How to I construct and operate the most environmentally friendly wood burning pizza oven?

April 1, 2009 11:23 PM

How do I reconcile operating a wood burning pizza oven with environmental friendliness?

I am as environmentally conscious as the next guy, likely more so, but to make pizza the Neapolitan way, one requires a wood burning oven. What steps can I take in the construction and operation of my oven to reduce the environmental impact?

I know there are carbon credits and things like that, but I'd prefer a reasonable solution that deals with the fuel or exhaust or trapping or something like that.

posted by FearAndLoathingInLJ to food & drink (19 comments total)

Install a catalytic system that filters and re-burns the smoke. Not sure how that would work on an oven, but this pdf from this page about wood-burning stoves gives a basic diagram.
posted by Dasein at 11:32 PM on April 1

By burning wood you're staying within the carbon cycle, whereas by burning fossil fuels you're liberating carbon that's been trapped in the earth's crust. If you can use local wood it would be even better.

My parents have been heating their house with wood for 24 years: I wouldn't be overly concerned or guilty about firing up a wood oven for pizza every once in a while, the scale of the operation sounds really small (unless you're doing this as a commercial venture?)

Have fun eating pizza!
posted by dunkadunc at 11:48 PM on April 1 [6 favorites]

Seconding dunkadunc... also, plant some trees for harvesting down the line if you have the space.
posted by jzed at 12:38 AM on April 2 [1 favorite]

Buy your wood fuel from sustainably managed forests.
posted by EndsOfInvention at 12:45 AM on April 2 [2 favorites]

I agree with dunkadunc. Also, how many pizzas a day are you making/eating? I would imagine this isn't in everyday use and so isn't going to have a major negative impact.
posted by Elmore at 12:50 AM on April 2

The wood you burn contains the same amount of carbon as a tree of equivalent volume. And trees take CO2 out of the air and use it to make their own tissue. So plant a tree or three and try to ensure the volume of wood you burn is smaller than the volume of plant matter you grow; that'll offset your emissions. Hemp and bamboo are a good plants to sequester carbon, too, as they grow fast. When your plant is grown, for bonus points, do something with the plant tissue to keep the carbon locked (it gets released back into the air when the plant rots or is burnt), so make crafts or something with your plants.
posted by pseudostrabismus at 1:37 AM on April 2 [1 favorite]

Without going into a lot of detail, what are your alternatives? Solar cooking? Wind powered or water powered ovens? Natural gas/methane/propane? Conventional coal fired electric? Oil? Nuclear?

You are using biomass, which technically, is carbon neutral. It is today's carbon. It adds no additional carbon to the world we live in.

Coal, oil, propane, natural gas are NOT carbon neutral. They add yesterday's carbon to the world we live in.

In addition, since electrical power derived from fossil fuels is in the area of 20%-30% efficient, if you cook in your electric oven, you use 3 to 5 times the fuel to cook your pizza than you need to compensate for conversion inefficiency and transmission losses.

Biomass heating is a decent alternative for local use of heat. (It is not so good for power production for the same reason that oil isn't good.) Don't lose too much sleep over it.

If you want to make a difference and contribute to global environmental health, there are scores of ways to compensate for your imagined insult to the planet.
posted by FauxScot at 3:35 AM on April 2

Um, what about air pollution, soot, the old-fashioned environmental stuff?
posted by rikschell at 3:53 AM on April 2

Like what has already been said, there is no need for you to worry. Not all carbon = bad. The problem is with burning fossil fuels which releases carbon that has been trapped under the earth for millions of years. If you are burning wood, the carbon you release is from our current carbon cycle, and within sensible reason you can feel fine burning wood; you aren't doing any harm to the environment.

Enjoy your pizza, I wish I had a wood burning pizza oven. Oh well, back to my frozen pizza :(
posted by tumples at 4:41 AM on April 2

About the smoke

I'm going to go out on a limb here, and while I agree with most of what has been said (carbon neutral, etc) you do need to know that burning wood is not just a matter of CO2. Burning wood also produces volatile organic compounds (VOCs), carbon monoxide, nitrogen oxides (NOx), and fine particulates. In other words, air pollution.

