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Coal Heating in the United States

Posted by Earth Stove on June 18, 2017 with No Commentsas , , ,

By John Ackerly & Melissa Bollman
Alliance for Green Heat

This paper was prepared for the Warsaw Stove Summit which brought AGH and scores of experts in coal and wood heating from 19 countries to Poland in May 2017.

Summary
The US Census Bureau estimates that approximately 127,000 households used coal as a primary heating fuel in 2015, or about 0.1% of American homes. Residential coal heating dropped rapidly until 2000 and since then has been relatively stable.

More than half of homes using coal heat are concentrated in Pennsylvania and New York, right where it is mined. It appears to be based on cultural traditions and local support for local jobs because its still a very inexpensive way to heat and easy to transport. Most of the United States has no restrictions on coal heating and there have been few attempts to restrict it. Rather, it seems to have gradually died out except in pockets of states where anthracite is mined. Bituminous and sub-bituminous coal is much more widely dispersed but it is used far less than anthracite.

Coal stoves, particularly those fueled with anthracite coal that principally comes form Pennsylvania, typically have less particular matter than wood or possibly even pellet stoves. However, their health impacts may be far worse, as coal often emits high levels of SO2 and oxides from nitrogen.  In addition, coal often has poisonous toxins such as flourine, arsenic, selenium, mercury and lead.  For more on health impacts of coal and wood heating in the US and Europe, we excerpted key parts of a World Health Organization report here.

Who heats with coal and why?

Homes that heat with coal tend to be concentrated near anthracite coal mines and in homes with lower or mid level incomes. In the wealthier and more urban counties of Pennsylvania that are within 100 miles of anthracite mines, virtually no households heat with coal. High use of coal heat does not correlate with high use of wood heat. Both coal and wood are favored by rural, lower-income populations but coal appears to be favored near anthracite mines, and wood is favored in nearby, rural counties, according to data from the US census. The highest percentage of homes heating with coal at the county level is about 13%.

A prominent 2008 New York Times article reported that residential coal heating was on the rise, but rise was modest, and petered out a few years later. That rise corresponded with a major recession from 2007 – 2009 during which rates of wood heat soared far higher than coal. The New York Times also reported that an additional 80,000 homes use coal as a secondary heat source and the US Census reported 104,000 used it as a secondary heat source in 2005. Only 4,000 homes use it to cook with and 22,000 used it to heat domestic hot water in 2005, according to the US Census.


In 2015, the top five states for residential coal heating were Pennsylvania, New York, West Virginia, Kentucky, and Indiana. Over 50% of US homes that heat primarily with coal are located in Pennsylvania, where anthracite coal is mined.

The primary benefits of heating with coal, compared to wood, is 1. it burns for longer periods of time, so less reloading is needed and a home can easily stay warm overnight; 2. Like pellets, it can be delivered in bags on pallets by a forklift, and does not need the time consuming splitting, stacking and seasoning that cordwood needs; 3. It is even more inexpensive per BTU (assuming you don’t cut the wood yourself); and 4. It is a very dense fuel, and takes up half the space that the same amount of wood takes, per BTU.

The downside of heating with coal is 1. The odor, which most people find moderately unpleasant; 2. The black dust which is harder to clean than dirt and wood pieces from cordwood; and 3. Its hard to light, requiring most people to start the fire with wood, before switching to coal.

While the above pros and cons are widely agreed upon, other less tangible factors play a role. Coal has increasingly gained a stigma as a dirty, non-renewable fuel, whereas wood is regarded as far more environmentally friendly (even though particulate matter from wood can be equally high). On the other hand, the dwindling economic prospects of coal towns and counties tends to make those populations want to support the fuel to combat what they often see as an unfair bias against coal.

Coal and coal stoves

Coal stoves are either stokers or batch. Stokers automatically feed coal pellets (much like pellet stoves) into the stove, require electricity and only use anthracite. Batch stoves are loaded by hand and can take anthracite or bituminous.

Most coal used for heating in the US is anthracite but anecdotal estimates by experts say that no more than 25% is bituminous, primarily in areas where its abundant.

The EIA stopped collecting data on residential coal consumption in 2008. In 2007, the EIA reported that US residents consumed 353,000 short tons (320,171 metric tons) of coal, which represented only 0.03% of the nation’s annual coal use (1.1 billion short tons or around 1 billion metric tons). The overwhelming majority of course (93%) of US coal is used to generate electricity.

