Results of the 2018 Wood Stove Design Challenge

 By John Ackerly

The first day of testing, showing Ben Myren Prof.
Phil Hopke and Rebecca Trojanowski.
Photo: Kittner/BNL.

Conducting rigorous and transparent field testing of thirteen stoves in five days is a feat that is unheard of in the wood stove community.  The goals were also unique: fairly test stoves against one another with cordwood; help each team to improve their units and help educate a wider public about novel stove technologies that challenge how we think about the traditional, manually operated EPA certified wood stove.

The 2018 Wood Stove Design Challenge took place from Nov. 9 - 13, featuring 10 stoves in competition and 3 showcase stoves. The stoves were selected and judged by members of the

Large screen monitors provided real time data during
a test run of the Integrated Duty Cycle fueling
protocol under development. Photo: Kittner/BNL

Organizing Committee.  The Alliance for Green Heat (AGH) was the principal architect, organizer and host of the event.  Each of the 10 competition stoves received a $10,000 grant made possible by the DOE's Bioenergy Technology Office.

The Wittus team from New York
and Germany. Photo: Kittner/BNL

In the automation stove category, there were three market ready stoves that successfully went through a rigorous fueling protocol and proved that they could burn relatively cleanly and efficiently even when an operator tried to turn down the heat setting too far and at the wrong times.  An SBI stove and the VcV stove that had been in development for many years showed the value of multi-year R&D and testing, resulting in stoves that may only cost $500 more than a similar,

Staffers from EPA, DOE, USDA and Congressional
offices were able to learn about stove testing and
 engage with teams and judges. Photo: AGH

  

non-automated version.  To us, this is a major breakthrough and stoves like these should show a path to far cleaner cord wood heating in America.  

The SBI team. Photo: Kittner/BNL

The other automated stove was a German-American unit that heated water, made electricity and provided a living room fire experience with a downdraft flame into a lower chamber. While this was not an affordable stove to most Americans, it could have a reasonable pay-back over a number of years, depending on the users cord wood price.  This stove impressed both the Brookhaven National Lab and the Masonry Heater Association testing teams with ultra-low carbon monoxide numbers in the single digits under some conditions, and ultra-high efficiency.  

Ben Myren, one of the top wood stove testing experts
in the US, talking with Larry Brockman of the EPA's
BurnWise program.  Photo: Kittner/BNL

Automated stoves are regarded as one of the best, and only ways to help ensure that manually operated EPA certified stoves perform well not just in the testing lab, but in the homes of consumers.  For automated stoves to start gaining a foothold in the market federal, state and local government recognition and support will be required.

An automated pellet boiler by Maine Energy Systems capped with a Stirling Engine was the most

A Tesla owned by Osprey Foundation head, Bill Clarke,
 being charged by Maine Energy System pellet 
boilers with a Stirling engine. Photo: Kittner/BNL

futuristic of the entries, especially since it was charging a Tesla car in front of the tent. This compact unit could heat a business or multi-family dwelling and provide up to 5 kW of electricity.  

The five testing teams used different equipment
to gather a variety of data. Photo: Kittner/BNL

In the thermoelectric category, the judges concluded that “the most innovative thing is that almost all teams used commercially available thermoelectric modules and showed that it is feasible to generate useful electrical energy without sacrificing the energy efficiency or impeding the heat quality of

This is a Swiss-made electrostatic precipitator for
residential wood stoves that reduced PM by 50 -
90% in our testing.

the wood stove.  Most designs returned the waste heat after electricity generation into useful radiant heat into the room to increase efficiency.  These designs prove that the woodstoves is a good potential commercial opportunity for thermoelectrics to generate useful electrical energy and also increase their commercial appeal for consumers.”

It was clear that stoves or boilers with Thermoelectric Generators (TEG) could produce 100 to 250 watts of power. While this is a relatively modest amount of electricity, larger automated stoves or boilers operating 15 to 20 hours per day may help supplement limited solar power output during winter months. 

