Burning Ground* - Geothermal Energy in New Hampshire

This week I am going to take a look at geothermal energy - the energy source that lies right beneath our feet. When we discuss geothermal energy we must be aware that there are essentially two forms of geothermal energy.

The first is the type that utilizes the high temperatures of underground rock formations in areas where there is a lot of geologic activity which is often indicated by the presence of hot springs and geysers. Places like Yellowstone immediately spring to mind. In this form of geothermal energy, water is pumped down deep wells, some as deep as 5 miles, to access rocks that have temperatures in excess of 212^oF. The water is heated by the rocks and is drawn back to the surface to produce steam which can be used to drive turbines and generators to produce electricity. The source of energy in these sites comes from the earth's internal heat which is produced from the decay of radioactive elements in the rocks or the heat flow from the earth's mantle where the earth's crust is thinner.

There are a good number of locations where we can access this energy, and as the US geothermal heat flow map below shows, these red colored areas lie largely in the western portion of the US. To generate electricity from geothermal sources, one needs rock temperatures in excess of 212^oF at reasonable depths. Interestingly, on close examination of the geothermal map below, one can see that there is a hotspot in NH located in the White Mountains area. At depths of 6.5 miles, rock temperatures in this area are in excess of 400^oF due to the abnormally high natural radioactivity of the granite in this area. This is a source of energy we might have to tap one day.

Graphic Sources: http://www1.eere.energy.gov/geothermal/pdfs/egs_chapter_2.pdf

The other type of geothermal energy we can access comes from the dirt beneath our feet. In many areas, the temperature of the ground, 4 or more feet below the surface, is a moderate 50 to 55^oF. We can utilize this property of the earth and draw heat from the ground in the winter or use the cooler ground temperatures to dump heat into during the hot summer months. This utilization of the energy in the ground beneath our feet is more correctly termed "geoexchange". Some like to call these arrangements earth exchange or ground source heat pump systems. This form of earth-based energy is very different from the "hot rock" type of geothermal energy as the source of energy in these geoexchange systems actually comes from the sun's warming of the earth surface. So, in essence, these geoexchange systems are indirectly a form of solar energy.

Because the ground temperatures are so low compared to the traditional geothermal systems which utilize the temperatures of hot rocks deep below the earth's surface to produce electricity, these geoexchange units cannot produce electricity. Instead we use the earth as a heat sink – we dump excess heat energy into the earth during the hot summers and we draw heat energy from the ground in the cold winter months to preheat the circulating air or water in our homes. But, and this is important in the understanding of these systems, it takes energy, in the form of electricity, to make these low temperature systems work. The electricity is needed to drive a device called a heat pump.

Most of us are familiar with heat pumps but we don't recognize them as such. The refrigerator in your home is a heat pump. What the refrigeration system is doing is drawing the heat from inside your refrigerator and pumping it into your kitchen. It does this through the compression and expansion of a refrigerant gas which provides the medium whereby heat is drawn out of the refrigerator and pumped into the kitchen. Because this device requires electricity to run the compressor pump and the warm air of the kitchen to work, it is referred to as an air-source heat pump. This is the same principal an air conditioner works on, which is pumping heat from inside the home into the warm outside air. With the geoexchange units we don't pump the energy into the hot summer air outside the home; instead we pump the energy into the cooler ground below our feet, which is why these units are called ground-source heat pumps. The fact that the ground is cooler than air makes these ground source units more efficient than the air-source units in typical air conditioners.

These heat pumps can also work in reverse. They can draw the heat from the air outside the house, or the ground, and pump it inside to warm up your home. You might be thinking that sounds awfully complicated when you can simply heat up the inside of your home with an electrical heater or your natural gas or oil burner. However because you are drawing energy from the moderate temperatures in the earth, you do not need as much energy as you would from an electrical or fossil fuel heater. In fact because you are drawing on the indirect solar energy stored in the earth, these heat pumps require only 25% to 35% of the energy you need to heat your home compared to an electrical heater. The ratio of energy needed to heat a space with an electrical heater to the energy used by a heat pump is termed the Coefficient of Performance, or COP, and is the basis of comparison between different heat pumps. For example, the COP value for a heat pump that requires only 25% of the energy to heat your home compared to an electrical heater is 4, calculated as follows

Coefficient of Performance = Electrical Energy required to heat home
                                               Electrical Energy consumed by heat pump

           = 100%
                25%           
            = 4.

Ground-source heat pumps range in performance with COP values of 2.5 to 4, with typical values in the 3.3 to 3.8 range. It must be noted that these values are highly dependent on proper engineering, the quality and efficiency of the mechanical device as well as the temperatures in the ground.

In geoexchange systems there are two main components, the heat pump and the circulation system that is drawing the heat from the earth. The circulation systems come in several different configurations. The most common, and the one most often used for homes, is the horizontal configuration in which the piping, containing an inert fluid, is buried in a shallow trench 4 to 6 feet deep alongside a home. The piping is made of plastic and is laid at the bottom of a trench in a slinky arrangement as shown in the figure and photo below.
 

These are referred to as closed loop systems as the circulation fluid, similar to antifreeze, is never directly in contact with the ground. Instead it is circulated between the heat pump and the ground through the piping. The heat pump draws the energy out of fluid, cooling it in the process and pumps the heat energy into the house. The cooled fluid is then circulated through the piping buried in the ground where it is heated up again to the ground temperature before returning to the heat pump.
 
Another type of closed loop configuration is a vertical system where the piping is enclosed in wells which penetrate deep into the ground as shown in the figure below. The advantage with these vertical closed loop systems is that, in these deep wells, the piping can come in contact with the ground water and water is a highly efficient medium for transferring the heat from the ground to the circulating fluid. These vertical systems also require a smaller surface footprint than the horizontal equivalents which can be crucial when space is limited or the heating loads are large, such as one might find in a school or apartment building.

A different type of system is the open loop configuration where the circulating fluid is ground water that is drawn from a vertical well and injected back into the ground via another well as shown in the diagram below.

 

There are many variations on these types of open loop systems including a standing-well system where the water is drawn from the bottom of a deep vertical well and is then returned to the top of the same well. With these standing-well systems, there is often a small amount of the circulating water, typically 5 to 10% of the water flow, that is not returned to the well. This bleed stream depletes the water in the well and this encourages the flow of fresh ground water into the well which promotes the maintenance of constant temperatures in the well and circulating water.

