Sunday, June 21, 2009

Electricity in New Hampshire - The Merrimack Station Scrubber Project

A discussion about electricity in New Hampshire would be incomplete without mention of Merrimack Station in Bow, NH.   Readers may recall that Merrimack Station is one of the 5 largest power plants in the state.  In fact, Merrimack Station is New Hampshire's largest coal-fired power plant, as well as the largest plant in PSNH's power generation portfolio.

Merrimack Station's two coal-fired units were built in the 1960s and are rated at 496 megawatts total, together providing over 10% of the power generation capacity in the state.  Because it's fueled by coal, Merrimack Station is always able to produce power at a lower cost than any other fossil fuel powered plant in the state.  As a result, it's almost always running at its maximum output.

Coal arrives at Bow Station from Portsmouth multiple sources (see comments below for more info)
Coal is the least expensive fossil fuel for power plants by far.  The heat energy contained in a fuel is measured in millions of British Thermal Units (MMBtu), and fuel costs are compared using dollars per MMBtu.  For 2009, coal is estimated to cost $2.16 per MMBtu, natural gas $4.35, and oil between $8.60 and $12.23 depending on the grade.  The cost for each fuel can bounce around wildly, but coal seems to always end up the cheapest.

OK, coal is cheap.  So what's the problem you might ask?  Well, coal may be cheap, but burning it emits lots of pollution and those emissions result in health and environmental issues that come with their own costs.

Fuel emissions data from
In the table above, the pollutants listed are carbon dioxide (CO2), sulphur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), and particulate matter (PM). 

Over the years, our collective understanding and appreciation of the dangers of these toxins has increased and that's resulted in several mandates to reduce emissions at power plants around the country.  In 2006, the NH legislature decided that NH too needed to clean up the output from its coal-fired power plants.  The result was a directive to PSNH to install a mercury and sulfur dioxide scrubber at Merrimack Station.

PSNH got moving on the directive and made a plan to connect the scrubber to the exhaust from the plant's two generating units.   You can see the stack for the new scrubber on the left side of this recent photo from Merrimack Station in Bow.

The photos below show that construction is well underway.  Even on a Saturday, when these shots were taken, crews were hard at work all around the site.

I couldn't help but notice the porta potty sitting on a platform at the top of the new stack.  I guess it makes sense, as  I'm sure it's a long trip down.  Seeing this close-up gave me renewed appreciation and respect for the construction workers who take on projects like this.  I'm not that afraid of heights, but that stack is waaaay up there!  

Although construction on the scrubber is well underway, the project has become very controversial lately.  The main source of the controversy was a cost increase that PSNH announced last year.  The original estimate for the scrubber was $250 million dollars, but once PSNH had completed the design and started the contracting process, they increased the estimate to $457 million.  

Since I'm late to the party, I won't get into a detailed analysis of the pros and cons of the project.  Check out the links at the end of this post, or google "merrimack station scrubber" if you're up for some digging.   

I'll end with a  list of the highlights of the pros and cons, as well as a listing of some of the hidden and not so hidden forces at work pushing for and against the scrubber.
Arguments in favor of the scrubber:
  • Coal is cheap (about $2.00 per MMBtu compared to $4-10 for gas or oil)
  • Using coal keeps our energy portfolio diversified and secures supply (comes from US and south america not middle east)
  • The plant itself is paid for and has life left in it
  • The project will result in needed jobs in industries that are suffering
  • It's needed to comply with the law and in the end we'll have one of the cleanest burning coal plants in the country
Arguments against the scrubber:
  • Coal may be cheap but when you add in the scrubber, the cost per mwh is no bargain
  • The plant will still emit lots of bad stuff  even after scrubber is done
  • The plant is very old and big stuff could break in the next 15-20 years, costing more money
  • The plant's boilers are old and finicky - they only burn special coal blends that can be tough to find and cost more
  • New cap-and-trade legislation and other laws could make emisions more costly than they are now - Many argue that this plant requires an emissions "free lunch" to be cost competitive.  Once the costs of the plant's other non-scrubbed emissions are priced in the plant could become very expensive
As with any public decision, politics and special interests are usually at work, sometimes behind the scenes.  $457m is a very large project so there's plenty of raw cash at stake.  But IMO, there's more than just the construction dollars at play as far as special interests go.
Forces pushing for the scrubber:
  • Deregulation laws prevent PSNH from building or owning new plants - once Merrimack Station closes, PSNH loses about 40% of its generation capacity for good
  • Equipment manufacturers, construction workers, powerplant workers, and associated unions and trade groups will gain from project contracts
  • The coal industry wants to secure demand for their product
  • Some ratepayers believe keeping the plant operating as long as possible will keep rates lower
Forces pushing against scrubber:
  • Environmentalists don't like coal because it pollutes and the mines leave behind a mess - they'd prefer the plant shut down
  • Independent power producers (TransCanada Hydro, FPL, etc) will have less competition if the plant shuts down
  • Regional natural gas and oil suppliers would prefer their fuels were used to make power instead of coal
  • Some ratepayers are worried about rates skyrocketing because of the project

Google Map of Merrimack Station in Bow, NH

View Larger Map

A brief PSNH infomercial on the scrubber project



  1. Nice summary! I put one together for the Telegraph back when this issue first surfaced, but yours is better. I'll happily steal from it ... er, I mean, be guided by it in the future!