Usually coal is sold in 40 or 50 pound bags or by the ton. Coal may be sold directly to consumers from the mine, a fuel supplier, or a hardware store. Blaschak is one of the largest suppliers of bagged anthracite coal and sold 374,000 tons in 2014. Forty pound bags of anthracite coal (any size) from Pennsylvania usually run $ 6-$ 8. A ton of anthracite typically costs between $ 190 and $ 210 per ton, before delivery charges (which can increase price to $ 250-$ 300). One fuel seller, Central Maine Coal, sells about 200 short tons (181 metric tons) of residential coal per heating season.

Bituminous coal is usually considered a better coal for blacksmithing than heating, but can be burned in some coal stoves and is often only $ 80-$ 100 per ton.

Institutional heating with coal is somewhat relevant to residential coal heating and data indicates that institutional coal heating is declining much more rapidly that residential heating.

According to the EIA, US educational institutions consumed 700,000 short tons (634,900 metric tons) of coal in 2015, down from 2 million short tons (1.8 metric tons) in 2008. Twenty of the 57 US educational institutions that used coal in 2008 reported not using it 2015 due to sustainability initiatives. It is likely that most of the coal consumed at educational institutions is used to generate heat. Most US schools no longer heat with coal. Recent (2015-2016) news articles report that only five public schools heat with coal in West Virginia and four schools heat with coal in Cumberland, Maryland. One of the Maryland schools uses 517 tons of coal annually at a cost of $ 120 per ton.

Coal stove companies

Most coal stoves are made in Pennsylvania except for one big producer, Hitzer stoves located in eastern Indiana. Sales of coal stoves are reported to average 4,000 to 7,000 a year, but in 2008 they may have topped 10,000. In comparison, about 140,000 wood stoves are sold each year. There are about a dozen companies making coal stoves and one notable trend is that the larger wood stove companies are getting out of the coal stove business. Vermont Castings, Harman and Moreso used to sell coal stoves and now don’t. The one company that still focuses on both fuels is US Stove Company, based in Tennessee. Coal stoves cost about the same as wood stoves and range between $ 2,000 – $ 3,500.

Stove policy

Coal stoves remain exempt from EPA emission regulations. Coal stoves have never had a certification program at the EPA or at any state level, although the federal government and some states have indicated an interest in developing emission regulations. Regulation would likely drive up the cost of coal stoves and may reduce sales of coal stoves but other strategies may reduce their use faster and more economically. But without emission regulations, there is little data on coal stove emissions from various types of coal stoves, and there is little incentive for stove companies to try to produce cleaner stoves. Tests conducted in the 1980s suggested that wood stoves emitted higher levels of particulate matter than anthracite stoves, but lower levels than bituminous stoves (Houck, 2009). Of course, wood emits fewer other toxic chemicals than coal.

One significant policy change in 2015 was the ban on advertising dual coal/wood use in stoves unless the stove was certified with wood, and the company also tested for coal emissions and provided that data to the EPA. To our knowledge, no company has done this so no stove should advertise the ability to burn wood and coal any more.

The EPA is currently funding research on coal emissions and has developed an unofficial, draft test method at Robert Ferguson’s lab. However, this is being undertaken only because of an EPA program to change out coal stoves on the Navajo Indian reservation, not because it has any apparent mandate or serious plan to start regulating coal stoves.

It is unlikely under the Trump administration that any certification program would be initiated by the EPA, and the only state with enough coal stoves to justify the effort would be Pennsylvania, which is unlikely to do so.

Restrictions of the use of coal stoves

Unlike the United Kingdom, there has never been any national effort in the US to reduce reliance on coal stoves. Krakow, a major Polish city is banning coal stoves in 2019, after a multi-year effort to provide subsidies for alternative heating sources.

Two states – Washington and Oregon – effectively ban them because they only allow stoves that meet specific emission requirements, but those states would have very little coal heating anyway.

Many air districts that have poor air quality and high particulate matter levels employ temporary burn bans apply to coal stoves and well as wood stoves. A few jurisdictions, such as Fairbanks, Alaska, offer homeowners financial incentives to recycle their solid fuel burning appliance (including coal stoves) or replace it with a less polluting appliance (coal stoves are not eligible). However, most change out programs only remove old wood stoves and do not allow coal stoves to be replaced with wood stoves. A Pennsylvania county offered $ 200 to trade in old wood or coal stoves, but that program has been suspended.

