The Merrimack River - Renewable Energy

We all know that hydroelectric power is renewable energy. As an engineer of a sort and historian of a different sort, I've been asked a few times what the actual hydroelectric power potential of the Merrimack River at Lowell is. Many months ago I did a post that covered some of this. However, I don't quite trust my math and that wasn't the pure focus of that post, so I decided to do another one.

The questions are:

1. How much power - at peak - can the Merrimack theoretically provide? Because of large seasonal variations in flow, this number can vary by a magnitude. So, we are also interested in how much power, in dry spells, it can reliably provide.
2. How much water can go through the canal system? This number I figure should be very close to the historical figures. We've all seen in the summer that the river underneath the Pawtucket Falls Bridge is bone dry as it is all diverted into the canals. In the spring, there's a ton of water down there that is not being used for any mechanical purposes. 
3. How much electricity does Lowell currently produce off of the Merrimack, at various sites around the city?
4. Are there ways to produce more power we haven't implemented?

The first figures aren't hard to get. We just need to go to the USGS website and look at some flow figures for Lowell, since waterpower is a simple formula of volume times drop times weight of the water.

Total Power Available

So, we'll start here. This is the statistics for the amount of water in the Merrimack River below the Concord River. So, this isn't really at the point we are interested in, but for our purposes, it should be fine. You can surf around the site if you'd like, but it seems like the Concord River contributes maybe 10% of the water volume at this point, so we'll be within reason to use these figures and maybe round down as appropriate.

Two numbers in this chart are the most important: High flow and low flow.

Low flow, in August, is about 2,500 cfs (cubic feet per second). This is the reliable amount of energy available to the city. We can assume that due to the dam and lock system, the height of the canals, that is, the drop part of the equation, is constant.

High flow, in April, is nearly ten times that: 22,000 cfs. Again, the canal and dam system controls the level of the water in the system.

Now, that formula. I'm going to mention Patrick Malone's excellent Waterpower in Lowell book, which, in addition to having extensive data on the water the mills used (we'll get back to that), and the way it was captured, utilized, and researched, contains the formula I mentioned above. It also mentions, as we are often told, that the Merrimack River drops about 30 feet at Lowell and water weighs 62.4 lbs per cubic foot.

So, on the low end, we're talking about

2,500 cfs * 62.4 lbs per cf * 30 ft = 4,680,000 lb-ft per second.

Now, let's step back to high school physics. What is a pound-foot per second?

Well, a foot-pound is a unit of energy, equal to 1.356 Joules. A Joule per second is a Watt, a measure of power. So...let's convert foot-pounds to joules:

4,680,000 lb-ft * 1.356 = 6,345,228 joules

Since we're interested in joules per second, the number is directly equivalent to a watt. Our math says that at lowest flow, Lowell can expect 6.35 MW of power from the river before we factor in the energy efficiency of a turbine (which can be as high as 90%). That's a lot of lightbulbs! A horsepower is 746 watts so we're talking 8,509 horsepower, or a few dozen cars. Let that sink in as you think about gasoline: If you drive a 250hp car, your car produces about 1/30 the guaranteed power available from the entire Merrimack River at one of the best sites for an industrial city in the nation.

Now, sometimes the drop in the river is listed as 32 or even 34 feet. What's that do to these numbers? 34 feet is 7.19 MW.

Now, high flow:

22,000 cfs * 62.4 lbs per cf * 30 ft * 1.356 = 55.85 MW. Much better!

How much power is this?

Well...the US Energy Information Administration says that the average Massachusetts house uses 618 kilowatt hours a month. Let's assume that's ballpark for Lowell. Note that electricity usage is low in the Northeast because of the lack of electric heat and heavy air conditioning use. If you're using 618 kw/h a month, you're using 20.6 kw/h a day, or about 0.85 kw/h an hour. The hours cancel out so that's an instantaneous draw of 0.85 KW, or 850 Watts. You could run 850 homes on a Megawatt then, or over 5,000 homes off of the reliable energy the river can produce. Multiply by 10 for the high flow data. There are about 106,000 people in Lowell, and it looks like reasonable estimates are 30,000 households (which isn't exactly a house but close enough for us). That's one in six we could power, and that includes no other electricity uses from businesses and factories to street lights.