Fred Legget of Vulcan Energy 
with a TEG adapted to a Wiseway.
Photo: Kittner/BNL

The George Washington University, Unforgettable Fire and ASAT teams all successfully used off the shelf technology, while TEG expert Fred Leavitt of Vulcan Energy used commercially available TEGs by Hi-Z, and adapted the gravity fed Wiseway pellet stove to get a more steady 130 watt output. 

The Wittus cord wood stove was by far the most market ready and was able to make 250 watts, and it peaked at over 300 when using low moisture pressed wood logs.  Ken Adler, AGH’s Program Director of Thermoelectrics, coordinated the thermoelectric side of the competition and the thermoelectric testing.

University teams have been a key part of the Design
Challenge with SUNY Stony Brook competing this year.

Scoring was done using a numeric rubric based mostly on data produced by the testing equipment but judges did have discretion to award some points based on their subjective assessment in several areas.  Judges assessed automated stoves by these criteria and thermoelectric stoves by these.

And the awards goes to …

The Wittus team won both first prizes.
Photo: Kittner/BNL

·     * First Prize for automated stoves: Wittus.  Great performance on particulate matter, CO, efficiency and safety.

·     Second prize for automated stoves: SBI. A fully automated non-catalytic stove using only 2 sensors that may only cost $500 more than if it were non-automated.

·     * First prize for thermoelectric stoves: Wittus - again;  The highest electric output of up to 250 watts, and an integrated design that can maintain stable electric output.

·     * Second prize for thermoelectric: Vulcan Energy, using the Wiseway pellet stove that produced more than 100 watts and good PM reduction.

Stove testers Tom Butcher, Jake Lindbeg, Rebecca 
Trojanowski Photo: Kittner/BNL

·     Innovation prize: SBI, for simplicity.  The use of only one thermocouple and a sensor on the door, enabled the designers to regulate the stove despite attempts by the testers to turn the heat demand down and make it perform poorly. 

·     * The People’s Choice Award: 509 Fabrications.  Despite being a new, small company without an extensive social media network, the 509 Fabrications pressed log stove was a consumer favorite, garnering more votes than any other stove. 

The MHA testing crew: Ron Pihl, Jim 
Schales, Norbert Senf, Mark Seymour 
and Boris Kukojl. Photo: MHA

Unique and rigorous testing

The 2018 Wood Stove Design Challenge pushed the limits of rigorous wood stove testing both in terms of the amount and variety of technology used, and the fueling protocol, which is far more rigorous than any standard fueling protocol.   More details about this will be forthcoming.  Data produced by this event will show the extent to which automated stoves can navigate fueling protocols where testers try to make stoves go into smolder mode, to see if the automation is robust enough to avoid that.  Data is also more valuable for understanding real world venting conditions, as EPA approved test labs terminate in a warm indoor space, not the colder outdoors.  

Real time emission displays allowed testers teams
and judges to learn more about performance patterns.
This shows exceptional  CO and stack temps on the
Wittus. Photo: Senf

Between Brookhaven National Lab and the Masonry Heater Association, we had up to 5 separate testing teams, allowing many stoves to be tested at once.  We

Jonathan Male, head of DOE's Bioenergy
Technologies Office introducing the awards
Photo: Kittner/BNL

also wanted to have ensure that the Brookhaven and MHA teams could  periodically test the same stove at the same time.  Norbert Senf of the MHA had worked for months to automate the Condar, and the new Condar controls worked very  well, with minimal glitches. They did three runs simultaneously with Brookhaven National Laboratory who used a diluter and Testo 380. Comparisons of the two approaches will be published at some point.