Most geoexchange units are, energy plant wise, relatively small scale units and are designed for specifically for individual residences or facilities such as hospitals, office complexes or nursing homes. There are also fair number of vendors of these systems that have been operating for a number of years in NH. As a result, it is difficult to get good reliable data on the total installed base of geothermal energy units in New Hampshire and my best guess is that there are many thousands of these units installed in homes and buildings throughout NH. In fact, some developers are building whole housing complexes and communities that make extensive use of geothermal energy.

In my chats with geoexchange system installers and folks who have these units in their homes, I have learned the following:

• These units are expensive to install and prices for a residential system, including the well, heat pump and circulating system, range from $20,000 to $35,000
• Because the installed costs are so expensive, sometimes the units are under-designed to save on upfront equipment costs. As a result, the systems are undersized and do not work well, particularly when temperatures are colder (or hotter) than usual. In these undersized systems, there can be an enormous draw on electrical backup heating systems which then significantly diminishes the savings.
• For the well-based systems, the choice between a closed loop and an open loop system is a difficult one and can be quite site specific. Each system has its own pros and cons and each has its advocates and detractors
• After installation, the owners either love or hate them. I have heard stories where owners are disappointed that the promised savings did not materialize or where there have been issues associated with the circulating systems or heat pumps. And then there are the owners who are delighted with their units and pleased to share with me that they no longer have fossil fuel bills.

I was interested in determining the financial return for installing a typical geoexchange system into a home with a pre-existing forced air heating/and cooling system so I ran some calculations based on my residence which is a typical New England home. Here are my assumptions

• Home Footprint: 2500 square feet
• Electricity Use: 12,000 kWh/year @$0.13 per kWh
• Oil Consumption for Heating: 800 gallons per year @ $3.75 per gallon.
• COP for Geoexchange System: 3.5
• Installed Cost: $25,000 with 30% federal tax rebate

With this data I determined that my annual savings would be $1800 per year which would yield a 9-year payback which is OK if I intend to stay in the house for more than nine years. However, I decided to do a more sophisticated calculation in which I assumed a 2% annual increase in the costs of electricity and a 4% increase in the cost of oil. On this basis, the payback period drops to 7.5 years and a single one-year long oil price spike would probably push that down to 5 years. Further calculations showed that the calculated rate of return for the project over 20 years is 14% which means I would be ahead of the game if I funded this project by borrowing for anything less than 14% which is pretty easy to do in these low interest days. Certainly food for thought and it looks like an option I might want to consider, however the best time to do so would be when I eventually have to replace my oil burner. In this situation I would be able to incorporate the costs of a new oil burner into the calculations and now the payback period drops to 4 or 5 years which makes a geoexchange system very attractive.
 
In NH we don't have the readily accessible hot rocks and burning ground* type of geothermal energy the folks out West do, but just 4 feet down we can access the solar energy stored in the cool earth. There are lots of opportunities for us to do so and I encourage you to consider a geoexchange unit when you build a new home or you have to replace the natural gas or oil burner in your home. Yes, it is a hefty investment but forward-looking, energy-conscious folks consider a 4 to 5 year payback to be a good return on an energy project.

Next week I will be discussing a large and impressive geoexchange project in NH I have recently visited plus I will share with you some geoexchange cautionary tales. I would be interested in your experiences with geoexchange systems so be sure to share them with us in the comment box below.

Until next week, remember to turn off the lights when you leave the room.
 
Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
5/20/13 

(*Burning Ground – A fabulous tune by Van Morrison from his 1997 Album "The Healing Game". One of those driving songs that makes you want to roll down the window, crank up the volume and sing along.)

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This is the Happy House* - Ways to Measure Building Energy Efficiency

(I am travelling in South Africa this week and I have been meeting with some of the large mining companies down here to discuss their sustainability and energy programs. I have learned that our energy challenges in New Hampshire pale in comparison to the issues here on the southern tip of Africa. My time has been tight and so I have invited Laura Richardson, the Director of Operations at The Jordan Institute, to contribute a guest blog this week. - Mike Mooiman)

When you wander the parking lot at the car dealership, dreaming about your next ride, each new car has a Monroney sticker on it explaining the features and details of the vehicle. It's a standardized sticker and it allows you to understand those features at a glance. The largest font is reserved for gas mileage – city and highway, and, interestingly, one of the smallest fonts is the price of the vehicle.

Here's an image of the 2012 Chevrolet Volt's Monroney Sticker.

The sticker was developed by Almer Stillwell "Mike" Monroney, a senator from Oklahoma who sponsored the Automobile Information Disclosure Act of 1958. In the 1970s, the EPA added fuel economy standards to the sticker, and starting this year information about the energy electric vehicles use – kWh, emissions, and other environmental aspects will be added.

 

Regardless of your requirements of a car, we all have a basic understanding of the value of good gas mileage versus bad gas mileage, and the Monroney stickers provides useful information so we can balance those needs pretty quickly. Based on the number of really big SUVs and much more efficient smaller cars I see on Route 93, I think that disclosure tool works well. The gas guzzlers are usually the ones zipping past me, all urgency and comfort, using even more fuel. And so it goes, but at least they knew what they were buying.

 

When we consider buying a building – new or used, residential or commercial – we are usually first interested in the cost, the location, the size and features as well as the appearance. Operational costs sometimes come up in the conversation, but the other factors often outweigh them in immediacy. And rarely do we really know what we bought until those first utility bills arrive. Considering that in New Hampshire 59% of our energy is used in and for buildings, it is a serious shortcoming that we do not give more thought to the annual energy consumption in buildings.

Currently, there is no Monroney-energy sticker for buildings, although there are some very smart people working to develop one. The Multiple Listings Service sheet available through real estate professionals offers many of the details of buildings, and recently the Northern New England Real Estate Network added a box on their MLS sheet for "building certifications." This box often remains blank because most buildings cannot claim certifications. The empty box provides a placeholder to acknowledge above-code certifications such as EnergyStar, HERS, LEED, Green Globes, Passive House, Net Zero, or some other accomplishment. The box's emptiness signifies that the building isn't as optimal as it could be. This placeholder provides a very important first step, and until all buildings have a metric that we can understand at a glance, many building owners are going to be continually surprised at their operational costs. 