Oregon is the only state where it is illegal to sell a coal stove, or any other uncertified solid fuel burning appliance. Oregon also requires uncertified solid fuel burning appliances, including coal stoves, to be removed and destroyed when a home is sold. According to the latest (2015) Census data, only 143 homes rely on coal for primary heat in Oregon.

At the local level, there may be a number of cities or counties that do not allow coal stoves, but the only one we could find is Summit County, Colorado that forbids the installation of a coal stove (uncertified solid fuel burning device) in a new home or as a replacement unit for an existing non-certified stove.

Key sources

Dr. James Houck, “Let’s Not Forget Coal,” Hearth & Home Magazine, December 2009, pp.

World Health Organization, “Residential heating with wood and coal: Health impacts and policy options in Europe and North America,” 2015.

Tom Zeller, “Burning Coal at Home Is Making a Comeback,” New York Times, Dec. 26, 2008 
Heated Up!

Hybrid Residential Solar and Thermoelectric Power Generation

Posted by Earth Stove on June 16, 2017 with No Commentsas , , , , ,
by Ken Adler, Senior Technical Advisor at the Alliance for Green Heat
Some of you may be wondering about thermoelectric wood stoves and why we decided to include them in the 2018 Wood Stove DesignChallenge, which will be held in November 2018 on the Washington Mall.  Our goal of this competition is to support development and commercialization of a revolutionary thermoelectric wood stove that produces electricity equal to 50 percent or more of the winter time output of a residential solar photovoltaic system. By combining a thermoelectric wood stove and a residential solar PV system and home battery, like the TESLA Powerwall, we can support residential and grid-based distributive power goals, and incentivize greater investment in solar power. 
Specifically, thermoelectric wood stoves can help solve the problem of low winter time solar PV output in northern climates, where useful solar radiation is limited to 2 – 4 hours per day.
While a thermoelectric wood stove may sound revolutionary, the technology behind the stove has been used since the 1980s in oil and gas field operations, where methane gas provides a low-cost source of heat to power the thermoelectric generator. Wood stoves, like waste methane gas, can provide a free source of heat for the thermoelectric generator.
Alphabet Energy Thermoelectric Generator
Thermoelectric generators are like solar panels, however, instead of turning light into electricity they turn heat into electricity. To generate electricity, one side of a thermoelectric module is heated by the wood stove while the other side is cooled with either an air or water-cooled heat sink. For applications above 100-watts, water-cooled heat sinks are the most common approach because of their ability to extract greater amounts of heat from the thermoelectric module.
60-Watt Water Cooled Thermoelectric Generator
In northern climates like New England, Canada and northern Europe, low winter time solar radiation increases the cost and reduces the efficiency of solar PV systems, and the cost-effectiveness of battery storage systems like the Tesla Powerwall.  According to NREL, solar radiation in northern areas like Vermont peaks at 6.0kWh/m2 in June and declines to 1.7kWh/m2 in December. This means that an average 4,000-watt residential solar system will go from producing 571kWh in June to 191kWh in December–a 66% reduction is solar power output.  This project will demonstrate how a thermoelectric wood stove can cost-effectively supplement a solar PV system.
Building on our experience from 3 previous Design Challenges, we will work with wood stove manufacturers, universities and others to build and test 100 to 200-watt thermoelectric wood stoves that could effectively increase by 50% the winter time output of a 4,000-watt residential solar PV system.   

Thermoelectric generators are currently sold as accessories for wood stoves; however, these accessories are limited in size and efficiency. By integrating a thermoelectric generator into a wood stove we can achieve far greater power output, efficiency, and lower cost. For example, a wood stove with a 150 to 200-watt thermoelectric generator operating 20 hours per day could generate 93 to 124kWh of electricity per month, which compares favorably with the December solar PV output of 191kWh in Vermont.

Russian Thermoelectric Wood Stove 
(not certified for sale in the U.S.)
There are several reasons why now is the time to consider thermoelectric wood stoves. First, the price of the thermoelectric modules, which are a component of the TEG, has dropped substantially because they are now being mass produced in China.[1] Second, the EPA’s recent wood stove NSPS regulation is helping to make new wood stoves cleaner and more efficient and, coupled with cordwood testing and automated features, a new generation of cleaner stoves could also generate electricity. Third, thermoelectric wood stoves can produce electricity up to 24 hours per day eliminating load management concerns common with solar and wind power. Lastly, the stoves are powered by local wood supplies, making their fuel low carbon and locally sourced.
The 2018 competition on the Mall will demonstrate the role thermoelectric wood stoves can play in promoting solar power, energy storage systems and biomass energy, while also reducing energy costs, supporting climate change goals, and increasing distributive power.   