Air quality testing during the Design Challenge

During the Challenge, we monitored indoor and outdoor air quality to get some sense of the impact

Tinted stove pipe donated by Olympia Chimney, 
showing mostly invisible smoke during the event
Photo: Kittner/BNL

from 9 – 13 wood and pellet stoves operating under one roof.  We used a Thermo Scientific pDR-1500 Aerosol Monitor, an Speck indoor PM monitor and a Purple Air PA-II - SD monitor.  Results were mixed, with most indoor readings between 20 - 35 micrograms per cubic meter, but with far higher spikes. The EPA short term PM standard is 35 micrograms per cubic meter.  Outdoor numbers were usually around

Les Otten, right, with Maine Energy Systems
Okofen Pelletmatic E-max CHP unit. Photo: MYSys

10 micrograms per cubic meter. Often the Speck showed  moderate to elevated inside the tent, but on several occasions, prototype stoves released excessive smoke into the tent – and outside of it.  We will issue a more detailed report on this. 

A note of gratitude

Julie Tucker of the USDA Forest Service, with
DOE's Jonathan Male and  AGH's John Ackerly
Photo: Kittner/BNL

 The Wood Stove Design Challenge is a collaborative process involving three major donors - the Department of Energy's Bioenergy Technology Office, New York State Energy Research and Development Authority and Osprey Foundation and scores of in-kind and volunteer partners.  Olympia Chimney and Masonry Heater Association were key in-kind partners, along contributions by West Penn Power

Dusty Henderson with the 509
Fabrications pressed wood log stove
that won the People's Choice Award. 

Sustainable Energy Fund, HPBA, Schott-Robax, Lignetics, Chimney Safety Institute of America, Society for American Foresters, National Fireplace Institute, Catalytic Hearth Coalition, Biolite local sweeps and installers and others were key in enabling the event to occur.  

Unless otherwise noted, photos taken by Sam Kittner and made possible by funding from Brookhaven National Lab and can be used freely by all, with attribution to "Sam Kittner for Brookhaven National Lab."  Photos attributed to AGH can also be used freely and attributed to "Alliance for Green Heat."

The GW University Team. Photo: Kittner/BNL

The innovative rocket stove entry from
ASAT being tested by Ben Myren
Photo: Norbert Senf

Our tent was right between the Capitol and the Washington Monument.
Photo: Kittner/BNL 

Photo: Kittner/BNL

Meet the Teams: A micro CHP pellet unit makes its debut on the Washington Mall

This post is the eighth in a series introducing the 12 teams participating in the 2018 Wood Stove Design Challenge in November.

By John Ackerly, Ken Adler, and Shoshana Rybeck, Alliance for Green Heat

The Pellematic e-max with a cut-away
view of the Qnergy Stirling engine that
makes the electricity.

If all goes as planned, Maine Energy System’s (MESys) ÖkoFEN Pellematic e-max will power all the testing equipment, lights, computers and audio equipment for this year’s Wood Stove Design Challenge on the National Mall. Having recently hit the market in Europe, the Pellematic e-max is designed for “commercial enterprises, hotels and residential complexes,” producing up to 4,000 watts of electricity.

Renewable combined heat and power (CHP) technologies that can supply 100% of heat and electricity to a home or small business come in many forms and are often part of an integrated system with solar panels. The key is matching the electrical needs with the heat needs because 95% of the energy from a pellet CHP unit will be heat and only 5% will be electricity. Thus, hotels or restaurants that need a lot of hot water year round make up many of ÖkoFen's customers for this product.

A smaller version, producing heat and electricity for single family homes, was slated to come to the Wood Stove Design Challenge until organizers asked for the larger version. The residential one has a track record with scores of homes in Europe that use solar panels for electricity in the summer and additional electricity from pellets the winter.   

The Pellematic e-max is designed for a “medium power range”, producing 50-60 kW of thermal power and 4-5 kW of electrical power. To yield these energy outputs, the Pellematic uses ÖkoFEN’s pellet heating system paired with Qnergy’s Stirling engine technology, which has allowed the model to be energy-efficient, low emitting, and a reliable source of heat and power, simultaneously. 

