River’s Gonna Rise* - Hydro Power in New Hampshire – Part 3: PSNH Hydro Operations and River Flows

In my last few posts, Down by the Water  and Take Me to the River, I mentioned that my office looks onto the Merrimack River and the upstream Amoskeag hydroelectric operation that has been producing electricity for the past ninety years.  From this view, I often take note of river flows and whether the water is spilling over the top of the dam wall, as in the photograph below. In this post, I discuss the variability of river flows and how hydro plant electricity outputs are very dependent on these. I also look at the capacity factors of the Merrimack River hydro operations and compare them to national averages.

Photo: PSNH Flckr Photostream

Weather and precipitation are the most important variables in hydro electricity operations because these determine river flow. I dug up some relevant information about Merrimack River flows near my office from the United States Geological Services (USGS). The chart below shows the river flows at the Goffs Falls monitoring point, which is just downstream of the Amoskeag Dam. The jagged blue line shows the data for 2013 and it is surprising how variable the flow is from day to day. The orange dots show the average flowrates over the past 76 years. This historical data shows that river flows generally rise during April to June due to snow melt, reaching flows that are four times the average value, and then drop off considerably during the dry August to October period, to about one quarter of the average. Interestingly, the summer of 2013 was a wet one, as indicated by the higher-than-average river flows during this period.

Source: USGS

A simple relationship dictates the generating capacity of a hydro operation:

Power = Constant x Flow x Height

In an operation such as Amoskeag, the height (or head) is essentially fixed because this is a constant-level run-of-river operation. However, since Merrimack River flows do vary, I took a look at the 2013 monthly river flows and compared them to monthly electricity production (measured in MWh) for the two larger operations on the Merrimack River. These are plotted in the figure below on the left, with river flows in the green bars, and Amoskeag and Garvin Falls electricity generation in blue and red, respectively.

Data Source: USGS and EIA

As expected, high river flows, particularly during the April snowmelt or the wet July of last year, generated higher amounts of electricity.  Low river flows, such as in the dry months of August to October, were associated with lower generation rates. 

The chart on the right plots energy generation against river flows for the Amoskeag plant. I was somewhat expecting a 1:1 linear relationship and was initially surprised to note how generation tended to start leveling off at high flowrates. However, the PSNH hydro folks pointed out that the maximum flowrate through the Amoskeag turbines is 5000 cubic feet per second (cu. ft/sec), so one would expect to see generation level off above this flowrate. Moreover, an average monthly flowrate of greater than 5000 cu. ft/sec does not necessarily mean that flow rates are higher than 5000 cu. ft/sec for 24 hours a day – there may be periods when it is substantially higher and then there are periods of lower flows.

In one of my recent posts, Down by the Water, we noted the simple mathematical relationship between energy and power:

 Energy = Power x time.

Applying this relationship to the Amoskeag operation, which has a nameplate capacity of 16 MW, and assuming 30 days per month and 24 hours per day of operation, the maximum monthly generation from the Amoskeag Dam can be calculated as

Energy = 16 MW x 30 days x 24 hr/day = 11,520 MWh

This is pretty close to the maximum monthly generation output on the chart above.

I was also surprised to note that the power generation of Garvin Falls was half that of Amoskeag although its generation capacity (12 MW) is 75% that of Amoskeag (16 MW). Calculating the total generation for both operations for 2013, I noted that Amoskeag produced 66% of its maximum electricity output (also termed its capacity factor), whereas Garvin Falls produced only 44%. It turns out that Garvin Falls is a more troublesome operation because it has a gatehouse and a narrow channel for a head race that is used to direct water into the power houses. River-borne debris, such as leaves, branches, trees, etc., build up behind the gatehouse and restrict flow to the channel, which significantly compromises the steady generation of electricity from this operation. Regular maintenance, involving the removal of debris from the screens where the water enters the power house, is required.

The Energy Information Agency, EIA, produces an average annual capacity factor for all hydro operations across the US. In 2013 it was 38.1%, which is much lower than I would have anticipated. I was expecting capacity factors for hydro operation to be of the order of 80% or so but the annual data from 2008 to 2013 shows US capacity factors ranging from 37.2% to 45.9%. The national data does indicate that the Garvin Falls and particularly the Amoskeag operation have capacity factors greater than the average US hydro operation.

There are several reasons for these lower-than-expected capacity factors for hydro operation:

• Precipitation and river flows are variable and the maximum flow of water that the generators can handle is not always available.
• River-borne debris and winter ice can at times significantly compromise water flows into the generating units.
• The generating units need to be slowed or shutdown for periodic maintenance.
• Even though hydro plants are generally the lowest cost producers of electricity when selling into the wholesale markets, they can be underbid by other generators, particularly heavily subsidized wind operations which will sometimes even pay to produce electricity. At times like these, there might not be any call for hydro power and the units are shutdown.

PSNH owns and operates several hydro operations in NH. Those listed below are owned and operated by Northeast Utilities, the parent corporation of PSNH.

Source:PSNH

Based on recent documentation submitted to the NH Public Utilities Commission, hydro operations will be responsible for about 11% of  the ~3,016,000 MWh of electricity that PSNH is planning to generate from its own facilities in 2014. These are PSNH’s lowest cost electricity generators and are thus an important asset to keep in operation and perhaps even consider expanding, even though the impacts of new or expanded hydro operations could be considerable and permitting could be extremely difficult. We have to recognize that there is a price to be paid for every energy source we use but, unlike fossil fuels where every ton of carbon dioxide we dump into the atmosphere intensifies the green-house effect, hydro plants will be still generating electricity one hundred years from now and will still not be pumping carbon dioxide into the atmosphere.

