Friday, November 1, 2013

Common Questions and Answers about Wood Heating

                                                                                        Updated: Jan. 2021
Q. How clean can wood heat get?
A. Residential wood and pellet heating is getting cleaner and has the potential to become far cleaner still.  The difference between a clean stove and a dirty stove is partially how the operator uses it.  One of the main motivations behind the WoodStove Design Challenge is to encourage more automation so that stoves are more assured to run clean, despite the operator’s behavior.  EPA regulations required lower gram per hour wood stoves as of May 2020, but they are still vulnerable to misuse in the hands of consumers unless innovation can begin to mitigate that problem.
Q. How many homes use wood heat and where are they?
A. There are about 12 million households that heat wood and pellet stoves of which about 2.3% use it as a primary or sole heat source.  The top 10 states that have Congressional districts with the highest number of wood and pellet heaters are, in descending order: Maine, Vermont, Arizona, Michigan, Montana, California, Wisconsin, Oregon, New Mexico and New York. The large majority of wood heaters are in rural and suburban areas.  US Census data shows that only 3% of homes that use wood as a primary heating source are in urban areas. 39% were in suburban areas and 58% were in rural areas. 
Q. Does the Alliance for Green Heat support incentives for stoves?
A. Yes, we especially advocate for incentives and rebates for the cleanest pellet stoves, but smart incentives can also be designed for wood stoves. Maryland and New York have innovative incentive programs for stoves that include efficiency criteria. And, Maryland has a model program that gives incentives for the cleanest stoves to families who heat with oil, propane or electricity.  Since almost all urban and suburban homes in Maryland have access to gas, this focuses new installations in rural areas and helps those families with the highest heating bills to access a more affordable and renewable fuel. More info.
Q. Does the Alliance for Green heat ever support banning new installations of wood stoves?
A. Yes, but only in very limited cases and never for pellet stoves. A number of urban areas and smaller towns that experience weather inversions that trap smoke have banned the new installation of fireplaces and wood stoves.    Those bans are almost always preceeded by incentives and a variety of other measures.
Q. Where does the wood come from?
A. Several studies, including one from the USDA, say that the majority of people who heat their wood harvest or gather some or all of it themselves.  Many cut live, dead or downed wood from their own land or from nearby state or federal land that allow firewood gathering.  Firewood vendors are often tree trimmers, or they buy logs from commercial loggers that were not marketable as saw logs for lumber.  Unlike many other countries, firewood harvesting in the US is very sustainable.  This is not to say, however, that levels of particulate matter from stoves are sustainable in many communities.
Q. How can we know that firewood is sustainably harvested?
A. Because most of it is gathered by the homeowner, or sold by very small mom and pop operations, most firewood comes from very small-scale, decentralized operations that are unlikely to pose significant sustainability issues.  The only report we have seen of significant unsustainable practices came from an operation in California that was making bundled, kiln dried firewood packaged that could be transported nationally and is mostly used in fireplaces, not wood stoves. 
Q. Isn’t wood heating likely to continue its historic decline since the 1930?
A. Not necessarily.  Wood and pellet heating experienced a significant comeback between 2000 and 2010.  When the Census started tracking wood heating in 1950, more than half of homes heated with coal and nearly a quarter with wood.  Wood and coal heating declined drastically (with coal continuing its decline and heating less than .1% of homes nationally) and wood bottomed out in 1970 when only 1.3% of homes used it as a primary heating fuel. Wood spiked after the 1973 oil embargo to 4% of homes nationally, and today is at 2.3%.  Wood use is closely tied to prices of competing fuels, and rises in oil, propane and electricity prices can move many homes back to wood. More info.  As states and communities seek to bolster renewable sources of energy, there should be a rise in incentives - and sales - of pellet stoves and boilers.
Q. Isn’t heating with wood simply too much work and too messy for most people?
A. Urban populations tend to avoid wood heating, but nationally wood and pellets were the fastest growing heating fuel between 2000 and 2013, according to the US Census.  Using wood pellets offers a much easier, cleaner and more automated option and modern more efficient wood stoves use far less wood. In rural areas, wood heating has great resilience because wood is so abundant, affordable and many people enjoy it as a heat source.

