Category Wood Energy

Insulation is one of the most important factors in improving building energy efficiency. Heating, ventilation and cooling (HVAC) often accounts for more than half the energy expense of a building. Insulation helps to improve the energy efficiency of heating and cooling. Depending on the selected insulating material, the economic impact on heating costs can be quite dramatic.

To understand how insulation helps improve building heating and cooling, it’s helpful to review the dynamics of building heat loss as it applies to building materials and outside actual air temperatures.

To calculate the heating requirements for a building, the overall heat loss from a building can be derived as a function of the combined heat loss of transmission through the roof, walls, windows, doors, and floors, as well as heat loss caused by ventilation and air infiltration. In general, without getting too scientific, the heat loss from transmission through roof, walls, doors, and windows represents the largest impact and is primarily a function of the temperature difference between the inside and outside air and thermal conductance of he building material. For a more detailed review of building heat loss see Heat Loss.

The difference between inside and outside temperature plays a critical role in building heat loss. The first step is to understand heating and cooling requirements from weather data. Heating degree day (HDD) are a measure of energy demand required to heat a building. HDD is derived from the difference between the daily outside temperature observations and the ideal indoor air temperature, say 65 degrees Fahrenheit (18.30 Celsius). The heating requirements for a building in a specific location can be derived from the HDD data in conjunction with building factors such as insulation, windows, solar heat gain, and use. Air conditioning also has a similar metric and is defined as cooling degree day (CDD) and measures the amount of energy used to cool a building.

From the historical data on outside air temperature, an average heating and cooling degree day can be assigned to a specific region. To calculate degree days for both heating and cooling Daily Temperatures can be assessed by zip code to capture historical data on specific climate zones.

When it comes to selecting building materials and insulation, material suppliers often supply two measures – the R-value and C-value. A material’s R-value (thermal resistance) is the measure of its resistance to heat flow. The C-value (thermal conductance) is the reciprocal of thermal resistance and measures the ability of a piece of material to transfer heat per unit time or more specifically, specifies the rate of energy loss through a piece of material.

The US Department of Energy (DOE) has provided revised R-value recommendations based on climate zones. To understand the energy impact of selecting the right R-value insulation material for your building, an on-line heating calculator will help illustrate the heating requirements and associated energy costs for different insulating materials. Building heating requirements are often expressed in BTU (British Thermal Units) per cubic foot.

The Heater Shop BTU Calculator Heating Calculator provides some useful insight into managing energy expenses. The calculations were based on an average of 25 HDD for New York City.

Figure 1 illustrates the heating requirements as measured by BTU per square foot of building space for corresponding insulating materials across ceiling heights from 10 to 40 feet to capture cubic feet. As seen from Figure 1, the heating requirements show significant variance depending on insulation assumptions.

Figure 1 BTUs per Square Foot
Source: Heater Shop BTU Calculator

Taking the building heating requirements one-step further, different insulating assumptions (no insulation, average, and good) translate into wide dispersion in operating costs. The on-line heating calculator was used to estimate the building heating requirements based on the following assumptions: 10,000 square foot facility with ceiling height of 10 feet for 25 HDD for no-insulation average insulation, and good insulation. To derive fuel costs, the BTU per square foot for each insulation category was applied to a heating system operating for five heating months with approximately 1,400 hour of operations to coincide with a gas furnace at 90% efficiency and 20-minute on-cycle and 30-minute off-cycle. Gas pricing for heating are based on $17.00 per million BTU.

Figure 2 Heating Energy Cost
Source: Green Econometrics research

Figure 2 demonstrates that heating cost per square foot for good insulation saves approximately $2.90 per square foot in comparison to no-insulation at all. If we compare the heating costs savings to the cost of insulation, the payback period for insulation can be achieved in a year under most circumstances.

Figure 3 Insulation Cost
Source: Green Econometrics research

To assess the C-value and R-Value of various building materials, there are some useful charts available on the web. Insulation and Building Materials R-Values

The bottom line is that insulation is one of the most important building components materials to improve energy efficiency and lower utility costs.

To understand current energy prices it may serve us to examine historical energy prices. Our theme is energy economics and specifically that energy prices follow the laws of supply and demand to set pricing.

There are some interesting perspectives on historical energy prices from several books including Security Analysis, 1940 edition by Benjamin Graham and David Dodd, The Great Wave, by David Hackett Fischer; and The Industrial Revolution in World History, by Peter Stearns. These books provide extensive data on pricing, industry revenues, and the framework that energy and technology serve in the economics of the industrial world.