An important debate regarding these facilities is presently underway in NH (discussed in Should I Stay or Should I Go). In order to complete the electricity deregulation process in New Hampshire, it has been proposed that PSNH should be compelled to sell these hydro generating operations, along with their wood- and gas-fired operations and the large coal-burning plant on the Merrimack River in Bow. However, with electricity prices shooting up this winter and with PSNH customers, for the time being at least, somewhat shielded from these increases, this does give one pause for thought and to consider that ownership of generating operations may perhaps have some benefits. This is certainly a topic I will return to in a future post.

Until next time, remember to turn off the lights when you leave the room and, if it is raining, contemplate that the river’s gonna rise* and the hydroelectricity output will increase.

Mike Mooiman

Franklin Pierce University

mooimanm@franklinpierce.edu

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(*River’s Gonna Rise – An instrumental tune by Patrick O’ Hearn, a LA bass player and electronic musician who has had a long and varied career, including stints playing bass in Frank Zappa’s band, the New Wave group, Missing Persons, as well as releasing over a dozen solo albums featuring electronic and ambient music. He is well known for his film scores and in the past few years has been playing bass in John Hiatt’s band. Here is the title track from Patrick O’ Hearn’s 1988 album River’s Gonna Rise.)

Down by the Water* - Hydro Power in New Hampshire – Part 1

My office is in Manchester, in Franklin Pierce University’s graduate school which is located in one of the renovated mill buildings located on the Merrimack River. From the conference room there is a great view of the river and the upstream Amoskeag dam. This is a 30-foot high, 710-foot long concrete dam that holds back the Merrimack River at this point so that the water can be directed through the turbines at the Amoskeag Power House located on the western bank of the Merrimack.  These turbines have a combined generating capacity of 16 MW. The photos below show my view of the dam wall and a Google Map satellite image for an overhead view. This dam was originally commissioned in 1924 to service the Manchester mills. While gazing at the river this week during a meeting, I decided it was time to turn my attention to the topic of hydro power in New Hampshire. This post is the first in a multi-part series on this topic.

Man has utilized the power of water (hydro power) for centuries. In the late 1700s and into the 1800s, advances in technology, powered by running water (and eventually by steam) is what lead to the industrial revolution. Throughout New England, textile mills were established along the main rivers, most notably the Blackstone River that runs down through Worchester, Massachusetts into Rhode Island and the Merrimack River that follows a route through New Hampshire into Massachusetts. The river flow turned water wheels and turbines which, through a system of gears, shafts, and belts, were used to drive machinery inside the mills.

In the 1880s, water-driven turbines were combined with electric generators to generate the first hydroelectricity, and in 1882 the world's first hydroelectric power plant started operation on the Fox River in Appleton, Wisconsin. From that point on, the use of hydroelectricity grew phenomenally and, in 1940, hydro generated 40% of all electricity in the US. Since then, demand for electricity has increased ten-fold, but natural gas-, coal-, and nuclear-fired operations were established to fill the need. Hydro power output grew, but its share of electricity production has dropped off to about 6 to 8% of the electricity generated in the US today.

Hydro operations range in size from the very large 6809 MW Grand Coulee Dam in Washington state, the 2515 MW of the Robert Moses Niagara Power Plant and the 2080 MW of the Hoover dam on the Colorado River to “hobby” projects less than 1 kW in capacity. (Remember there are 1000 kW in a MW.) There are about 1750 hydropower operations in the US: most of them are much smaller than in size than the very large Hoover Dam operation which we usually associate with hydropower.  In fact, most hydroelectric operations in the US are much smaller - almost 90%  are less than 30 MW in size.

Hoover Dam Hydroelectric Plan

All hydropower operations, whether private, municipal, or state-owned, are licensed by the Federal Energy Electricity Commission  (FERC) – the  federal “godfather” of the electricity business. There are 41 FERC-licensed hydro operations in NH, ranging in size from 136 MW to 58 kW.  Small projects, such as those less than 10 MW installed on an existing dam or those of less than 40 MW installed on a waterway used for another purpose (such as an irrigation canal), are exempt from FERC licensing. There are 43 such exempt facilities in NH, ranging from the 3.5 MW Gregg’s Falls operation on the Piscataquog River in Goffstown to a 5 kW operation on Marden Brook. FERC licenses often involve combinations of hydro operations run by a single operator on a stretch of water:  for example, the three PSNH operations on the Merrimack River are combined into one license. I also noted that the very large Moore and Commerford hydro plants on the Connecticut River are listed by FERC as Vermont operations. These licensing/classification artifacts can cause confusion, especially when data on generation, as provided by the Energy Information Agency (EIA) and used later in this post, is reviewed.