Q. How many people could sustainably heat with wood or pellets?
A. We think 5 – 10% of American homes could heat with wood or pellets as a primary fuel, compared to the 2.3% who use it as a primary fuel today.  While we think the number of homes using wood or pellets for primary heating could double or triple in the next 5 – 10 years, it could also cause rises in the prices of pellets and cordwood which have been more stable than fossil fuel prices.  In Vermont, about 15% of homes already use wood or pellets as a primary source of heat and about 50% use it as a secondary source of heat.   The limiting factor is emissions, not availability of wood.  A rapid rise of pellet heating would be much more manageable than a rapid rise in wood, unless a new breed of automated wood stoves could operate more consistently in the emission range of cleaner pellet stoves.
Q. How clean are certified stoves compared to older, uncertified ones?
A. Average emissions from older, uncertified stoves are often estimated to be in 25 – 40 grams per hour range and average emissions for EPA certified stoves in the hands of average homeowners may be in the 4 – 15 grams per hour range.  When tested in the lab, stoves are typically far cleaner than in real world settings. The problem is exacerbated because for every certified stove there are still 2 - 3 uncertified ones in operation.  In the hands of consumers, certified stoves can burn dirtier than uncertified ones if the homeowner uses unseasoned wood, does not give the stove enough air and/or doesn’t use enough kindling to get a hot fire started quickly. The emergence of automated stoves shows that there is a solution for poorly operated manual stoves.
Q. How much energy do wood and pellet stoves make in a year? And compared to solar?
A. Space heating by wood and pellet stoves make almost 10% of all residential space heating in the US per year, according to the EIA.  The EIA’s 2013 Annual Energy Outlook says wood and pellets made .45 quadrillion Btus per year for space heating, which is more than propane and almost as much as heating oil for space heating.   One reason that wood stoves save consumers so much money is that aside from the cost of fossil heating fuels, the fans and pumps on our fossil fuel furnaces and boilers consumer .13 quadrillion Btus a year, as much as all washing machines and dishwashers in the US.  Wood and pellet heating make 40% of the energy made by ethanol used in gasoline blending, according to the EIA, without virtually any subsidies. In a more relevant comparison, wood and pellets make .45 quadrillion Btus per year for residential space heating and solar panels make the equivalent of .15 quadrillion Btus for residential electric use, again without any significant subsidy.  See EIA report here.
Q. If wood and pellet stoves make so much more energy than residential solar, why is there so little policy focus?
A. Existing wood stoves are widely seen as not clean enough to incentivize in a broad way, but the lack of policy focus and incentives on pellet stoves and boilers is more difficult to explain.  Generally, the lack of policy focus at the federal and state level has hindered technology advancement.  In Europe, wood and pellet heating receive much more policy, incentive and R&D parity with other renewables.  In Italy alone, 1.7 million high efficiency pellet stoves have been installed since 2012 compared to less than 100,000 in the US. The absence of an Energy Star program, a green label or even any requirement to measure and report efficiency, leaves manufacturers with few incentives to build extremely clean and efficient appliances and leaves the public with virtually no way of knowing which appliance will save them more money. For more.  Since efficiency testing and reporting was required by the EPA in 2015, more and more stoves have reliable, third party efficiency values. For more.
Q. What types of technology will be at the Wood Stove Design Challenge?
A. The 2013 and 2018 Design Challenges featured several distinct kinds of technology that will be competing against each other.  in 2013, there were 3 masonry stoves, whose designs originate centuries ago but have been finely tuned in recent years.  There are 2 somewhat similar hybrid stoves that mix secondary and catalytic combustion systems and have among the very lowest emissions and highest efficiency of existing EPA certified stoves. Four stoves are controlled electronically through oxygen and/or temperature sensors.  One is a German downdraft model and one is a modified dragon stove design.  There will also be a range of innovative stoves, equipment and components in the exhibition area.
