Gensets for Critical Operations

April 6, 2013

Allan Prosser, director of sales for MTU Onsite Energy, points out that there are two reasons to have onsite power generation and backup power.

“One is from an economic sense-obviously if you lose power, there’s an economic equation and risk mitigation,” he says. “The other one is where it’s legally required, such as in a hospital, an office building with elevators, or a wastewater treatment plant.”

Bill Clary, the managing director for Miratech, says while the obvious reason for backup power is grid failure, “the other issues we keep running into are power availability and power quality,” he says.

“When you have situations where there are brownouts or the power quality is really poor, like when the voltage is unsteady for any sort of critical electronic equipment-computers as well as a lot of hospital equipment-then you have to have the backup power to stabilize the power supply to the office building.”

While the need for onsite power is becoming less of a question for many facilities, the issue then becomes: what type of fuel should one seek for a generator set?

Over the years, Harlan Martin has witnessed a progression in the market for generator sets and the fuel that drives them. Martin Machinery-with locations in Missouri and Pennsylvania-started in 1976 as a rebuilder of used generators for the standby market. After acquiring D-OEM (Distributor Original Equipment Manufacturer) status with Cummins in 1981, the company tapped into a growing market demand for new generators. The company’s generators range from 20 kW to 2,800 kW.

“In the last 10 years, our market has shifted more toward the green energy,” says Martin, the company founder. He adds that 80% of demand for his company’s products is related to recovering methane gas from digesters on landfills or old coal mines to produce onsite energy 24/7.

Dairy farms are the primary clients for the methane gas production, Martin says.

“They have a lot of cow manure that gets pumped into the digester and comes out the other end in 21 days. There are several benefits: first of all, the bacteria works in there to keep that slurry a steady 100 degrees Fahrenheit by using the heat from the same engine that’s running all of the methane, and that bacteria is working to produce methane gas.

“We capture that, run it into the carburetor of the engine, produce electricity to offset what they have to buy for the farm, and, in most cases, the farms can sell electricity to the utility.”

Another major client is landfills, where decaying garbage is producing methane.

“The EPA is increasingly requiring these landfills to put wells in and draw the gas and flare it if you do nothing else, because if you don’t do that, this gas tends to migrate and it can go down in to drainage ditches and even get into people’s houses. Instead of flaring that gas, you may as well run an engine that produces electricity.”

While landfills usually cannot benefit from the heat from the engine as do the digesters, they can produce electricity, Martin points out. Abandoned coal mines and shaft mines are another source of methane.

“They can put a negative pressure on those and harvest methane out of those old coal mines,” says Martin.

The other 20% of Martin Machinery’s business is for standby units-both diesel and natural gas.

“Natural gas is used for Combined Heat and Power [CHP] units,” says Martin. “It’s for facilities where they use natural gas to run the engines to produce electricity. They might in some cases be parallel to the utility and sometimes be buying power from the utility and sometimes be selling power to the utility.”

The heat from the engine and the exhaust is used to produce hot water or steam for laundry facilities, car washes, or food processing plants where there is a significant need for hot water, says Martin.

“Instead of just burning off the natural gas in a boiler to make hot water or steam, they burn it in an engine to make electricity and hot water and/or steam,” he adds.

Yet there are applications in which Martin objects to natural gas generators being used.

“Over the years, we have serviced generators in hospitals and what I would call critical applications that were natural gas-fueled,” he says.

While Martin’s company will provide a natural gas-powered generator to meet a client’s specifications, he will also write a cover letter on a request for a quote advising against it.

“I’d say for emergency standby use, you should not be dependent on an external utility,” he says. “The same reason the electrical utility may have failed-flooding, earthquake, sabotage, or war- may also cause the gas to fail. I don’t think you should have any critical load applications, such as a hospital depending on an external fuel source. But our objection doesn’t stop anybody from doing it.”

Martin says he considers diesel as more reliable for quick startup and quick load applications, and he believes diesel is capable of a quicker response to load changes.

“Diesel has an edge in reliability,” he says. “When we can influence it, we try to influence it for emergency standby.”

Martin points out that in recent years, the “with the dramatic shift in the price of fuel, the interest in natural gas has actually strengthened. I keep telling people if you’re talking about emergency use only, the difference is so insignificant. In general, for the same kilowatts-especially if you’re talking over 150 kW-it will cost you considerably more for the initial installation costs for natural gas than the diesel will cost. You won’t pay it off with just standby use. The difference in fuel costs is not worth it.”