There are many different ways of classifying hydro operations. The first is by size. Large hydro plants in the US are generally considered to be those above 25 MW in capacity but international standards consider those above 10 MW to be large. Most of the hydro plants in New Hampshire are small operations: within this class there are subclasses which typically have the following size ranges:

·                                Mini                <1 MW

·                                Micro              <100 kW

·                                Pico                <10 kW

·                                Family             <1 kW

To give you a sense of what these capacities mean, it is important to remind ourselves of the difference between power and energy.  I discussed this topic in the I’ve Got the Power! blog a while ago. As a reminder, remember that electrical energy is the ability of an electric current to do work − such as producing motion, heat, or light. The units of electrical energy are kilowatt hours (kWh) or megawatt hours (MWh). There are 1000 kWh in one MWh. Electrical power, on the other hand, measured in kilowatts (kW) or megawatts (MW), is a capacity, i.e., the rate at which energy can be produced from a generator. Large generators, which can produce more energy per unit of time, naturally have larger capacity or power ratings.

The confusion between power and energy often stems from the similarity of the units: kilowatt hours or megawatt hours are energy units, and kilowatts or megawatts are power units. However, it is important to understand that even though the units seem similar, there is a world of difference between them. This difference stems from the simple mathematical relationship between energy and power;

Energy = Power x time.

I find it is always useful to understand these relationships from a homeowner’s point of view. Consider that an average US household uses 11,000 kWh per year of electricity (~900 kWh per month). If you had to generate that electricity yourself and you were going to do it over 24 hours a day for 365 days per year, you would need generator with a power rating of 1.3 kW.

The calculation would be done as follows:

Energy = Power x time

Power = Energy / time

Power = 11,000 kWh/(365 days x 24 hours/day) = 1.3 kW.

Of course, this calculation is based on a daily average, but our daily electricity use is actually rather “lumpy”:  there is a first peak in the morning as we turn on the lights, make coffee, heat up the house, and take hot showers, followed by a second and larger peak in the late afternoon/evening when we are making dinner, watching TV, doing the laundry, turning on the electric blanket, reading this blog, etc. If you were to actually buy a generator, you would want a unit that has a capacity of more than the average 1.3 kW so that it could handle the peaks in usage. This is why backup generators for homes often have sizes of the order of 5 kW to 15 kW. But I digress somewhat (I may come back to the topic of home generators in a future post)….

The second classification of hydro plants is by type of operation. The three main types are:

• Reservoir or Pond-and-Release Operations: We most commonly associate these with hydropower and they involve large concrete dams holding back enormous reservoirs of water with the power plant at the base, as shown in the Hoover Dam picture above. The reservoir provides for a great deal of storage and steady power generation even during the dry season. These operations usually involve the upstream flooding of large tracts of land and significantly impact downstream water flows. The water level in the reservoir can also fluctuate greatly, depending on the incoming water flows and the discharges through the power station.
• Run-of-River Operations: These hydroelectric plants depend on the natural drop in the river elevation. A portion of the upstream river flow is sometimes diverted through a large pipe (called a penstock) to a downstream generator plant, after which the water flow is reintroduced into the river (see the figure below). These operations often have dams at the upstream location to provide the water diversion point but their storage capacity, called pondage, is limited and, as such, these operations are more subject to the vagaries of seasonal precipitation and natural river flows. With limited storage, the reservoir level tends to remain fairly constant – excess river flow simply spills over the top of the dam. Electricity production can therefore vary substantially over time. Because these operations don’t involve large amounts of storage or flooding of large acreages of land, they tend to viewed as more environmentally friendly or “greener” than the larger reservoir operations.
• Pumped Storage: These operations involve pumping water from a river uphill to a reservoir at a higher elevation during low electricity demand and low cost periods. When electricity demand increases and prices are high, these operations then run in reverse and the water in the reservoir is drained through a turbine back into the river, generating electricity in the process. There are a three of these operations in New England with a combined capacity of 1696 MW.

Source: IPCC

In NH, we do not have any pumped storage operations but we have reservoir and run-of-river operations.  Data from the EIA indicates that there are 92 hydro generators in NH with a combined name-plate capacity of 446 MW and a total winter capacity of 511 MW. The ten largest NH hydroelectric operations are listed below.  The Moore and Comerford dams, located on the Connecticut River which runs between New Hampshire and Vermont, are the largest hydro operations in all of New England. All operations listed are individual dams, except for the Great Lake Hydro-owned operation on the Androscoggin River in the Berlin area which is a series of different dams and 21 generating facilities. The largest PSNH-owned operation in NH (and the one that distracts me during meetings)  is the Amoskeag dam on the Merrimack River.

Source: EIA

As a wrap-up for this post, I thought a comparison with other New England states would be interesting. The table below lists total electricity production capacity (the power of the generator) and hydro capacity by state for 2012, as well as total production of electricity and hydroelectricity. The data include conventional hydro only and excludes pumped storage operations. We can see that Maine is the “hydro powerhouse” of the New England region, with the largest capacity, followed by NH. The upper New England states, New Hampshire, Vermont, and Maine  provide the bulk of the region’s hydro generation capacity.

I note with interest that, even though Maine total hydro capacity was only 17% of its total generating capacity, 26% of their electricity output for 2012 was generated from hydro. This means that their hydro plants worked very hard in 2012, which is indicated by the highest capacity factor for their combined hydro plants. (Recall from I’ve Got the Power! that capacity factor is the ratio, expressed as a percentage, of the actual electricity output from a generator over a year compared to the theoretical output if the unit operated 24 hours/day 365 days per year.) The comparative numbers for NH are quite different. In orange I have highlighted that hydro represented 10% of NH generating capacity but, in 2012, it was, surprisingly, only responsible for 7% of the NH total electricity output. The capacity factor of all NH’s hydro plants, in yellow, was therefore an extraordinary low 33%.

