This map shows which states historically have the highest percent of residents claiming the energy tax credits, including the credit for wood and pellet stoves.
Feb. 9, 2018 – Today President Trump signed into law a budget deal that included a one year, retroactive extension of the wood heater tax credit. Thus, consumers who bought stoves that are 75% efficient or higher may qualify for a $ 300 tax credit on their 2017 taxes.
However, stove manufacturers often mislead consumers into thinking they are buying a stove that is at least 75% efficient when in fact it may be in the low or mid 60s. Manufacturers are allowed to self-certify which stoves are eligible for the credit and some appear to ignore any common sense definition of the Congressional language which stipulated requiring a stove “which has a thermal efficiency rating of at least 75 percent.” The Alliance for Green Heat is calling on HPBA and stove manufacturers to publicly support and abide by a policy of only recognizing the average, overall efficiency of stoves based on third party testing at an EPA approved lab. Currently, some manufacturers will self-certify a stove to be eligible for the tax credit if it reached 75% efficiency on only one of its 4 burn rates. Others self-certify that their stoves are eligible when the stove did not reach 75% efficiency on any burn rate.
The Alliance for Green Heat supports tax credits and other incentives that focus on the cleanest and most efficient stoves. However, he federal tax credit has no criteria for grams per hour and virtually all stoves have claimed to be at least 75% efficient, minimizing the underlying intent of a tax credit.
The definition of 75% efficient is still unresolved. The IRS recognized the use of the European lower heating value (LHV) efficiency measurement until 2010 when Congress removed the LHV language. The efficiency measurement should have reverted to the North American standard of using HHV, but industry has continued to use LHV. (A stove measuring 75% efficiency using LHV would be about 70% efficiency using HHV.)
We will update this blog as it becomes more clear which companies are self-certifying stoves at 75% efficient when they may only be in the low or mid 60s.
To be sure that you are buying a higher efficiency stove, check the EPA’s list of certified wood stoves, and choose one that with an actual, verified efficiency. There are many non-cat stoves over 70% efficiency and many catalytic and pellet stoves over 75% efficiency. Unfortunately, if you are buying a stove in 2018, there is no guarantee that you will be able to get a tax credit for it. Congress may make the credit retroactive again in 2019, but then again, they may not.
For more background on the wood heater tax credit, click here.
2017 may not have been the most momentous year for wood and pellet stoves, but every year is full of important stories and these are what we see as the top 10. Think we missed one of 2017’s top stories? Leave a comment.
1. Wood stove sales lag
Warmer winters and lower fossil fuel prices are likely the main causes of continued sluggish sales of wood stoves and inserts in 2017.Gas appliances continue to gain in popularity.The 2015 EPA regulations are rarely cited as contributing to the current malaise in the market, and local restrictions are unlikely to have much of an impact either.The final weeks of 2017 and first week of 2018 brought arctic temperatures to much of the US, boosting sales of both pellets and stoves. But will it last?
2. Funding for change out programs rolled back
Whoever thought a motorcycle company would deal a big blow to the stove industry?To be fair, it had little to do with motorcycles and a lot to do with the Trump Administration wanting to do away with out-of-court air quality violations settlements that allowed polluters to pay part of their fine in programs that improve air quality. Harley Davidson happened to be the poster child of companies willing to support a change out program, but not allowed to do so by the Trump Administration.That pipeline of funding, up to 10 million a year, is now cut off, dealing another blow to programs seeking to get people to part ways with their old wood stove, and exchange it for a new pellet, gas or wood stove.
3. Congress – lots of expectation but no action
Three key initiatives – the BTU Act, the NSPS delay and the biomass heater tax credit – did not come to fruition in 2017.All three initiatives remain in play in 2018, but with each passing month, 2018 will get more consumed by the fall election season. The BTU Act would help the entire biomass thermal energy sector and has some key backers, such as Senator Susan Collins (R-ME). The bills to delay NSPS deadlines by 3 years passed committees, largely on party lines.With the razor thin majority in the Senate, Democratic support for these initiatives may be more important in 2018.
4. Cordwood test methods are on the rise
The ASTM E3053 cord wood test protocol developed largely by industry members was completed and is now an accepted alternative test method.However, companies don’t appear to be lining up to use it to certify their stoves.Meanwhile, NESCAUM is taking the lead in designing what they say is a much more realistic cordwood test method as it takes into account more frequent reloading.That method appears to have EPA’s interest and may be more likely to be referenced by the federal and/or state governments.
5. The renewable energy movement gains steam, helping pellet systems
Despite a President who champions coal and fossil fuels, the renewable energy movement is gaining ground worldwide.Automated pellet and chip heating systems are being installed more rapidly in Europe and are gaining wider acceptance in the US. Pellet stoves and boilers are also becoming more recognized in green building circles.Campuses, towns, cities and states striving to reduce fossil fuel use usually start with electricity and transition to green heating options.
6.Anti-wood smoke groups gain legitimacy
In 2017, we saw a rise of clean air groups campaigning for more restrictions on wood stove installation and use.Some of the core activists emerged years ago when their communities or homes were subjected to excessive smoke from outdoor wood boilers.In 2017, the focus shifted more to wood stoves, mostly in communities in the West, but to some extent in the Northeast.Often, tensions rose over lack of enforcement by local jurisdictions who didn’t have the resources, training and/or political will to deal with those creating excessive smoke.Overall there is a growing recognition that wood smoke is a serious health concern and debates in local and state forums will likely grow in coming years.
7. Consolidation of stove and pellet plants continues
In the wood and pellet stove world, Hearth & Home Technologies (HHT) did not announce major new acquisitions in 2017, but the company consolidated by moving Quadra-Fire and Vermont Castings production to its Pennsylvania facility.However, 2017 also saw market share continue to slip away from higher-priced manufacturers like most HHT brands to the lower priced manufacturers that sell from hardware chains.On the wood pellet front, Lignetics continued its buying spree, finalizing a deal to acquire New England Wood Pellet at the very end of 2017.
8. DOE co-sponsors Wood Stove Design Challenge
After many years of sitting on the sidelines of thermal biomass, the Department of Energy found an entre in the 2018 Wood Stove Design Challenge.DOE is providing funding and its PR department is issuing news releases, lending greater credibility and a higher profile to the event.The competition features automated stoves and stoves that produce electricity to supplement wintertime solar PV output, showcasing new roles that wood stoves could play if they run more reliably cleaner in real world settings. The competition will also showcase cordwood testing protocols and fossil fuel reductions achievable by wood stoves compared to solar panels.
9. NY, MD and MA recognize efficiency in stove programs
In 2017, three states began using efficiency criteria to determine eligibility in incentive or change out programs.NY now requires pellet stoves to have verified efficiencies on the EPA list of certified stoves.MD & MA provide higher incentives for stoves with verified efficiencies, as Oregon does, but with a far simpler formulas.The rampant practice by most manufacturers of providing misleading and exaggerated efficiency values – a practice not tolerated in other HVAC sectors – motivated these states to act.
