Is the Future of Renewable Energy Stuck 400,000 Years in the Past?

14 teams compete to build a super-efficient wood stove, one of humanity’s oldest inventions.

National Journal
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Brian Resnick
Nov. 20, 2013, 5 a.m.

On a cool, gray Sat­urday, the tent host­ing the first wood-stove dec­ath­lon on the Na­tion­al Mall looked something like a Nat­ive Amer­ic­an long­house, but covered in vinyl and with a dozen met­al chim­neys pok­ing out. From the out­side, those met­al stacks emit­ted no smoke, which made it a sur­prise to en­counter a wall of heat upon walk­ing in­to the tent.

All of the 14 stoves in­side — equipped with the latest in oxy­gen sens­ing tech­no­logy, cata­lyt­ic con­vert­ers, and re­mote con­trols — were burn­ing there in the face of this fact: Some 400,000 years after the dis­cov­ery of fire and the first hu­man stoves, we’re still try­ing to per­fect the tech­no­logy.

“It is seen as a hill­billy en­ergy; it’s not seen as a fu­ture en­ergy,” says John Ack­erly, the founder and pres­id­ent of the Al­li­ance for Green Heat, the event’s main spon­sor. With this event, on the heav­ily traf­ficked Na­tion­al Mall, he’d like to change that.

Over the course of the five-day dec­ath­lon, the 14 units will be tested for emis­sions out­put and fuel ef­fi­ciency. The $25,000 prize — and, con­ceiv­ably, the title of “most ad­vanced home stove in hu­man his­tory” — will go to the team that has the best com­bin­a­tion of scores.

The Prom­ise of Wood Heat

“Wood can be very dirty,” Tom Butcher, a con­test judge and com­bus­tion re­search­er with Brookhaven Na­tion­al Lab, tells me. It’s far more pol­lut­ing than gas or oil if burnt in an open pit (as half the world’s pop­u­la­tion does). And it’s not just emit­ting the usu­al prob­lem pol­lut­ants — such as car­bon monox­ide and car­bon di­ox­ide — but also ac­rid chem­ic­als such as ben­zene and form­al­de­hyde. In the de­vel­op­ing world, the World Health Or­gan­iz­a­tion es­tim­ates, 2 mil­lion people die pre­ma­turely due to in­door use of wood fire. 

That’s be­cause in that dirty — though de­li­cious-smelling — smoke from the open pit, there still are com­pounds that could be fur­ther broken down. For fire to burn clean, it has to burn com­pletely. In some designs, that means burn­ing hot­ter. But then the fuel gets spent too quickly. Reach­ing the op­tim­al bal­ance of emis­sions re­duc­tions and ef­fi­ciency is a del­ic­ate bal­ance — and the cent­ral chal­lenge of the dec­ath­lon.

“Some people like to say, ‘This is not rock­et sci­ence — it is a lot harder,’ ” says Butcher.

There are two main ways to burn wood com­pletely, he ex­plained. One is gas­i­fic­a­tion.That’s when the wood is heated to a point where it breaks down to a gas. Then, that gas is burned. (It’s ac­tu­ally a 19th-cen­tury tech­no­logy that was used to power some early cars — and a few cur­rent gonzo ones.) An­oth­er strategy is to em­ploy a second com­bus­tion cham­ber in which the smoke from the first burns and passes through a cata­lyst to be more eas­ily ig­nited for a second time.

The con­test has also in­spired some out-of-the-box think­ing.

A few months ago, Taylor My­ers and his team at the Uni­versity of Mary­land didn’t know the first thing about wood stoves, but de­cided to take on the chal­lenge any­way. At least on Monday, their stove, Mul­ciber — named after the Ro­man fire god — was lead­ing the rank­ings in terms of emis­sions.