Source: EIA

This anomaly is quite striking and some follow-up research is warranted. It is clear that hydro power is intriguing topic and I plan to continue my explorations in future posts. Now, when I gaze out the windows at the Merrimack River and the upstream Amoskeag dam during faculty meetings, my colleagues can be assured that my distraction is not idle daydreaming; instead I will be thinking of river flows, generating plants, and capacity factors!

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

Mike Mooiman

Franklin Pierce University

mooimanm@franklinpierce.edu


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(*Down by the Water – A great tune by one of my favorite indie groups, The Decemberists. These guys are great song writers and I always look forward to their new releases. Here they are from Austin City Limits – the best music show on TV. Enjoy Down by the Water.)

Sixteen Tons* - Tough Times Ahead for Coal-Fired Electricity in New Hampshire

Prior to the commissioning of the Seabrook nuclear power plant in 1990, a large portion of the electricity generated in New Hampshire came from the combustion of coal. Since then, as shown by the data in the figure below, the importance of coal-fired electricity has diminished substantially. Last year coal was only responsible for 7% of the electricity generated in the State. In this post, we take a look at the coal-fired electricity business in New Hampshire and some of the challenges it faces.
 

To understand the coal-fired electricity business, we should start with the fuel – coal. Coal is the most abundant fossil fuel on the planet and it consists largely of carbon plus varying amounts of hydrogen, oxygen, nitrogen and sulfur. Coal used for electricity generation normally has a carbon content greater than 75% and it also contains compounds of aluminum,calcium and silicon that form coal ash when coal is combusted. On top on those elements, coal is also contaminated with deleterious metals, such as cadmium, mercury, selenium and lead. The key problem associated with coal is that, on burning, it releases these nasty elements and they end up in the off-gases, from which they have to be removed in expensive particulate capture and gas scrubbing units. In spite of these air cleaning units, considerable quantities of these metals are released into the atmosphere.

In a coal-fired power plant, the coal is pulverized and fed into a burner which heats a boiler that produces steam. The steam, in turn, drives a turbine which turns the generator to produce electricity. The main inputs to a coal-fired power plant are coal, water and labor; the outputs, other than electricity, are numerous and problematic. First of all, there are all the nasty contaminants such as sulfur and the deleterious metals that need to be removed from the off-gases in large water-based scrubbing units. These metals are recovered from the scrubbing solutions and then need to be disposed off as hazardous waste. A basic flowsheet for the coal-fired electricity business with the main inputs and outputs are shown in the figure below.

Generating electricity from coal is highly inefficient so there is a great deal of waste heat that is created. As I noted in Not So Classical Gas, the conversion efficiency for NH coal-fired power plants is only 31%. In other words, only 31% of the energy in the coal is converted into electricity and the other 69% is lost as waste heat. A great deal of this waste heat is transferred to the cooling water that is critical for the operation of these power plants. This cooling water either comes from natural waters in rivers and lakes or from the large evaporative cooling towers such as the ones shown in the figure below which are typical of power plants located away from large natural water supplies. The problem with using natural water supplies is that large volumes of water are needed to absorb the waste heat. In the process, the water is filtered, treated and is warmed up. This, of course, negatively impacts any fish and other aquatic creatures that might be sucked into the cooling water intakes. On the discharge side, the receiving water body might have a limited capacity to absorb the waste heat and this can impact the natural water ecosystem, affecting both plant and aquatic life forms.

Coal ash is another byproduct of coal combustion. This largely consists of a fine, non- combustible silica and calcium oxide residue and it often contains appreciable amounts of deleterious elements like mercury, cadmium, chromium and others. The ash is stored on-site at power plants or is disposed of in landfills. In some cases it can even be used as a component of Portland cement.
 
It is all these nasty byproducts - hazardous waste produced from the scrubber solutions, coal ash and a great deal of waste heat – that are behind the assertion that coal is a dirty fuel. And this does not even begin to consider the issues associated with coal mining - which is a difficult, complex and hazardous operation that has significant environmental impacts. Coal's only redeeming factors are that the US has large coal reserves and, until recently, on an energy equivalent basis, it was less expensive than natural gas.

New Hampshire has two large coal-burning plants both owned by Public Services of New Hampshire (PSNH): the large 440 MW facility located on the Merrimack River in Bow and the smaller Schiller plant located on the Piscataqua River in Portsmouth. Some technical details for these operations are provided in the table below.

Due to lower costs of wholesale electricity, driven by low natural gas prices, both of these operations have been challenged the past few years to provide electricity at prevailing market rates. As a result, the outputs from these operations have dropped off considerably and in 2012 the Merrimack plant only operated at 31% of its theoretical capacity and the older Schiller Station only ran at 9% of its theoretical capacity. However, as the chart below shows, in the first quarter of 2013, with the brief period of natural gas pipeline limitations that we encountered in New England, these operations, and particularly the Merrimack Station, were again able to operate at higher rates. In the first quarter the capacity factors of the Merrimack and Schiller operations were 0.83 and 0.32, respectively, which are higher than the 2012 numbers presented in the table above. Unfortunately, this improvement is most likely a short-term event. Recent monthly data from the EIA show that, in the second quarter, these plants are barely operating again. Other than in the unlikely advent of high natural gas prices, it appears to be another tough year ahead for these coal-fired operations.