10. The new EPA wood heater regulations move forward
OK, 2017 was not a big news year for the new heater regulations, known as the NSPS.But in 2017 all large forced air wood furnaces were required to be certified (including smaller ones who pretended to be large to evade certification in 2016).In April, there were only six EPA certified furnaces ranging from 48% to 89% efficiency, now there are 16.2017 was a pivotal year in that it marked the midpoint between 2015 and 2020, when all heaters must meet stricter emission standards.And, with each passing month, more heaters become 2020 compliant as manufacturers hedge their bets in case Congress, the Administration or the courts do not derail the 2020 deadline. In 2017, some exciting new innovation hit the market, including automated MF Fire Catalyst, the Optima designed just to burn pressed logs and more coming soon. Did we miss something? Post a comment!
Retailers say BTU output can be most confusing issue
Glenn Robinson is one of many retailers struggling to help consumers avoid relying on manufacturer claims about BTU output.
Glenn Robinson has been selling and installing pellet, wood and coal stoves in Pennsylvania for 11years, and one of the biggest problems he faces is sizing the stove. “I became tired of false information from manufacturers about how many BTUs they claimed their stoves put out” he said in a recent interview. “Customers see these exaggerated BTU numbers from a small stove and think it will heat their home, but it won’t. The result is that the stove is undersized and there is premature wear and tear. One model from a big name brand would only last for 3 – 4 months before needing repair or even full replacement,” he said.
Glenn is not alone in identifying exaggerated BTU listings as one of the biggest problems consumers face in buying a stove.Scott Williamson, a Massachusetts pellet installation and repair technician says that he sees stoves “all the time that are being run on high 24/7 and pellet stoves just aren’t designed to do that.”Both installers say that under sizing of pellet stoves is one of the biggest problems, and urge customers to consider larger (higher BTU output) stoves if they live in average size homes in the northern half of the country and plan to use the stove a lot.
Buying a pellet stove can be a confusing process for consumers. Retailers are likely to push the brands they sell and manufacturer websites don’t tell the whole story.Objective, third party reviews are rare and often outdated.Consumer Reports did a pretty good review in 2009 but used very limited criteria and didn’t test for durability.The Alliance for Green Heat (AGH) also undertook third party testing in 2015 and issued a detailed online reporton some issues including BTU output, maintenance and efficiency. (Like Consumer Reports, AGH conducted completely independent testing by purchasing all the units and doing all of our own testing.)
This blog identifies and discusses six rules for consumers to keep in mind when buying a pellet stove, with a focus on sizing.This is not an exhaustive list but it’s a good place to start: 1. Don’t undersize, 2. Beware of cheaper stoves, 3. Look for range of heat output, 4. Understand maintenance requirements of the stove, 5. Look for cleaner stoves and 6. Beware of stoves with no efficiency on the EPA list
AGH tested six popular pellet stoves. Almost all performed well during intensive 30 day testing, but did not live up to some manufacturer claims.
Pellet stoves can be a very effective and affordable way to provide primary or secondary heat for your home without the smoke that wood stoves often create in the hands of the typical user. Wood stoves require lots of work on the fuel side of the equation, but pellet stoves involve more work on the appliance side of the equation.
The Alliance for Green Heat also monitors advertising of pellet stoves and has found over the years that the great majority of companies vastly overrate the amount of heat their stoves put out.The EPA list of certified wood and pellet stoves is not perfect but it remains the best source of BTU output for consumers.
Most EPA-certified pellet stoves are listed as producing a maximum of 25,000 – 40,000 Btu and minimum of 7,000 – 13,000 Btu. The average pellet stove on the EPA list, according to data provided by third party test labs, put out a maximum of approximately 31,800 Btu and a minimum of approximately 10,050 Btu.
The stove with the highest maximum Btu on the EPA list is the Harman P68 at 53,500 Btu (advertised at 71,200 Btu input).When a stove manufacturer lists Btu input, it refers to amount of Btus in the fuel, if you were to get 100% of those Btus into the room.But the average pellet stove is around 73% efficiency, which means you will get 73% of the fuel’s potential heat into the room.(This is similar to the AFUE – the annual fuel utilization efficiency – that is used on gas and oil boilers and furnaces.)
The stove with the lowest maximum Btu is the Thelin Gnome pellet stove that puts out up to 9,000 Btus.However the company advertises three times that – 27,000 Btus – without any explanation.Manufacturers usually exaggerate Btu, thinking that it will make their stoves more attractive, but in the case of the Thelin Gnome, there are people looking for stoves to heat very small places and the exaggerated Btu output may make them think even the Gnome is too big.
Here are six critical things for consumers to keep in mind when purchasing a pellet stove:
1.1. Don’t undersize. If the stove is going to be your primary heat source you will likely need a medium or large pellet stove, even if a smaller unit advertises high BTU output.Ignore BTU numbers on manufacturers websites and literature and check the EPA list.The maximum output for pellet stoves is in the 30,000 – 50,000 range, enough to heat all or most of a small or medium house in most climates. “Don’t plan to run the stove all the time at its highest setting,” warns Scott Williamson “or you will be calling someone like me to fix it quicker than you think.” When we tested six popular pellet stove models, we calculated an output of no more than 21,000 BTUs, far below what the EPA listed and even farther below what manufacturers claimed.
(It is possible to oversize the stove and that can be a problem, but is not nearly as common as under sizing.“For example, the Harman P68 is notorious for being installed in small areas like mobile homes but they gunk up when they aren’t allowed to get up to temperature for a bit before they shutdown,” says Scott Williamson.)
2.2. Beware of cheaper stoves. There are some good budget wood stoves on the market, but with pellet stoves, you are more likely to get what you pay for than with wood stoves.“If you want a reliable stove that puts out a lot of heat, we urge customers to ignore pellet stoves under $ 2,500,” says Glenn Robinson. Scott Williamson generally agrees but has seen some basic stoves like the Pel Pro and Englander hold up pretty well.
3.3. Check for range of heat output.Most stoves can put out about 3.5 times more heat at their highest setting, compared to their lowest.Some stoves have a tiny range, putting out only 1.5 times more heat at their highest setting.If you live in a more moderate climate, in the early fall and late spring, you may want just a little heat, and still have the capacity for much greater heat output on the coldest days and nights of winter.All other things being equal in a stove, you may want a stove with a larger range of heat output and you can check the range of all stoves on the EPA listof certified stoves. In our tests, we found that the Enviro M55 insert ran continuously for an impressive 49 hours on its lowest setting with a tested hopper size of 60 pounds and it ran for 22 hours on its higher setting.However, with a 37-pound hopper, the Englander 25 PDVC only rain for 15 hours on its lower setting and 13 hours on its highest setting, indicating a very low turn down ratio.