Figure 1 Historical Energy Prices

With the risk of oversimplification, our first figure shows there have been four distinct energy prices waves that have rippled through history. The scarcity of wood that was used for building homes, heating, and tools became increasing scarce as deforestation spread through Europe in the 1300s and followed again in the 1600’s. Coal prices rose rapidly with the War of 1812 and the Napoleonic Wars. Oil prices peaked in 1982 and to an all time high of $145.16 on July 14, 2008.

Figure 2 Medieval Wood Prices

During the Medieval period in world history wood prices increased nearly threefold according to David Fischer in the The Great Wave. Wood prices rose with scarcity and peaked in 1320 as impact of the Bubonic Plague began to kill a quarter of Europe’s’ population. Twenty years from its peak in 1320, wood prices declined by 48% as the Bubonic Plague reduces the population and in turn, lowering the demand for wood.

Figure 3 Wood Prices

Figure 3. Illustrates the rapid rise in the demand for wood as the growing world populations benefited advances in science and agriculture from the Renaissance period. Wood is used for just about everything and prices climb as more land is used for agriculture leading to deforestation exacerbating the wood shortage. As demand for wood increases, prices subsequently follow. By the end of the 1600’s, coal begins to substitute for wood as an energy alternative.

With advances in technology came improvements in coal mining and transportation that allowed coal to substitute for wood as an energy source. With the invention such as Thomas Newcomen’s steam, powered pump in 1712 that facilitated coal mining and James Watt’s steam engine in 1765 that lead to advances in transportation including railroads and machinery, coal grew in importance as an energy source. These advances in technology enabled greater supplies of coal to enter the market which lead to declines in energy prices.

Figure 4 Coal Prices

We can gleam from Figure 4 that coal prices peaked in 1810-to-1815 coinciding with the War of 1812 and the Napoleonic Wars. The technological advances in mining and transportations fostered the development of an infrastructure to support the coal industry. The price of coal rose as wars ragging in Europe and the US, increased the demand for materials and supplies such as coal. However, as the wars came to an end, the abundant supplies of coal allowed prices to fall keeping energy prices low.

Oil entered the picture with the drilling of the first oil well in northwestern Pennsylvania in 1859 and the Internal Combustion Engine in 1860 that facilitated the development of the oil industry.

As oil emerged to become the dominant fuel of the 20th Century, it’s only recently that we face supply shortages. To better understand the dynamics of energy pricing in the face of changing demand, a review of spending on railroads and electricity may serve as a surrogate for discretionary and consumer stable spending patterns.

Figure 5 Industry Segment Revenues

Figure 5 illustrates changes in the aggregate revenues of railroads in comparison to electric utilizes during the Great Depression. Copious notes taken by Graham and Dodd for their book Security Analysis help to demonstrate the economic laws of supply and demand.

The change in demand was most pronounced in railroad revenues. Expenditures on railroads, the more discretionary of the two industries, declined 51% from 1929 to 1993 as measured by gross receipts for the railroad industry. Over this same period, spending on the consumer stable, electricity only encountered a decline of 9%. In economic terms, railroads demonstrate greater demand elasticity meaning there is greater change in demand at prices change or this period, disposable income. While there is some discretionary portion of our spending associated with oil, a large portion of spending on oil is out of necessity. Therefore, even during times of great economic distress, the propensity for energy consumption is not eradicated entirely.

The bottom line: Energy pricing will continue to be dictated by supply and demand. Hydrocarbon fuels such as oil are finite in nature and therefore, without definitive strategies to cultivate alternative energy resources we will remain hostage to the vagaries in energy prices..

From the Industrial Revolution we learned that economic growth is inextricably linked to energy and as a result, our future is dependent upon equitable access to energy. When the Stourbridge Lion made entry as the first American steam locomotive in 1829 it was used to transport Anthracite coal mined in nearby Carbondale, PA to a canal in Honesdale that in turn linked to the Hudson River and onto New York City. Coal fueled the growth of New York and America’s Industrial Revolution because coal was cheap and more efficient than wood.

Advances in science and technology gave way to improvements in manufacturing, mining, and transportation. Energy became the catalyst to industrial growth. Steam power such as Thomas Newcomen’s steam powered pump in 1712 developed for coal mining and James Watt’s steam engine in 1765 were initially used to bring energy to market.

In terms of heating efficiency, coal at the time offered almost double the energy, pound for pound, in comparison to wood. Energy Units and Conversions KEEP Oil offers higher energy efficiencies over coal and wood, but as with most hydrocarbon fuels, carbon and other emissions are costly to our economy and environment.