 
On top of the market price challenges, the Merrimack plant has had to deal with new operating permits for discharge of wastewater from their operations, which limits water-borne metal discharges as well as waste heat. The latter limitation could even result in the installation of those large expensive cooling towers shown in the photo above. At this time I believe the wastewater discharge permit, which took the EPA 14 years (!) to draft, is still in dispute.
 
To compound PSNH's coal-fired electricity challenges, the NH Public Utilities Commission (PUC) recently released a report which discussed the challenges associated with PSNH's high cost of electricity, its dwindling customer base in a competitive environment, the challenges of recovering costs of past investments from a smaller group of customers and even the divestiture of PSNH electricity-generating operations, including their coal-fired power plants. If PSNH were to divest themselves of their generating assets, this would complete the process of deregulation, leaving PSNH just in the distribution business. But to do so would require the State to come to terms with how to compensate PSNH for past investments and fixed costs that they have not recovered through the sales of electricity. This is indeed a difficult and contentious issue and will require a lot of study. This would have all been easier years ago, before the advent of cheap natural gas, when coal plants still had value and stranded costs could have been recovered by higher prices for generating units. Now there is even some speculation that PSNH NH coal-fired power plants have no value at all.
 
So NH coal operations are being squeezed every which way. They have to deal with cheap natural gas, tougher air and water discharge restrictions, customer loss due to competitive landscape, and then - just two weeks ago - President Obama mentioned in a recent speech that he has directed the EPA to prepare to limit carbon dioxide emissions from new and existing coal-fired power plants. This is not good news for coal-fired energy in NH and perhaps it is time for PSNH to consider converting these their coal-fired operations to natural gas operations, which is what some utilities in other parts of the country are doing. Something has to be done otherwise we and PSNH are going to be singing that that famous line from the Tennessee Ernie Ford coal mining song, Sixteen Tons*, "Sixteen tons and what do you get - another day older and deeper in debt."
 
Quite frankly, it is all a bit of a mess. Because of foot dragging, extended negotiations during restructuring deliberations and legal actions by various parties, PSNH has perhaps held onto to its generating assets long after they should have been sold. With the recent advent of cheap natural gas, those coal-fired assets are now worth substantially less and, because legislation allows for cost recovery in the case of divestiture, modification or retirement of assets, NH residents are going to be on the hook one way or another for investments made by PSNH to maintain their coal-burning attributes.

Such are the joys and responsibilities of a public utility. On one hand, we want them to provide cheap and reliable electricity, we want them to be there as a backstop to other providers, we want them to invest in infrastructure build out and investors and lenders, who foot the bills for the infrastructure projects, quite correctly expect a financial return. Oh yes, and then we want them heavily regulated in a competitive environment as well. All of that comes at a price. The verdict on the wisdom of restructuring is, in my mind, still out. Yes, there is cheap electricity available and many folks are benefiting from lower rates, but we are still are going to have to foot the bills for past public utility investments, one way or another. If the message goes out that lenders and investors have to bear the brunt of the write-offs, this will send a chilling message to this group and future large-scale infrastructure investments, which we very much need, will become difficult to fund. There are tough days ahead as we work through the consequences of the restructuring programs underway.
 
There is perhaps some gloating over the way PSNH is being squeezed from all sides but it is important to note that natural gas is not necessarily an all-around better option. Yes, it is a cleaner fuel with far lower deleterious contaminant levels, but the means of recovery from shale via fracking has a host of associated issues including wastewater treatment, methane losses and seismic disturbances. A recent study showed that the greenhouse effect impact from fugitive methane emissions associated with shale gas is rather shocking. The article, published in the journal Climate Change, analyzed the methane emissions connected with shale gas exploitation and the authors compared the effect of higher methane emissions associated with fracking for natural gas with conventional gas wells. Even though methane combustion releases less carbon dioxide than coal burning, the increased methane emissions from shale gas extraction, coupled with the fact that the greenhouse effect of methane is 25x that of carbon dioxide, means that, in the short term (20 years), the greenhouse gas impact of shale gas is considerably higher than that of coal. However, over a 100-year period, shale gas is equivalent to that of coal because methane has a shorter atmospheric lifetime than carbon dioxide. This study suggests that transitioning from coal to natural gas produced from shale gas will do little in the short term for global warming trends. Now that is pause for thought.

So where do we stand at the moment? A week ago PSNH published a lengthy but well reasoned response to the PUC report and it is clear that there is much to be taken into account in the debate regarding the fate of PSNH's generating assets. The New Hampshire legislature has recently passed legislation SB 191 which requires NH to establish a ten year state energy strategy plan. We have a lot to think about and deal with in the next year or so and it is now time to set up conferences, roundtables and meetings so we can come up with a well-researched and thoughtful plan for the future. Remember: it is not just about us. It is about future generations as well and they expect us to make wise decisions. Let's make the best of this opportunity and not leave them with a battered can that we have just kicked down the road.

Until next time, remember to turn off the lights when you leave the room.
 
Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
7/5/13

(*Sixteen Tons – A song written by Merle Travis and made popular in the 1950s by Tennessee Ernie Ford. Johnny Cash did a great cover but here it is featuring one of my favorite guitar slingers Jeff Beck playing with Billy Gibbons of ZZ Top. Enjoy Sixteen Tons)

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Windfall?* – Wind Energy in New Hampshire

In March last year I went skiing at Crotched Mountain, near Bennington, NH, with my son. It was a perfect day for skiing – the weather was mild, the sun was shining and, most importantly, the lift lines were short. A couple of times that day we took a breather at the top of the mountain to admire the view and we briefly considered the wind power potential of the site but I had no idea at that time that I was skiing at the site that was the birthplace of the wind energy industry.

In 1980 a company by the name of U.S. Windpower established the first wind farm in the world by erecting twenty 30 kW wind turbines on Crotched Mountain. The design was based on research and development work conducted by Professor William Heronemus at the University of Massachusetts, Amherst. For a variety of reasons, including unreliable equipment and poorly understood wind resources, the project was not a commercial success and was dismantled after a year, but the developer went on to set up wind farms in California which were not a commercial success either. Nevertheless, a lot was learned from these projects and failures and these early efforts were the genesis of the wind energy industry as we know it today. It is quite remarkable to consider, that starting with establishment of the Crotched Mountain operation in 1980, we have moved from an installed wind energy capacity of 0.6 MW from 20 turbines to approximately 282,000 MW of worldwide capacity from over 200,000 turbines in the space of about 30 years. In the process we have gone from wind turbines with 15 ft long blades powering 20 kW units to turbines with blades longer than 200 ft powering 7.5 MW units. This is an impressive advance in engineering technology and a testament to what we can accomplish when incentives and subsidies are available. As my students in the Franklin Pierce MBA in Energy and Sustainability Studies learn, successful energy development requires the combination of correct government policies, the correct technology and financial incentives.

After the Crotched Mountain project not much happened in NH wind-wise until 2008 when Iberdrola, the large renewable energy company based in Spain, established their first NH-based wind farm on the hilltop ridges near Lempster. Since then we have had two other wind farms established near Groton and Dixville Notch and there are a bunch more seeking permitting or in development.

The key reason that wind development has not taken off in a bigger way in New Hampshire is that we simply do not have the wind power potential that is present in other parts of the US. As you can see from the US 50 meter (165ft.) wind resource map below, most of the US wind resources lie in the center of the country, from Texas up to North Dakota. This is where the wind blows the hardest and most consistently and these are the choice areas for the establishment of large land-based wind farms.

 If we take a closer look at NH, we can use the 50 meter wind resource map shown below to examine where our winds blow the hardest. The areas of most interest are those highlighted in purple, red and blue. The high wind resources are towards the western side of the State and increase in power as we curve over to the north in the White Mountains area.

I have overlaid on this map the locations of the operating and proposed wind projects in New Hampshire so you can gauge where these operations are relative to the high wind resources and you can also assess where future projects might be sited. The table that follows provides the key for the locations shown on the map as well as information about the various operations.

The challenge with wind energy in NH is that, in order to harness the wind resources, we are forced to put wind turbines up at high elevations on mountain ridges. As a result there are wind turbines – 70 at last count - popping up on hilltops in New Hampshire which, according to your perspective (and location relative to the turbines), can either be the worst thing that ever happened to the wilderness of NH or part of necessary transition as we begin our move away from our dependence on fossil fuels. I do appreciate the argument that, because wind does not blow all the time, we always need a fossil fuel backup for these turbines. However, we should take into account that we are not breaking new ground and building new coal or natural gas power plants every time we put up a wind farm in the USA. What is happening is that, in the developed world, we are slowly ratcheting down the output from existing fossil fuel plants and reducing our output of greenhouse gases and other pollutants from these operations. Every ton of carbon dioxide that we do not emit is, to my mind, a good ton of carbon dioxide. By my estimate, the 282,000 MW of worldwide installed wind capacity led to ~740 million tonnes of carbon dioxide that we did not emit. I know this pales in comparison to the ~33 billion tonnes we likely emitted in 2012, but this is a start and every bit does help.

I also did some research at the Federal Electricity Regulatory Commission (FERC) website to see exactly how much power the three operating wind facilities are actually generating compared to their proposed output. One frequent condemnation of wind power is that the operations don't often measure up to their proposed output and therefore they are a waste of money and tax payer dollars created by subsidies and incentives. I wanted to see if that was the case and how the NH wind farms performed compared to their projections. One way of doing so is calculating the capacity factor, which is what I have done based on the FERC reports of energy sold by the various NH wind operations in 2012. If you recall from the I've Got the Power! post, the capacity factor is the ratio of the actual energy produced by a power plant to the theoretical amount that would have been produced over a year if the plant was operated 24 hours and 365 days of the year. The 2011 data from that post indicated that for the single wind farm in that set of data, the Lempster project owned by Iberdrola, the capacity factor was 0.314 (31.4%). In New England capacity factors for large-scale wind farms range from 0.15 to 0.35 with averages around 0.25.

The only two wind farms that operated throughout 2012 were the Lempster operation and the Granite Reliable Power facility near Dixville. The other operating plant, the Iberdrola Groton Wind facility, only started up in about October last year so there were very few energy sales and, as such, there were insufficient data to calculate capacity factors.
The table below shows their actual electricity production and the calculated capacity factors. I have also included the average prices for their electricity sales.

