New Mexico Biomass Blog

Much of the debate over Western Water and Power’s proposed biomass facility to be built just south of Estancia has centered around the plant’s emissions, and how they may impact the air quality in and around Estancia and throughout the Estancia Valley. Opponents have publicized numbers that have been  occasionally accurate and often not, but in virtually every case grossly out of context, in hopes of alarming the public and government officials alike.  Sure, any level of pollution expressed in ‘tons’ may sound like a lot, and may sound dangerous, but what the opponents apparently don’t want you to hear about is the tons of pollutants emitted by coal-fired power plants – the most likely alternative to biomass energy generation – by wild fires and even by our own vehicles and the furnaces that heat our homes.  It’s when we start to compare the biomass project’s emissions with those kinds of sources that we begin to see that the opponents’ arguments don’t hold up.

The bottom line is that biomass energy compares very favorably when measured against the emissions sources that are all around us, all the time.  Biomass energy is far better from an emissions standpoint than fossil fuel-based energy sources and biomass energy can help mitigate horrific pollution from wildfires. This article is for those concerned enough to really dig into some of the detail that backs up those statements.  If that’s you, read on. 

Before we delve into the comparisons, though, let’s take a step back and consider the general concept of using biomass for energy production. While we’ve now heard from some radical groups that oppose this alternative energy source, well-respected and responsible environmental organizations like the Sierra Club, in noting the benefits of biomass, say: “Biomass energy provides plant-powered heat and electricity. Plants absorb and store energy from the sun as they grow. With the right technologies and careful attention to responsible land-management practices, the energy contained in plants can be harnessed to produce heat and electricity.” And that’s just what is proposed in Estancia.

Even without all the misinformation flying around, air quality is a difficult subject.  Some confusion arises because the air quality standards that the biomass project is required to meet are not well understood by the general public.  The plant has to meet ‘national ambient air quality standards,’ but what does that mean?  A perfect example of how the misinformation has been spread was the unfortunate resident who came to the Environment Department hearing in Estancia back in April.  He said he believed his was the closest property to the plant site, and wanted to know what he could expect in terms of livestock deaths and crop losses.

In a nutshell, the national ambient air quality standards require that even if you go out to the plant and walk right up to the fence and stand there all day long – not just anyplace along the fence but in the worst possible spot, with the wind blowing right at you – the quality of the air you’d be breathing would still meet all of the federal government’s requirements for safe, breathable air.  Anyplace farther away, the emissions of the plant are even more dispersed and the impact goes down even further, but the point is that even right there at the fence-line the air is still clean.  So, the answer to the resident’s question is: no harm to livestock (let alone death), no crops lost and, most important of all, no harm to people.  That’s how clean the biomass project has to be to meet the requirements.

And, by the way, unless you’ve installed sophisticated air filtration systems in your home you’d probably be better off breathing the air right there at the fence-line than you are breathing the air in your own house.  And that’s regardless of how clean you think you keep your home.

Well, there have been a number of studies of indoor air quality in recent years, and what’s generally been found is that it’s worse than outdoor air.  For example, carbon monoxide levels in homes with gas stoves range from 5 to 15 ppm, or even higher than 30 ppm if the stove is not properly adjusted.  By contrast, the National Ambient Air Quality Standards (NAAQS) do not permit outdoor CO levels to exceed 9 ppm.  Radon, another interior hazard, is also found at greater concentrations inside residences than outside them: while the average indoor radon level is 1.3 picocuries per liter (pCi/L), the average outdoor level is about 0.4 pCi/L.  And it’s no different for volatile organic compounds (VOCs).  The EPA notes that “studies have found that levels of several organics average two to five times higher indoors than outdoors.” In short, the air quality in our homes would probably not in most cases meet the ambient air quality standards that the biomass plant has to meet.

Another person who  attended the hearing in March got up to express concern about how the biomass plant’s emissions would affect the air quality around her house which is located about ten miles from the Project.  She stated that she had severe lung disease. and she didn’t want the plant’s emissions to hurt her land investment.  She also stated that she heats her home with wood from the forest and she does not use public utilities.