What had set their con­trap­tion apart from oth­er mod­els was a nov­el idea: for­cing air in­to the stove. Usu­ally a stove draws in air via nat­ur­al con­vec­tion. The Mary­land team’s device in­jects air to fully com­bust the fuel. “We didn’t come in with any of the pre­con­ceived no­tions,” My­ers, a gradu­ate stu­dent, says of their suc­cess. “I think we’re on the verge of mak­ing something really great that can com­pletely change how people can use wood en­ergy.”

But Is Wood Heat Prac­tic­al?

However in­nov­at­ive the en­gin­eer­ing, a true wood-heat­ing re­volu­tion seems doubt­ful. In­terest in bio­mass fuel peaks up when costs of more con­ven­tion­al fuels are high, but the cur­rent nat­ur­al-gas boom is likely to keep gas in the status quo. And wood’s chief ad­voc­ates will ad­mit there’s a hill to climb in terms of emis­sions. “It’s nev­er go­ing to be as clean as gas,” Ack­erly says. “But we’re a re­new­able.”

It’s long been an in­tox­ic­at­ing en­vir­on­ment­al idea to cre­ate tech­no­lo­gies that help in­di­vidu­al homes work off the grid. But prom­ise doesn’t al­ways im­me­di­ately trans­late in­to prac­tice — just think about the pre­val­ence of sol­ar pan­els.

But in places where wood is abund­ant and cheap (per­haps even free), wood heat can make sense. Twenty per­cent of homes in New Eng­land have some form of wood-fired heat, the U.S. En­ergy In­form­a­tion Ad­min­is­tra­tion re­ports. And, over­all, “the use of cord wood and wood pel­lets as the primary res­id­en­tial space heat­ing fuel has in­creased by 39 per­cent since 2004, to about 2.5 mil­lion house­holds in 2012.” Add to that 8 per­cent of houses that use wood as a sec­ond­ary source of heat.

“Wood is at­tract­ive for a lot of reas­ons,” Butcher says. But “we have to get the emis­sions down from wood-burn­ing in or­der to achieve clean­er air.”

There’s a huge dif­fer­ence between the en­vir­on­ment­al im­pact of a clean wood burn­er and a dirty one — and the En­vir­on­ment­al Pro­tec­tion Agency has been reg­u­lat­ing them only since 1988. “Sev­enty per­cent of stoves in Amer­ica were built be­fore the EPA star­ted reg­u­lated them,” Ack­erly says. Be­cause wood is so vari­able (the type, mois­ture con­tent, etc.) EPA has the units tested over two weeks at dif­fer­ent burn tem­per­at­ures. “The cost, in­clud­ing safety [test­ing], is $30,000, $40,000, $50,000,” Steve Rhodes of HWAM, one of the dec­ath­lon con­tenders, says. His mod­el, cur­rently avail­able in Europe, is set by a com­puter ther­mo­stat, and its auto­ma­tion makes it dif­fi­cult for EPA to test at dif­fer­ent burn rates. The agency is cur­rently work­ing on up­dat­ing its stove reg­u­la­tions, mak­ing the emis­sions lim­its more strin­gent.

Walk­ing among the stoves, there’s a level of artistry and crafts­man­ship that just doesn’t go in­to your typ­ic­al home gas or oil burn­er. There are el­eg­ant stacked bricks, sharp in­dus­tri­al lines, old-timey enameled fire­boxes, and one mod­el with gi­ant met­al moose antlers. These are meant to be seen, not hid­den in the base­ment. There’s a “gath­er round” design ele­ment com­mon to all of them. Which is ne­ces­sary, be­cause the stoves re­quire some work, in load­ing the wood and keep­ing the fire go­ing.

“People like to come and just watch the flames; for us it’s a selling fea­ture — it has a beau­ti­ful flame,” says Niels Wit­tus, a con­tender with an el­eg­ant gas­i­fi­er stove. “A lot of people today don’t know that you can have — and this is not only ours — but the stoves here burn without any smoke es­sen­tially, and that’s a good thing.”