 

From a sales perspective this makes perfect sense because most of the building stock leaves a lot to be desired when it comes to energy efficiency. No salesperson seeks to highlight the inadequacies of their product. It takes a much more creative sales approach to acknowledge long-term costs and the burdens they may bring a building owner. The language of real-estate sales can be a bit of a parallel universe, with code words like "great location," "charming," "cozy," and "a handy man's dream" euphemistically telling the real story. 

 

Many commercial buildings are owned by one entity and leased by another in a triple-net lease arrangement, whereby the tenant pays not just rent but also all of the costs of running the building, including the taxes, insurance, maintenance, and utilities. This scenario provides little motivation for the building owner to make energy-related upgrades, because he/she doesn't pay those costs or recoup the savings. The tenant isn't motivated to make improvements either because he/she doesn't own the asset. This "split incentive" also effects residential rental units and leads to the gradual decline of the buildings.

 

Some banks now require HERS Ratings (Home Energy Rating System) before lending on residential Energy Efficient Mortgages (EEMs) or "green mortgages." All ENERGY STAR certified homes must earn a HERS Rating of approximately 85 or lower, depending on a variety of factors such as square footage. Banks that participate in EEM programs may lend at more attractive rates and value certain upgrades that are not included or valued in standard mortgages. These measures can include aggressive airsealing and insulation, more efficient heating or cooling systems, ventilation systems, ENERGY STAR certified appliances, renewable energy systems, and high-performance windows and doors.

The HERS Rating process confirms that energy-efficiency upgrades have been modeled and installed as designed and that energy use will be lower than its baseline comparison; the bank and the owner are confident that the monthly utility bills will be less than a code-built house, thus reducing the risk of default because of operational costs. Therefore the bank can lend a little more money on the building and/or at a better rate, and that additional amount to the mortgage covers the costs of the upgrades.

A HERS Rating of 100 represents the baseline energy code for a new home and 0 denotes net zero energy use. There are a lot of factors and analyses that need to be considered to arrive at a HERS Rating, and for the most part this metric is used for residential construction. The US Department of Energy has determined that a typical resale home scores 130 on the HERS Index. An average 1900s farmhouse would probably get a HERS Rating of 150 to 200, but why would they want to advertise that? A normal 1970s house would probably get about 120. A house built to the 2009 International Energy Conservation Code should get a HERS Rating of 100. This is the building energy code standard we use in New Hampshire. However, energy-code compliance rates in New Hampshire average about 50%, meaning that new construction does not always meet the expected standards.

Most ENERGY STAR homes, which also require the HERS Ratings, in New Hampshire, are in the 60-70 range without renewable energy systems. There are a handful of very high-performing homes in the mid-20s. The figure below provides the HERS scale along with some typical values.

 

England has developed a two-certificate system, one that denotes the modeled expectations of the building and the other that discloses how efficiently the building is being used. This is a really interesting approach. Much like a speed-demon driving a very efficient vehicle, buildings that are operated differently than the energy models anticipate and will thus have different outcomes. As the advertisements remind us, "your results may vary". 
 

But what about existing buildings? What about larger commercial buildings, the real energy hogs out there? For these structures, building science professionals use energy intensity metrics – Energy Use Intensity and Cost Use Intensity, although they are not as visible (yet) as those Monroney stickers.

 

Energy Use Intensity (EUI) is an easy metric to understand: Thousands of BTUs per Square Foot per Year. By collecting energy bills for the entire building – electricity, space heating, hot water heating, process heating, and, if incurred, the costs to dispose of waste heat – for one year and converting all of the energy units into one unit of measure, thousands of British Thermal Units (kBTUs), we can compare electricity and heating loads as well as year-to-year usage. Some buildings use a mix of fuel sources for heat and they have different units of measure – for example, electric (kilowatt hours) for space heating, propane (gallons) for domestic hot water, #2 or #6 fuel oil (gallons) or natural gas (therms) or wood pellets (tons) for heating. By converting all the fuels to one common unit, it is much easier to analyze. In our analysis, we prefer looking at three years of data to get a full grasp of energy use in the building. It is important to also realize that different types of buildings – hospitals, schools, apartment buildings, retail stores and warehouses all have different energy profiles and should therefore not be compared to buildings in general but rather to buildings of similar type.

To better explain this we will use, as an example, a mixed-use retail and apartment building, 32,635 square feet in size, heated with oil. The following chart is an analysis completed prior to making energy-efficiency upgrades. While a lot of us focus on our electricity rates, in fact in New Hampshire we rarely use electricity for heat, but rather use a tremendous amount of fossil fuels, as shown in the consumption chart below. 

Let's be honest, though, only a few of us really care about energy waste because it is waste, most of us care about the associated costs, and this is where it gets very interesting. Cost Use Intensity (CUI) uses the same utility bills, but instead of energy metrics, we analyze the dollars spent on energy. The metric here is Dollars per Square Foot per Year. The chart below shows this data broken out monthly, to better understand how the seasonal changes effect energy consumption.

This is when the dynamics of fuel costs enter the conversation. These days, a building heated with oil costs ~4 times more per BTU than one heated with natural gas or about double the cost of wood pellets. These factors lead to important fuel switching decisions. For example, the long-range forecasts on wood pellets – not to mention the other positive attributes of local and renewable fuels compared to fossil fuels – are relatively stable and supply is available. Switching to wood pellets will therefore dramatically reduce the costs for heating.

 

EUI and CUI information can be compared to data on similar building types. It is important to understand, however, that this baseline comparison work is relative to existing buildings. Did I mention yet that our existing building stock is very inefficient? Ergo, a decent result through a benchmarking exercise might be a winner in a slow race of poorly performing buildings.

Such benchmarking can be quite motivational for building owners who are considering Deep Energy Retrofits (DERs), comprehensive projects that will significantly drop the energy use in the building, improving costs, comfort, and occupancy. Often times, when building owners realize how much worse their buildings perform compared to otherwise similar buildings, a competitive side of them surfaces and they want to undertake a DER project.

 

A DER project typically seeks to reduce energy use by 50%, and it can happen in phases over a number of years. This is most easily achieved in the poorest performing buildings because as buildings improve, the cost to make such percentage reductions gets harder, a la diminishing returns. Typically, a DER will include a package of comprehensive measures such as airsealing and insulation, HVAC and distribution system upgrades, controls, lighting, perhaps windows or door, and renewable energy systems, such as solar hot water and/or wood pellet heating. This example building underwent all of these upgrades. Operator training to run the new and more sophisticated systems is key to success. Moreover, it is critical to monitor and verify that the systems perform as designed and installed – and working together! – and that on-going commissioning ensures that the systems continue to operate smoothly.

