Pictures from my January, 1993 tour of the plant
In 1969, Cincinnati Gas & Electric, Dayton Power and Light, and Columbus and Southern Ohio Electric Company decided to build a nuclear power plant at Moscow, Ohio along the Ohio River. The plant would generate 810 MW of power, employ 20 full time workers and cost 240 million dollars. CG&E was in charge of managing construction.
Construction began in 1972, and from the start was plagued by management and quality problems. CG&E used scrap steel instead of new and understaffed construction so severely that 70% of pipe welds on the site were later found to be deficient or not inspected. When workers threatened to blow the whistle, CG&E hired Thomas Applegate, a PI, to target the employees with trumped up false timecard charges. Applegate soon learned of the construction problems and took his concerns to management. Many construction workers were making plans to move their families at least 100 miles away from the plant prior to its start-up date!
Applegate was terminated, and sought help from the Institute for Policy Studies in Washington DC. Applegate was protected under the 1974 Eneregy Reorganization Law that created the Nuclear Regulatory Agency and also offers legal protections to whistleblowers. Under the light of publicity, it was revealed that the Nuclear Regulatory Commission had been destroying documents that showed that welds had not been inspected at Zimmer. James Cumming's, the NRC's chief inspector and auditor, was fired.
In November, 1981, the NRC fined the utility $200,000 for the first of an eventual 15,000 violations it found on the site. CG&E could not resolve the issues, and in November, 1982 the NRC halted all work at the site. After spending $1.6 billion, and while owing $500,000 per day in interest charges, the Zimmer Nuclear Plant was shut down.
In February, 1984, the utilities decided to convert the plant to a coal fired facility. The power output was increased from 810 to 1300 Megawatts by adding a second generator to be powered by a single, large boiler. Hundreds of additional acres were purchased to provide a landfill for the ash, the pile of which will become the highest geographical point in Southern Ohio when the plant reaches the end of its design life in 2030. Although CG&E had purchased a nuclear core, it had not taken delivery of it so no nuclear material ever entered the Zimmer site.
On January 1, 1991, after spending 3.6 billion dollars, electricity was generated for the first time. By choosing coal over nuclear, there were trade-offs.
One billion dollars was spent on the scrubber system to partially remove sulfuric and nitrous acids; but the tiny town of Moscow Ohio can be a miserable place to live when atmospheric conditions send the smoke plume over the town, and scrubbers don't remove the green house gas carbon dioxide.
Had the plant remained a nuclear facility, the entire waste produced over its lifetime, although highly radioactive, would have consumed no more volume than a high school gymnasium, and there would have been zero emissions of greenhouse gasses. There is no radiation on the site because the utility never took delivery of the nuclear core. The containment building, with its 12 foot thick concrete walls and hundreds of millions of dollars worth of equipment, was written off and remains on the site to this day.
In 1992 the Zimmer plant set a world's record for the most coal burned in a year by a single generating unit, consuming 4 million tons of coal. American Electric Power, the corporate owner of CG&E, decided that Zimmer would be its last generating plant and laid off its engineering and design staff. With the continued decline of the industrial economy in Ohio, electricity demand has been flat through 2006 and no new plants are needed.
Zimmer is now run by American Electric Power the corporate owner of the original Ohio utilities that began the project 35 years ago. The fact is, AEP produces electricity at low cost with coal, and defends its use vigorously. Coal has a lot of environmental problems, but not having cheap electricity throughout the Midwest would cause a lot of social problems. Also, with its advanced scrubber system Zimmer can burn high-sulfer Ohio coal, maintaining mining jobs desperately needed in southern Ohio.
On September 29, 2005, American Electric Power hired General Electric and Bechtel to design an Integrated Gasification Combined Cycle clean coal plant in the 600 MW range. If it works, the IGCC plant will turn coal into a synthetic gas that eliminates most of the sulfur dioxide, nitrogen oxides, mercury, and other emissions before the gas is combusted to produce steam. Critics argue that this "future promise" is being used as a shield to deflect emissions regulation tightening for existing plants. Like General Motors promising hydrogen powered vehicles in the "near future" while cranking out increasing numbers of SUV's, the utility industry will continue to burn coal the old fashioned way for decades to come.
Pictures from my Zimmer Plant Tour
As a graduate student in the department of electrical engineering at Ohio State, I had an opportunity to tour the plant in January, 1993. Click the photos to enlarge.
New! Babcock & Wilcox once-through super-critical 1300 MW boiler cross section, Zimmer Power Plant, 1990. This was only the ninth boiler that B&W had built on this scale.