4.4. Understand maintenance requirements. If you don’t clean your stove regularly and have it professionally serviced once a year, don’t expect high BTU output.Most consumers get subpar performance from stoves and have to repair them more often because they are not maintaining their stoves according to the owner’s manual.Pellet stoves are not like wood stoves: they have lots of moving parts and need cleaning of the burn pot and inside the stove on weekly, and depending on the stove, a daily basis.Pellet stoves that are not cleaned regularly can lose 10% or more of their efficiency – and their heat output, and lead to costlier repairs. Understand the daily, weekly and annual maintenance requirements from the start and don’t put them off.When we tested six popular pellet stoves, we found that the three more expensive ones (Harman, Quadra-Fire and Enviro) could go for a week or more without cleaning the burn pot.However, the Englander, Ravelli and Piazzetta needed daily burn pot cleanings.
5.5. Look for cleaner pellet stoves.Pellet stoves are far cleaner than wood stoves, even if they both have the same particulate matter in grams per hour.Particulate matter is the tiny stuff that smoke is made out of and pellet stoves should not have any visible smoke after the 3-minute start up.The average pellet stove used to put out about 2 grams of particulate per hour.But since the new EPA regulations took effect in 2015, the average pellet stove emits about 1.3 grams per hour that makes pellet stoves more suitable in more densely populated suburban and even urban areas.Choosing a cleaner pellet stove means a cleaner flue pipe and cleaner air around your and your neighbors’ homes.
6.6. Beware of stoves without an efficiency on the EPA list. As with BTUs, manufacturers routinely exaggerate the efficiency of their stoves on their websites, so if efficiency and saving money is important to you, check the EPA list of stoves for efficiency ratings.The problem is some companies still haven’t reported their efficiency to the EPA, so you may only want to purchase a stove that has an efficiency listing on the EPA list.Pellet stoves with listed efficiencies range from 58 to 87% efficiency, but those not listed could be even lower, drastically increasing your heating costs.
The EPA list includes some slightly exaggerated efficiency numbers, but they are not nearly as exaggerated as manufacturer websites and literature. The EPA used to allow companies to calculate efficiency based on a default of 78% efficiency, even though most pellet stoves are below that, explains Ben Myren, who runs one of the stove test labs approved by the EPA. The result is a 5-10% exaggeration of some stoves on the EPA site, something that the EPA has not publicly acknowledged. (Some incentive and change out programs – Maryland, Massachusetts, New York and Oregon – require that the stove have an efficiency listed on the EPA list to get the full rebate.)
Appreciating these six factors are likely to help you make a better decision, but we also encourage consumers to rely on feedback from friends, neighbors and others who own pellet stoves. One site that can be helpful for research is hearth.com.
A final note of caution is to take advertised hopper size with a grain of salt.Most manufacturers also exaggerate hopper size.Of the six models we tested, Harman and Ravelli exaggerated their hopper size by 15 – 18%, while Enviro didn’t exaggerate at all.Choosing a stove with an advertised hopper size of 50 – 60 pounds can be a good idea, as it means the hopper will likely hold 45 – 55 pounds and you can empty an entire 40 pound bag in it when its low.
Guest Blog: We are reposting a 2012 blog from Instructables by Tecwyn Twmffatt at Goat Industries. It describes an early effort to build a thermoelectric wood stove. This blog is part of a series of blogs providing information for the 2018 Wood Stove Design Challenge.
Introduction: Thermoelectric Power Generation (TEG)
These videos document my first attempts at generating electricity from a thermoelectric peltier device in 2012. The TEG that I used is a high powered unit able to withstand high temperatures and specially made for electricity generation.
In terms of instructions, I don't think many people would want to build the 10 TEG system as it was ridiculously expensive, so I'm putting in a section for creating the 1 TEG arrangement, which is relatively easy and low cost.
Step 1: Part 2 of 3
A ten unit Thermoelectric generator system is shown being constructed and then fitted to a wood burner. The theoretical maximum output is 200 watts. The video shows how the generator was put together and how the wood burner was modified to get maximum heat through the TEGs. The TEGs themselves are able to withstand a constant 325 degrees C on the hot side and require plenty of heat to get the 20 watts that each of them are capable of producing.
Step 2: Part 3 of 3
In part 3 we successfully generate a significant amount of energy from the woodburning stove. In the first session, a circulation pump, a fan and 10 x 10 watt flood lights are powered up. In the second session, we attempt to get a more balanced load wired up to the tegs and measure a noticable increase in power output. The 10 tegs are wired up in 2 parallel strings and, from the manufacturer's specification, the optimum output voltage is 14.4v . The nearest that we manage is 13.8v, at which we generate 120 watts. The specifications suggest that 200 watts is possible when the load is matched.
Step 3: Full Playlist
31 Minutes of Thermoelectric video heaven!
Step 4: Creating the 1 TEG Generator
Here we are going to build the single TEG generator shown in the first video.
Use the engineering drawing to produce internal coolant passage ways in the aluminium block. I ended up drilling all the way through to the other side and using more of the 1/4" blanks.
Connect the 1/4" pipe fittings to the block and plumb in the pump. Add antifreeze to the water in the water butt if it's likely to get cold at all.
To create a 'sandwich' with the hot block (steel block), the TEG and the cooling block, drill and tap holes in the steel block for the 5mm bolts.
Weld the hot block into the side of the wood burner and recreate the TEG sandwich, tightening the bolts up with a torque wrench (see attached file).
Connect up LEDs on the TEG, turn on the pump, light the wood burner and off you go! TEGinstallationandspecifications01.pdf
Step 7: 10 TEG Layout
If you really must build the 10 TEG generator, the photo above shows what is involved. I have got CAD drawings, PCB drawings etc. If anybody is interested. Not for the faint hearted!
PCB 03.pcb PCB 01.zip CAD files 02.zipHeated Up!
Chair of the Masonry Heater Association Technical Committee
Left to right: Mark Champion (in his VT test lab), Boris Kukolj (Tulikivi),
Chris Prior (MHA President), Norbert
Senf (blog author) and Jean Francois
Vachon (soapstone supplier). Photo credit: Mark Seymour.
EPA started regulating wood burning stoves for particulate (PM) emissions in 1988. Regulation was limited to airtight heating stoves. Masonry heaters were not regulated, the stated reason being that they were likely to be clean burning.
In Europe, only carbon monoxide (CO) emissions were regulated. CO is easy to measure, however PM can be very tricky. Wood smoke includes compounds that will only be captured by a filter if you cool them down and condense them. This is done in the laboratory by mixing them with air in a dilution tunnel, and this is thought to simulate what happens in the ambient air in the real world.
State and county air quality authorities soon started to address wood smoke, and would often pass a generic local regulation that banned all appliances except those that were EPA certified. We, the fledgling Masonry Heater Association (MHA), decided to seek EPA certification.
Although we “knew” that masonry heaters were cleaner even than EPA stoves, nobody had ever measured the PM on one with the dilution tunnel method. With funding help from the Wood Heating Alliance (now HPBA), we were able to participate in a $ 100,000.00 test method development project for masonry fireplaces and masonry heaters. The project took place at Virginia Polytechnic Institute (VPI) in 1989 and was headed by Dr. Dennis Jaasma.