For comparison, the Natural Gas plant on Tanner Street, L'energia, produces 80 MW peak. The Coal/Petroleum plant on Salem Harbor is 750 MW peak. Seabrook Nuclear Power Station is 1,200 MW peak!

So, how much can the canals harness?

Again, as far as we've gotten is that the low flow for the river is 2,500 CFS. We know all of that water can get into the canal system. We know when there is a lot more than that, it flows over the top of the dam unused. We don't know how much the system can actually produce. The best way to find out the answer to this question is to look at historical data: back to Malone's book.

The thing to remember here is that in early Lowell, water was a utility. James B Francis, the most famous of the Locks and Canals engineers, the "Chief of Police of Water", really had to know how much water he had and could provide each mill so he could provide it to them reliably - and charge them for it. There was a standard unit for sale called the Mill Power, which was equivalent to 25 cubic feet per second of water falling 30 feet, or 85 theoretical horsepower. Malone has all this data. At the build-out of the canal system, Lowell produced a reliable 140 "Permanent" Mill Powers, which would be 11,900 horsepower, or 15.95 MW. This is three times the expected minimum (but under a third of spring flow), which is why the dam systems were needed to keep the water levels high enough during the day - we turn the river into a giant mill pond that refills overnight if need be. Mill companies were allowed to buy extra water when it was available, and in 1859 (after the system was completed and before heavy use of steam power), Lowell was often using an extra 40 Mill Powers. Let's call that an easy extra six Megawatts for 22 MW. There is complex engineering related to flow rates lowering head and becoming counterproductive, plus backed-up water slowing wheels when the river was high - for details...read the book.

How much is installed?

Well, Locks and Canals, the company that provided the water, eventually ended up being owned by Italian energy conglomerate Enel. Enel, as Boott Hydroelectric, has a few sites in Lowell's mills as well as the main plant on the Northern Canal by the University Ave Bridge. Their statistics are surprisingly missing from the EIA map above, but they provide it here.

Their main plant uses 3300 cfs of water and drops it 37 feet. Using our formula to check their math, we get 10.33 MW. This is considerably lower than the 17.3 MW installed they claim here and there is no explanation for the gap. However, adding in the supplemental plants in the old mills, we get to 20.7 MW installed. If we take Lowell's historic max with surplus mill powers of 22 MW and we multiply by an efficiency factor of 90%, we get 19.8 MW... which is essentially what Enel says they can produce at maximum.

What I'm seeing is that if they are producing this power regularly, we are using all of the available water Lowell historically has had and this is not enough electricity, even in high water scenarios, to run the residential sector of the city.

Is there more somewhere?

An interesting fact about hydro power is that the technologies, because turbines are so efficient, haven't changed much since Francis was doing his experiments 150 years ago. Is there anywhere else we can squeeze out any more power at any price? Raising the dam would work, but we would flood out our neighbors upriver. There probably isn't much extra summer water, as we're already in control of the water all the way up the Merrimack's watershed to its source at Winnipesaukee.

The only way to get power out of water is to utilize its kinetic energy - it has to be moving. The Wikipedia article on hydraulic head provides a good graphic showing how a turbine, like those in Lowell, work. If you've ever seen a boat on the Merrimack in Tyngsboro or up by the Rourke Bridge up to the buoys above the dam, you know there isn't much motion to that water - it's being backed up by the dam. Go too much downstream, and you hit the 17 MW Lawrence dam installation - again, the water is not moving much above this point.

However, you have to wonder if during the summer months if it would be cost effective to install small run-of-the-river installations to catch the more-than-half of the power potential the river has. 

However, I'm not going to pretend to know anything about the math on that ;-)

In conclusion...

