D. Wood Heat Compared to Other Renewable Energy
Wood is arguably the most successful residential renewable energy technology in the US today. While there are thousands of homeowners purchasing solar panels, wind turbines and hybrid cars, there are millions of wood stoves heating US homes with a renewable energy (Fig. 9).
Figure 9: Renewable Energy Consumption in the Residential Sector (Energy Information Administration)1
This is not a surprising trend, as wood heat not only has a few thousand year head start, but it is also only a fraction of the cost of other residential renewable energies. Residential solar PV panels cost upwards of $20,000, as do most wind installations and the entire involved geothermal installation process. 2
Solar panel purchase is driven primarily by the consumers’ income level, with more wealthy families the primary solar purchasers. 3
Clean modern wood stoves on the other hand can be bought and installed for under $3,000. If stoves are used to replace a traditional fossil from of home heat, they can displace 1-10 tons of carbon a year (Fig. 10), depending on heating requirements, type of fossil fuel displaced and if the stove is being used as a primary or secondary source of heat.4
Figure 10: Tons of carbon per year per residential space heating unit (Hbh Gas Systems) 5
Due to the overwhelming prevalence of wood stoves, US wood stoves displace more carbon than nearly any other renewable energy (Fig. 11).
Figure 11: Renewable Energy Carbon Calculations (EIA, EPA, DOE) *Based on an average home’s carbon footprint from heating, assuming a cordwood appliance displaces 50% of fossil fuels for heating, and the more automated pellet stove displaces100% of the average fossil fuel heat6, although either could be used as a primary or secondary heating source.
||# of appliances installed as of 2010
||Tons of carbon saved per year per appliance *
||Total tons of carbon saved per year in US
|Pre 1990 stoves*
||9 million |
|EPA certified stoves*
||5.7 million |
||3 million |
||17.7 million |
|Solar PV panels
(4 kw) **
||1.05 million |
||2.5 million|| |
**Based on EIA Domestic Solar PV Shipments, EPA Greenhouse Gas Equivalency Calculator
***DOE Alternative Fuels and Advanced Vehicles Data Center, EPA Greenhouse Gas Equivalency Calculator
Because of the relative affordability of biomass stoves (Fig. 12), the payback period is generally shorter for the stoves than for most other renewable energy technologies. Of course, the pay back periods depend on many factors. For wood or pellets, it primarily depends on what fuel is being replaced. If pellets are replacing gas, it will take longer to recoup the investment, as pellets generally cost the same yearly as gas, but if pellets are replacing oil, propane or electric, the payback period will be much shorter. If self-harvested wood is replacing any of these energy sources, the payback period could be as short as a year.
|Wind ||$6,000-30,000 7|
|Solar PV||$16,000-20,800 8|
|Geothermal||$7,5009 - 14,000 10|
|Masonry stove|| $7,000-15,000|
|Biomass boiler|| $7,000-20,000|
Figure 12: Typical Renewable Energy Cost (Alternative Energy Resources)
State and Federal renewable energy programs have often overlooked biomass for residential heat, which is an unfortunate oversight. Biomass technology is not only much more accessible for low and moderate income consumers, but due to the low cost of each unit, incentive programs can afford more installations and so will yield greater environmental benefits than more expensive technologies.
1 Energy Information Administration. Renewable Energy Annual. 2010
2 Solar City <http://www.solarcity.com/residential/solar-pricing.aspx>
3 Schelly, C. “Testing Residential Solar Thermal Adoption." Environment and Behavior 42.2. Mar. (2010) 167
4 This is assuming the wood is harvested sustainably so over time the CO2 emissions amount to a virtually zero-carbon output.
5 Hbh Gas Systems. A Qualitative Comparison: Carbon Dioxide Emissions from Residential Space & Water Heating Using Propane vs. Electricity. 2008. Pg. 4 <http://www.blossmangreen.com/CO2%20Emissions%20Analysis.pdf>
6NPR. The Energy Costs of Cooling and Heating a Home. August 2007.
7Alternative Energy Resources. As accessed May 2011. <http://www.alternativeenergyinc.net/aboutus.html>
8Pinkham L. What is the Average Cost to Install a Solar-Electric System to Power your Home. Mother Earth News. May 2009. <http://www.motherearthnews.com/ask-our-experts/solar-electric-system-cost-z10b0blon.aspx>
9US Department of Energy. Selecting and Installing a Geothermal Heat Pump System. August 2008
10Hughes, P. Geothermal (Ground-Source) Heat Pumps: Market Status, Barriers to Adoption, and Actions to Overcome Barriers. Oak Ridge National Laboratory. 2008