As you will note, the Lempster operation has a relatively good capacity factor compared to most NE wind projects but the Granite Reliable Power facility only has a capacity factor of 0.15 which is rather low, as is the price it is getting for its electricity.

The low output from the Granite Reliable Power wind farm is a bit of a puzzle. Based on the NH wind resource map I would have expected the higher wind speeds in the northern part of the State to translate into higher capacity factors. There are a number of reasons that energy generation numbers would be lower than expected, including

• Lower than estimated wind speeds
• Turbulent wind conditions
• Wind turbine mechanical problems
• Deliberate output reductions due to lack of demand for produced electricity

I have not been able to determine the actual cause for the low output but, considering that Granite Reliable Power sells directly into the ISO-New England electricity pool, demand, as well as the price for its generated electricity, are dependant on what other power plants are bidding. However, the wind farm has very low operating costs as they have no fuel costs, so I would have expected that they would always make the choice to deliver into the pool even at the lowest clearing price. Perhaps my understanding of the electrical markets is not clear and I look forward to being set straight by someone with a better knowledge of these markets. Regardless, if I was owner of this operation, I would be somewhat grumpy about this situation and envious of the performance and higher prices obtained by the Lempster operation which has a power purchase agreement with Public Services of New Hampshire to purchase all its output.

At the end of this year it will be interesting to compare the output and capacity factors of all three operating wind farms and particularly to compare the operations of the two Iberdola facilities. If I were the developer of the large North County Wind facility planned for Coos County, I would be taking a very careful look at the performance of the Granite Reliable wind project and double checking my energy and revenue projections.

The importance of wind energy in New Hampshire is growing as are the objections against further development. I am not sure how this will all shake out, but it is clear that wind energy in New Hampshire will not be a windfall* for all developers.

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

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
6/2/13

(*Windfall – A fabulous tune by the group Son Volt which was a spinoff of the group Uncle Tupelo. The other Uncle Tupelo spin off was Wilco. Quite the pedigree. This week's challenge was picking the right "wind" song as there are so many to choose from - Dylan's "Blowin' in the Wind" was simply too obvious. Here is the link for Windfall – a song that makes you sad and hopeful all at the same time.)

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Not So Classical Gas* - Energy Conversion Efficiency and Improvements in Natural Gas Technology

Last week I covered a ratio called capacity factor which some folks confuse with energy conversion efficiency. While the topic is still fresh, I thought I would cover energy efficiency this week to make sure there is a clear understanding of the two concepts. In my last post I noted that a great deal of energy technology is about converting energy from one form to another. For example, in a nuclear power operation we convert the nuclear energy holding the uranium nuclei together into heat which is then used to boil water to produce steam which drives a generator that produces electrical energy. The key to energy technology is to make these conversions as efficiently as possible.

The example I provided was my Prius versus a Maserati. I noted that the higher powered and larger engine of the Maserati could more rapidly convert the chemical energy in the gasoline into mechanical energy, i.e., rotation of the crankshaft, which is then converted into forward motion, or kinetic energy. However, I also noted that the Maserati does so less efficiently and that was cause for some smugness on my part.
 

  (Picture source: Maserati)

Let's be sure we understand the term conversion efficiency. Energy conversion efficiency is the ratio of useful energy produced to the input energy of the fuel used to drive an engine. It is typically calculated as a percentage: 

 

Energy Conversion Efficiency = (Output Energy/Input Energy) x 100
 

In automobile engines, energy conversion efficiencies are measures of how effectively the engine converts the chemical energy in gasoline into the mechanical energy of a turning crankshaft. The efficiencies are typically 25 to 35% for gasoline engines such as those found in a Maserati, 37% for my Prius and over 40% for turbocharged diesel engines. In fact, some turbocharged diesel engines can reach 47% conversion efficiencies. The rest of the energy is lost as waste heat. The useful mechanical energy that is produced is then used to overcome friction, turn the wheels and move me and the hunk of metal that constitutes my Prius from Concord to Manchester. Indeed, if we were to calculate the energy required to move one 200 lb man from Concord to Boston, we would determine, on that basis, that efficiencies are only of the order of 1%. The rest of the energy is lost as waste heat, waste energy during idling, overcoming friction, powering the devices in the car and moving the bulky metal can around me. That low overall efficiency is, for me, always pause for reflection.

 

The challenge with conversion efficiency is that one needs to be sure what one is comparing and recognize that there are many measures of efficiency. For example, when discussing automobile engines, we must not confuse fuel economy with energy conversion efficiency. Even though the fuel economy of a Prius is three times that of Maserati, it does not mean that the Maserati has a conversion efficiency one third of my Prius. The Prius owes most of its higher fuel economy to a lower vehicle weight plus its regenerative braking technology. In other words, the three-fold better fuel economy is more a vehicle issue than an engine issue.

 

While we are on the topic of engines, let's take a closer look at those extremely large engines in New Hampshire that are used to produce electricity. These engines can be coal-, oil-, wood- or natural gas-fired or even powered by wind or water. In this case we will measure efficiency by dividing the produced electrical energy by the input energy in the fuel which is used to drive the generator.