The results were interesting, with some surprises. EPA did not accept the proposed test method. We immediately realized that we needed do a lot more testing,and that we would need to develop the capability to do it ourselves.
We were fortunate in being able to arrange for training with OMNI-Test, one of the leading EPA-accredited certification testing laboratories, then and now. OMNI developed a training session for us that took place in September 1996. It included presentations by regulators, an emission chemistry expert (Dr. Jim Houck),and laboratory testing personnel. Dr. Stockton (Skip) Barnett showed us the low cost portable dilution tunnel that he invented, known as the Condar. He developed it while working for the Condar Company. It was widely used at the time by the major stove manufacturers for in-house testing to develop their certifiedstoves.
The attached Powerpoint, Repeatability of Cordwood Combustion Particulate Measurements, presents a summary of the work we have done at the Masonry Heater Association to calibrate the Condar against the EPA Method 5G laboratory dilution tunnel. It includes a close look at the PM testing repeatability issues, a major discussion point over the years. We have recently completed 2 cordwood studies, using very carefully matched loads in a masonry heater. Repeatability was within plus or minus 15% – 25%, depending on the ignition method. With crib fueling, we were able to get within 10% repeatability on PM, and within 1.5% repeatability on CO.
The late Paul Tiegs, one of the greatest authorities on wood stoves, conducted the interviews for the EPA.
Long before the regulatory debate about wood stoves heated up in the 2010s, the EPA commissioned a series of fascinating interviews with the top wood stove experts in the country on a host of technical and policy issues. These interviews give a glimpse of the opinions and philosophies of industry and academic leaders at a time when they apparently felt free to go on the record about what became controversial topics.
The content of these interviews remains very relevant today for anyone interested in a behind-the-scenes look at many of the underlying issues in the 2015 EPA stove and boiler regulations.The interviewers – Jim Houck and Paul Teigs (who are top experts themselves) – asked questions ranging from whether masonry, pellet, boiler and furnace appliances should be regulated, to the vulnerabilities of catalytic stoves, to how lab testing can better reflect real world use of stoves.
These interviews remain a valuable resource because each of the nine experts was asked the exact same questions. Thus, if you are interested in masonry heaters, or catalytic or pellet stoves, or how labs coax the best numbers from stoves, it is relatively easy to scroll down and see how each person answered the question.Of the nine interviewees, four are from industry (John Crouch, Bob Ferguson, Dan Henry and Michael Van Buren), two from test labs (Rick Curkeet and Ben Myren), two from academia (Skip Hayden and Dennis Jaasma) and one from EPA (Robert C. McCrillis). Their full titles and affiliations are at the end of this blog along with the full list of questions asked.The full set of questions and answers are in Appendix B on page 58 and can be downloaded here (pdf).
In general, Bob Ferguson and Dan Henry tended to oppose further regulation, and felt, for example, that pellet stoves and wood-fired central heating appliances did not need to be regulated.Ben Myren tended to favor a blanket approach of closing loopholes and regulating all appliances.This difference in views between two industry experts and one test lab expert can be viewed through their respective economic interests and how it would affect their livelihoods.But these interviews also show deeper philosophical differences and illuminate the reasons for their positions, whether they concern the health impacts of wood smoke, profitability, practicality of test method changes, etc.
We have chosen to reproduce the answers to two questions and invite readers to refer to the full set of interviews to find issues that they may be more interested in, such as the impact of wood species on emissions, stress testing to see how durable stoves are, and options to promote or require education or maintenance of stoves by consumers.
When the Alliance for Green Heat began ten years after these interviews in 2009, much of the content had already been seemingly lost or obscured. Very few people, for example, knew of the origin or impact of the 35:1 air-to-fuel ratio loophole that allowed pellet stove manufacturers to make low efficiency stoves in order to avoid regulation.Right up until 2014, state and federal government agencies, along with top industry outlets, continued to propagate myths about pellet stoves.Even the EPA never advised consumers that uncertified pellet stoves were likely to have lower efficiencies due to the 35:1 loophole they created. These interviews provide the best information anywhere on how this came to be and what impact it had on the pellet stove industry and consumers.
We chose the question about whether central heaters should be regulated because this turned into one of the biggest issues in the 2015 regulations.Only one interviewee – John Crouch – saw a causal relationship between the rise of outdoor wood boilers and the 1988 emissions regulations.
Question: The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?
John Crouch, HPBA’s foremost wood stove expert.
John Crouch, HPBA: I wouldn’t use the term “close the loop-hole”. I would say, “is the proper place to cut off the definition of a wood heater?” We all know the whole discussion during the Reg-Neg ignored this emerging category of pellet stoves. So this gets back into my other broader comment, which is, instead of going back in and changing the NSPS in a piecemeal fashion, there needs to be a true revision of the whole thing that deals with the category of pellets and masonry heaters and outdoor furnaces. Rick Curkeet, Intertek: Yes. The way to amend the regulation is to simply remove the 35:1 air/fuel ratio exemption. This has never been required by fireplaces (they meet the 5 kg/hr minimum burn rate exemption criterion anyway). Pellet units are readily able to meet emissions requirements and the exemption only encourages making these units less efficient to avoid the regulation. Bob Ferguson, Consultant: The 35:1 cutoff was intended for fireplaces. However, pellet stoves are the only product that even take advantage of the air-fuel exemptions. Fireplaces generally use the burn rate exemption. Pellet stoves probably don’t need to be regulated at all. They are all quite clean burning. Let the marketplace decide if exempt stoves are acceptable. If pellet stove users demand products that use fewer pellets (more efficient), the manufacturers will respond.
Skip Hayden, Researcher: Yes. In Canada, we recommend that people buy only EPA-approved pellet stoves. We have developed a high ash pellet stove that’s operating around 85% and its emissions are about 0.3 g/hr or less.
Dan Henry, a founder of Quadrafire stoves is one of industry’s most articulate spokesmen.
Dan Henry, Aladdin: There is no data that indicates that even a poorly operating stove is a dirty burning appliance. They are inherently clean, becoming more and more reliable, and don’t fix them if they aren’t broken. Dennis Jaasma, University of VA: Pellet stoves are inherently clean burning unless there is something very bad about their design. I am not concerned about regulating the currently uncertified units unless their field emissions are bad compared to certified stoves. Robert C. McCrillis, EPA: Yes, all pellet stoves should be affected facilities and not subjected to that 35:1.
Ben Myren one of Amreica’s most thoughtful and experienced stove tester.
Ben Myren, Myren Labs: I agree, no more loop-holes. The new technology stoves that are coming on the market are going to be totally new critters. I don’t think that turning down the air- to-fuel ratio, to make it whatever it is, should get you out of the loop. Some of those suckers have got to be just filthy. I mean you look at the flame. I’ve seen them burn at the trade show; you know, the glass is sooting up on the edges. You can just see it.
