Residential Solar Spreading, But Outperformed by Wood Heat

By John Ackerly | July 01, 2013

The U.S. Energy Information Agency recently released 2011 residential energy generation data showing that solar is making gains, and added the equivalent of nearly 40 trillion Btu in 2011. Comparatively, wood and pellet stoves added just 30 trillion Btu in 2011, yet, according to EIA statistics, wood heating still produces three times more energy than solar panels and 11 times more than geothermal.

New EIA projections, however, predict solar may only produce the equivalent of .21 quadrillion Btu of energy in 2040, and that wood heat will produce .45 quadrillion Btu. This assumes a continuation of existing incentive policies that heavily favor solar. How many policymakers know that our government is predicting wood and pellet heating to still double the capacity of residential solar PV, even with all the rebates and incentives? I expect not many.

Residential solar and wood and pellet heat share some key attributes: both are distributed sources of energy powered by the sun. Solar panels convert the sun’s energy directly through photovoltaics, whereas wood and pellet stoves and boilers convert it through photosynthesis, storing it in the tree for later use. They complement each other beautifully, as one produces kilowatts and is inefficient to heat with, while the other produces Btus and is inefficient for electricity.

Solar is typically installed by urban, educated, wealthy families whereas wood and pellet stoves tend to be installed by rural, low- and middle-income families.  Policies that give generous incentives to wealthier families, and not to middle-income families, for their respective technology of choice are based on an array of values, perceptions, assumptions and choices. 

The growth differential is partially due to state, not federal, incentive structures. From 2010 to 2011, 70 percent of the growth in solar occurred primarily in California and Florida, states with healthy incentives. With wood and pellet heating, the growth is far more incremental and organic across many states. Five states provide some state-level incentives for modern U.S. EPA certified stoves, but are far less generous than solar incentives. Even without significant federal or state incentives or rebates, wood and pellet stoves added far more capacity than solar panels between 2006 and 2008. 

The EPA is about to announce new emission regulations for wood and pellet heating equipment, including furnaces and boilers that will be far stricter than existing regulations. Currently, wood and pellet stoves can emit up to 7.5 grams per hour. The EPA has floated a 1.3-gram-an-hour threshold to take effect 5 years after promulgation.  The emergence of cleaner and more efficient wood and pellet equipment is likely to help the growth of wood and pellet heating, as it has in Europe. There is also a green label for wood and pellet equipment being developed in the U.S., to help consumers easily identify the cleanest and most efficient heaters, and enable states to use that label in incentive programs. 

If the U.S. government predicts that residential wood heating will produce double the energy of residential solar PV, does this argue for even more aggressive solar subsidies? I believe we need to build on what works, and that means creating technology-neutral incentive structures. This would allow the consumer to decide what makes the most sense for their situation, based on their values, assumptions, and economic situations. Maine Sens. Angus King and Susan Collins just introduced S. 1007, the Btu Act of 2013, which seeks to include high-efficiency wood and pellet appliances in the provision of the IRS tax code currently giving  a 30 percent consumer tax credit only for solar PV.  Let the consumer decide, not the policymakers who seem to think solar PV is the only solution. 

The cleanest and most efficient wood and pellet appliances deserve incentives, otherwise consumers will likely buy less clean and less efficient appliances, or will keep using existing technology that is often very polluting and inefficient. It is time we guided the wood and pellet sector, as Europe has, maximizing its benefits instead of continuing to rely on outdated equipment.

Author: John Ackerly
President, Alliance for Green Heat


1 Responses

  1. Jeremy A D'Herville



    I'd like to see the UL standards get their head out of the firebox, fix the missing creosote assessment link, fix the negative pressure element - - and bollocks off the PM sampling 'symptom' based issue. We're not only testing stoves with catalytics - so why are we assessing them as if stoves had them. Fix the missing link that killed - and continues to kill the perfectly adequate, consumer friendly air tight wood stoves Bob Fisher designed. He improved many things but did not completely address the draft issues affecting indoor and outdoor pollution on the worst inversion winter days. Fans are not the smartest method to increase draw because they also cool the air by nature. Some countries are removing dampers to force a stove to burn hot and fast through the fuel, and also go out faster. Pellets fine as an option but never a necessary replacement. Soot and creosote is still happening from solid fuel appliances in situ, in the worst winter conditions. Why, because standards have never moved on from the firebox tested in ideal lab-based conditions, and the ignorance of negative pressure from the pressure differential above the exhaust - removing the necessary natural upward draft/ draw. Anything with a vertical flue will at times - especially in inversions get negative pressure - causing poor combustion and smoke out the appliance's door. The more complicated the appliance - double combustion air chambers, additional pipes and wet-backs - the more updraft is required. The EPA standard which other countries have copied into their standards is only moderately effective because it only attaches itself to the already inadequate safety standards. Fix soot and creosote from forming, fix emissions. By the way I love the work that Alliance for Clean Heat is doing. You guys are doing an awesome job.


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