 

The table below shows the calculated aggregated conversion efficiencies for the various forms of electricity generation in New Hampshire. (Unlike last week, we have to resort to 2010 data as a full set of 2011 data is not yet available from the Energy Information Agency.) In this table, I have compared electricity output with the input energy consumption for each form of electricity production.

 

The conversion efficiencies are presented in the last column and are ranked from lowest to highest. The conversion efficiencies are generally low, and if we were to consider all the energy in NH produced from a single enormous generator – the Megarac 4500 from last week – the conversion efficiency for this device would only be 34%. The rest of the energy, 66%, is lost as waste heat.

 

Biomass has the lowest conversion efficiency, only 23%, partly because some of the energy is expended in driving off the water in the wood chips which can contain as much as 50% moisture. Coal-, nuclear- and oil-based fuels have conversion efficiencies in the low 30s. The conversion efficiencies for the State's hydroelectric operations are only 35%, which I found somewhat surprising: large hydroelectric operations are reported to have efficiencies of close to 90%, which means they can harness 90% of the energy in channeled water flow; even smaller operations are reported to operate with efficiencies of the order of 50% so the 35% figure for NH is a little puzzling. Modern three-blade wind turbines typically harvest about 40% of the available wind blowing over the turbine area so the 37% figure for wind is as expected. Natural gas, at 45%, has the highest conversion efficiency.

 

Natural gas is particularly intriguing as we are presently witnessing the large-scale switchover from coal- to natural gas-fired electricity generation. The driver for this switch has been low natural gas prices, but there has also has been a lot of research and development into gas fired turbines used for electricity generation which has significantly improved the conversion efficiencies of these devices. With modern gas-fired units, we have moved away from the classical way of generating electricity - burning fossil fuels to boil water to make steam to turn a generator which produces electricity. Instead, gas-fired generators are now of the gas turbine variety, where the turbine is propelled not by steam, but directly by the hot expanded gas that results from the combustion of natural gas. Moreover, because of new advanced turbine materials, we can run them at higher temperatures of operation which also improves engine efficiencies. With higher operating temperatures, we then have exit gases leaving at elevated temperatures. We are then able to harness these high temperature off-gases in a secondary operation to boil water to create steam to drive a secondary steam-powered generator. These units are known as combined cycle units and they can operate at very high efficiencies. A basic schematic of a combined cycle unit is shown in the figure below.

 

(Picture Source: Wikipedia)

 

The chart below, which is from an MIT report that reviewed advances in gas turbine technologies, shows how gas turbine technical advances have led to increased efficiencies for both simple(those without a secondary steam boiler) and combined cycle units (those with a secondary steam boiler). At the time of the report, units with 60% efficiencies were foreseen and today commercial units from both GE and Siemens are available that can achieve 60% or even slightly higher. These advances come as a result of years of turbine research for aircraft engines and energy generation as well as advances in materials that can withstand even higher temperatures.

 

 

It is these increased conversion efficiencies that are part of the attraction of natural gas. Not only does natural gas release less carbon dioxide per unit of input energy, but the energy conversion efficiencies are substantially greater than those of coal-burning operations: this further serves to reduce carbon dioxide emission per megawatt hour of electricity produced. In fact, per unit of electricity produced, carbon dioxide emissions from natural gas operations can be less than one half of that of equivalent coal operations. Over time, as equipment is improved, new investments are made and older, less efficient equipment is retired, I would expect the conversion efficiency of natural gas-based electricity generation in NH to creep up from the 45% noted in the table above. There clearly is a lot we can do to improve the existing efficiency of natural gas combustion in New Hampshire.

 

Returning to the conversion efficiency table above, we note that conversion efficiencies for technologies other than natural gas are surprisingly low. Technological advances over time should improve these. However, breakthrough advances, like those we have seen for natural gas, are unlikely. Instead, we will see small incremental improvements over time and, in my mind, continual improvement in efficiencies should be part of the operating philosophy of every electrical generator and should perhaps even be part of the permit to operate. Small incremental improvements in conversion efficiency can result in large bottom-line benefits for both generating companies and for the planet, as this will reduce the amount of carbon dioxide released per megawatt hour of energy produced.

 

But, instead of waiting for breakthrough energy efficiency technologies, there is something we could do right away. We should be focusing on that 66% of waste heat. We should be investigating applications where we harness that unused heat and find ways to distribute it to the community, such as you would find in district heating applications that are in common use in many of the northern European countries. If we did this, then we would certainly be getting away from the classical way of doing things - simply burning fossil fuels to produce steam to turn turbines which only generate electricity and a lot of wasted heat.

 

Hopefully this week I have left you with an appreciation of how low our energy conversion efficiencies are for electricity generation and that there are opportunities for improvement. You should also have a good understanding of the difference between energy conversion efficiency and capacity factor. Remember, energy conversion efficiency is the ratio of useful energy output to the input energy and capacity factor is the ratio of a generator's actual output compared to what theoretically could be achieved if the generator could be run 24 hours, 365 days per year.

 

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

 

Mike Mooiman
Franklin Pierce University
mooimanm@franklinpierce.edu
3/25/13

(*Classical Gas is the name of a guitar instrumental tune, written and performed by Mason Williams in 1968 who, at the time, was a writer on the Smothers Brothers Show. For an instrumental, it was a big hit, reaching #2 on the charts. Forty five years later I still think it has a lot of appeal. Take a listen to the acoustic version without all the orchestral filigree.)

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