I’m writing in response to Katy Eiseman’s recent column, “Must stop subsidizing wood-fired energy,” [Recorder, April 5]. We’re concerned that readers may have walked away with a misunderstanding of the issue, and hope this column will clear things up.

“Modern wood heat” is the only wood heat that is part of the state’s Alternative Energy Portfolio Standard (APS) and can earn Alternative Energy Credits (AECs). Most people don’t know what we mean by modern wood heat. These are not wood stoves or pellet stoves. Instead, these are ultra-modern systems that go in your basement, replace your oil boiler or gas furnace, heat your entire home, are automatically fed (you just turn the thermostat), and are fueled by pellets or wood chips that are bulk-delivered, not in bags.

The vast majority of these systems are pellet boilers installed in single-family residential homes, where they replaced oil boilers. There are roughly 100 modern wood heating systems in the APS. Yes, you read that correctly. All this time, energy, and effort is being spent opposing 100 systems total in the entire state.

Ms. Eiseman and her organization, the Partnership for Policy Integrity (PFPI), are typically cagey when talking about the carbon impact of modern wood heat. In her column, she carefully references a Gov. Deval Patrick administration study and states that burning wood produces more CO2 than coal. This is misleading, as that study actually found a significant decarbonization benefit for high-efficiency thermal use of wood.

We’re uncertain why PFPI can’t simply be honest and concede that modern wood heat is a good decarbonizer but note they are concerned about air pollution instead of playing these word games. In short, the decarbonization benefit of modern wood heat in the APS has been conclusively proved in multiple peer-reviewed studies.

Modern wood heat systems are super-clean, emitting 99% less particulate matter than an older wood stove, and 99.999% less particulate matter than a fireplace. But the writer attempts to use a study of 30,000 wood stoves and tens of thousands of fireplaces to cast doubt on the emissions of 100 modern wood heating systems. This is either a foolish error or an attempt to deceive.

The state funded an air-sampling study by UMass Amherst of schools in rural Massachusetts that switched from oil boilers to pellet boilers. The study found that when they made the switch, their air quality typically improved, and that wood particulate emissions are likely less dangerous to human health than oil particulates, as peer-reviewed studies have shown.

If you’re complaining about incentivizing pellet boilers because of air pollution and you have a 20-year-old oil boiler in your basement, you’re likely producing more (and more dangerous) particulates than your neighbor who switched to a pellet boiler.

Despite this, we’ve heard continued complaints about air emissions. As a result, we introduced a bill that would grant an additional Alternative Energy Credit for modern wood heat systems that install an electrostatic precipitator (ESP) or other emissions control device. We believe the facts show these aren’t needed, but an ESP can remove up to 99% of particulate matter, taking modern wood heat systems very close to zero particulate emissions.

The issue is that these ESPs are expensive, which is why a credit incentive is necessary to encourage adoption. Will this encourage a lot more people to install pellet boilers? We don’t think so. At the current low price of credits, we estimate the return on investment of installing an ESP for an extra credit is 7-10 years — not enough to get more people to switch from oil, since the up-front cost of a modern wood heating system is high, even if ongoing fuel costs are low.

All the modern wood heating systems in the state combined earn less than $50,000 in credits per year, less than a penny per year for the average ratepayer. So even if they all install an ESP, that’s still just a fraction of a cent per year in additional expense to ratepayers. In the meantime, combined heat-and-power systems fueled by fracked natural gas earn nearly $15 million in Alternative Energy Credits annually.

But groups like PFPI don’t seem to care. If the reason is that natural gas systems are low in particulate emissions, that’s a reason to support our bill.

We hope this cleared up confusion about modern wood heat and the bill before the Legislature.

Chris Egan is the executive director of the Massachusetts Forest Alliance, which represents forest landowners, foresters, timber harvesters, and forest products companies in Massachusetts.