It would appear we are using the majority of water that Lowell has ever had available to it for power generation purposes already, and, while not an insignificant amount, is not anywhere near the electricity needs of the modern city...never mind its resource-poor suburbs. Always, always be conscious about claims of renewables replacing our dwindling fossil fuel reserves.

Saint Joseph's Hospital Demolition

I was coming across the University Ave bridge this afternoon and noticed that the demolition work on the old Saint Joseph's Hospital building - to make way for University Crossing - was progressing rather quickly. Since we have pretty good light today and this is a weekend day when nothing is going on, I ran home for my  camera and came back to shoot a few photos before the whole thing is gone.

Pawtucket Street side.

Stair tower, Merrimack Street.

Salem Street entrance.

I have very few memories of the inside of this building, save my mom working there for a few years when i was a kid, and that was in the back of the building which still stands. However, I know a lot of people have happy and sad memories of this place. I was unaware when the University bought it that it was going to be demolished - I've heard there were structural issues. Either way, the wings coming down were built in the 1950s. The later additions to the back will remain standing.

Maternity ward?

Note the map of the hospital still on the wall.

I have written a bit about the hospital before, but honestly, I don't know all that much. This page covers the history up until the merger with Saint Jospeh's in 1992 forming Saint's Memorial Medical Center.

Rest of the photos:

St Joseph's Hospital Demolition - Aug '12

Long Time, No Posts

I've certainly been running out of steam with this blog.

When I started out in 2006, I was new to Lowell and was sharing a lot of what I was learning about the city as I went. A few years ago, I moved over to Blogger and the topics moved from Lowell "As It Is and As It Was" to broader issues with a local focus. At this point, I feel that many other, exponentially more popular blogs, cover this stuff really well. What they don't cover is often available on Facebook, where numerous Lowell groups and pages have sprung up. For example, I helped found the Innovative Cities: Lowell, Massachusetts group, and am an admin/content creator on the Lowell Downtown Neighborhood Association and Lowell Historical Society pages. Both of these pages also have blogs. I almost never use it, but I'm also on Twitter. You'll see that I updated my reading list panel with a few blogs that weren't there before. I've also set up my Facebook for public subscribing. I'll give that a try, if I can remember to post publicly: http://facebook.com/corey.sciuto (Well that didn't work out - didn't realize that not only is the post itself public, but all the comments on it! I don't want my friend's posts to me nor my replies back being public. Too bad. Maybe I need to learn to love Twitter.)

I've also been really busy. In addition to my Facebook work, I have a new Real Job and have been involved in various other things. I've become more involved with Mill City Grows recently, and I also am now a graduate of The Lowell Plan's Public Matters program.

I was invited to speak to the City Manager on Channel 99 last week with members of the mainstream media and fellow bloggers. Mimi over at Left In Lowell, has a post linking to all the other posts about the Round-table discussion. I think it went really well - the questions were excellent and the members of the Lynch Administration (now completing six years!) who were present did a great job answering our questions. There was a lot of buzz of course about the license commission, but other great questions asked the administration why there are few or no women/minorities on the various city boards and why Lowell has one of the highest commercial tax rates in the Commonwealth. Lowell CFO Tom Moses explained that land values in Lowell tend to be lower so overall tax burden is fairly average. Furthermore, compared to other expenses, property tax burden tends to be a non-issue, especially when compared to the major reasons a company may choose to locate in a particular community (things like infrastructure and available workforce). Of course, questions on what the administration has done a great and a poor job of came up, as did schools, etc.

I don't exactly see a replay of the Round-table on 99, and I don't see it available for steaming - but if it's out there, give it a viewing.

That all said, I do plan to still post, so continue to follow me on Blogger, or subscribe to me on Facebook. I've been keeping an eye on the developments along Tanner Street and the Rourke Bridge and have tried to make the meetings when I can. The Hamilton Canal District is still progressing. 110 Canal Street and the new  Canal Street bridge are the next steps in the project - the bridge is complete and the groundbreaking of the 110 Canal Street groundbreaking is imminent. I've included some photos from Craig Thomas, our new Urban Renewal Project Manager (taking over from James Errickson), of the progress at the bridge over the past few years. What a change!