In the example shown below, the building started out with an EUI of 89.18 and after the DER it dropped to 30.2. The CUI value dropped from $2.64 to $1.40/square foot.

An interesting metric being used by building scientists to compare the energy performance of buildings across regions incorporates Heating Degree Days into this calculation. This normalizes the energy numbers in a way so we can compare the heating use in a New Hampshire building with one in a very different climate location. This step is helpful in comparing buildings across regions and climate zones., (Electricity and Cooling Degree Days are often similarly considered in warmer climates.)

The metric is : BTU / Square Foot / Heating Degree Day. 

 

Using the example above, this metric would create a single number – yippee! – that could be used on buildings across the country to demonstrate their energy performance and it could in time become as effective as a Monroney sticker on a car. This particular building started out at a value of 13.5 and and after a deep energy retrofit now celebrates a value of 6.0. This is very exciting and demonstrates what can be accomplished in reducing the energy efficiency of our building stock.

 

These building energy efficiency measures are growing in popularity as they allow us to determine operating costs for buildings, benchmark existing and new buildings as well as measure the outcomes of energy savings projects. Energy is all about the numbers and these are good metrics that allow us to measure our progress and perhaps one day they will be as prevalent as the Monroney stickers on new cars. 

Laura Richardson
5/14/13

 

Laura Richardson is Director of Operations at The Jordan Institute in Concord, NH. The Jordan Institute, an energy think tank, mission-driven to find solutions to climate change, helps commercial building owners significantly reduce the energy used in their buildings. She managed nine energy programs funded by the stimulus for the NH Office of Energy and Planning, coordinated the StayWarmNH initiative, and co-founded the NH Sustainable Energy Association in 2003. She and her husband have lived off the grid since 2001 in a PV-powered, passive-solar and cordwood/TARM heated home. The home earned a 54 HERS Rating. Her Toyota Prius has 288,000 miles on it and still gets between 45-50mpg.

 

(*One of her all-time favorite bands is Siouxsie and the Banshees. *"Happy House" is a great tune, full of irony and cynicism about how wonderful we pretend things are when really they are a mess. Sort of like our building stock. Enjoy Happy House!)

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A Hundred and Ten in the Shade* – Long-Term Heating and Cooling Season Trends in New Hampshire

I am in the Southern Hemisphere this week, and as I headed from a cool New England spring to a warm South African autumn, my thoughts turned to long-term temperature trends in New Hampshire and their energy implications.

In January this year, I read an interesting press release from University of New Hampshire in which Mary Stampone, the NH state climatologist, pointed out that 2012 was the hottest year on record in NH and much of New England. The chart below was included in the press release, and the data showed the variation above and below the long-term average calculated from the 1895 to 2012 data. The largest positive variation was for 2012 in which the average annual temperature was ~10% (4^oF) above the average of 43.4^oF. The data also shows that we are getting more and more of these large positive variations over the past 20 years.

 

Having spent a considerable amount of time shoveling my driveway this past winter and seeing my air conditioning bills increase the summer before, I was interested in trying to understand if these higher annual temperatures meant hotter summers, warmer winters or both. The tack I took was to look at cumulative temperature values, known as heating and cooling degree days, that are of great use to designers of heating and cooling systems for buildings. However, instead of looking at a single value for the year, I split the year into two periods – a winter or heating period from October to March which is normally when our home heating systems kick in and a cooling or summer period from April to September which is normally when we turn on our air conditioners.

 

But, before I present that data, allow me to explain the concept of heating degree days. To calculate the heating degree value, we take a reference temperature - normally 65^oF (when we don't really need heating or cooling) - and then we subtract the average daily temperature from the reference temperature. For example, if the average daily temperature is 30^oF then the heating degree value for that day is 65 - 30 = 35. There is a direct correlation between heating degree value and the energy we use to warm our homes. The lower the outside temperature, the greater the heating degree value and therefore the more energy we need to bring our home up to that reference temperature of 65^oF.

 

Typically building engineers that size heating systems use cumulative heating degree days, amongst other factors, to size a heating system. To get a sense of the accumulated heating degree day numbers, consider the following example. If you have a month of 30^oF days in the winter, then the total heating degree day (HDD) value for that month is 30 x (65 – 30) = 1050. If similar temperatures are experienced over a six-month period then the total number of HDDs is 6 x 1050 = 6300. This is a rather rough calculation for the six-month heating season as some days are a lot colder than the 30^oF temperature I used, but, of course, some are warmer. Nevertheless, the HDD value of 6300 gives us an order of magnitude understanding of data in the figure below. This chart show the six-month total of HDDs for the October to March period for each year since 1895. The six-month HDD totals are plotted in blue. Even though there is considerable variation year to year, the long-term HDD average is 6240 which is close the approximate value we just determined. To give you a sense of how this numbers varies across the country, the equivalent number for Florida is 650 because the winter months down there are so much warmer. Clearly those folks down south are not spending a lot of time worrying about home heating, and they could probably get away with a nice thick sweater and a few extra blankets in winter.

 

I have also placed two trend lines over the data to draw out the long-term story. The first trend line, shown in red, is the simple linear average and it clearly demonstrates how the HDD value for the heating months has declined from 6500 to 6000. I have also overlaid a 20-year moving average which snakes above and below the linear trend line, but it too demonstrates the long-term decrease in HDD values. This long-term decrease indicates that our winters are getting warmer and that, as a result, we should be using less energy to heat our homes.

 

Having looked at our warming winters, my immediate next thought was; what about the summers? For the summer analysis, we use the concept of cooling degree days (CDDs). To determine the cooling degree days, we calculate the difference between the average daily temperature and the reference temperature, 65^oF. So if the average daily temperature is 70^oF then the cooling degrees for that day are 70 – 65 = 5. A month of similar days would give 30 x 5 = 150 CDDs for the month, and six months of similar days would lead to 6 x 150 = 900 cumulative CDDs. These numbers are a lot lower than the heating degree totals because they are mean daily temperatures and thus averages of cooler nights and warmer days. The actual numbers for NH are very much lower and the long-term average (1895 to 2012) for the six-month April to September period is 306 CDDs. For comparison purposes I determined that the equivalent number for Florida is 2500 CDDs. So, compared to the Florida folks, we need a lot less air conditioning but that appears to be changing as I will show. In the chart below I have plotted the long-term data for the six month accumulation of CDDs in blue as well as some trend lines. As you can see from the red linear trend line, the CDD average has increased over the 117 years of this data set. As with the with HDD chart, I have also included, in black, the 20-year moving average and again the upward trend is apparent. We have moved from a 20-year CDD average of 300 to a recent value of 350. Compared to Florida, this is no big deal, but for us that 17% rise represents a big fat increase in our air conditioning energy usage.