And where is just about the worst indoor air quality? Homes heated with wood. A recent study done by the National Environmental Research Institute and the University of Copenhagen investigated the effect of residential wood-combustion on air quality.  Particle levels in the wood-heated residential area were higher than those at a nearby background site.  In fact, these levels were comparable to the local traffic contribution observed at a busy city street. So, for the woman with the breathing problems, the answer is that with the biomass plant up and running the air in her yard is still going to be clean, and probably an awful lot cleaner than the air in her house.

So, what is all the fuss about then?  Tough to say.  With all that as background, though, let’s go ahead and compare the emissions figures for the biomass plant with some everyday sources of emissions to better understand the impact of the Estancia facility.

Everyday Pollution: Emissions from Driving and Heating

Even though it’s easier not to think about it, we have to keep in mind that even the most mundane of our daily activities emit pollutants into the atmosphere. The Estanica biomass project will generate electric power, and most forms of power generation do involve emissions, but beyond the electricity we use, emissions are generated by everything from the planes and trains we travel on and the factories that make all the consumer goods we use each day, to the cars we drive and the way we heat our homes.  Ranching and farming operations add to those emissions, too.  So, before we get upset about a small biomass project, and rather than talking about ‘tons’ of pollutants in the abstract, we at least ought to understood how the plant’s emissions measure up some other emissions sources we can all understand.

As a practical matter, there are too many variables in peoples’ habits and consumption – and not enough data – to really quantify the whole pollution footprint or carbon footprint of the average home with any degree of accuracy, so to give us something worthwhile to consider we need to limit the scope, make some reasonable assumptions and be conservative.   The following table details just some of the pollution derived from a ‘typical’ household, focusing on its vehicular and home heating emissions.  In this case, our typical household is assumed to own one passenger car and one light truck, and we assume the family drives the car and average of 12,500 miles per year and the truck an average of 14,000 miles per year.  The heating numbers correspond to an average home with oil heat that consumes 50 million BTU of 80-AFUE fuel oil per year. Again, while these figures cover two major household sources of pollution, they do not include a great many other sources, like travel, agricultural activities or the purchase or use of consumer goods.

(NO_x is nitrogen oxide, CO is carbon monoxide, CO₂ is carbon dioxide and SO₂ is sulfur dioxide.)

In order to make a comparison here we also need to break the biomass plant’s emissions down to a per household basis – that is, if the plant supplied the electricity to our typical household, what fraction of the plant’s emissions would be attributed to that household’s electricity use.  Here we have some helpful guidance from Public Service Company of New Mexico:  PNM generally considers 1 megawatt to power approximately 1,250 homes, so at 35MW rated capacity the Estancia facility will supply enough energy for about 43,750 households. With that, we can calculate the per household emissions of the plant and construct the table below comparing the per household emissions associated with meeting household transportation and heating needs with the per household plant emissions associated with meeting household electricity demand. 

The first column below combines the vehicular and heating emissions noted in the previous table.  The second column details the per household emissions from the proposed biomass plant (assuming it will power 43,750 households), while the third column adjusts for a  life cycle analysis from the National Renewable Energy Laboratory (part of the U.S. Department of Energy) which shows that direct-fired biomass residue plants can actually remove carbon dioxide from the atmosphere.  Specifically, the study found that such systems can have 134% carbon closure, meaning that they remove 410 g CO₂ equivalent per kWh produced. This net reduction in greenhouse gas emissions is attributed to the emissions from biomass decomposition that are averted by the cleaner and more efficient process of combusting the residue.

As you can see, the per household SO₂ emissions from the biomass plant are only a shade higher, and the NO_x, CO and CO₂ emissions are noticeably lower, than those from a typical household’s most basic needs.  In short, the plant emits on a per household basis approximately 1/10 as much NO_x, 1/148 as much CO and 2/3 as much CO₂ (not counting the NREL carbon closure factors) as comes from personal driving and home heating.  Again, this comparison does not include other sources of pollution like the life cycle impact of consumer goods or activities like farming – which would be sure to raise the household emission levels.  Bottom line, the biomass plant’s emissions – covering all of a household’s electricity needs – compare very favorably with what’s coming out of our tailpipes and chimneys.  Again the question: what’s all the fuss about?