With rapid growth in automobile production in the U.S., oil became the predominant form of fuel. According to the Energy Information Administration, in 2004 the U.S. spent over $468 billion on oil.

Figure 1 U.S. Energy Consumption by Fuel

We all need to become more conversant in understanding energy costs and efficiency and as a corollary, better understand the benefits of renewable energy such as solar, wind, and hydrogen fuel cells. A common metric we should understand is the kilowatt-hour (KWH) – the amount of electricity consumed per hour. The KWH is how we are billed by our local electric utility and can be used to compare costs and efficiency of hydrocarbon fuels and alternative energies.

One-kilowatt hour equals 3,413 British Thermal Units (BTUs). One ton of Bituminous Coal produces, on the average, 21.1 million BTUs, which equals 6,182 KWH of electric at a cost of about $48 per short ton (2,000 pounds). That means coal cost approximately $0.01 per KWH. To put that into perspective, a barrel of oil at $90/barrel distilled into $3.00 gallon gasoline is equivalent to 125,000 BTUs or 36.6 KWH of energy. Gasoline at $3.00/gallon equates to $0.08 per KWH. So gasoline at $3.00 per gallon is eight times more expensive than coal.

Is oil and gasoline significantly more efficient than coal? Let’s compare on a pound for pound basis. A pound of coal equates to about 10,500 BTUs or approximately 3.1 KWH per pound. A gallon of gasoline producing 125,000 BTUs weighs about 6 pounds equating to 6.1 KWH per pound (125,000 /3,413 /6). While gasoline is almost twice as efficient as coal, coal’s lower cost per KWH is why it is still used today to generate electric.

The Bottom Line: the economics of energy determines its use – coal still accounts for approximately half of our electric generation because it has a lower cost than other fuels. However, there are two factors to consider 1) the cost of carbon is not calculated into the full price of coal or other hydrocarbon fuels and 2) the cost of conventional fuel is calculated on a marginal basis while alternative fuel costs are calculated on a fixed cost basis. Meaning the cost of roads, trucks, and mining equipment is not factored into the price of each piece of coal, only the marginal cost of producing each ton of coal. For solar, hydrogen fuel cells, and wind energy systems, the cost to construct the system is factored into the total cost while the marginal cost of producing electric is virtually free. We need a framework to better measure the economics of alternative energy. The impact of carbon on our climate and global warming are clearly not measured in the costs of hydrocarbon fuels nor is the cost of protecting our access to oil such the cost the Iraq War.

Despite the carbon issues surrounding coal, (coal has higher carbon-to-hydrogen ratio in comparison to oil or gas) coal is more abundant and therefore is cheaper than oil. As electric utilities in 24 states embrace alternative energies through such programs as Renewable Portfolio Standards (RPS), perhaps the benefits of alternative energies will begin to combat the negative economics of hydrocarbon fuels.

Without greater investment into solar and hydrogen energies, we are held hostage to rising oil prices. Alternative energies such as solar and hydrogen fuel cells offer tremendous potential to provide energy independence and energy security. The dependence of the U.S. upon imported foreign oil raises inflation, weakens our currency, exacerbates the trade deficit, and forces consumers to pay higher prices for home heating and transportation. With oil exceeding $80 a barrel in late September 2007, the only beneficiaries are countries exporting oil and oil conglomerates. I guess when countries such as Dubai, after accumulating a large trade surplus based on inflated oil prices, decides to diversify away from oil and buy a non-voting stake in the NASDAQ market, it’s a wake-up call.

To better understand the potential of alternative energy, we should try to understand two basic concepts of energy: Specific Energy and Energy Density. Without digressing into chemistry 101, (Molecular Weight Calculator) the specific energy of a fuel relates the inherent energy of the fuel relative to its weight. Typically, specific energy is measured in kilo-joules (kj) per gram. A joule is a measure of kinetic energy – one joule is the amount of energy needed to move two kilograms at a velocity of one meter per second. Or a kilo-joule equals one kilowatt-second meaning one kilowatt-hour (KWH) equals to 3,600 kilo-joules. Your local electric utility bills you by the KWH, which according to the US Department of Energy Average Retail Price of Electricity in 2007 is approximately $0.11 per KWH.

Table 1 Specific Energy and Energy Density

The specific energy of a fuel tells us how much energy can be derived from a measured amount fuel by weight. By ranking each fuel by its specific energy, one can determine how efficient each fuel is. Specific energy and fuel density are often proportional to the ratio of carbon and hydrogen atoms in the fuel. A reference to the specific energy and energy values of most fuels can be found at Hydrogen Properties

Figure 1 Specific Energy
Figure 1 illustrates how fuels compare according to their specific energy. As we can see, hydrogen, because it’s extremely light, has the highest specific energy in comparison to hydrocarbon fuels.