Pairing the Pellematic e-max with solar panels and a smart controller enables the system to use whichever energy source is cheapest at that moment. It plans for upcoming days based on weather forecasts. When its sunny, the system prioritizes the solar panels and can store electricity in a battery for cloudy days. If electricity from the grid is cheapest at night the controller will take electricity from the grid and also store cheap night time electricity to a battery. In the winter, when a lot of heat is needed, the controller will prioritize pellets. The homeowner or business owner does not have to do anything as the system switches between pellets, the sun, the battery or the grid. ÖkoFEN also manufacturers Pellesol solar thermal panels that combined with the pellet boiler can produce hot water for heating and all hot water needs year round.

Alone, the ÖkoFEN boiler provides reliable, economical and efficient heat output when the combustion conditions are kept constant, which makes it a strong base load boiler for commercial  buildings and reliable primary heating source for large households. However, with the attached Qnergy Stirling engine, this powerful heater can be used to produce substantial amounts of electricity

If a home has an electric car, the system
can also switch from pellets to solar to the
grid, depending on which combination of
electric sources is available and cheapest.

as well. When heat from the boiler is transferred to the Qnergy engine, pressure increases and works with the engine’s cooling circuit to create the temperature and pressure differential needed to move the Stirling piston and create electricity.

Developing MESys

Dutch Dresser (middle), Les Otten 
(2d from left) and MESys colleagues

Generating electricity from wood stoves was anything but the projected path for Dutch Dresser. His undergraduate education was in biology and Masters and Doctoral degrees are in science education. Before helping to create MESys in 2007, Dutch had an array of careers in education, computer networking and land development in Maine. Dutch says that he was moved to develop the company when his friend and partner, Les Otten, saw that the region was exporting monumental amounts of money for heating fuel and systems. 

Using the European heating market as an example, Les, Dutch, and Bill Strauss saw that there was a alternative way to run the heating market so that it supports the local economy without fossil fuels. Unlike the northeastern US, the European heating market kept heating dollars in the local economy by selling renewable, locally sourced units. Inspired by the European model, Dutch and Les set out to work with European heating technology to create a local market in Maine, and eventually grew throughout the Northeast.

After getting rejected by many European heating equipment manufacturers who feared working in the litigious America marketplace and one early experience with a problematic product, MESys began working with the Austrian company ÖkoFEN in 2009. Since then, MESys has become the  North American manufacturers for ÖkoFEN.  The bread and butter of Maine Energy Systems are residential pellet boilers that typically cost $8,000 to $15,000 after state incentives in Maine, New Hampshire, New York, Vermont and Massachusetts. The cost of the E-max for small business or multifamily

A comparison of the economics of
four installations of the E-max.

units would be $30,000 or more, but case studies have shown a payback period of 3 - 11 years in Europe.  While the economics of the e-max can make sense in Europe, the demand for the unit is also driven by customers who want to go the extra mile to use renewables, based on their values and the values of their customers.

The barriers of bureaucracy

Different emissions and safety testing protocols have been one of the major challenges to bringing innovative pellet central heating technologies, like the ÖkoFEN e-max, to the market. (European certification testing requirements are not accepted in the US so they have to be certified again in the US.) In Europe, new pellet boilers are being introduced every year and consumers can see these improved products online. But there is no way that an American company can pay to have each model EPA certified in for the US market when sales are still low. Dutch says that the time these tests can take can be “a barrier to innovation.” For Dutch, slow technological transfer in the marketplace is “a system wide issue, not just about boilers or cars, but about absolutely everything.” But it impacts appliances with low sales volumes the most. 

Europe’s best at the National Mall

Maine Energy Systems typically sells to the northeastern US and all of Canada, so the team sees this challenge as an opportunity to expose European boiler technology to a new continent. For Dutch’s vision of global collaboration to make ever more efficient renewable technologies, this challenge means a lot. With such low fossil fuel prices in North America, very few people know about the low carbon heating technologies that are very common in Europe. And the Pellematic e-max is a leading edge technology as it produces heat and electricity that can be paired with solar and other technologies to supply 100% of a home's energy needs.  

Contact the team

Dutch Dresser
dutch@maineenergysystems.com

Dan Wheeler
dan@maineenergysystems.com