight of wood = 0.45
Weight of water = 481,800 – weight of wood
By substitution of the second equation into the first, the weight of wood is:
Weight of wood = 481,800/ (1.45) = 332,275 tons of equivalent dry wood
Now do we have other evidence of what ‘bone dry’ could mean? Possibly.
· In WWP’s draft “Project Design Basis Summary” of March, 2007 the burn rate is given as 75 tons/hr. If we assume this is a ‘wet’ weight and then use the conversion of ‘wet’ to ‘dry’ wood weight from the data obtained from the Sandia Ranger District (see our original fuel estimate for reference), this would yield a dry weight of 56 tons/hr which is very close to the 45% moisture value of 55 tons/hr in the air quality permit. So perhaps, WWP has already done the conversion to equivalent dry weight. In which case our original analysis stands as is.
· As pointed out in our original fuel analysis, the (PNM’s) range in tons of dry wood per acre (tpa) is 3 to 32 with an average of 20 tons per acre of wet wood. A detailed study by the USFS and the University of Washington of piñon-juniper forests (which represent most of the forests within the 50-mile radius and are the main basis for WWP’s air quality permit) reveals that the tons of wet wood per acre for piñon-juniper forests ranges from less than 2 to 42 tons per acre and the average is 14.5 tons of wet wood per acre or 10.9 tons of dry wood per acre. For comparison, a recent USFS Nevada study indicates that there is only an average of 7.8 dry tons per acre of piñon-juniper biomass statewide.
Note that other studies indicate that PNM’s estimate is not an estimate of ‘bone dry’ fuel but is much more consistent with other estimates of wet wood tons per acre.
Bottom line, we have no independent way to evaluate the PNM calculations since they will not share them with us and we have plenty of evidence that our original calculations are correct.
2. Our use of ‘Rocky Mountain Juniper’ instead of one-seed juniper, pinon pine, and alligator bark juniper.
Contrary to WWP’s thinning contractors assertion that we used these data to ‘skew the output’ we used the data because it was available and the PNM data are not available to us. But beyond that Mr. Racher's assertion is incorrect and misleading. First the USFS data set we relied on did include pinon pine and some one seed juniper (see http://depts.washington.edu/nwfire/dps/ Site PJ 14 for example). However, there are no alligator bark junipers in the study and few one-seed junipers. Therefore, we appreciate Mr. Racher pointing out that we systematically overestimated the amount of biomass because the Rocky Mountain juniper is a bigger tree than either the one-seed juniper or the alligator bark juniper (see: http://www.ars-grin.gov/cgi-bin/npgs/acc/display.pl?1727184, http://plants.usda.gov/java/charProfile?symbol=JUSC2)
3. Prescriptions for Thinning.
Our report was based on the premise that some type of thinning prescription would be followed on state, federal, and private lands. So the question was, what prescription should we use? First we found the most recent and nearest thinning project to the proposed location of the biomass plant. That prescription came from the USFS Thunderbird project, a project that included pinon, juniper, and ponderosa pine. That prescription called for thinning 45 to 75% of the material. Mr. Racher is correct that in also applying a diameter cap we may have double counted. However, Mr. Racher failed to recognize that, as we stated, the USFS also mandated leaving 5-7 tons of biomass on the ground for soil development and stabilization. In our analysis we did not subtract this biomass from our available fuel calculation.
Next Mr. Racher questions our use of a diameter cap. Not only do we think a diameter cap is advisable we also believe that it is consistent with the original language of the REA and the stated position of WWP. Throughout the entire public process of permitting of this biomass plant, WWP has claimed they would only cut “small diameter trees”. For example, Mr. Maddox spent considerable time explaining (at the March 2007 air quality permit hearing) that one study in New Mexico shows “215 million trees less than five inches in diameter.” Over and over we have been told the biomass plant will solve the problem of juniper encroachment. For example, the WWP web site (nmbiomass.com) states that ‘Along with juniper, such trees are expanding at a rate of 10 thousand acres per year, which is not sustainable or healthy.’ They fail to mention that if this is indeed the fuel for the plant, these trees are all very small in diameter (from 1 inch to a few inches). In fact, if the goal of this plant was to address juniper encroachment, an age based thinning prescription could be developed since we know the timing of the start of juniper encroachment. Any age based thinning prescription would severely limit the available biomass. As the NRCS points out, mature juniper trees are typically 5 inches in diameter and 150 years old (ftp://ftp-fc.sc.egov.usda.gov/GLTI/technical/publications/Pinyon.pdf) But land treatment is not the reason for this biomass plant. It only exists for one reason – the Renewable Energy Act.
As PNM’s own analysis concludes in its executive summary:
Sufficient biomass would only be available if the following conditions are met:
- thinning yields must be maximized
- thinning is conducted on forests owned by multiple entities
In other words, they know they have to take it all.