Until next time...

Could Greater Lowell Feed Itself?

There is a lot of interest in sustainability, local agriculture, and permaculture these days. I had a discussion with a friend tonight: Could Greater Lowell grow its own food? It's sort of an artificial question as the area that comprises Greater Lowell is physically quite small - much smaller than you'd really want to count as hinterlands, but I'm always up for a little number crunching, so here's my (completely non-scientific) stab at it:

How many people in Greater Lowell and how much land?

This was by far the easiest part, and the only part with good, hard numbers. Wikipedia provides this data for recent years. Now, of course, much of the land is already built on and much of it is probably non-arable. Back to that later.

Municipality	Land area, in square miles	Population
Lowell	13.8	106519
Chelmsford	22.7	33802
Dracut	20.9	29457
Tewksbury	20.7	28961
Tyngsboro	16.9	11292
Billerica	25.9	40243
Westford	30.6	21951
Dunstable	16.6	3179

Total Population: 275,404
Total Land (In acres [1 square mile=640 acres]):107,584. This works out to be a circle with a radius of about 7 miles. Again, compare to the concept of the 100-mile diet - a circle of over 20 million acres! Again, the Lowell Food Security Coalition seems to be looking at a 30-mile radius, and their goal doesn't seem to be total self-sufficiency.

How much land does it take to feed a person?

This was a lot harder as the answer is heavily dependent on numerous factors. One major factor of course is the type of diet a person eats. Beef, for example, takes a huge amount of land to raise compared to chickens compared to a vegetarian diet. That said, grazing animals can take advantage of land that vegetable farming cannot, so again, not that simple.

So, after spending some time on Google, I came across a Cornell study from the last five years that figured a series of diets using foods local to New York and how much land they would take. New York is at our latitude and has similar soil and rainfall numbers, so I figure it's a fair starting point. As I really only read this person's analysis (Can New York State Feed Itself?), it is not clear on how intensive the farming here discussed is - or how sustainable the practices are. Clearly, if the numbers don't factor in crop rotation or heavy use of chemical fertilizers and pesticides, more land would be needed to replenish the exhausted land over time. Either way, the studies for many diets came out between about half an acre and an acre per person. These numbers appear throughout many estimates on traditional agricultural methods I found online, so let's split the difference and say .75 acres will feed a person a reasonable and sustainable diet.

So how many people will that feed? How much land is there per person?


107,584 acres will feed 80,688 people, or under 1/3 of Greater Lowell. Remove Dunstable from the equation and a net 5,000 more would go hungry.


Not great numbers.


Now, we could all eat if we could sustainably eat on .39 acres of land a head. Of course, we don't have houses in this model yet. Let's all live at the average population density of Lowell: 7,500 people per square mile. That's 36.7 square miles given over to housing. Add in a few roads, schools, businesses and other non-agricultural uses ... call if 50 square miles, and that seems low. Remember that we should be feeding people out of their own yards when possible though and the 50 seems more fair. That's 32,000 acres taken off of potential food production either way.


Now we need to feed 275,404 people on .27 acres each. Would it be possible in any situation? Well, potatoes can produce somewhere in the neighborhood of ten million calories per acre (Google around - I saw estimates from six to 17 million!). So, on a quarter acre that's about 2.5 million calories / 365 days =  6,849 calories per day per acre. A person really only needs 2,500. So, if you could really live on just potatoes, and could grow them in the same soil year after year, it'd be no problem at all. My guess is that on any realistic diet it would be quite difficult for us to grow enough varied foods to feed ourselves. Probably impossible in reality.


How much food do we even produce today?