Biomass Compared with Coal

Even though pressure has been mounting for the United States to increase its alternative energy generating capacity, over 50% of the domestic electricity supply derives from coal combustion.  This energy source is the worst offender in the incontestably dirty fossil fuel sector.  America’s energy needs continue to grow tremendously, and most analysts believe that the demand can only be met by increasing coal and, yes, nuclear generating capacity.  With the difficulties, expense and hazards associated with nuclear plants, however, coal is the most realistic choice.  There are other options, however, and biomass can play a critical role.  Every renewable energy plant constructed can effectively reduce, by whatever small amount, the number of coal plants that will continue to be constructed in this country.

When it comes to alternatives, some would prefer wind or solar over biomass.  Even these technologies, clean as they are, and aside from their high cost, have environmental and aesthetic drawbacks of their own.  Just as importantly, however, they are intermittent resources, working only at certain times of the day – i.e., when the sun is shining or the wind blowing – that do not necessarily correspond with electricity demand.  For our utilities to run their electricity grids they have to be able to match supply with demand at all times, and that is where biomass – a so-called firm resource that can provide power on demand – comes in to take the role that will otherwise fall to coal or other fossil fuel-fired power plants.  So, it makes sense to take a closer look at how the biomass plant’s emissions stack up to the typical coal plant.

The Union of Concerned Scientists notes the following: “Biomass reduces air pollution…it reduc[es] carbon dioxide emissions by 90 percent compared with fossil fuels. Sulfur dioxide and other pollutants are also reduced substantially.” The National Renewable Energy Laboratory study offers visual comparisons between coal and direct-fired biomass systems in terms of greenhouse gas, CO, particulate, SO₂ and NO_x emissions:

The second and fourth columns above are of interest for the purpose of this comparison. While a typical coal-fired power system has 0% carbon closure and emits 1,042 g CO₂ equivalent are per kWh produced, a direct-fired biomass residue system has 134% carbon closure and removes 410 g CO₂-equivalent per kWh produced. Again, this is because the fuel for the biomass facility – the biomass itself – emits more pollutants if left to decay than it would if combusted in a biomass facility.  Thus, the biomass facility actually provides an improvement from the status quo.

In addition, total system CO emissions from direct-fired biomass residue systems are notably lower than those from coal-fired plants:

Compared to systems that burn coal, those that combust biomass also offer substantially reduced particulate emissions per kWh produced:

Biomass offers a distinct advantage over coal in terms of nitrous oxide emissions:

Finally, sulfur dioxide – one of the main triggers of acid rain – is reduced substantially by direct-fired biomass residue systems.

Despite the environmental drawbacks of coal-fired systems, there are currently plans to add 2,350 MW of coal-based generating capacity in New Mexico.

 While the proposed biomass facility in Estancia would generate only 35 MW of capacity, it would help meet NM’s growing demand for energy in a way far more environmentally benign than will the coal plants currently envisioned.

Biomass Compared with Open Burning

Since the fuel for the proposed biomass plant is tree residue, one must consider the environmental impact of open burning – one of the residue’s alternative fates, and an especially likely one in some parts of the country like New Mexico.  Another study from the National Renewable Energy Laboratory offers the following comparison:

The numbers speak for themselves.The open burning of forests can have drastic environmental and economic consequences, not to mention the cost in human and animal life. According to the National Interagency Fire Center, “an estimated 6.9 million acres of wild land burned in 2002, costing federal agencies $1.6 billion to suppress. Forest fires worldwide emit at least 85 million tons of carbon dioxide, 13 million tons of carbon monoxide, 2.2 million tons of nitrogen oxides (a precursor of ground-level ozone), particulate matter, hydrocarbons (such as benzene), aldehydes (such as formaldehyde) and trace minerals.”

If biomass energy did nothing more than mitigate these emissions, it’d be worth it, but we get much more than that.  Terrible pollution is replaced with vastly lower emissions and a green energy source capture.  Economic losses are replaced with economic development.

Conclusion: Overcoming the Spin

We hope that the above numerical comparisons have helped provide some badly needed context for considering the emissions from the proposed biomass plant. Electricity generated from a biomass facility represents a pretty modest and reasonable component of the overall household emissions footprint.  And it is surely better to harness biomass as an energy source than it is to burn coal or to let rotting trees go up in wildfires.  Take care before accepting the statements of so-called environmentalists at face value.  Let’s overcome this bout of statistically-induced myopia and look towards cleaner air and a cooler planet.