Article source: www.woodheat.org

Wood Energy Economics and Heating Security

Comparing Firewood to Conventional Heating Fuels

Fuelwood is unlike any other mainstream heating fuel, in that users are engaged physically and mentally in its consumption, and for many, in its production as well. Users of oil, gas and electric heating are typically involved only in paying energy bills and adjusting thermostats. As a result, any cost comparison of wood with other fuels is likely to be inaccurate, if not misleading, because it cannot account for either the labour costs or the intangible benefits of wood heating.

Householders considering a switch to wood heating would find it useful to know how much money they might save compared to the use of conventional fuels, in the same way that other major purchases are evaluated. The problem with this approach is that the cost-benefit analysis of wood heating is not easily reduced to a simple matter of money. Considering the rising prices of conventional fuels, it is probably accurate to say that households located outside major urban centres where there is significant forest cover could save money using firewood on a strictly heat-energy-per-dollar basis. But how can the other less tangible costs be evaluated? These costs might include:

  • the space required to store a winter’s supply of firewood outside the house and space inside the house for a few day’s supply
  • the physical strength and stamina required to split, move and stack firewood
  • the time consumed in managing the fuel supply, tending the fire and dealing with regular maintenance tasks like ash removal
  • the impact of the inevitable ‘mess’ of wood chips, bark and wood ash on the time consumed by household cleaning

The intangible benefits are equally difficult to evaluate in monetary terms.

  • the satisfaction one feels in having mastered home heating largely by personal labour and ingenuity
  • the sense of security both in terms of energy price stability and in the ability to remain comfortable in the home during electrical power interruptions
  • the beauty and ambience created by a fire burning behind clear glass doors
  • the special kind of warmth given off by a wood stove located in the main living area (this may be debatable in terms of physics, but it is mentioned by most users of wood fuel as an important benefit)

Several online sites offer fuel cost comparison methods. The calculations are fairly complex, accounting for local fuel pricing, housing type, climate zone, fuel type, appliance type and efficiency. However, a good indication of the imprecision of these calculation methods is that only whole-house heating to an even temperature throughout can be considered. This type of calculation cannot accommodate a wood stove used as a partial or complete heating replacement for a central furnace using conventional fuel. Compared to central heating, the use of a wood stove for space heating, especially if it is located in the main living area, can mean a reduction in heat energy needed by up to 25 percent, regardless of the cost of either fuel.

How Wood Heating Strengthens the Local Economy

Let’s look at some real-world examples of how people save money by heating with wood. Some families buy their firewood already split so their work only involves stacking it to dry. They might spend $250 for each cord (4’x4’x8’), the equivalent of almost $440 in fuel oil at $2.75 a gallon. That family’s savings wouldn’t be large, but they would gain all the tangible and intangible benefits of wood heating.

Small-scale harvesting and processing equipmentSomeone working in his woodlot, harvesting trees and processing them into firewood can save most of the cost of heating using other methods. For him the cost of a winter’s firewood is two week’s work and a few gallons of gas for the saw, splitter and pickup truck. Harvesting and processing the household’s heating fuel can save two or three thousand dollars every year.

What if dozens of households in a small town decided to save money by heating with wood instead of oil? Each of the twenty households would have a few hundred to a few thousands of dollars more to spend around town this year. Every dollar saved through wood heating is another dollar of spending that strengthens the local economy.

Rural areas tend to have large ‘trade deficits’ on consumer goods and most commodities. Their ‘exports’ are usually based on their natural resources such as mining, agricultural and forest products. Revenue from external sources is commonly in the form of tourism and recreation expenditures by non-residents. Overall, as population, industry and political decision-making concentrates in large cities, rural areas have not fared well economically.

A household that produces its own fuelwood supply saves $2,000 or more each year, an amount that can be used to reduce expenses in a household of marginal income, or that can be spent on other goods and services like home improvements. This household trades its own labour for big savings in household operating expenses.

A woodlot owner who produces and sells firewood provides employment and income to the area. If that same producer practices effective management, the quality and value of the woodlot are enhanced at the same time. When a local household buys its winter fuel supply from a neighbour, that transaction has a multiplying effect by keeping the money circulating within the community, increasing local incomes and job creation.

Local economic activity, including jobs and incomes, is increased through the use of fuelwood as a substitute for fuels purchased from outside the community. In a time of uncertainty about the future price and security of supply of conventional energy sources, fuelwood provides some price stability for residents of rural areas, as well as a sense of security because, if necessary, each household could produce its own fuel supply with a relatively small outlay of cash.


