President Obama’s Clean Power Plan has generated the expected level of outrage from the usual suspects, and among the emerging angles is this one: the Clean Power Plan is a top-down approach that removes the personal responsibility factor from the carbon emissions equation. Nanny state! Well, fear no more. A research team has come up with a new carbon capture system that could potentially involve me, you, and anyone else who is hooked up to a municipal wastewater treatment plant.
That covers a lot of ground, so let’s see what’s up.
Wastewater Treatment & The Clean Power Plan
The famous 20th century bank robber Willie Sutton once famously said that he robbed banks because that’s where they kept the money.
Similarly, the Clean Power Plan focuses on power plants because, collectively, that is the single largest source of carbon emissions in the US.
Outside of the Clean Power Plan, the US Environmental Protection Agency has identified several other sectors for targeting carbon reduction, and the wastewater treatment/water supply sector is one.
According to the EPA, collectively, these systems account for 3–4% of energy use in the US, accounting for about 45 million tons of greenhouse gases yearly.
The picture really comes into focus on the local level, where wastewater/water systems can chew through 30–40% of total energy consumption:
Because these services are so energy intensive, they provide an excellent opportunity for efficiency, savings, and reductions in greenhouse gas (GHG) emissions. Improved energy efficiency is also an important component of a utility’s overall management and will help ensure the long-term sustainability of our Nation’s water and wastewater infrastructure.
In terms of the Clean Power Plan, when states start figuring out their compliance strategy, some may find that they can get a lot of mileage out of by shaving down the amount of energy used by local wastewater treatment plants.
A New Method For Carbon Capture At Wastewater Treatment Plants
Where were we? Oh, right, the new carbon capture system. It’s coming to us from the University of Colorado–Boulder under the name MECC, short for Microbial Electrolytic Carbon Capture.
MECC actually provides a threefer: it reduces the energy needed to run a wastewater treatment plant, it captures carbon emissions from the plant, and it generates renewable energy.
Actually, make that a fourfer. The new system also cuts the cost — and energy consumption — of transportation and storage involved with conventional carbon capture systems.
… And fifth, the process also generates usable solid byproducts.
Wait, a sixth thing has popped up! To get your head around this one, keep in mind that many US treatment plants are located along coasts:
The study may also have positive long-term implications for the world’s oceans. Approximately 25 percent of CO2 emissions are subsequently absorbed by the sea, which lowers pH, alters ocean chemistry and hence threatens marine organisms, especially coral reefs and shellfish. Dissolved carbonates and bicarbonates produced via MECC, however, could act to chemically counter these effects if added to the ocean.
Here’s the rundown from CU–Boulder:
…MECC uses the natural conductivity of saline wastewater to facilitate an electrochemical reaction that is designed to absorb CO2 from both the water and the air. The process transforms CO2 into stable mineral carbonates and bicarbonates that can be used as raw materials by the construction industry, used as a chemical buffer in the wastewater treatment cycle itself or used to counter acidity downstream from the process such as in the ocean.
The renewable energy factor kicks in as a byproduct in the form of hydrogen gas, which the research team anticipates will be used in hydrogen fuel cells.
Wasn’t I just saying that renewable sources could help fuel cells compete with batteries in the future electric vehicle market?
Although the research is still in the proof-of-concept stage, the team anticipates that MECC could also be used to treat industrial wastewater on site.
That’s probably code for fracking wastewater, and to that I say: fine.
The final version of the Clean Power Plan, released on August 3, does include a new measure aimed at promoting renewable energy over natural gas. However, natural gas will most likely continue to be a go-to replacement fuel for coal in the foreseeable future, and that means fracking wastewater issues will need to be addressed.
Onwards & Upwards For Wastewater Treatment Plants
For the record, US treatment plants already have a head start on the Clean Power Plan.
The photo accompanying this article shows the digester “eggs” at the massive Newtown Creek treatment plant in New York City, which reclaim methane from decomposing waste to use as fuel.
Biogas capture is becoming common at municipal wastewater systems. It is typically used on site but, back in 2010, the city of San Antonio became first in the US to sell its biogas offsite to the commercial grid.
A couple of years ago, New York also started up a food waste recycling program to piggyback on the Newtown Creek facility, which if successful would cut carbon emissions related to solid waste disposal.
Since municipal wastewater is rich in nutrients, it could also be used to grow algae for renewable biofuel.
As for hydrogen generation, aside from UC–Boulder, a few years ago, UC–Denver announced a system that uses reclaimed hydrogen to run a desalination system in tandem with wastewater treatment.
If you have a favorite wastewater story that could assist compliance with the Clean Power Plan, feel free to share in the comment thread.
Photo Credit (screenshot): Newtown Creek digester eggs courtesy of NYC DEP.
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