This however, is not the full story because volume or energy storage requirement becomes a significant factor for gaseous fuels. Specific energy is important to analyze fuel efficiency by weight, but for hydrogen that must be pressurized and cooled to bring to a liquid state, the energy density become more relevant to fuel efficiency.

Figure 2 Energy Density: KWH per Gallon

Figure 2 illustrates how fuels compare according to their energy density, that is, energy relative the container size. As we can see from figure 2, hydrogen, because it is so light, requires 15.9 times the container volume to provide the energy of diesel or oil. In comparison to diesel, ethanol requires 1.6x the container size for the same amount of energy.

The container size becomes a significant detriment for housing hydrogen. Energy density is usually measured in kilo-joules per cubic meter (kj/m3). As kilo-joules are readily translated into KWH by multiplying by the number of seconds in an hour (3,600) and the College of the Deserts’ computation into gallons, we are converting the data into KWH per gallon for those of us in the U.S.

Hydrogen fares poorly relative to energy density. However, technology offers an approach to enhance the benefits of hydrogen with fuel cells. Fuel cell enable hydrogen molecules to interact with oxygen through a membrane that allows transmission in only one direction to convert H2 into an electric current to power your automobile. Fuel Cell Basics Fuel cells often capture the hydrogen electron from hydrocarbon fuel such as methane allow convention fuels to generate hydrogen for electric generation.

In a hydrogen-based economy, solar energy can provide electric to generate hydrogen through electrolysis and vice versa. Jeremy Rifkin’s The Hydrogen Economy eloquently illustrated the hydrogen economy where fuel cell act as mini power plants and the electric network resembles the Internet where cars plug into an electrical grid supplemented by solar cells at your home and work. Electric power generation moves from large utility generation to a distributed generation – everyone plugged in can generate power to the grid. The key benefit of hydrogen is that it democratizes the energy economy bringing power to all countries in the world.

An interesting technical analysis of hydrogen energy is provided by Ulf Bossel and Baldur Eliasson Energy and the Hydrogen Economy The bottom line is that solar and hydrogen energies offer tremendous potential to low long-term fuel costs and improve our environment and climate. More research is required to lower costs and improve feasibility.

To measure the efficiency of conventional hydrocarbon fuels, we need a common measure of energy. The Kilowatt-Hours (KWH), the billing quantity of electric usage, serves as a useful measure of energy because we can equate KWH to engine horsepower performance, heat energy of a fuel, and compare energy costs on a common level. KWH can be used to determine which fuel is most efficient by measuring the heat output of each fuel.

A BTU is the amount of heat necessary to raise one pound of water by one degree Fahrenheit and each fuel has its own BTU measure. For example, one ton of coal produces about 21.1 million BTUs, which would equate to 6,182 KWH. One KWH equals 3,413 BTUs.

A framework to measure energy costs is to convert each fuel type into KWH of energy. Some helpful links to common fuel conversions Energy Units and Conversions KEEP, BTU by Tree, and Fuel BTUs

We want to establish common energy measure to evaluate home heating fuel efficiency for each fuel type. Our first step is to measure the BTU value for each fuel type. The next step is to divide the BTU value for each fuel by 3,413 to arrive at its corresponding KWH energy value.

Kilowatt-Hour per Unit of Fuel
The energy value of a unit of fuel depends on its mass, carbon and hydrogen content, and the ratio of carbon to hydrogen. In general, hydrogen generates approximately 62,000 BTU per pound and carbon generates around 14,500 BTUs per pound. The combustion process is complex and while higher hydrogen content improves energy BTU levels, not all hydrogen goes to heat. Some hydrogen combines with oxygen to form water. Coal Combustion and Carbon Dioxide Emissions

Energy Comparison
1 pound of wood = 6,401 BTUs = 1.9 KWH
1 pound of coal = 13,000 BTUs = 3.8 KWH
1,000 cubic foot of natural gas = 1,000,021 BTUs = 299 KWH
1 gallon of oil = 138,095 BTUs = 40.5 KWH
1 gallon of propane = 91,500 BTUs 26.8 KWH

Figure 1a Kilowatt-Hours per Pound

As seen from figure 1, natural gas provides the highest efficiency level followed by oil. Wood offers the lowest efficiency per pound at 1.9 KWH/lb and is followed by coal with twice the efficiency at 3.8 KWH/lb. Oil offers almost a 70% efficiency improvement over coal and propane is just slightly more efficient than coal.