    Dave Brooks, the Telegraph

  2. Dave,

    Wow. I'm honored to get a comment from IMO, the best science, technology, and energy reporter in the state.

    I follow your blog at and look forward to your articles in the Telegraph. Thanks again!


  3. One of the pushes against this plant has been to go to alternative energy. In fact groups have pushed to have this plant eliminated and a new one built that runs on Natural gas. The trouble is there is no feeders anyplace near this area with the needed capacity to feed a "same sized" plant. The nearest plant that is run on Natural Gas is Granite Ridge which went bankrupt when the volatile price of natural gas increased 4 fold just as it went on line. It was sold to other interests and now sells on the spot market when demand is high. Trying to get a natural gas line to the current Bow Plant would require massive construction of a long distance feeder line which means right of way land takings. This flies in the face of the gas shortages in the early 70's , mid 80's and mid 90's when cold winters caused natural gas shortages along with power plant closings and home natural gas shortages. There is also the cost to remove the existing plant and build a replacement.
    As for going to alternatives I live in Henniker and everyone came out of the wood work to fight against any form of Bio Mass because they would see , hear or smell the plant so it would depress the value of their homes. I'm a former member of the planning board and heard the exact same complaints about "anything" that was built on any hill top so forget about wind power. A recent study up north said there is not enough Bio Mass to support a 60 MW power plant.
    Now the current owners of PSNH have signed a letter of agreement to "look" at importing power from Quebec Hydro. The trouble is it is just a piece of paperwork because they have no idea what route the power lines would take and they would be very large specialized high tension power lines. That means the NIMBY's and enviormentalists have not had a chance to fight the placement of the lines. Also more importantly no one has tried to lock in a long term contract with Quebec Hydro. Several groups up north checked and the pricing offer heard would be tied to what it would cost to produce power as if it was generated by an oil fired generator not hydro power and the market price fluctuations would show in the pricing. ISO New England has stated it will not fund upgrades to the Northern loop where several wind power groups along with Bio Mass groups want to tie in but they would exceed the capacity of that set of lines. Of course it appears a lot of people have forgotten that during the big ice storm of 10 years ago that most of Quebec was without power for a month when the ice storm collapsed many of the high tension towers. Other groups talk about solar when in fact just two winters ago we had building roof collapses occurring due to snow overload.
    If this state is so concerned about going to alternative energy and it has to be environmentally clean then it is time we looked to the future and started building dams in this state that will create Hydro Power plus will create reservoirs for the future drinking water needs of this state. We also need to start placing wind power in places were it is often windy and land taking is not involved like placing wind power on the median of I-95 , I-93 and I-89 in places where it is feasible. That would simplify utility placement.
    The trouble is all the same groups that would fight the Bow Plant will fight these alternatives that can in any way be seen , heard or smelled from the comfort of their front yard or their commute.

  4. As concerns the coal used at the Bow Plant it does not come through Portsmouth. The coal comes into Portsmouth is used at the Portsmouth location. Currently there is train loads of imported coal that comes through the port of Providence RI and is delivered by the Providence and Worcester Railroad.

    The other coal is usually from one of the Consol mines in Kentucky and is delivered in unit coal trains by Norfolk Southern Railroad. The coal used is the kind the Merrimack generators where built for. You can build for Hard Coal , Soft coal or Lignite coal. Other variations are plants that burn coal delivered by coal slurry lines and coal gasification. There has also been occasional deliveries of coal from the Powder River Basin coal fields.
    By the way the coal from the Powder River Basin has a much lower sulfur content but it also has a much lower BTU output so you burn more to get an equal amount of energy. In fact many coal mines send their coal to a mixing plant that washes the coal and mixes it to get a desired amount of sulfur output and needed BTU output.

  5. Don,

    Thanks for the comments and the correction about the coal. I was relying on this info from pg 85 of PSNH's 2007 Least Cost Integrated Resource Plan.

    ...Merrimack Station has been able to take advantage of the favorable offshore coal prices by transshipping a large percentage of its coal requirements through Schiller Station. This coal is transshipped through Schiller Station’s coal yard and is delivered to Merrimack Station via truck service. The cost savings of using foreign coal, as compared to displacing and burning higher priced domestic coal of similar quality is significant.

    Since the doc is almost 2 years old now, I guess it's no surprise that things have changed.

    Also, your comments about the transmission line upgrades are interesting. I know there are issues with transmission line capacity w.r.t. both power from Canada and the proposed biomass plants in Berlin and I hope to dig into those issues in a future post.

    Thanks again for the comments,



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