Article source: www.woodheat.org

Energy Return on Energy Invested

Looking at the energy cost of energy

Economists focus on the money cost of energy, but the energy costs of energy can provide better insights into environmental costs and the underlying reasons for the money cost. For this reason, the energy return on energy invested (EROEI) should be included in any appraisal of the quality, impacts and appropriateness of various energy sources. Here is a sample EROEI analysis for fuelwood compared to other energy sources. Note that the value of labour is not included in the calculation.

  • hardwood fuel example: 24 million btu per cord of sugar maple
  • 1 gallon of gasoline: 115,000 btu
  • average round trip for fuel delivery:  50 miles
  • fuel consumption of pick up truck: 15 mpg
  • two round trips per cord = 6.7 gallons
  • chainsaw fuel per cord: 0.5 gallon
  • log splitter fuel per cord: 1 gallon

Total fossil fuel consumption: 8.2 gallons/cord x 115,000 = 943,000 btu
Calculation: Energy content per cord: 24 M btu divided by fossil fuel input: 943,000 btu.
Energy return on energy invested: 25:1

An EROEI of 25:1 may not be worst case for fuelwood, but it is close for rural areas. Harvesting from their own woodlot, some people probably produce firewood at an EROEI of 30 to 40:1.

For comparison, back in the heyday of oil, when discoveries were peaking and consumption was just ramping up, one barrel invested would yield about 100 barrels for sale, a cheap energy bonanza if there ever was one. Today, gushers are a thing of the past, most of the biggest oil fields are in decline and the ‘new’ oil fields are tiny and found under oceans. The EROEI of oil and gas has now fallen to 10:1 to 20:1, depending on age, type and location of the field. So-called unconventional oil such as the bitumen extracted from the Canadian tar sands has an EROEI of as low as 1.5:1 to a high of 4:1, depending on how the calculation is done and who does the calculating.

This is a graph produced by Charles Hall and his colleague John Day The green bars are the minimum EROEI and the baige parts are the observed range.

The chart at right was developed by Professor Charles Hall and his colleague John Day. Note that firewood is asigned an EROEI of around 30:1, which is a similar result to the analysis done for this paper.

Wood, in the form of natural firewood, compares favorably with other fuels regarding the amount of net energy realized after processing and transportation. This bodes well for a degree of price stability for fuelwood in the future. Price stability is not likely for the fossil fuels because as the easily accessible deposits are consumed the EROEI rises dramatically, as does the retail price.

Sustainable forestry

What if everyone heated with wood?

This beautiful graphic was created for RSF-ICC, a fireplace and chimney company. Used with permission.Critics of wood heating like to say that if everyone decided to heat with wood, the air would be polluted and every forest in the country would be mowed down to produce firewood. Maybe, but the whole idea is pretty silly, considering that wood is a lousy urban energy source and is best used locally. Even the most ardent defenders of wood heating would never promote it as a universal energy source.

Large parts of the country are relatively thinly populated and have highly productive forests. These are the regions where wood heating makes sense. Foresters have said that wood heating could easily double or more in many regions without putting undue stress on the forest resource. Our forests do need to be managed sustainably, but the methods are well known and can be summarized in a single sentence: Uneven-aged selective harvesting, thinning of dense stands and removal of poorer quality trees, while leaving seed trees of all present species and ages, and some standing dead trees to provide wildlife habitat.

Many woodlots in farm country can offer a striking model of sustainable forestry. The careful work by generations of farmers and other woodlot owners, visible in healthy, productive woodlots that have provided generations of owners with their heating fuel and other products, provides the stewardship model that others can follow.

And while many woodlot owners understand and practice sustainable forest management, others exploit the resource for short-term profit. Unfortunately, some farmers have maximized short term profit by clear cutting their woodlots and converting the land to cash crop production. Some companies and individuals have made a practice of buying large parcels of unused forest land, stripping them of all the commercial trees and then reselling the depleted parcels. These profiteers do meet the definition of woodlot owners, but they do not maintain ties to the lands they buy and sell.

A healthy, well-managed woodlot can provide firewood and other products indefinately.It has long been said that a healthy, well-managed woodlot can yield half a cord of wood per acre per year forever – one full cord being a pile eight feet long, four feet wide and four feet high – and that a ten acre woodlot could sustainably produce enough firewood each year to heat a house. Although that guideline is old and not very precise, it still holds true. In fact, it takes a lot less than five cords of wood, and therefore less than a ten acre woodlot, to heat a new energy-efficient house using a modern wood stove. There is some evidence that carefully designed and built houses can be heated with as little as 1.5 cords of firewood.