  

So if we put this data together it is clear we are, on a long-term trend basis, looking at warmer winters and hotter summers. This presents some challenges and perhaps opportunities if you are in the air conditioning business. A particular challenge for NH is that warmer winters mean less snow, a shorter skiing season and tough times for the ski industry. Some of this has been overcome with mechanical snowmaking, which is good for vendors of snowmaking equipment, but it does increase the industry's costs as snowmaking is a highly energy and water intensive process. Warmer winters do result in lower heating bills in the winter and reduced oil consumption which many home and business owners find helpful. This warming trend has likely contributed to the observed reduction of energy consumption in NH homes and business that I referred to in my Where have all the BTU's gone? post.

 

Reduced oil consumption is always welcome, but it has been replaced, in part, with increased air conditioning usage. One benefit of less heating and more cooling is that we are substituting oil for heating with electricity for cooling. Even though electricity is largely driven by natural gas and coal combustion, an increase in electricity demand does, in the long term, provide more opportunities for nuclear and renewable electricity production. I admit I am stretching here trying to find the tiny bit of silver lining on the big black cloud of global warming. The real concern is that as our winters warm and our summers heat up, we will have to deal with all the other consequences of climate change, including rising sea levels, more severe weather excursions, the spread of diseases and many others.

 

What can you and I do in the meantime? Well, the simplest and least expensive thing we can do right away is to better insulate our buildings as this will immediately reduce energy consumption in our homes and businesses. This would reduce energy consumption in both the heating and cooling seasons. If we all did this, it might help to slow down the long-term trend of warmer winters and hotter summers and in the process it might help to avoid some of those hot, humid days when it could get to be a hundred and ten in the shade.*

 

Until next time, remember to turn off the lights when you leave the room.

 

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
5/5/13

(*A Hundred and Ten in the  Shade is a tune by John Fogerty from his Blue Moon Swamp album which received a well deserved Grammy for Best Rock and Roll Album in 1997. It is a slow tune that perfectly catches the listlessness and despair of hot, humid days when you have to go out and work in the fields. Just listening to it makes me break into a sweat)

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Between a Rock and a Hard Place* – Wood-Fired Electricity in New Hampshire – Part 3

In my post, It Don't Come Easy, we took a look at the revenue side of the wood-fired electricity business in New Hampshire and we determined that later this year the biomass plants could be earning about $100/MWh for the electricity they produce. Half of this amount will come from selling electricity into the wholesale markets in New England and the other half will come from the sale of renewable energy credits, RECs. Their revenue stream is very much dependent on the high prices which presently exist in the REC market, but I expressed some concerns that the flood of RECs coming from the Berlin plant could have a downward impact on REC pricing. As a reader of this blog, Bob Baker, pointed out to me just this past week, there is another dark cloud looming on the horizon. Within New England, the REC market is an interstate one, and in Connecticut the local utilities purchase a lot of out-of-state RECs in order to meet their renewable energy quotas and avoid the fines levied through the alternative compliance payments. It has been reported that in 2010 that 76% (!) of the Class 1 series of Connecticut RECs have come from wood-fired plants in New Hampshire and Maine. 
 

One of the fundamental principles of economics is that of unintended consequences. This economic principle states that the actions of individuals, organizations and governments often have unintended and unexpected consequences. The REC program in Connecticut is a very good example of the unintended consequences of a well-meant program to support renewable energy in Connecticut that has ended up providing support for older, out-of-state renewable energy operations. Utility regulators in Connecticut are naturally grumpy that they are not helping newer Connecticut renewable energy companies, the price of renewable electricity is high (due to high REC prices) and they are supporting wood-fired plants in New Hampshire and Maine that were already in place before the establishment of the REC program. As a result, they are now looking to modify their renewable energy incentive programs in ways that would, in essence, exclude the older out-of-state wood plants. This would leave the NH wood-fired power plants looking at substantially smaller and less attractive markets for their RECs and as a result REC prices could plummet. 

 

We have spent quite a bit of time looking at the revenue side of the wood-fired electricity business and it is time we got down to looking at the cost side. An enterprise in the commodity business is termed a price taking business. Price takers, selling an undifferentiated product, such as electricity, accept the prevailing price the market offers. They are not a company like Apple which sells a unique product and who can, for the most part, set the price for that product. Price taking businesses can be very successful, but they require a laser-like focus on costs and, in the case of wood-fired power plants, the costs for producing electricity are considerable. Let's take a closer look. 

 

Woodchips are presently selling for about $30/ton and, based on Energy Information Agency (EIA) data for biomass plants in NH, it appears to take about 1.7 tons of woodchips to generate one megawatt hour of electricity. This is a lot of wood and is a result of the low energy content of green woodchips, which contain as much as 50% moisture, as well as the low conversion efficiencies of these operations, which I noted in a previous post was only about 23%. 

Using 1.7 tons of woodchips at $30/ton, means that the fuel cost alone is $51 per megawatt hour of produced electricity. The other costs these plants face include labor, operating and maintenance costs other than fuel, depreciation and financing costs. My very rough estimate of their cost structure per MWh of produced electricity is shown in the table below.

 

I might be high on the depreciation and finance costs but my estimate is that their costs are of the order of $80 to $90 per MWh. If they are earning $100/MWh from a combination of electricity and REC sales, this means that these operations are earning a profit of $10 to $20/MWh at this time. It is important to note that my estimates are based on my research, engineering judgment and business experience and are, at best, rough approximations. The actual financial information for these wood-fired operations is confidential and correctly so. However, if better information is publically available I would be interested in learning about it.

 

This cost structure does indicate that these plants are not viable based on just selling electricity at $50/MWh. They unquestionably need the RECs to remain in business, and moreover, they need attractive REC pricing. Anything below $30 to $40/MWh for REC pricing could lead to unprofitability and could be hugely damaging.

