Water treatment, water power
Note: The following document was published in August 2007 on the old TCLocal web site. It was circulated to City government and announced to local sustainability groups, but the web site as implemented at that time did not provide for publicly visible input. We are republishing the report now to allow the community to comment and to present these ideas to a broader audience.
[Prepared by Jon Bosak, with input and discussion from TCLocal.]
To: Mayor and Common Council, City of Ithaca; Board of Public Works, City of Ithaca
CC: Superintendent of Public Works, City of Ithaca
From: TCLocal (Jon Bosak, Chair)
Date: 5 August 2007
Revised TCLocal Statement on the City of Ithaca Water Plant Decision
The members of TCLocal believe that in the future, energy will become increasingly expensive. At some point in the next 20 years, geological limits on the rate at which fossil fuels can be extracted will combine with global population growth and development to create an ever-widening gap between global supply and demand, causing the price of energy to rise continuously until some completely new source of energy is discovered. We also believe that climate change caused by the emission of greenhouse gases such as CO2 is a real threat, to which we must respond by using less energy or by getting our energy from a clean source. We conclude that policy decisions should prefer choices that would preserve current function while using as little dirty energy as possible.
In March 2007, TCLocal submitted an opinion to the City of Ithaca Board of Public Works on the City Water Treatment Plant decision. That opinion favored the option of rebuilding the existing water treatment plant over the option of becoming a customer of an expanded Bolton Point plant. We recommended the Rebuild option because of the savings in electrical use, greater self-sufficiency, and greater system redundancy (three local water source and treatment plants rather than two). The fact that two-thirds of the City’s water “never sees a pump” but rather flows out to users by gravity made this an easy call; at Bolton Point, all the water has to be pumped, and adding the City’s demand would roughly double the amount of electricity consumed and CO2 produced there.
After submitting TCLocal’s recommendation, we were asked to reconsider our position based on data regarding chemical use. Treating the relatively turbid water of Six Mile Creek requires a substantially greater chemical input (chiefly to precipitate suspended matter) than is required to treat the much clearer water of Lake Cayuga, raising questions about the future economics and energy use of chemicals.
Hydropower aspects of the Rebuild option
In the process of reconsidering our previous recommendation, TCLocal became aware of a hydropower plan studied in the 1980s that would use the water now flowing through Six Mile Creek to generate electricity — enough to easily provide for the electrical needs of the rebuilt water treatment plant with some left over for other City uses. Substituting this clean, renewable energy for some of what the City now buys from NYSEG would simultaneously make the City’s water supply independent of fluctuations in the price of electricity while reducing the total CO2 emissions due to City of Ithaca Operations. We calculate that this reduction would be equal to 60 percent of the CO2 reduction the City has committed to achieving by 2020 under the Local Action Plan.
The 1989 Van Natta’s Dam proposal accompanying this statement provides further detail on the power plant option. (Note that the attachment, vannatta.pdf, contains just a small portion of the many documents related to this plan that are still on file with the City.)
Based on careful study at the time, and with due regard to environmental concerns (which were found to be almost nonexistent, the dam being located at the lowest part of the watershed that is considered environmentally sensitive), it was determined in 1989 that rehabilitation of the old turbine facilities at Van Natta’s Dam would enable the flow of water past the existing dam to generate a calculated 1.42 million kWh per year. If we generously allow for 5 percent downtime, this nets out to 1.35 million kWh per year.
In 2006, the last year for which figures are available, the City water treatment plant used 634,500 kWh of electricity, or about 47 percent of the total annual output of the proposed power plant. Thus, rehabilitation of the Van Natta’s Dam powerhouse as described in the 1989 proposal would not only make the City’s existing water treatment system (aside from chemical inputs) completely energy-independent, but it would also make over 700,000 kWh of virtually free, zero-emission energy available every year for other purposes. A rebuilt water treatment plant might or might not use more electricity than the existing one; there still seems to be some uncertainty about this. But even under the most pessimistic estimate, which projects an additional 45 kW average continuous demand, the electrical needs of the rebuilt water treatment plant (about 1.03 million kWh per year) would still be comfortably accommodated by the projected output of the power plant.