Michael van Buren was a technical expert with The Hearth Products Association, now HPBA
Michael Van Buren, HPBA: I don’t know what that loop-hole does, whether it really affects the operation of the stove and the efficiency of the stove. Question: According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified? John Crouch: The  EPA New Source Performance Standards killed the indoor furnace industry and created this little loop-hole which the outdoor furnace industry is beginning to exploit and kind of underscores the need for a more comprehensive wood burning regulation which sets out over a several year period to codify all forms of wood burning technology.
Rick Curkeet tested stoves for Intertek labs and is one of industry’s top experts.
Rick Curkeet: I don’t know how many new units are being produced but I’m sure it’s a very small number. Still, one really poor unit can be a significant problem if it’s in your neighborhood. There have never been any standards for testing this type of product for emissions and efficiency. However, we have adapted existing methods and can say that the performance range is very wide. Poor designs may be 30% or less efficient and produce nearly 100 grams/hr emissions rates. Good designs are able to approach certified wood stove performance levels. Bob Ferguson: I don’t feel there are enough units being sold to merit any activity what-so-ever. There are only a handful of manufacturers. I don’t think there has been anything published–so if testing has been conducted, it is probably a good assumption that the numbers aren’t that good. They shouldn’t be certified, as you would have to develop test methods and standards. The country would be better off using the money to pay manufacturers to phase out of production, sort of like the agricultural method of paying farmers not to grow certain crops.
The late Skip Hayden, one of the main wood stove authorities during the 1980s and 1990s.
Skip Hayden: The number of central wood furnaces in Canada, certainly in comparison to the United States, would be higher. In our Eastern provinces, it’s a relatively common add-on to existing oil furnaces. Generally, they are as dirty as can be. Dan Henry: I think a lot of these are used in rural areas and considering the fuels that are out there, I don’t think they should be regulated. Maybe just a spot check of some sort. I think the only thing that would benefit would be the testing laboratories. If it emits particulate into an air shed where it can have an adverse effect on the industry (my ability to make a living), then yes.
Dennis Jaasma also ran a research test lab at the University of VA.
Dennis Jaasma: Yes, central heaters merit further evaluation. I don’t know how many models are available. I think EPA has done some work on them, but I do not know any results. Yes, they should be certified. They are in danger of becoming extinct if they don’t wind up with a certification program. Robert C. McCrillis: In some localities I think these furnaces are a problem; I don’t know how many are commercially available. I think I can name off six or eight companies and each one makes several models, but I don’t know what the total market is, maybe 10,000 – 15,000 a year. The little bit of testing that we did here, says that they are probably on a par with a conventional wood stove. The way those things work, they have a thermostatically operated draft and when the thermostat shuts off the draft closes, so you get this real smoldering burning situation. Secondary combustion technology probably wouldn’t work. Possibly a catalytic technology would, but I just don’t think it stays hot enough in there. I guess that really depends on the impact.
Ben Myren: I don’t think they should be exempt for any reason. As to the rest of it–are there emissions data for them? I suspect there are. Should they be certified? Yes they should be certified. Nobody should be exempt from the process. Michael van Buren: I think there should be some type of testing on them.
List of Experts Interviewed
Mr. John Crouch, Director of Local Government Relations, Hearth Products Association (CA) [now HPBA]
Mr. Rick Curkeet, P.E., Manager, Intertek Testing Services (IL)
Mr. Bob Ferguson, President, Ferguson, Andors and Company (VT)
Dr. Skip Hayden, Director, Combustion and Carbonization Research Laboratory (Ontario, Canada)
Mr. Daniel Henry, Vice President, Aladdin Steel Products, Inc. (WA) [now Quadrafire]
Dr. Dennis Jaasma, Associate Professor, Department of Mechanical Engineering, Virginia Polytechnic Institute and State University (VA)
Mr. Robert C. McCrillis, P.E., Mechanical Engineer, Air Pollution Prevention and Control, Division, U.S. EPA (VA)
Mr. Ben Myren, President, Myren Consulting (WA)
Mr. Michael Van Buren, Technical Director, Hearth Products Association (VA) [now HPBA]
RWC Technology Review
Environmental Protection Agency Order no. 7C-R285-NASX
OMNI Environmental Services, Inc.
Beaverton Oregon 97005
1. State-of-the-art of wood stove combustion and emission control technologies.
1.1 Are in-home emission reductions as compared to conventional stoves shown in Table 1 for catalytic and non-catalytic certified stoves reasonable?
1.2 Are efficiencies shown in Table 2 for catalytic and non-catalytic certified stoves reasonable?
1.3 Can catalytic technology for use in wood stoves be fundamentally improved?
1.4 Is the use of manufactured fuel (densified and wax logs) a credible emission
reduction strategy? See Tables 1 & 2 .
1.5 For non-catalytic stoves the heat retention adjustment with refractory material of various densities can reduce particulate emissions. How big an effect can this have?
1.6 Approximately one half of the particulate emissions occur during the kindling phase for non-catalytic wood stoves and more than half for catalytic wood stoves. Are there improvements in technology that can mitigate this problem? Can specially designed high BTU wax logs be used to achieve a fast start and reduce kindling phase emissions?
1.7 Should masonry heaters with tight fitting doors and draft control be classified as a wood stove and be subject to some type of certification even though most weigh more than 800 kg?
1.8 Are the emissions and efficiencies for masonry heaters, based on in-home tests, shown in Tables 1 and 2 reasonable?
1.9 The OMNI staff feels the emissions per unit of heat delivered (e.g., lb/MBTU or g/MJ) is a more appropriate way to rank the performance of wood burning appliances than emission factors (lb/ton or g/kg) or emission rates (g/hr). — Comments?
1.10 Default efficiency values are used for wood stoves. This coupled with the fact that emission factors or rates (not g/MJ) are used to rank wood stoves does not provide an incentive for manufacturers to increase the efficiency of their stoves. — Comments? Should an efficiency test method as described (FR v. 55, n 161, p. 33925, Aug. 20,1990) be required to be used and the results listed?
1.11 Have certified stove design and performance improved since the first certified stoves? If so, how?
State-of-the-art of fireplace emission control technology.
2.1 Are the emission factors and efficiencies for the in-home use of fireplaces and inserts shown in Tables 3 and 4 reasonable?
2.2 There appear to be only a few practical design or technology options for fireplaces that will potentially mitigate particulate emissions. — What designs and technologies are available? What retrofit options are there?
2.3 The use of wax fire logs reduces emissions over the use of cordwood. Can the formulation of wax logs be changed to produce even less emissions?
2.4 What are the distinctions between a masonry fireplace and a masonry heater?
2.5 As with wood stoves, the OMNI staff believe that the mass of emissions per unit of heat delivered is a better way to rank the performance of fireplaces than emission factors or emission rates.
State-of-the-art of wood-fired central heating furnace emission control technology.
3.1 According to a Department of Energy survey out of the 20.4 million households that used a wood burning appliance in 1993, less than 0.3 million used a wood burning furnace as their primary source of heat. Are there enough wood-fired central heating furnaces in use to merit their closer evaluation? How many commercially available models are there? Are there emissions data for them? Should they be certified?