 

However, the high dependence of their costs on woodchips is cause for concern. Even a relatively limited increase of $6/ton in woodchip prices at 1.7 tons/MWh leads to a cost increase of $10/MWh which gets close to putting these plants underwater, profit-wise. Therefore, wood plant operators worry a lot about woodchip prices and their escalation. Here they have two major concerns. The first is that woodchip prices are highly dependent on diesel fuel costs. As noted in Songs from the Wood, wood harvesting, chipping and transportation involves a lot of high powered machinery and is therefore fossil-fuel intensive and woodchip prices, in large part, reflect prevailing diesel fuel prices. This is demonstrated in the chart below which shows there is a strong long-term correlation between diesel costs and woodchip prices. As the diesel price, plotted in blue, increases, the woodchip price, plotted in red, follows and rises accordingly. In the long term diesel prices are bound to increase and so we can expect to see woodchip prices increase as well.

 

The other woodchip price concern the existing wood-fired plants face is the startup of the large Berlin biomass plant later this year. As noted in Knock on Wood, this plant is a behemoth and it will increase woodchip consumption in the State by almost 50%. This increase in demand is bound to put upward pressure on woodchip prices. The price increase will be somewhat moderated by trucking in woodchips from out-of-state sources but I suspect that the pending Berlin plant start-up is cause for concern at the smaller wood-fired operations. The wood-fired power plants are faced with a challenging future and they are likely to find themselves squeezed between falling revenues and rising fuel costs.

So what could they do? Here are some options for consideration:

1. Lobby aggressively for the expansion of renewable energy programs that favor wood-fired energy and that would support high REC prices or even seek some other form of outright subsidy. Without significant subsidies, through RECs or other means, wood-fired power plants are likely to reach the point of unprofitability.
2. Figure out a way to use that 67% of waste heat and consider the implementation of district heating programs in the vicinities of the plants. The challenge is that these plants are in rural communities and getting the waste heat to local communities in the form of hot water will require long and very expensive pipe runs. Perhaps projects like low income housing, trailer parks, nursing homes, industrial parks, or heat intensive industries could be considered for development nearby these power plants so that the waste heat could be harvested and used.
3. Consider the investment in new technology to improve conversion efficiencies but it must be understood that these investments would be in the tens to hundreds of millions of dollars with long, long payback periods. These investments could include installation of unit operations to pre-dry woodchips using the waste heat or even entirely new technologies that involve the gasification of wood to produce a combustible gas that could then be fired in combined cycle gas turbine units. However, according to the EIA, these newer wood-fired technologies would cost of the order of 4 to 8 times that of an equivalent natural gas-fired electricity operation. Energy companies would be hard pressed to make this investment in renewable energy unless they were assured of a higher price for electricity through a favorable power purchase agreement or subsidy.  

Many of these ideas are a stretch but, in the meantime, I am sure legislative developments in Connecticut as well as the low costs of electricity, created by low natural gas prices, are keeping the owners and managers of these wood-fired power plants awake at night. Perhaps expanding renewable energy subsidies to support home grown and produced NH energy is not necessarily a bad idea, however, we do need to think through the unintended consequences of these subsidies beforehand, rather than after the fact like the folks in Connecticut. I am concerned that without substantial subsidies, through RECs or other means, our smaller wood-fired power plants will find themselves being squeezed between lower revenues and higher costs – the proverbial rock and hard place* with nowhere to turn.

Many folks believe that subsidies are the wrong way to go and that renewable energy plants need to compete in an open competitive energy market alongside fossil fuel operations. I do not agree with that approach and I believe we need to support renewable energy through subsidies even if it means paying more for the fossil fuel based energy we presently use. There are even some that say renewable energy subsidies are OK but that wood-fired electricity should not be subsidized because it is a "dirty" form of renewable energy owing to the fossil fuel used in harvesting, transporting and chipping the wood. Again, I don't agree because the reality is that every type of renewable energy is "dirty" in one form or another. When it comes to energy, there is no free lunch. There is an environmental and social impact associated with every form of energy utilization, renewable or not. What we need to do as a society is decide which of those impacts we are willing to live with and to make decisions about subsidies that will provide good options for future generations instead of leaving them with depleted oil wells, piles of poorly stored nuclear waste and exhausted coal mines. We need to think long term and not just about our children. We need to think about our children's great grandchildren. Making good decisions today that will give future generations viable energy options is an enormous responsibility and not one we can push off anymore.

 

Until next week, remember to turn off the lights when you leave the room.

 

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
4/29/13

  

(*Rock and a Hard Place is a great rock and roll tune by the Rolling Stones from their Steel Wheels album which came out in 1989 after the rift between Mick Jagger and Keith Richards was repaired. To my mind this was the last decent album the Stones put out, but it pales in comparison to Sticky Fingers, my personal favorite. However debating the best Stones album would be worthy of a blog by itself.)

 

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It Don’t Come Easy* - Wood-Fired Electricity in New Hampshire – Part 2

As I have been learning about the wood-based electricity industry in New Hampshire, I have come to appreciate that this industry is an important part of the State's economy. The wood-fired power plants generate electricity from a renewable energy source we harvest right here in NH and, in the process, they support the livelihoods of foresters, wood harvesters, equipment dealers, sawmills and many other associated industries. As important as these biomass plants are, they are facing some significant operating challenges. In an earlier post, Songs from the Woods, I noted that operating wood-fired electricity plants in NH were built in the late 1980s and, through state renewable energy incentive programs, were able sign 20-year contracts with our largest electrical utility company, Public Services of New Hampshire (PSNH), to sell electricity at attractive and pre-agreed rates. 

Twenty years have now gone by, and a few years ago many of these contracts came to the end of their terms. At this time, PSNH did not want to extend the purchase agreements as the contracted purchase price of electricity was higher than what PSNH could get selling that electricity on the local wholesale electricity market in New England, known as ISO-New England. At the same time, the plans for the large Berlin biomass electricity plant were coming together, and the developer of this plant began negotiating with PSNH for a power purchase agreement, which was a critical step in getting funding for the project. The operating wood-fired power plants took advantage of the opportunity, and in 2010 and 2011 they campaigned against PSNH signing a rate order to purchase electricity from the Berlin wood-fired power plant. In a compromise with PSNH, five of the six smaller biomass plants managed to negotiate for 20-month power purchase agreements to sell electricity direclty to PSNH, thereby giving them some additional time to adjust to selling electricity at prevailing wholesale electricity prices. These agreements allowed PSNH to contract with Berlin Biopower and the project was able to secure financing and move forward.