Despite its considerable advantages, fuelwood is not a good solution for all households to the problems of high home heating costs and global warming. Fuelwood is not a suitable energy source in all locations, such as densely-populated urban areas, because its air emissions tend to be higher than other options, and the air is already burdened with pollution from industry and transportation. A winter’s supply of wood takes up a lot of space, and the price of firewood in urban areas is normally too high to achieve savings. Successful heating with wood also requires a level of physical fitness and the learning of a special set of skills. Clearly, wood heating is not for everyone.


Article source: www.woodheat.org

Advanced Wood Burners Cut the Smoke

The new wood burning technology found in EPA certified stoves goes a long way toward solving all three wood smoke problems: airshed contamination, nuisance wood smoke and indoor air pollution. These advanced stoves, inserts, fireplaces and furnaces cut wood smoke by up to ninety percent compared to older so-called ‘airtight’ stoves, and also spill less smoke into the indoor air because fires don’t tend to smoulder in them, the condition that most contributes to smoky indoor air.

Smoke emissions from older conventional wood stoves average at least 25 grams per hour of operation, while the emissions from older wood-fired outdoor boilers range from 50 g/h to well over 100 g/h. In contrast, the EPA regulation limits emissions of certified wood stoves to no more than 7.5 g/h. However, since the regulation was first established in 1988, the average emissions of certified stoves have declined steadily due to advances in technology and competition among manufacturers. Today, most current wood stove models emit only 2 to 4 g/h.

Although the EPA emissions limits are stated as solid particles (particulates) collected on filters, other detailed testing has shown that the emission of the scary-sounding polycyclic aromatic hydrocarbons like fluorene and benzo (a) pyrene, as well as volatile organic compounds like benzene and xylene are all far lower in the exhaust from advanced wood heating equipment than from old style wood burners.

Despite what some anti-wood heating activists have claimed, the technology is effective in reducing pollution. The reduction in smoke emissions has been a significant technological breakthrough in wood burning and is noticeable at the top of the chimney where no visible smoke is seen.

Advanced equipment is more efficient too

Just as noticeable to users, however, is the increase in efficiency that results from burning and not wasting the energy-rich smoke. Conventional wood stoves range in efficiency from a low of about 35 percent for a cast iron box stove or furnace to a high of as much as 55 percent for a 1970s era ‘airtight’. Most older outdoor boilers are less than 50% efficient. In contrast, EPA certified wood stoves average around 70 percent and none are less than 60 percent efficient. The new breed of emissions certified outdoor boilers are also much more efficient.

The difference in efficiency between conventional wood burning equipment and the advanced low-emission models is so significant that users can immediately see the difference when they upgrade and begin using a new stove. The reduction in fuelwood consumption by up to one-third is significant for each household that uses the new technology, but it also has the potential to increase the number of houses that can be heated based on the sustainable harvesting of a given area of forested land. Another significant factor that reduces a wood-heated household’s impact on the forest resource is the lower heat energy requirements of modern housing. Together, the increase in wood burning appliance efficiency and improvements in housing energy conservation can roughly double the number of dwellings that can be heated by the yield from a given woodlot compared to just 25 years ago.

An outdoor boiler firing up.Community-wide smoke problems are uncommon in areas where level topography does not produce the same number or severity of winter inversions that trap smoke close to the ground. While community level smoke problems are relatively rare, nuisance smoke caused by thoughtless neighbours has been identified as a problem in dozens of towns. One technology in particular has been the focus of many complaints. Outdoor wood-fired boilers (OWB), which look like metal garden sheds and send hot water to one or more buildings through buried pipes, have become notorious for the dense smoke they produce. Small towns have enacted bylaws restricting the installation of outdoor boilers by either banning them from residential areas or placing limits on their proximity to property lines.

The source of the problem is that central heating furnaces and boilers, including OWBs, were exempt from the original EPA emission rules back in 1988 on the basis that there were too few of them to bother regulating. Well, that was then. Now OWBs are very popular and as a result a new smoke emissions test for OWBs has been approved and certified models are now on the market. On paper the new breed of OWBs look much better than the older, smokier versions. Time will tell if they are clean burning enough to satisfy regulators and reduce public complaints.