At a current rate of 10 cents per kWh, a power plant at Van Natta’s Dam would yield a savings to the City of about $135,000 annually, which is certain to increase substantially as electricity becomes more expensive. Equally important, the CO2 contribution due to use of electricity in City Operations (which would otherwise be supplied almost entirely by burning coal at the Milliken plant) would be reduced by about 1,300 metric tons a year, or 60 percent of the target reduction of 2,180 tons of CO2 specified in the Local Action Plan to Reduce Greenhouse Gas Emissions for City of Ithaca Government Operations adopted by the City in 2006.
While there is little doubt that the cost of chemicals will rise in the future, there is no reason to assume that their price will, over the long run, rise any faster than the price of electricity, so the anticipated run-up in savings on electricity can be considered a hedge against increases in the cost of chemicals. And if we are considering a doomsday scenario where the national infrastructure fails entirely, we think it better to have a guaranteed supply of gravity-fed water that may need to be boiled for some relatively small percentage of uses rather than to have cleaner water sitting in the lake with no way to distribute it.
Rehabilitating Van Natta’s Dam will obviously cost much more now than the projected one million dollars it would have cost in 1989; a safe guess in advance of an expert reappraisal might be in the neighborhood of three million dollars. If electricity prices were to remain what they are now for the next 25 years, that’s about how long it would take for the project to pay for itself. With proper care, the plant would then continue to pay off for centuries by producing electrical power of increasing value, so 25 years is not a bad payoff for this essential piece of civic infrastructure; but actually, it’s exceedingly unlikely that the cost of electricity will remain flat over that length of time. The likelihood is exactly the opposite, and the odds are that the project would pay for itself more quickly.
It seems to us that the hydropower possibilities put the Rebuild option for the water treatment plant in a new light. The need to develop as many local sources of renewable energy as possible and the imperative to reduce our production of greenhouse gases are excellent reasons — reasons we understand much better now than we did back in 1989 — to seriously consider the Van Natta’s Dam rehabilitation plan on its own merits, independent of the water treatment plant. But if the Van Natta’s Dam plan were to be implemented, the Creek maintenance needed to support a rebuilt water treatment plant would come for free, because the expensive part — the system of dams — would be the same for both the drinking water supply and the power supply. So it’s our conclusion that the Rebuild option should not be considered in isolation but rather as a way to enable the construction of a new hydropower plant using the same basic infrastructure as the water treatment plant.
Environmental concerns: the big picture
Such a plan would, of course, be subject to the same aesthetic concerns that have been expressed regarding the Rebuild option as currently proposed. As people who are convinced that we and our descendants will have to make do with what we can find just a short distance from where we live, the members of TCLocal are as anxious as any City residents to preserve the beauty of the Six Mile Creek Natural Area. But it seems clear from the description of impacts in the current Draft Scoping Document (attached as draft-scope.pdf) that these aesthetic concerns have been overstated. Most if not all of the maintenance needed to keep the dams operational will be required for safety reasons anyway, even if the City abandons its water plant and does nothing with its hydropower potential; compare the “Impact on Aesthetic Resources” of rebuilding the water plant (page 12 of the Scoping Document) with the virtually identical “Impact on Aesthetic Resources” of not rebuilding the water plant (page 13 of the Scoping Document).
It’s also clear from the Scoping Document that the environmental impact of the construction needed for the Bolton Point option would be at least as great as the impact of the construction needed to rebuild the existing water treatment plant. In fact, given that maintenance of the Six Mile Creek system will need to be carried out in any case, the net environmental impact of the Bolton Point option appears to be considerably greater than the net environmental impact of the Rebuild option.
We believe that the minimal impact of maintaining Six Mile Creek as a critical part of our civic infrastructure poses no meaningful threat to enjoyment of this resource and is a small price to pay given the urgent need for energy independence and a reduction in greenhouse gas emissions. The integrity of the Six Mile Creek Natural Area is threatened much more by climate change caused by GHG emissions than by any carefully executed maintenance of the City water system that has shaped the beauty of the watershed for the last century.
It is our considered opinion, based on the information currently available and attached to this statement, that the hydropower potential of a rebuilt City water treatment plant makes the Rebuild option a clear long-term winner in terms of finances, environmental impact, GHG reduction, and energy independence. We urge the City to carefully consider the combined benefits of a rebuilt water treatment plant and a rehabilitated power plant before it throws away a valuable piece of our local infrastructure and a once-in-a-century chance to do the right thing for our community and the larger world.
Van Natta Dam Water Power Rehabilitation Project
Draft Scope Document