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

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

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 resources page) 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 site for 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.