BY BRIAN LIBBY
In the current January 7 edition of the Portland Business Journal, Lee Van Der Voo reports that the City of Gresham has found a way to power about 80 percent of its sewage treatment plant's electricity needs (currently about $500,000 per year) through a unique micro-hydro project involving outfall pipes.
This is a great example of both state-of-the-art alternative energy technology and green power at its most primative. Centuries ago the site of a riverside mill with a giant wheel generating power by the movement of the water current was ubiquitous. In fact, watermill technology dates back to ancient Greece.
The City of Gresham's sewage treatment plant, at 201st Avenue and Sandy Boulevard, treats sewage for 108,000 people and releases 13 million gallons of treated wastewater to the Columbia River each day. The water falls through a 48-inch pipe and down a slope to the river. Now the city is placing a turbine in the water path.
The project would cost $800,000, with half of the cost funded by a state Business Energy Tax Credit and a grant from Energy Trust of Oregon. So by spending about $400,000, the City of Gresham will reduce its power bill at the treatment plant from $500,000 to $100,000. In other words, a one-time expenditure of $400,000 will allow for $400,000 in annual savings: a one-year payback.
Once added to the pipe, the water turbine will have a peak energy generation capacity of about 50 kiloWatts. But that will be augmented by the plant's solar power, adding about 419 kiloWatts. That is not a gigantic amount of power, but 50 kiloWatts alone is enough to power about five single-family homes annually. Even so, given the open-and-shut case for the money it will save, the treatment-plant turbine is the latest of many reminders how, even as gas prices have stabilized, green power is an irresistible opportunity to save money.
The idea for the treatment-plant turbine, said Dave Rouse, the recently retired Gresham environmental services director, came from the Oregon Association of Clean Water Agencies, acting on the results of a 2008 study funded in part by the Energy Trust of Oregon on whether energy efficiency and renewable power sources could drive energy needs at wastewater plants. Some might say it's common sense that a turbine producing energy from 13 million gallons of falling water is a no-brainer, but it took the proof of the Energy Trust study to move Gresham to take action.
Of course, if this is such a good idea, it begs the question: what about all the other cities with sewage treatment plants. Every city has one. What about Portland's? Eugene's? Salem's? What about legislation stipulating this at all Oregon water treatment plants? It starts with one entity like Gresham taking the first step, but initiatives such as these ultimately only do real good if they are followed like falling dominoes. And it's not as if water falling from sewage treatment plants is the only falling water that could be harnessed for turbines. Last time I checked, Portland lies at the confluence of two rivers. Is it time to bring back the water mill at an unprecedented mass scale?
This story also reminded me of some interviews I recently conducted for Oregon Business magazine as part of their recent 30th anniversary issue, in which business leaders from all around the state were asked for their ideas about the next 30 years. One person whom I interviewed, Gerding Edlen Development president Mark Edlen, focused on alternative energy:
"The holy grail I think for us is trash to energy," he said. "Renewable energy is a foregone concludsion. Processing sewage will be a foregone conclusion, and turning that into potable water. The notion of taking our trash and not just recycling but taking it and converting it into energy at a city level or community level will be a foregone conclusion."
Related to the sewage water Gresham is using, Edlen also said of the next 30 years, "Water’s going to be bigger than energy. I think we will more and more think about how natural systems happen and how we can work with them instead of against them."
Not that it exactly relates to alternative energy, but Edlen also pointed out how such technical and ecological innovation more broadly helps establish the city as it competes with the rest of the world.
"I see us being a city and a state where we will be leaders in new ideas," he explained. "I think that’s coming out of the sense of community we’re creating here. It involves leadership in urban design, in alternative transportation, deep leadership in sustainability - and not in just the built environment and energy but manufacturing, agriculture, even apparel, for example. As I look down the road 30 years, we are positioned up and down the west coast as being an affordable alternative and with a rich sense of community and well positioned on the Pacific Rim...I think the opportunities are coming out of these intstitutions along with the thought leadership and innovation, creativity, and the way we’ve built."