This year we come to the end of those 20-month power purchase agreements. The wood-fired power plants are now faced with the reality of having to sell electricity into the New England wholesale electricity market just like any other merchant electricity producer. Like any other business, these biomass power plants are faced with the two most fundamental issues that any for-profit enterprise has to deal with: the first is the price they can sell their product for and the second is the cost of producing that product.

 

Let's start with the price for their product. Later this year these wood-fired power plants will only be able to sell the electricity they produce at the prevailing rates in the ISO-New England wholesale market. These prices do fluctuate and the historical values for wholesale energy prices for NH are shown in the chart below. Over the 10-year span of the data, it can be seen that there is considerable fluctuation in prices and even recently, in January and February of this year, we had a spell where prices spiked. This particular price spike occurred because we are heavily dependent on natural gas for electricity generation in New England and during the cold spells there is additional demand for natural gas for home heating. With limited natural gas pipeline capacity and increased demand, prices for natural gas spiked and electricity prices followed. However, despite these occasional spikes, there is an overall downward trend in wholesale electricity prices over the past decade. This is show by the red linear trend line I have overlaid on the price data: it is clear that we have gone from an average price of $62 per megawatt hour (MWh) to $49/MWh – a 20% decrease in the price of electricity. (A megawatt hour is roughly the amount of electricity an average US home uses per month.) This downward trend has, in large part, been driven by low natural gas prices. This past summer, wholesale prices were even lower and averaged about $30/MWh. Natural gas prices have risen substantially from their market lows last year and, as a result, we are not likely to see electricity prices this low for a while.

 

Lower prices for their product is part of the headwind that the wood-fired power plants are facing. Fortunately, they have access to another source of revenue. Because burning wood to generate electricity is considered to be renewable energy production, these operations are able to sell the renewable attributes of their production to counterparties who need these attributes to meet certain obligations. These renewable energy attributes, called renewable energy certificates (RECs) or green tags, are traded separately from the underlying electricity. For example, a NH wood-fired electricity plant can sell each megawatt hour of electricity for the prevailing price on the wholesale electricity market, say for $50 a megawatt hour, and then they can sell the renewable energy attribute for each megawatt of renewable energy produced. Each megawatt of renewable electricity gets assigned a unique certificate number and a date of production and it then becomes a tradable instrument - a REC that can be bought and sold like a stock or bond. The counterparty who buys this REC could, for example,  be a state-regulated utility in Connecticut that is required to produce 20% of their electricity from renewable energy sources. If the utility does not have the renewable operations to meet that goal, they can purchase the renewable energy certificates from a facility out of State that does produce renewable energy.

 

If the state-regulated utilities do not meet their renewable energy quotas, they are required to make what are termed "alternative compliance payments" to their state for every megawatt hour of renewable energy they did not produce or source. These alternative compliance payments are essentially fines to encourage the utilities to produce or support renewable energy, but one thing they do do is put a cap on the REC market. Once REC prices exceed the alternative compliance payments, the utility will elect to pay the fine, i.e., the alternative compliance payment. Generally speaking, the REC market is a complicated one as there are different classes in each state for these RECs, depending on how the renewable energy is produced; there are different local markets in each state and there are also different alternative compliance payments in each state. This is a topic we can perhaps cover sometime in a future blog.

 

As it turns out, a great deal of the RECs from the wood-fired power plants in NH are sold into the Connecticut market, where local utilities purchase them in order to meet their renewable energy obligations. If these utilities cannot generate sufficient renewable power themselves or purchase the equivalent RECs, they have to pay an alternative compliance payment of $55 per MWh to the State of Connecticut. As I have discovered, sales for these RECs go through brokers who work to match buyers and sellers and, in the process, they take a commission. Much of the trading information on these RECs is considered to be proprietary and it proved to be difficult to find recent market data. However, a call I made to a broker who deals in RECs for the Connecticut market, indicated that he had a shortage of NH biomass-based RECs and was willing to pay up to $55/MWh (the cap price created by the alternative compliance payment) for 2012-based RECs.

 

For the biomass electricity producers in NH this is good news as the REC market is presently in their favor. This has not always been the case. The chart below shows how pricing in the various state-based REC markets has fluctuated over the past few years. This chart only shows information to May 2012 but it does indicate that in 2010/2011 there was a fallow period when the RECs in the New England market were trading at a low of $15/MWh. Since then prices have increased. The most current data on this chart indicate that RECs in the Connecticut market were trading for $48 in May 2012 and, as I noted above, prices have now risen further to close to $55/MWh.

 Source: US Department of Energy

 

Prices have risen because demand for NH-based biomass RECs exceeds the supply, which is always a good situation for a supplier of a product. I was not able to determine how large the NH biomass REC demand overhang was, but, as an operating producer of biomass electricity in NH, I would be concerned about the start-up of the Berlin biomass plant. Wood burning-wise, this plant is a behemoth, and is three to four times the capacity of the average NH wood-burning plant. This plant will be producing a great deal of renewable energy and a boatload of NH biomass RECs. There is likely to be considerable impact on the REC market when this additional supply becomes available.

 

When we look at the revenue stream for these biomass plants, it is clear that they have two products to sell. They have electricity which they will be selling into the wholesale market, where prices are now of the order of $50/MWh, and they have the associated RECs that they sell into the New England state compliance markets and where prices are presently close to $55/MWh. So, in total, the NH biomass plants are earning approximately $100 to $105/MWh, which is certainly more than what a fossil fuel-based electricity generator, that can only sell electricity with no accompanying RECs, will earn. In some respects biomass plants are better off, revenue-wise, than a fossil fuel plant but there is some apprehension associated with their revenue streams. Specifically, their concerns are:

• There has been a long-term downward trend in the price of electricity with some recent large decreases driven by cheap natural gas. With the recent increase of natural gas prices, electricity producers are hoping that local wholesale prices may stabilize or even see an increase.
• The REC market for NH biomass has improved since 2011, but the availability of a lot of RECs from the large Berlin biomass plant could put downward pressure on REC pricing later this year.

On top of these revenue concerns, biomass plants also have to deal with the second central business issue and that is the cost of producing electricity. Even here, the biomass plants are facing challenges. Prices for their fuel, wood chips, have increased, and the Berlin biomass plant is certain to put  additional upward pressure on this market - but that is the topic for next week's post. Clearly, it don't come easy* if you are running a biomass electricity plant in New Hampshire.

Until next time, remember to turn off the lights when you leave the room. You will be saving energy, water and trees.