Well, according to the Northern Middlesex Council of Governments, there are under 6,500 acres listed as agricultural today in the seven towns I used (they also track Pepperell while I did not). Assuming that this farmland was split up in a way that represented complete diets instead of a heavy emphasis on say, dairy, and was always producing all the time, at half an acre required to feed a person, that's a mere 13,000 people fed.




I guess the answer is we have a long, long way to go if we wanted to be self-sufficient for food as a region. Again, the region we're talking about here is very artificially small. Even still, more carefully and scientifically gathered numbers are probably even worse: If the Cornell study said that the 35 million acres in New York State were not arable enough to feed 19 million New Yorkers, than the 6.7 million acres of land in Massachusetts couldn't possibly feed 6.5 million Bay Staters. The 275,000 Greater Lowellians - a densely urbanized area - have zero chance under any current farming model of feeding us on 100,000 acres.


I know this was sloppy - Thoughts?

Photo Tour - Lowell City Hall

As I've mentioned before, back in my grade school days, I went to the Academy of Notre Dame in Tyngsboro.  The building was already nearly 70 years old, and even as a young child, I was fascinated by the architectural detail of the mid-20s Collegiate Gothic building. The floors were marble, the granite entranceway lead to a grand cast-iron staircase; the ceilings were 15 feet high. There were huge oak windows, massive transoms, push-button light-switches, and opulent entertaining rooms. The building had gone through a host of renovations, leaving clues of prior uses in certain rooms. My first-grade classroom was once a chapel; the spaces for the statues were still there. My 7th grade classroom had five doors - from when it was a series of small bedrooms and closets for live-in nuns.

Even in its old age, it was a beautiful structure - built with pride and intended to instill that pride in those who were students there (originally boarding students actually). I used to love exploring whenever I could - it would take hours to find every nook and cranny and there were a lot of doors that were always locked with those old skeleton keys. I managed to sneak up into the attic one night - not really much up there. Years later, I'd learn that there used to be a massive bell-tower above that, even in the 90s long gone. I never snuck into the tunnels to the outbuildings, but I knew where they were. A lot of my interest in architecture and urban exploration can certainly be traced to my nine years in that massive old school.

There was one other building I saw frequently that I was that impressed by - Lowell City Hall. Even though I was quite used to the sight of the building and had been inside it for various things over the years, I had never really taken a good look around. Recently, I attended the special meeting regarding late-night downtown disorder. Even though I actually didn't get any closer to the chamber than the hallway, I was really amazed at how detailed the council chamber was - I'd never bothered going to a meeting there before! This is clearly a building designed to instill pride in the citizenry - and they just don't make them like they used to. I contacted fellow Lowell Historical Society board member and city Historic Board employee Kim Zunino, looking for some sort of photo documentation of the building and a history. I got something far better - a guided tour! So, on a beautifully sunny and warm day in March, I snuck off for a few hours to look around from the cellar to the clocktower.

More after the jump.

Tanner Street Economic Development Plan

Got an email about an interesting community workshop coming up in a few weeks:

The first Community Workshop for the Tanner Street District Economic Development Plan is scheduled for Monday, January 23, 2012 at 6:00PM at the LRTA Building - 100 Hale Street.  Click here for the meeting flyer.  All are welcome!!

More information here: http://www.lowellma.gov/depts/dpd/TannerStreet/TSEDP

The Tanner Street corridor is a great opportunity for Lowell to do some very interesting work; hope to see you there!

Lowell Cultural Resources Inventory

A crosspost from the Lowell Historical Society blog at http://www.lowellhistoricalsociety.org/blog/2011/12/23/lowell-cultural-resources-inventory/:

From Lowell Historical Society board member and Director of UMass Lowell’s Center for Lowell History Martha Mayo:

The first batch of Lowell Cultural Inventory Reports of Buildings in Downtown Lowell [369] are available on the UML Digital Commons site. They can be viewed here. They can be viewed here –http://digitalscholarship.uml.edu/cri.

Please share this effort was part of an Mass Bureau of Library Council Grant for digital preservation. Please share with others interested in Lowell History through email, blogs, facebook, and other social media.