[1]The cost of a thermoelectric module has fallen below $ 2 per watt (uninstalled), compared with $ 3.50 per watt for solar panels (installed).

Heated Up!

Thermoelectric Wood Stove, Solar Power, and a Floating Cabin!

Posted by Earth Stove on June 16, 2017 with No Commentsas , , , , , ,

Guest blog post, by Margy Lutz

Finally this winter, our thermoelectric wood stove generator is fully operational. Following our test runs, we placed the pump to recycle cold water down in the lake water under the cabin. In winter, it gets about 5 degrees C (41 F). That’s plenty cold for a good differential between the 300 degrees C on the hot side.
Most system owners don’t live in a float cabin four feet with a constant cold water source under the floor. The typical user has to use a recycled liquid (usually including a water/antifreeze mixture) that runs through a radiator for cooling.
In addition, a charge regulator/controller is used to protect the batteries and prevent overcharging. The model that came with our system has lights to let you know the status of the charging process.

Wayne likes to know more about the charge we are getting. He installed an ammeter and a volt meter. The switch in the middle controls the water pump down below the cabin. To maximize the charge to our cabin battery bank, we’ve installed a separate solar panel and two six volt batteries wired in a series to run the pump.

Living off the grid has its challenges, but having an alternative power sources has made our winters much brighter (pun intended). Do you generate power? What are some of the solutions that have worked for you? — Margy

Postscript by Ken Adler, AGH Technical Advisor: 

Congratulations to Wayne and Margy on their thermoelectric wood stove. In a follow-up communication with Wayne, he reported that they are no longer using the system because the thermoelectric modules failed. Wayne doesn’t know why they failed, however, the most common reason for failure is overheating.  The modules can also fail if Bellville washers are not used to allow the module to expand and contract during heating and cooling. Wayne also reports,

Even when I was partially (marginally) operational, I produced less than 2 amps at 12V DC (23 watts) to recharge my cabin battery bank. This would have been enough to put a top-off charge on my cabin batteries (normally recharged via my solar system), particularly valuable in the winter when solar power is minimal and my wood stove is operating nearly 24-7. The primary reason for the low amperage was the need for a 1,8 amp 12V (21.6 watts) water pump to feed the cold side of the modules. In many ways, I reside in the perfect test location for this thermoelectric system, since 

I have a nearly infinite supply of very cold water 4 feet below my wood stove. I live in a floating cabin on Powell Lake BC, and the lake is extremely deep and very cold in all seasons. What an opportunity to serve as a source of cold water through the cooling system! The pump only needed to pump the cold water up 4 feet and then outflow back into the lake. Even with this tremendous advantage, I couldn’t get everything fully operational.

Does this make me a non-believer in thermoelectric from a wood stove? Absolutely not — I still believe this is an important future source of electrical power in my cabin, since even a top-off voltage during the solar-depraved Canadian winter would be worth the price. I’d be one of the first in line if a recreational property thermoelectric system was available, and I’d be quick to try again. Thus, I wish you all of the best with your preparation for the 2018 conference. I’ll be following the results closely.

In an earlier post, Wayne reports that he is using three 25 watt thermoelectric generators for a total rated power of 75 watts of output, however, he’s only getting 23 watts of power for his battery. Part of this is due to his pump, which is drawing almost 22 watts of power. If you are interested in building your own thermoelectric wood stove, there are a few improvements that you may want to consider. First, TEG suppliers (see our resourcespage) now sell more efficient lower wattage pumps. Second, consider starting with a thermoelectric generator rated for 100 to 200-watts. While this is more expensive, if you go with a smaller system much of your power will be consumed by the pumps and/or fans you need to cool the modules. Third, Bellville washers are critical for allowing the modules to expand and contract.

If you are interested in designing a thermoelectric wood stove for our 2018 Wood Stove Design Challenge, please visit our web sitefor more information. For more information on Wayne and Margy’s life on a floating cabin, please visit their blog at Powell River Books Blog.

For an overview of the potential of thermoelectric wood stoves, click here.

Heated Up!