Wood Biomass: The Good, the Bad, and the Ugly
Biomass energy has been on ISF's radar for years as a way to make excess forest biomass into electrical power. We are particularly interested in microgrids powered by biomass. Microgrids operate independently of the main electrical grid, although some are designed with optional connectivity.
Last year, when PG&E demurred on building more capacity in southern Humboldt, we interviewed Redwood Coast Energy Authority's executive director, Matthew Marshall, about whether their priorities for energy development include biomass energy. We learned that biomass energy is still not a sufficiently mature technology for grid-tied applications. So while Humboldt County has "emerged as a center of microgrid innovation," biomass energy in Humboldt has not kept up. All Power Labs has a good summary of the options and their respective challenges.
Biomass energy is also hampered by the logistics of collecting the biomass from the forest. Excess forest biomass tends to be widely scattered in challenging terrain with poor access. And transporting the biomass is expensive relative to its energy density. Forest waste must be dried and chipped. Chipped material has to be stockpiled under cover and loaded into the generator.
Converting biomass to electricity also produces substantial heat. The technology for utilizing this heat is much simpler than making electricity. Using the heat helps make biomass energy projects cost-effective. But the problem with using heat made from biomass is that the uses for the energy are usually far removed from the biomass sources - same as for electricity from biomass, but heat is much less economical to store and deliver. Where biomass energy has been successful in the United States, there is both a steady supply of biomass and a need for heat in close proximity, such as the Scotia Lumber biomass plant. But biomass is only as clean as its combustion, and Scotia power plant emissions have a poor track record.
Other countries have succeeded with biomass energy by using feed-in tariffs favorable to grid-tied power (e.g., Italy) or with very cheap labor to collect fuel for off-grid power (e.g., Vietnam).
Energy from biomass is only as carbon-neutral as the management practices in the forest or region where it is harvested. The key is whether overall forest practices build or deplete carbon reserves. To be sustainable, forest management must return surplus biomass to the limit of what the soil can digest (ideally more). Healthy soil incorporates carbon reserves in addition to what is visible. But when a forest is clear-cut and replaced with a monoculture plantation, it depletes both soil carbon and soil health.
Conventional power plants were built big to make energy cheaply from plentiful liquid and gaseous fossil fuels. Large-scale biomass plants require extensive plantations of fast-growing conifers for fuel. Theoretically, biomass energy plants have the same economy of scale as fossil fuel plants, but in practice they do not pencil out due to soil and water depletion by tree plantations and the cost of transporting the fuel, in addition to the vastly reduced habitat value of even-aged monoculture and the high risk of losing tightly spaced conifers to wildfire.
ISF believes that small-scale biomass power from forest thinnings has a place in the portfolio of energy sources for Humboldt County. Small local or mobile biomass power can be compatible with forest management that is truly sustainable.
Quoted material below is from Tom Wheeler and Luis Neuner of EPIC.
The Gonoike Biomass Power Plant, Kamisu City, Ibaraki, Japan. Photo by Σ64 via Wikimedia Commons (CC BY 4.0).
The concept behind wood-based biomass energy production is relatively simple: take forest debris, incinerate it, and use the released energy as a power source. Its large-scale usage, however, is often ethically tricky. In the best-case scenario, biomass could be a tool to address bad forest practices and help in the energy transition by producing baseload electricity or fossil fuel alternatives such as hydrogen. In most cases, however, using biomass for energy production can harm public health, incentivizes forest overharvesting, and contributes large quantities of greenhouse gas emissions (GHG) to an already burdened atmosphere.
Understanding the pros and cons of biomass is tricky. It requires nuance, a case-by-case approach, and the dissemination of science and conflicting information. We at EPIC have broken wood-based biomass into three admittedly over-generalized, but still useful categories: the Good, the Bad, and the Ugly.