See these EPA pages:

Comparison chart of fine particulates emitted by different heating devices (fireplace, wood stove, certified wood stove, pellets...)

Heath effects of wood smoke

That being said, unless you are going to start a business and cook pizzas all day every day, I wouldn't worry about it too much. Just plant 2 trees for every 1 that you burn.


Constructing an environmentally friendly oven

There are several options for creating an oven from natural materials. You can, of course, use bricks. But it is also possible to make a great pizza and bread oven from cob, a mixture of clay, sand, and straw. The fun part is that cob can take on any shape you want on the outside; I've seen one shaped to look like a pig's head, and another that looks like a chicken.

One of the best books I have seen about this is:

Build Your Own Earth Oven

I'd imagine that you could get some inspiration from that, combine it with some know-how about brick pizza ovens, and come up with a great solution. Good luck!
posted by bengarland at 5:54 AM on April 2

Carbon monoxide is not that big of a deal environmentally because it reacts with oxygen and becomes CO2 pretty quickly. Of course it binds to hemoglobin even faster so it will take you out pretty effectively, but that's different from the environmental impact. (Similarly, copper is a bigger environmental hazzard than lead - this mostly is about the solubility of salts.)

Rather than get all hand-waving-freakouty about your wood burning oven, I'd say invest a couple hours/bucks in making your house or car more energy efficient. 1% of your gasoline consumption is probably a bigger environmental impact than 100% of your wood burning oven's impact.

All that being said, if your making it out of brick and such, build it to last. Lots of energy goes into making bricks, mortar and the like. Spend the extra on firebrick and refractory mortar. (Or dig your own clay as bengarland pointed out.)
posted by Kid Charlemagne at 6:26 AM on April 2 [1 favorite]

As long as you are getting your wood from sustainably-managed forests (one where they are harvesting the wood and replanting it, not "strip-mining" the trees from the land and moving on, which is unfortunately what a lot of logging operations do), I'd say you should go forth and eat pizza.

The more efficient you can make your stove, obviously the better, but I suppose there are probably limits to that for a pizza oven. It's not like a wood stove where you can engineer the thing to death because all it has to do is convert wood into heat as efficiently as possible. (Some "EPA stoves" are tremendously efficient, like 90+% thermal; you can look into how they work if you are interested — perhaps you can get some of the same features in a pizza oven, although I'm doubtful.)

But really it's the fuel source that makes you part of the problem or not; if you're burning wood that comes from unsustainable "wood mining" operations (ones that result in deforestation), you're probably doing more damage than if you just burned oil. Oil, at least, doesn't serve much function when it's sitting underground — forests do.
posted by Kadin2048 at 7:27 AM on April 2

- buy "farmed", and dry wood, possibly from a source near you
- build a well engineered oven, there's lots of guides around

with a good draft, and the right kind of wood (you don't use logs of firewood as much as well dried bundles of thin sticks), your oven is going to easily reach temperatures in excess of 900 F, so nasty byproducts of combustion should be a secondary concern.
posted by _dario at 8:07 AM on April 2

This is an issue to which I've given a lot of thought. I would very much like to build a wood-fired oven (particularly of the type shown in the Build Your Own Earth Oven linked above), but I haven't done it because of environmental and health concerns. Burning wood is not a problem in itself (at least in my area), but poor combustion can create a lot of pollutants and I'm not convinced that a simple design will be good enough to avoid this problem. I've cursed people in my neighbourhood with poorly-burning woodstoves many times, so I'm hesitant to add to that problem. I think that your location (are you in an urban, suburban, or rural area) should have a lot of influence on your decision to build.

I think the gold-plated option would be to build a white oven (where the fire is in a separate chamber) which integrated a catalytic converter into the design, but that would be tricky and expensive. You could also integrate a EPA-certified stove, but that would also be expensive. To do this on the cheap, I think your best bet is to build a well-tested design that will allow for a good draft (i.e. one with a chimney). Have you seen The Bread Builders? The design in that book is fairly complicated, but there is a lot of good information in there. Burn very dry wood and build your fires so that you can get them up to a good temperature as soon as possible.

