Wood fuel: Difference between revisions

Wood heat continues to be used in areas where firewood is abundant. For serious attempts at heating, rather than mere ambience (open fireplaces), stoves, fireplace inserts, and furnaces are most commonly used today. In rural, forested parts of the U.S., freestanding [[boiler]]s are increasingly common. They are installed outdoors, some distance from the house, and connected to a [[heat exchanger]] in the house using underground piping. The mess of wood, bark, smoke, and ashes is kept outside and the risk of fire is reduced. The boilers are large enough to hold a fire all night, and can burn larger pieces of wood, so that less cutting and splitting is required. There is no need to retrofit a chimney in the house. However, outdoor wood boilers emit more wood smoke and associated pollutants than other wood-burning appliances. This is due to design characteristics such as the water-filled jacket surrounding the firebox, which acts to cool the fire and leads to incomplete combustion. Outdoor wood boilers also typically have short stack heights in comparison to other wood-burning appliances, contributing to ambient levels of particulates at ground level. An alternative that is increasing in popularity are wood gasification boilers, which burn wood at very high efficiencies (85-91%) and can be placed indoors or in an outbuilding. There are plenty of ways to process wood fuel and the inventions today are maximizing by the minute.

There are numerous ways to process wood fuel, and wood is still used today for cooking in many places, either in a stove or an open fire. It is also used as a fuel in many industrial processes, including smoking meat and making [[maple syrup]]. As a sustainable energy source, wood fuel also remains viable for generating electricity in areas with easy access to forest products and by-products.

[[Image:Firehome3.jpg|thumb|right|[[Fireplace]] and [[chimney]] after a wildfire, [[October 2007 California wildfires|Witch Fire]], [[California]]]]As with any [[fire]], burning wood fuel creates numerous by-products, some of which may be useful (heat and steam), and others that are undesirable, irritating or dangerous.

In some of the most efficient burners, the temperature of the smoke is raisedhot enough to a much higher temperature where the smoke willburn itself burn (e.g. {{cvt|609&nbsp;°|C|F}}<ref>{{cite web

}}</ref> for igniting carbon monoxide gas). This may resultsignificantly in significant reduction ofreduce smoke hazards while also providing additional heat from the process. By using a [[catalytic converter]], the temperature for obtaining cleaner smoke can be reduced. Some U.S. jurisdictions prohibit sale or installation of stoves that do not incorporate catalytic converters.{{Citation needed|date=April 2007}}

The technique of compressing wood pulp into pellets or artificial logs can reduce emissions. The combustion is cleaner, and the increased wood density and reduced water content can eliminate some of the transport bulk. The fossil energy consumed in transport is reduced and represents a small fraction of the fossil fuel consumed in producing and distributing heating oil or gas.<ref>Manomet Center for Conservation Science. 2010. Biomass sustainability and Carbon Policy Study: Report to the Commonwealth of Massachusetts Department of Energy Resources.[http://www.manomet.org/sites/manomet.org/files/Manomet_Biomass_Report_Full_LoRez.pdf] {{Webarchive|url=https://web.archive.org/web/20180108120416/http://www.manomet.org/sites/manomet.org/files/Manomet_Biomass_Report_Full_LoRez.pdf |date=2018-01-08 }}</ref>

Wood burning creates more atmospheric CO₂ than biodegradation of wood in a forest (in a given period of time) because by the time the bark of a dead tree has rotted, the log has already been occupied by other plants and micro-organisms which continue to sequester the CO₂ by integrating the hydrocarbons of the wood into their own life cycle. Wood harvesting and transport operations produce varying degrees of [[greenhouse gas]] pollution. Inefficient and incomplete combustion of wood can result in elevated levels of greenhouse gases other than CO₂, which may result in positive emissions where the byproducts have greater [[Carbon dioxide equivalent]] values.<ref>{{cite journal |title=Greenhouse gases from biomass and fossil fuel stoves in developing countries: A Manila pilot study |doi=10.1016/0045-6535(93)90440-g | volume=26 |issue=1–4 | journal=Chemosphere |pages=479–505|year=1993 |last1=Smith |first1=K.R. |last2=Khalil |first2=M.A.K. |last3=Rasmussen |first3=R.A. |last4=Thorneloe |first4=S.A. |last5=Manegdeg |first5=F. |last6=Apte |first6=M. |bibcode=1993Chmsp..26..479S |citeseerx=10.1.1.558.9180 }}</ref>

In an attempt to provide quantitative information about the relative output of CO₂ to produce electricity or domestic heating, the United Kingdom Department of Energy and Climate Change ([[Department of Energy and Climate Change|DECC]]) has published a comprehensive model comparing the burning of wood (wood chip) and other fuels, based on 33 scenarios.<ref>{{cite web |title=Biomass Emission and Counterfactual Model |url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/394758/beac_2015.xlsm |format=spreadsheet |access-date=25 March 2015}}</ref> The model's output is kilogram of CO₂ produced per Megawatt megawatt-hour (MWh) of delivered energy. Scenario 33 for example, which concerns the production of heat from wood chips produced from UK small roundwood produced from bringing neglected broadleaf forests back into production, shows that burning oil releases {{cvt|377&nbsp;|kg|lbs}} of CO₂ while burning woodchipwoodchips releases {{cvt|1501&nbsp;|kg|lbs}} of CO₂ per MWMWh hof delivered energy. OnHowever, the other hand,in scenario 32 inof that same reference, which concerns the production of heat from wood chips that would otherwise be made into particleboard, releasesshowed that only {{cvt|239&nbsp;|kg|lbs}} of CO₂ per MWMWh hwas delivered energyreleased. Therefore, the relative greenhouse effects of biomass energy production very muchare dependsdependent on the usage model.

The environmental impact of burning wood fuel is debatable. Several cities have moved towards setting standards of use and/or bans of wood burning fireplaces. For example, the city of Montréal, Québec passed a resolution to ban wood fireplace installation in new construction. Wood burning advocates claim{{Weasel inline|date=February 2013}} that properly harvested wood is carbon-neutral, therefore off-setting the negative impact of by-product particles given off during the burning process. In the context of forest wildfires, wood removed from the forest setting for use as wood fuel can reduce overall emissions by decreasing the quantity of open burned wood and the severity of the burn while combusting the remaining material under regulated conditions. On March 7, 2018, the [[United States House of Representatives]] passed a bill that would delay for three years the