4. State-of-the-art of pellet-fired wood stove technology.
4.1 Are the emissions and efficiencies for the in-home use of pellet stoves shown in Tables 1 and 2 reasonable?
4.2 The 35:1 air-to-fuel ratio cut-off for certification has produced two classes of pellet stoves — those that are certified and those that are not. The latter class may have models that are less efficient and have higher emissions than the former. Should the regulations be amended to close the loop-hole and discourage the practice of intentionally designing models with a higher air-to-fuel ratio to avoid certification?
4.3 Have pellet stove design and performance improved since the first models were introduced? If so, how?
1. Ramifications of ISO.
5.1 The International Organization for Standardization (ISO) has a technical committee for developing emissions, efficiency and safety test standards for wood-fired residential heaters and fireplaces. (See Table 5 for comparison of the draft ISO method 13336 with EPA methods 28, 5G and 5H.) Do you feel that the EPA methods should be replaced with or be made comparable to an international standard?
Correspondence between in-home and laboratory emission test results.
6.1 How accurately do certification tests predict in-home performance?
6.2 How would you design research testing in the laboratory to simulate in-home use?
EPA Method 28 strengths and weaknesses.
7.1 Method 28 is in part an “art”. Fuel loading density, fuel moisture, fuel characteristics (old vs new growth, grain spacing, wood density) and coal bed conditioning can be adjusted within the specification range of the method to influence results. In your experience what things have the most effect on particulate emissions? How much influence can they have?
7.2 Burn rate weighting is based on very limited data and the cities from where the data were obtained are not very representative of wood use nationwide (see Table 6). How can the weighting scheme be improved to be more representative of the nation as a whole?
7.3 The equation for the calculation of the air-to-fuel ratio as in Method 28A is in error. The error produces a small but significant difference in the calculated air-to-fuel ratio. Should the method be corrected or should it be left as a “predictor” of the air-to-fuel ratio?
7.4 The assumed mole fraction of hydrocarbons (YHC) is defined as a constant in the air-to-fuel ratio calculations in Method 28A. The mole fraction of hydrocarbons in the vapor phase will vary significantly with fuel and combustion conditions. Should hydrocarbon vapors (more appropriately, organic compound vapors) be measured as part of the method?
4. EPA Methods 5G and 5H correlations.
8.1 The comparison data to demonstrate the correlation between 5G and 5H are limited. Should the correlation between the two methods be reevaluated?
Performance deterioration of EPA-certified wood stoves in the field.
9.1 It is the opinion of many in the wood stove industry that catalysts last only five years and that a stove designed for a catalyst operated without a functioning catalyst can produce as much emissions as a conventional stove. — Comments?
9.2 Field studies in Glens Falls, NY, Medford, OR, Klamath Falls, OR and Crested Butte, CO showed that emissions from some catalytic stoves became appreciably worse even after two to three years of use. Inspection of stoves in Glens Falls showed that catalyst deterioration and leaky bypass systems were responsible. Have improvements been made in the design of catalytic stoves to minimize these problems? Is it reasonable to require homeowner training on the proper use of catalytic stoves and/or to incorporate into their costs an inspection and catalyst replacement program?
Stress test pros and cons.
10.1 A short-term laboratory woodstove durability testing protocol was developed to predict the long-term durability of stoves under conditions characteristic of in- home use (see EPA-600/R-94-193). It was concluded in that study that damage occurs during those occasional times when a woodstove is operated in the home at exceptionally high temperatures. The laboratory stress test was designed to operate a woodstove at very high temperatures over a one to two week period to predict long-term durability under in-home use. Is this a reasonable approach?
10.2 Should a stress test be made part of the certification process?
Feasibility of developing separate emission factors for dry and wet wood and for
softwood and hardwood species classes.
11.1 Optimum wood moisture for low particulate emissions seems to be in the 18% to 20% range. Are you aware of any data that will allow the impact of wood moisture to be isolated from other variables? Could it be different for wood from different tree species?
11.2 Wood from different tree species clearly burns differently. The chemical make-up and density of wood from different tree species is different. For example wood from coniferous trees has more resin than wood from deciduous trees. It is believed that particulate emission factors will be different for wood from different tree species. If this is true different parts of the country may have different emissions factors for residential wood combustion. Are you aware of any data that document different emission factors for wood from different tree species?
8. Routine maintenance.
12.1 Would routine maintenance of stoves once they were in a home reduce particulate emissions? Would this be more relevant for catalytic stoves than non-catalytic stoves? Would this be relevant for pellet stoves with electronic and moving parts?
12.2 Should the home owner be provided with a maintenance manual or a training course at the time of purchase? Should a maintenance program be part of the purchase price particularly for catalytic stoves?
12.3 What would the key elements of routine maintenance be?
When Rod Tinnemore was invited to speak about wood stoves, he didn’t sound like a regulator. He spoke his mind, he made people laugh and he was never at a loss for words. Rod was in charge of wood heater regulations in Washington State, the state with the toughest regulations in the country. By the time he retired in April 2017, he left behind a far-flung community of stakeholders who admired him – or at least respected his judgment.
Rod Tinnemore became an Environmental Planner at the Department of Ecology in 2008, years after the state was pummeled by industry for the audacious move of requiring all heaters to meet a standard of 4.5 grams of particulate per hour. Rod became the guy who enforced that decision, and it was one he was happy to enforce, because he felt stoves could and should be required to burn cleaner than the federal standard of 7.5 grams an hour.
Washington State also required that all stoves sold and installed in the state be EPA certified. To enforce this, Rod regularly emailed residents residents trying to sell old, uncertified stoves on Craigslist. “Most people didn’t know the regulations and were happy to discard the stove instead, but some just sold it another way. Periodically, we found big box stores selling new, uncertified stoves and had to send them overnight certified letters as well,” Rod recalled.
Rod’s retirement leaves a vacuum among the regulator community, as there are very few non-federal stove regulators who have the depth of experience and expertise that Rod had. He influenced policies in change out programs in Washington State and beyond and was one of the most influential state regulators in the EPA’s process to develop the New Source Performance Standards (NSPSP).
“Rod was able to build bridges between different factions and he was a diplomat – but he also knew when to take a stand,” said Lisa Rector, a Senior Policy Analyst at the Northeast States for Coordinated Air use Management (NESCAUM).
Many key figures in the wood stove industry thought highly of Rod, in part because he was accessible, responsive and practical. “Rod had a healthy appetite for knowledge and was a great listener with no preconceived bias. He was always asking great questions so as expand his knowledge base,” said Chris Neufeld, a vice president at Blaze King and Co-chair of the solid fuel section of the Hearth, Patio and Barbecue Association (HPBA).
Some in industry butted heads with Rod because Washington State regulations prevented almost all outdoor and indoor wood boilers from being sold and installed in Washington. But even companies representing those appliances often said that they he dealt with them fairly.