Fuel Energy Efficiency
Wood = 1.9 KWH per pound
Coal = 3.8 KWH per pound
Natural Gas = 6.9 KWH per pound (liquid and gas measures are calculated at 6.3 pounds per gallon)
Oil = 6.4 KWH per pound
Propane = 4.3 KWH per pound

This is not the full story. While the energy efficiency of the fuel is important, a lot depends on the fuel efficiency of the stove or furnace that is used to heat your home. The heating efficiency of your stove or furnace has a substantial impact on the overall efficiency of the fuel’s heat value. The adjusted KWH in figure 1 indicates the fuel efficiency adjusted for the efficiency of the heating system. There is also some variance in the fuel efficiency given impurities, temperature, and water presence.

Adjusted Fuel Energy Efficiency
Wood @ 1.9 KWH per pound and stove efficiency of 70% equals 1.3 KWH/lb
Coal @ 3.8 KWH /lb and stove efficiency of 70% = 2.7 KWH/lb
Natural Gas @ 6.9 KWH /lb and furnace efficiency of 95% = 6.5 KWH/lb
Oil @ 6.4 KWH /lb and furnace efficiency of 85% = 5.5 KWH/lb
Propane @ 4.3 KWH /lb and furnace efficiency of 95% = 4.0 KWH/lb

Figure 1b Kilowatt-Hours per Kilogram

Figure 1b proves the same fuel types measured by liters and kilograms. While the absolute numbers are different, the relative fuel efficiency among the fuels is the same.

Energy Economics

The final phase of our fuel efficiency exercise is to compare an economic measure of fuel cost. The market price of fuel will vary by location, usage amount, and market conditions. Our prices were quarterly average U.S. energy prices by fuel type:
Natural Gas Prices, , Oil Prices, and Propane Prices
Coal and wood prices were based on local residential delivery.

Figure 2 Cost per Kilowatt-Hours

Coal and wood are among the lowest priced fuels. However, coal and wood require extensive hands-on control and cleaning which are not factored into costs. Natural gas is offered in many urban areas and is currently priced below oil or propane. Natural gas offers higher energy efficiency and is priced lower than oil or propane, but is not available in all urban markets and very limited rural availability.

The trade off between oil and propane, which can be found in most markets, is operating efficiency and maintenance. Modern oil furnaces are demonstrating higher operating efficiencies, but cost significantly more than propane. Oil does offer higher efficiency than propane, but maintenance costs are higher for oil furnaces and that cost is not reflected in these fuel costs measures.

Electric heat in some markets where utility rates are below oil or gas may offer favorable economics, but electric rates might be going higher as utilities switch to lower carbon emission fuels. The challenge is to migrate electric utilities from lower-priced coal with high CO2 emissions to natural gas with lower carbon emissions. The cost to lower CO2 emissions from coal burning utilities could force natural gas prices to rise. The bottom line is that energy prices will continue to rise with natural gas tide to oil production. Even with higher fuel prices, there is still a tremendous disparity between conventional and alternative energies with the cost of solar near $0.38 per KWH and residential electric rates of $0.11 per KWH.

Carbon Economics

Emission of CO2 from hydrocarbon fuels depends on the carbon content and hydrogen-carbon ratio. When a hydrocarbon fuel burns, the carbon and hydrogen atoms separate. Hydrogen (H) combines with oxygen (O) to form water (H2O), and carbon (C) combines with oxygen to form carbon dioxide (CO2).
How can a gallon of gas produce 20 pounds of CO2

From this example, a carbon atom has an atomic weight of 12, combines with two oxygen atoms each with a weight of 16, to produce a single molecule of CO2 an atomic weight of 44. To measure the amount of CO2 produced from a hydrocarbon fuel, the weight of the carbon in the fuel is multiplied by (44 divided 12) or 3.67.

Wood has half the carbon content than coal, but coal is twice as efficient as wood and therefore both have nearly the same high level carbon footprint. Oil benefits from having higher energy efficiency than propane giving oil 30% lower CO2 emissions pound for pound.

Figure 3 Pounds of CO2 by Fuel Type

Natural gas, because of its low carbon content and high fuel efficiency, achieves lower CO2 emissions than oil, propane, or coal. Natural gas produces 46% less CO2 than coal and 10% less than oil. With coal relatively abundant and cheap in comparison to oil or natural gas, energy prices may increase as electric utilities switch to lower CO2 emission natural gas or invest into emission reduction processes that add to capital costs and operating expense.