Control Panel for Coal Pulverizer #14. In today's plants, the coal is pulverized and burned as a dust. The future "clean coal" plants will actually gassify and purify the coal, greatly reducing pollution. Coal has terrible things in it, like mercury and sulfur, that have a lot of down sides for our health. AEP does the best it can. For example, the coal is sprayed with a rubber compound so dust won't blow off the piles. The ash is treated so it has a solid, rocky form that won't blow dust. But still, coal is coal...Circuit Diagram for the main power feeds. The two circles at the top left are the two giant generators. The rest represents the switchyard for connecting to the grid. To start the plant, the generators must be spun up and synchronized to the standard 60 Hz waveform. When the system falls apart, which it does from time to time, you have to choose one plant to start and then successively sync and add generators to the grid. Looking behind the control panels. No wonder these plants cost a fortune. I didn't take a picture of it, but the main control panel showed the plant generating 1400 MW and putting 1300 MW on the grid. The crushers, blowers, conveyors, pumps and scrubbers ate up the 100 MW difference!One of the two generators. The picture shows the exciter (front box), generator, and two coupled steam turbines driving it. The generator produces 729,500 kw (978,275 horsepower). It puts out 20,000 amps at 22,000 volts, and is cooled by hydrogen gas flowing through its windings. It turns at 1800 rpm and was remarkably quiet. Hydrogen gas is used to cool the generators because of its efficiency. You couldn't pick a more flammable coolant, however, so it just adds to the sense of danger you feel standing next to this monster.Turbine side view. The turbine actually consisted of two coupled turbines. This generator was ordered in 1973, but didn't produce electricity until 1991 due to the failure to complete the nuclear plant for which it was intended. The nameplate for this generator appears at the top of the page.Here is the coupling between the two steam turbines. The floor of the generator room actually bisects the center line of the rotating machinery, for easier access I guess. Let me say that the generator hall was gleaming. They mixed ash into the floor cement to make a nice, polished surface. AEP tries hard to find ways to use its ash, most recently it is going into wallboard. Here is the other generator. It is arranged at a ninety degree angle to the first one, so the generator hall is like a big letter "L". This part of the hall was added after they switched to coal in 1984. They had to pass pipes through the completed walls of the abandoned containment building, so they used diamond coated wires to slowly saw through the 12 foot thick concrete walls. That containment building is going to last a thousand years...Another view. The generator hall was spotless and gleaming. The floor was actually made out of coal ash that had been baked into a ceramic at high temperature, and then polished after applying to the floor! All the ash from the Zimmer plant is treated in this manner so that it is more like chunks of brick when they ship it to the landfill. Obviously, AEP is eager to find a commercial use for all its ash...These three phase conductors carry 20,000 amps at 22,000 volts to the step-up transformer outside. A gas, Sodium Hexafluoride, serves as both a coolant for the conductors in the pipes as well as a high-dielectric insulator that is hard to break down under arcing conditions.This transformer steps up the voltage to 765,000 volts for transmission out of the plant. 765 KV is the highest transmission voltage used in the United States. The entire output of the plant , all 1300 MW, can be carried by one 765KV transmission line carrying about 1000 amps per phase. It can take over a year from placing an order to receiving one of this giant units. These 765 KV transformers take a long time to make, and turning them on for the first time is a nerve wracking moment. Any kind of ground fault can be explosively damaging and take a long time and a lot of money to fix.Another view. I think the large tank contains extra oil for the transformer. Oil serves as a coolant and has a high breakdown voltage. Unfortunately, it is flammable which makes transformers failures into infernos sometimes.High voltage conductors heading for the switchyard.In 2005, Zimmer produced 10 million megawatt-hours of energy which generated $850 million dollars in revenue. This ranked Zimmer the 89th largest power producing plant in the nation that year.Another view of the switchyard. The red pylons on the left support the coal conveyors.The scrubber system is a massive chemical plant arrayed around the base of the smoke stack. The scrubbers remove nitrous and sulfuric acids from the exhaust, thus reducing acid rain in the Northeast.The scrubber system cost one billion dollars, and this impressive engineering model is a testament to the complexity of the system.Standing atop the boiler building, looking at the path the exhaust takes to the smoke stack. The scrubbers are arrayed in the foreground as well as around the base of the stack. Those silos on the left hold lime, which combines with the acids to produce solids which are landfilled instead of released to the atmosphere. Scrubbing the exhaust doesn't eliminate any waste, just changes its form from gas to solid.These conveyors deliver coal to the crushers. AEP is a pioneer in coal conveying. Some plants in the AEP system were connected directly to mines using miles of conveyor belts. AEP even owns its own riverboat transport company to keep the coal flowing. They pile up something like 90 days supply on the grounds in case of flooding on the river or a coal miner strike.Coal conveyors, and part of the switch yard. When starting up, the plant can consume up to 100 MW of power. This plant consumes 7% of the power it produces just to operate itself! I believe they had some large natural gas generators to help bootstrap the plant on start-up if the grid was down.Coal conveyors. The coal arrived by barge on the Ohio River and was piled up at the end of the plant. It was then conveyed up to one of fourteen coal crushers. The coal is burned in a powdered form in the boiler so it will combust more efficiently. Because of the scrubbers, this plant can, and does, burn high sulfur ******* Ohio coal.The ash waste is trucked out to a landfill several miles away. This landfill will be the highest land formation in southern Ohio when the plant's service life is over. The plant's service life is determined by the capacity of the ash landfill.I believe this was part of the water treatment for the boiler. If the boiler water has any minerals in it, they will adhere to the boiler tubes and cause hot spots, eventually leading to tube failure. Also, foaming in the boiler can be dangerous. Specially treated water is a must.The towering smokestack. Stacks are tall to maximize the draft, and to get the exhaust plume high enough so that it will travel far away from the surrounding area and disperse. Unfortunately for the citizens of Moscow, Ohio next door to the plant, this doesn't always happen depending on the weather.Looking up at the cooling tower. Cooling towers cool the exhaust water from the turbines by letting it waterfall down the inside while air rises through the middle. Their classic hyperbolic shape is optimal for maximizing draft. Basically, it is better to dump waste heat into the atmosphere than into the Ohio River.