The Good: Sustainably-Fed Micro-Plants
Let’s start with the best-case scenario. After centuries of systematic forest mismanagement, through means of fire suppression policies, clear-cutting, plantation creation, and overall gross negligence, our forests have become overloaded with fuels. To avoid high-intensity wildfires and push for healthier forest ecosystems, thinning operations generally use pile burning to reduce fuel levels. This fuel reduction is often considered a prerequisite to reintroducing low-intensity burns into the landscape.
The energy that is currently released into the atmosphere during these localized, small thinning projects could potentially be harnessed to help power nearby rural communities through small-scale biomass plants. When, for example, transmission issues arise, and renewable energy options such as solar and wind drop out of the grid, these micro-plants could be used to generate a baseload of electricity.
Because pre-commercial thinning has historically not produced a merchantable product, these projects all have had to be paid out of pocket. The U.S. Forest Service has packaged pre-commercial thinning projects with commercial timber operations to help pay for the pre-commercial work. Small, local biomass plants could therefore provide some money to help offset the costs of this type of forestry, both saving money and reducing pressure to log for profit.
Public health concerns regarding air pollutants and carbon emissions would remain, but the alternative to pile burning is also associated with similar side effects. More importantly, these energy sources’ minor, localized nature would also result in little risk of over-thinning forests compared to their large-scale counterparts.
The downside: small-scale biomass is mostly conceptual, as the costs to operate are high. Federal and state subsidies may make this a more viable tool in the future. There is also still the risk that once an investment is made to create a biomass plant, that facility would need to be fed in perpetuity, risking that energy production could force bad logging practices.
The Bad: Large-Scale Energy Dependence
Over the past 30 years, California has increasingly grown dependent on large-scale biomass facilities to supply a percentage of “renewable” energy units to the grid. While carbon emissions from biomass are part of the natural carbon cycle, unlike fossil fuels which put new carbon into the system that had been previously sequestered, the emissions from biomass are still considerable and are working to drive climate change now. Carbon emissions per energy unit produced from biomass are larger than that of coal. The fundamental importance of curbing emissions in the short-term means that large-scale biomass should not be heavily relied on in the green energy transition.
One example of biomass we should work to move away from is the Scotia biomass power plant, which produces energy from Humboldt Sawmill Corporation’s timber waste. The plant provides around 15 percent of the Redwood Coast Energy Authority RePower energy portfolio and is rated for around 30 megawatts (MW). It is also one of the greatest carbon emitters in Humboldt County, emitting far more carbons per energy unit compared to Humboldt Bay’s natural gas facility. Additionally, Humboldt Sawmill has frequently and periodically violated air quality regulations, emitting harmful, cancer-causing pollutants into the Scotia neighborhood and beyond.
To reduce these toxic emissions and address the climate crisis, the Scotia biomass plant will need to be phased out. How that happens—and how fast—is a question for public debate. A successful shutdown requires an operational alternative that prevents waste from turning into landfill emissions. That could be large-scale composting, other wood products, biochar, or a cleaner, more efficient hydrogen production plant. For that to happen, however, decision-makers must incentivize alternative ways to dispose of that mill waste now.
The Ugly: Poor Forest Management
Large-scale biomass schemes are uncomplicatedly bad ideas. Because the energy density of woody debris is relatively low compared to its coal cousin, trucking thinned forest debris over long distances is financially unfeasible. Therefore, a large facility that can consume a lot of residuals would require extensive tree-cutting within a certain radius to remain economically profitable. At EPIC, we see this as incompatible with responsible forest management practice.
A proposal brought forward by Golden State Natural Resources (GSNR) would build two new pellet plants in Lassen and the Sierras to process biomass into pellets (a more energy-dense form of wood) to ship across the seas for energy purposes. These proposals all but guarantee to contribute to greenhouse gas emissions heavily, resulting in bad forest management practices by creating the need to feed the beast — all while providing little benefit to local communities. Large-scale biomass, such as the GSNR plan, will likely never be effective, and EPIC is committed to fighting against it.