At least once, in 2013 when HPBA did not like an initiative Rod was spearheading, they had a lobbyist go to the legislature to send a message that Rod’s department’s funding could be in jeopardy if he pursued the initiative. Rod ultimately had to back off, ending his exploratory work to start a consumer green label for wood stoves.
Rod was also considered one of the insiders of a small group of regulators in the United States who really knew what he was talking about. Rachel Sakata, who did similar work for the State of Oregon as an Air Quality Planner, said that she continually relied on Rod’s expertise. “Rod also was a champion for pushing for cleaner devices and thanks in part to him, we now have stricter regulations for wood heating devices that help protect the public,” said Ms. Sakata. “And he continued to push for developing testing protocols that mimic real world conditions,” she said.
The Alliance for Green Heat also worked closely with Rod, recruiting him to serve as a convener and a judge for our Wood Stove Design Challenge events in 2013 and 2014. He also served on a committee that we pulled together to integrate stoves into energy audits, leading to BPI adopting them in 2015. The Alliance was also one of the stakeholders urging Rod to develop a consumer green label for stoves.
After Rod left office, the Alliance for Green Heat interviewed him, in between various trips and activities, for this blog.
Q. What do you consider one of your successes? A. Working on and helping to fund a new cordwood test protocol that someday could become a Federal Reference Method (pdf) or possibly a state sanctioned cordwood protocol. We focused on testing various tree species to see which ones produced more PM, but most importantly we tried to get a protocol that resembled how homeowners start and use their stoves – which Method 28 did not. This initiative is now being managed by NESCAUM using Mark Champion’s lab in Vermont and I am very pleased with how it’s progressing.
Q. What was something that you did not succeed at? A. Not being able to continue working on a consumer green label for wood stoves. This country needed a label to recognize high performing stoves and we still don’t have one that is robust and well recognized.
Q. Who were your closest colleagues? A. Decades ago, West Coast regulators led the efforts to reduce wood smoke, but more recently, its shifted to the East Coast. California is very progressive but not influential on wood smoke issues because it is so fragmented into so many air districts. Other than Oregon, it was more fruitful for me to work with NESCAUM, NYSERDA, Brookhaven National Lab and the Wood Stove Design Challenge events.
Q. What was the best advice your boss ever gave you? A. He told me early on that my job could be whatever I made of it.
Q. What was best guidance from your department? A. The Department of Ecology had a policy of returning phone calls within 24 hours and emails within 48 hours. I thought that was good policy and I tried to live up to it every day.
This month, New York became the first state in the country to set a minimum efficiency requirement in an ongoing pellet stove incentive program. The State will now only provide its $ 1,500 – $ 2,000 rebates to pellet stoves that are listed as 70% efficiency (HHV) or higher on the EPA’s list of certified stoves.
Two other states use efficiency values and a third is about to announce a similar change in their program.Oregon has long provided far higher rebates to stoves with higher efficiency listings on the EPA list of wood and pellet stoves.Massachusetts’ annual change-out program gives an additional rebate if the stove is listed at 65% or higher on the EPA stove list.
The change in New York’s program, run by the New York State Energy and Research Development Agency (NYSERDA), will limit the number of currently eligible pellet stoves to about 30 models.NYSERDA also requires that pellet stoves emit no more than 2 grams an hour and that the home does not have access to natural gas, two requirements that the Maryland rebate program also has.
Last year, NYSERDA gave rebates to help install about 500 pellet stoves and the Maryland program averages about 800 pellet stoves per year.In both states, this is asignificant boost to pellet stove sales.One of the biggest differences between the two programs is that New York requires the trade-in of an old wood stove, unless you are a low income household, but the Maryland program does not.
Part of the motivation by states and programs to require that stoves have an efficiency listed on the EPA list of stoves is to counter the widespread misinformation provided by manufacturers to consumers.The Alliance for Green Heat has consistently urged incentive and change out program managers to include efficiency and other best practices in program design.
This can be particularly problematic with lower income families who may have tried to calculate savings when purchasing a pellet stove, and are relying on manufacturer claims to get one of the higher efficiency stoves.Incentive and change out programs that give larger amounts to lower income households may be helping those families purchase pellet stoves that are under 60% efficient, saddling them with higher fuel costs for the lifetime of the appliance.
The New York program provides a rebate of $ 2,000 for lower income households compared to $ 1,500 for others, and now protects them from misleading information about efficiencies.A large portion of the NYSERDA rebate recipients are low-income households. Both New York and Massachusetts qualify lower income families if they earn less than 80% of median income. The Massachusetts program was the first to use efficiency in a change out program, giving an additional $ 500 for stoves listed at 65% or higher on the EPA list of certified stoves. Stoves made by manufacturers who do not disclose actual, tested efficiencies to the public are not eligible for the bonus in Massachusetts or for anything in New York. Massachusetts also gives a higher rebate amount if you purchase an automated wood stove.
Many retailers welcome the change, as they are often caught between manufacturer efficiency claims and confused consumers.However, the main hearth industry association representing residential wood and pellet stoves, the Hearth, Patio & Barbecue Association, continues to resist efforts to use stove efficiency in incentive and change-out programs.HPBA provided this statement about the changes in the NYSERDA program: “Unfortunately, there are some very clean, and potentially very efficient, pellet stoves that were certified before efficiency data was required by the new NSPS, but NYSERDA’s program requirements exclude them from consumers’ options.”
Of the approximately 30 pellet stoves that are 2 grams an hour or less and 70% efficiency or more, there are a wide range of more expensive brands carried by specialty hearth stores and very inexpensive ones carried by big box stores.And more than a third emit no more than 1 gram an hour.The most efficient pellet stoves on the EPA list, from the Italian Extraflame line, are 87% and 85% efficiency, but do not appear to be on the US market yet.
For consumer tips on how to choose a wood or pellet stove, this websiteoffers advice on stove selection, installation, rebates in your state and how to know when a stove needs replacing.
Payback calculations are common in the residential solar photovoltaic industry where homeowners want to know how long it will take for them to recoup their initial investment. If you purchase panels outright, payback periods depend on a variety of factors including a utility’s price for electricity, tax incentives, and amount of daily sunlight hours. A range of 5 to 8 years is possible however, it can be as wide as 3 to 15 years.
Answering the payback question for thermoelectric wood stoves is one of the objectives for the 2018 Wood Stove Design Challenge. In the meantime, there are several ways to begin answering this question with information already available. It is also useful to look at how use of a thermoelectric wood stove in combination with another energy-saving system, i.e., solar, could prove beneficial to the homeowner and thus both industries as well. For example, in northern states and Canada, a thermoelectric wood stove could reduce the number of residential panels needed and thereby save the homeowner thousands of dollars in panel costs.