Q. If automated wood stoves are practical and so much cleaner, why aren’t they already on the market?
A. A few of them are, but so far the sensors and automated technologies are still mostly confined to the high-efficiency indoor wood and pellet boilers made in Europe and starting to be made in the US.  The next step is moving that technology from the basement to the living room.  Here is one analysis as to why American stove manufacturers have been resistant to integrating automation.
Q. What do mainstream environmental groups think about wood heating?
A. Most of the big environmental groups do not have much informational or policy focus on wood stoves, if any at all. But in the northeast in particular, many local and statewide environmental groups support wood heating.  There are regional groups that have mobilized around the pollution from outdoor wood boilers, an incredibly low-tech, high impact technology that is often very polluting.  And there is a campaign being run by the Dogwood Alliance and NRDC against using wood for electricity and especially against exporting wood pellets to Europe to make electricity.  The Environmental Defense Fund recently joined in a suit to require the EPA to expeditiously promulgate their new residential wood heating regulations. 
Q. Shouldn’t the focus should be on replacing older, uncertified stoves and on changing them out for newer, certified stoves?
A. Partly.  Changeout programs can be very effective, especially in small valley towns, where every single wood stove makes a difference in the local airshed. In larger regions, change outs would be very expensive.  To reduce PM 2.5, change outs are most effective by replacing old wood stoves for new pellet and gas stoves. Regulations banning the installation of exempt, uncertified or unqualified units are also very effective and should be a precondition to change out programs.  We also think regulations requiring new stoves to meet stricter emissions requirements are equally important.  More info.
Q. What do new EPA regulations hold in store for wood stoves?
A. The EPA promulgating new regulations for residential equipment in 2015, more than 25 years after their first regulations on stoves.  The 2015 regulations herald a much cleaner and more efficient future for wood and pellet heaters.  One of the biggest benefits is that outdoor wood boilers and many cheap steel wood stoves are no longer exempted from regulation.  The 2015 regulations also began requiring manufacturers to test and report their efficiencies.  More info.
Q. Is there a shift by consumers away from wood stoves and toward pellet stoves?
A. Yes, but it is erratic. Some years pellet stoves are far more popular in the marketplace than other years. In 1999, pellet stoves only had an 11% market share and but some years its closer to 40%, on average.  However, with rural lower income families, wood stoves are still the most popular because families harvest or collect all of some of their fuel on their own and do not have to pay for it.  For more.
Q. Is there any pending federal legislation that would impact wood heating?
A. Yes. The Biomass Thermal Utilization (BTU) Act of 2013 (S. 1007, H.R. 2715).  The Act would give a 30% tax credit for the installation of wood or pellet stoves or boilers that are 75% efficiency using higher heating value (HHV).  This would likely include up to 25% of existing wood and pellet stoves.  Co-sponsors: Senators King (I-ME), Collins, (R-ME), Shaheen (D-NH), Franken (D-MN), Merkley (D-OR), and Sanders (I-VT), and Representatives Michaud (D-ME2), Welch (D-VT), Gibson (NY-19), Kuster (NH-2), Nolan (MN-8), and Owens (NY-21).  More info and analysis.
Q. Are there any existing federal or state incentives for wood and pellet stoves now?
A. Yes.  Congress just passed a 26% investment tax credit for high efficiency wood and pellet heaters.  The credit is 26% for 2021 and 2022, declines to 22% in 2023, and goes away in 2024 unless it is extended, which is possible if not likely. Heaters need to be at least 75% HHV, based on efficiencies in the EPA database of certified heaters. The following states have rebates, tax credits or tax deductions for stoves: Idaho, Maine, Maryland, Montana and Vermont. In addition, Maine, New Hampshire, New York, and Vermont have incentives for pellet boilers. More info here and here.

1 comment:

  1. In the book you will read about the challenges of designing low-emissions biochar production systems from small-scale stoves to farm-scale pyrolyzers. Another section of the book is devoted to explaining simple tests to characterize biochar and methods for conducting valid field trials.Thanks:)