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
4/22/13
 

(* It Don't Come Easy was a 1971 hit record for Ringo Starr recorded after the breakup of the Beatles and it has become his signature tune. It was written by George Harrison and the original recording featured Steven Stills on piano. Here it is from the Concert for Bangladesh and it was also recorded by the Smithereens, a highly underrated and still performing New Jersey group from the 1980s.)

 

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Knock on Wood* – Using Wood for Energy in New Hampshire

In my blog post Songs from the Wood, we took a first look at the business of generating electricity from wood. I am impressed at how much electricity we generate from our forests, and I believe there is more opportunity to use the natural resources of NH for energy purposes. In this post, I dig a little deeper to understand just how much energy we could sustainably harvest from New Hampshire's forests. This is an important issue as we have more and more homes and commercial enterprises changing over to wood for space heating applications and we also have the very large Berlin-based biomass plant that will be firing up sometime this year. We need to be sure that we do not overtax our forests and end up depleting them in a rush for biomass-based energy. 

To understand how much biomass we could harvest from our forests, we need to understand the extent of our forest reserves, their growth rate and the other products that are produced from this resource. In NH we have 5.7 million acres of land, of which 81% is considered to be viable timberland. This has not always been the case, and the history of New Hampshire's forest reserves is a fascinating one. The chart below, which is taken from "The Economic Importance of New Hampshire's Forest-Based Economy – 2011," produced by the Northeast State Forester Association (NEFA), shows the long-term forest coverage for NH all the way back to the 1600s.

 

 

 

In the 1600s, before the European settlers arrived, it is estimated that over 90% of NH was forested, but then as the settlers moved in and started aggressively harvesting the forests and converting them to farmland, the forest coverage decreased to just below 50% in the 1850s. In the latter half of the 19^th Century, we then had migration out to the West to develop the wide open western farmland. At the same time, we had the move from agrarian to industrial livelihoods prompted by the industrial revolution. These factors reduced our aggressive forest harvesting here in New Hampshire and over the next 100 years the forests naturally recovered to about 90% coverage in the 1950s. Since then, development for homes and businesses has nibbled away at forest acreage but we are still at an impressive 84% of coverage.

 

The USDA Forest Services estimates that the 4.6 million acres of viable timberland in New Hampshire translates into 304 million green tons of tree-based biomass - or what they refer to as "growing stock". The forest stock grows by about 2.2% per year, so the net annual growth is about 6.6 million tons. This is the amount of forest-based biomass we could sustainably harvest from our forest without depleting this natural resource.

 

We don't just harvest trees to produce wood chips for electricity generation. Trees are harvested to produce lumber, pulp for paper making, firewood for home heating and woodchips which are used to produce wood pellets as well as electricity. Based on 2009 and 2010 data, my estimate of wood usage for these various applications is shown in the table below.

 

 

My data and analyses suggest that we are using about 3.9 million green tons of wood based biomass per year or 59% of the sustainable harvest amount.

 

It should be noted that my forest utilization numbers are somewhat higher than the 2.8 million ton figure reported by NEFA in their 2011 report. Their figures suggest that we are only using 40% of the wood that we could sustainably harvest. The differences in the two sets of figures are, in part, due to some gross simplifications that I applied as I assumed that all wood harvesting and wood utilization happens in State. However, there is a considerable amount of wood that is exported out of State for further processing - such as that which is transported to the wood pulp operations in Maine. Also some wood-fired electricity plants will, depending on their geographic location and local woodchip prices, bring in woodchips from out of state. Regardless of the exact number, both utilization figures are relatively low, which means that our forests are growing and maturing and we also have substantial capacity for further sustainable utilization of our forests.

 

Let's now consider future usage of our forest resources. Presently the NH wood-fired power plants consume approximately 1.8 million tons of wood chips per year. The Berlin-based, Burgess Biopower operation, the State's largest biomass burning operation, will add another 750,000 tons to the wood chip usage when it starts up this year.

 

We also need to take into account that wood usage for home and commercial heating applications is increasing in NH. According to 2010 US Census data, there are approximately 515,000 occupied housing units in New Hampshire and 33,470 or 6.5% of the occupied residences are heated primarily with wood. Wood usage in these residences is captured in the wood pellet and cordwood data presented in the table above.

 

If we assume that, in an extreme case, 50% of the remaining homes in NH were converted to wood-fired heat, this would represent an additional 240,000 homes. Assuming the average NH home consumes 850 gallons of oil per year for heat, this would be equivalent to a consumption of ~6 tons of wood pellets per year per home. Overall, this would result in an increased wood pellet usage of approximately 1.45 million tons, which would require ~2.9 million of green tons of harvested wood. If we add these future applications to the existing wood usage for the State, we get the data shown in the table below. The totals indicate that usage could, in the extreme case I present, climb to 7.5 million tons - which would exceed the sustainable harvest limit by 15%. Naturally in an extreme situation like this, economics would kick in, wood prices would rise and wood would be drawn in from neighboring states and even from Canada

 

 

The scenario of 50% of the homes in the State using wood for heat is clearly an extreme one, but it does indicate that we need to be proactive and cautious about our wood- based resources. It appears that, if land development is well planned and we maintain our large acreages of woodland and we responsibly utilize our forests, we are, in the near term, far from overburdening the woods. There is available biomass capacity and, knock on wood, we should be OK for the near future for increased utilization of forest-based biomass.

 

Even though I am urging caution in the long-term utilization of our forests, there is another potential application for wood-based energy in NH that is worth consideration. With the growing aversion to renewable energy projects in the State, I have become intrigued with the possibility of using even more wood by using a combination of wood and coal, so called "co-firing", in some of the large coal-fired burners in the State. The Europeans do a fair amount of co-firing of wood and coal and this would be another way for us to use a home-grown fuel source as well as a way to meet some of our renewable energy portfolio requirements. It would also reduce the carbon footprint of NH's coal-fired operations. I will take the opportunity in a future blog to explore this possibility in more detail.

 

Until next time, remember to turn off the lights when you leave the room. You will be saving energy, water and trees.

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
4/15/13
    

(*Knock on Wood is a song recorded by Eddie Floyd on the Stax label in 1966. It has been covered by a number of artists including Otis Redding and David Bowie. A disco version was also recorded by Amii Stewart which became a big hit during the late 1970s. Here is a great live version of the tune featuring Eddie Floyd with the Blues Brothers Band.)

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