Please report back and let us know which design you build and how it burns.
posted by ssg at 9:02 AM on April 2

There is no mention of your location, which could be important. Nearly all commercial lumber out of Canada that isn't bug kill or burn recovery has been harvested using a sustainability plan. How sustainable is a different issue, but most are required to plant trees and other silverculture projects. The firewood guy with one truck? Who knows what he is up to.

Essentially you have two issues: air pollution and replacing the trees being used for fuel. I don't know much about the air pollution end of it- trap or srub would be my guess. To offset the wood you are burning by planting trees you will need an accurate estimation of the total wood you are using, and most people overestimate the amount of wood being used. Of course most people haven't choped down a tree so that's to be expected. A reasonable replanting would be at least 4 times that, or 10 times if it an operation that just plants the trees. Most planted trees won't reach maturity, so lower than this isn't sustainable. It is not terribly expensive for example look at the Arbor Day - in particular at their rainforest replanting project where it is thousands of square feet for dollars. Or the gorongosa project, where you pay for someone's wages to plant trees, essentially buying thousands of tree plantings, and supporting the local economy.

Local is great to - here in Chicago we've got Chicago Gateway Green who have made my trips around the city nicer to look at. They also do maintenance, so the cost per tree is substantially higher. The fact that you are weighing these options is really great, last year my household's carbon offset was like 60 bucks. I expected it to be way higher. Of course there is a whole debate about the effectiveness of these sorts of things, but its a start.
posted by zenon at 9:46 AM on April 2

Short answer: Wood is pretty enviro friendly. Do it & figure out a balance.
posted by zenon at 9:48 AM on April 2

Wood burning is not enviro friendly. Wood burning is about the dirtiest household fuel available -- 100 to 1000 times dirtier than natural gas or propane even with the best certified wood stoves. The particulate matter is extremely dangerous to health. The microscopic particles penetrate into the smallest airways and are particularly damaging to children.

Maybe if you are in a remote area the damage may be smaller, but if you are in an urban area you aren't doing your neighbors any favors. Would you be okay with some of your neighbors coming over to smoke their cigarettes in your house? Carbon neutrality isn't the most important issue.

Is there really any taste difference between a wood burning oven and a gas or electric oven? I would assume that if a smokey taste is the benefit, then you are creating the worst kind of smokey fire. Could you tell the difference in a blind taste test? Is it worth polluting your neighbors?
posted by JackFlash at 11:10 AM on April 2

Not to be a total spoil sport, I suppose it's okay if you do this once in a while for a short period of time, like a barbecue, but if done regularly, your neighbors have a right to be offended.
posted by JackFlash at 11:40 AM on April 2

A wood oven can run be full time and not irritate or pollute your neighborhood, but it will add expense and relative to other cooking options it is dirtier. A commercial wood pizza oven will apparently run about $10 000 USD, and that's before its shipped or installed. To deal with air pollution electrostatic precipitators can be built in to the unit to dramatically reduce the particulate matter (PM) it produces. To further reduce PM you can install a commercial secondary air cleaner - those big gray boxes on the roof of your favorite chain restaurant that prevents it from smelling up the whole neighborhood. Here's a popular one: Smog Hog.

Modern wood burning stoves* all must meet much stricter PM requirements, and some are 90% cleaner than older wood units. Note that all wood burning operations will be dirtier than all Gas fired units because it is possible and not terribly expensive to get eliminate PM from a gas fired unit. Its not a great comparison because burning wood produces an infinitely larger amount of PM than gas, that doesn't necessarily mean it is infinitely worse. With scrubbers and a secondary filter it is possible to meet the strictest air pollution requirements, but these have additional costs. I think you can reasonably reduce the impact of a wood oven, but I can't say if that something you can afford given other options. If you are serious about environmentalism and keep asking questions about your impact hopefully you'll find answers that address and meet your needs.

*Its not clear if the EPA has requirements for commercial wood ovens or its only for wood stoves/ heaters. But the tech is there regardless.
posted by zenon at 1:59 PM on April 3