Early Thoughts on Payback
The retail price of a thermoelectric module is around $ 57.50 for a 22-watt module, or $ 2.61 per watt. One critical point to make here is that the power output of our 22-watt module assumes an optimal hot-side temperature of 300 C (572 F) and cool-side temperature of 30 C (86 F). This ideal temperature differential is very difficult to achieve in real world conditions, so the real-world cost per watt for thermoelectric modules will be higher. However, cost should decrease and efficiency improve with widespread adoption of thermoelectric modules, similar to what happened in the solar industry. For example, DOE estimated that the installed cost of a solar panel declined from $ 7.06 per watt in 2009 to $ 2.93 in 2016, a reduction of 60 percent. If we go back to 1977, the cost of a solar panel was $ 77 per watt. It is not unreasonable to expect a decline for the cost of thermoelectric modules as economies of scale reduce production costs.
Of course, when a thermoelectric module is placed into a wood stove there are other associated costs. The primary cost by far is the heat exchange system. As I’ve discussed in a previous post, to generate at least 100 watts of power, it’s likely that a water-cooled heat exchange will be needed. The current retail price for a 100-watt water cooled thermoelectric generator, which includes eight thermoelectric modules, is $ 599, or $ 5.99 per watt. One question the competition will attempt to answer is how much this heat exchange will cost when it is integrated into the design of the wood stove.
Secondary cost considerations include the price of the wood stove, its installation, and fuel costs. The price for a larger size 50,000 BTU wood stove can range from $ 900 to over $ 4000, and the average consumer spends about $ 2,500. Since a thermoelectric wood stove would be providing both heat and electricity, it is difficult to separate out how much of the cost of the stove is for each function. The more crucial point for now is that many larger size stoves, which can generate up to 50,000 BTUs and meet the 2020 EPA NSPS standard, are available for as little as $ 1,300. While this does not include the cost of installation, it does suggest that the wood stove portion of the costs should not be a major obstacle.
The cost of installing a thermoelectric wood stove into a home should not necessarily be that much greater than the cost of installing a traditional wood stove. One additional cost will be attaching the power outputs from the thermoelectric wood stove to an inverter. However, if we assume that early adopters will already have or are planning to get a solar PV system (more on this below) the cost of the inverter would not be a major obstacle.
Finally, one can assume that the fuel cost for a thermoelectric wood stove is essentially zero because the wood stove is already being used to heat the home. A thermoelectric module will convert only 3 to 6 percent of the heat from a woodstove into electricity, while the remaining 94 to 97 percent passes through the module and is released as heat into the home. In other words, the module is only using a very small percentage of the heat generated by the stove to produce electricity.
Value in Combining Technologies
While more in-depth analysis is needed, it’s possible that a thermoelectric wood stove could help reduce the size and cost of solar PV systems in northern climates that have limited sunlight/solar radiation in winter. For example, a typical 5000 watt solar PV system in Vermont produces 6,280 kWh of electricity per year, while the same system produces 7,913 kWh in Los Angeles. Most of this difference is due to the low winter time output in Vermont between October and February: For example, the Vermont system produces 239 kWh in December, as compared to the Los Angeles system’s 473 kWh. If the Vermont resident wanted to generate the same amount of power as in Los Angeles, they would need to increase the size of their solar PV system from 5000 watts to approximately 6300 watts. At the current cost of approximately $ 3.36 per watt installed for residential solar, this could cost the Vermont resident an additional $ 4,368 for additional solar panels.
Alternatively, instead of purchasing extra solar panels, the Vermont resident could invest in a thermoelectric wood stove to boost their winter time power output. As we mentioned in our previous blog, a wood stove with a 150 to 200-watt thermoelectric generator operating 16 – 20 hours per day could generate 93 to 124kWh of electricity per month, which would be a good boost to the Vermont output of 239 kWh in December. And, at 0.16 $ /kWh for electricity in Vermont, the thermoelectric wood stove could save the homeowner an additional $ 15 to $ 20 per month.
While a real payback calculation for a thermoelectric wood stove will need to wait until prototypes go through more testing and we get results from the 2018 Wood Stove Design Challenge, the available information suggests thermoelectric wood stoves could help reduce the cost of residential solar installations, and potentially save homeowners thousands of dollars.
by John Ackerly, President of the Alliance for Green Heat reprinted from Biomass Magazine
Many in the biomass heating movement bemoan warm winters, low fossil fuel prices and the slow pace of conversions to biomass heating systems. But systems are being put in place to adopt renewable heating and that we can be part of, but we are not.
Scores of cities across the US and Canada have already pledged to go 100% renewable.Even more will be announcing their plans in the next year or two.Some cities are only focusing on 100% renewable electricity, but many are adopting a two stage approach.The first stage addresses electricity needs while the second stage addresses heating.
Take Portland, Oregon, Hanover, New Hampshire and East Hampton, New York. Portland is shooting for 100% renewable electricity by 2035 and plans to tackle heating from 2035 to 2050.Hanover is planning for 100% renewable electricity by 2030 and 100% renewable heating by 2050.East Hampton, NY is moving even faster: 100% renewable electricity by 2020 and 100% renewable heating by 2030. Much of this heating will be fueled by electricity but chip and pellet systems could also be in demand.
A parallel trend is the Zero Net Energy (ZNE) movement.To be considered a ZNE building, a house, There is no one accepted definition of ZNE, so cities, campuses and communities have some leeway in how they define it.A strict definition says biomass has to be grown and harvested on-site, but other definitions could include biomass harvested from within 30 miles, for example.After all, the sun isn’t on-site either but the energy from it is produced on-site.
building or campus, it cannot use more energy than the renewable energy it generates.
The point is that aggressive renewable energy strategies need to address heating and if the biomass community is not at the table, we may be left out of policies and definitions.The Hearth, Patio & Barbecue Association has been at the table in some instances, but they are mostly fighting with the natural gas industry against gas restrictions in ZNE initiatives.
The Biomass Thermal Energy Council (BTEC) is a natural leader for this type of advocacy, as they represent industry players that heat buildings and campuses.This advocacy is not cheap and could easily require a full time person to engage with all the organizations and agencies involved in these movements.But this would be an investment in the future that would pay dividends over the next 10 – 20 years.
The renewable electricity movement is taking off because laws require utilities to sell or produce a certain percentage of their electricity from renewable sources. The mandates typically increase until a target year, such as 20% renewables by 2020, or 25% renewables by 2025.Legislatures can do this because state-level public service commissions (PSCs) have authority over public and private utilities.But why don’t we regulate the heating grid the same way as we regulate the electric grid?
Piped gas is just like electricity in many respects and is regulated in many of the same ways, but are there any gas companies required to ensure that 20% of their BTUs are renewable by 2020?If gas companies had to install some percentage of their business as geothermal, solar thermal or biomass thermal, the renewable thermal sector would develop quickly, just as renewable electricity has.Gas companies could install the systems themselves, just like utilities can install their own wind turbines or solar farms, or buy renewable energy credits from companies who build and operate them.
During these Trump years, federal policy and funding of renewables will dwindle, but that is making some states, cities and campuses even more motivated to push forward.Renewable heating is part of the equation, but are we at the table?
(This article is reprinted from Biomass Magazine. The Biomass Magazine version had a slight error in the text.)