Photo: Global Power
“I’d say for emergency standby use, you should not be dependent on an external utility.”

Twinsburg, OH, recently installed a new diesel-powered, 350-kW standby power system to back up fire, police, and other city departments. Previously, the city’s government center-constructed in 1977-depended on standby power from a 125-kW generator housed in a separate building. When the city upgraded its emergency power system, it became evident that the 35-year-old generator set was insufficient to supply power for the entire building during a power outage, nor did it work well with the facility’s modern UPS system. When the city would test its critical systems by going on standby power, some power quality problems would wipe out the electronic systems-thus the addition of the new generator setup from MTS Onsite Energy.

Another consideration was sound attenuation-the new generator set was located within 10 feet of the government center-closer than the previous one. To address that, the city also purchased an MTU Onsite Energy “Level 3″ enclosure to provide not only sound control, but weather protection as well. The enclosure is constructed of 14-gauge steel, and features 1.5 inches of polyether polyurethane sound-attenuating foam that meets UL standards for flame and heat resistance.

Brandon Kraemer, senior product manager for MTU Onsite Energy, says the company is working on the development of biofuel-natural gas with diesel combined-for a diesel engine.

“Diesel fuel is increasing in costs just like oil is increasing in costs and natural gas is relatively stable and decreasing in cost in the US because of the abundance and the reserves we have,” says Kraemer. “Diesel engines for the gensets today start on diesel fuel and as soon as the engine is operating, then they start bringing on natural gas fuel. It’s a less expensive fuel to run in these gensets without having an effect on performance.”

Paralleling is another approach now being taken up more with gensets due to the technological advances and the simplicity of the setup, Kraemer says.

“Multiple generator sets are combined in parallel and synchronized to each other and to the main bus so you can have the same amount of power that you would do with one big generator set,” he says.

“It adds to the fuel efficiency, the maintenance, and the redundancy advantages, because now you can always shut one down when you don’t need it,” adds Kraemer. “You have the redundancy in case one fails. You can run certain emergency loads on one.”

Natural gas has been the direction in which gensets are going in terms of fuel sources, points out Jim Kukla, marketing manager for Kohler Power Industrial Systems, adding that the company has offered natural gas-powered gensets for many for years.

The decrease in natural gas prices has increased the popularity of natural gas generator sets in the industry.

“Our industry focuses on capital costs and the payback of those capital costs,” says Kukla. “As natural gas prices come down, the payback on the capital costs between a diesel power generator set and a natural gas-powered generator set becomes closer.”

Also factored into consideration are EPA’s Tier 4 final regulations for diesel generators, the implementation of which will be phased in from the beginning of this year through 2015.

“It makes payback greater on natural gas because of the systems that have to be added to achieve Tier 4 final regulations on a diesel engine,” adds Kukla.

That adds a “major amount of cost” to a generator set to outfit it for non-emergency applications, he says.

Tier 4 emissions standards apply to non-emergency stationary engines. Generators classified as emergency standby are exempt from Tier 4 standards, but are limited in the amount of time they can be operated in a non-emergency situation such as testing or maintenance.

“When they decided on the emissions regulations for diesel and the natural gas power generator set, they made the ruling a little different for gaseous generators than they did for diesel,” says Kukla.

Diesel engines had to be certified from the original equipment manufacturer.

“In natural gas, they allow you to actually self-certify the generator set on site or field-certify it to be compliant with that standard,” says Kukla. “It gave a little bit more flexibility for manufacturers to when you add after-treatment to a gas engine, it has to be able to meet the standard, but we don’t have to do it from the factory. Things have progressed that are really making gaseous generator sets more favorable in the marketplace than diesel was in the past.”

Monitoring fuel usage and storage are different for diesel and natural gas.

“Pipeline natural gas comes out of the pipe-it’s easy, and it never spoils, whereas diesel has a tendency to go bad,” says Kukla. “Some of the biggest complaints you get as a generator manufacturer or any kind of standby equipment manufacturer is that the fuel goes bad.

Photo: MTU
There are two reasons for onsite power says MTU’s Prosser: budget and risk mitigation.

“You can pull fuel out of a tank, polish it, and put it back in the tank, and two to three weeks later it ends up in the same condition that it was before because of the bacteria in the fuel. You’re not cleaning the bacteria out of the fuel-you’re filtering it and putting it right back in.”

And although there may be additives coming on the market to stop fuel from going bad, “if you burn an additive, it goes into the atmosphere and you end up breathing it,” says Kukla.

APR Energy installs, operates, and maintains temporary power solutions on a turnkey basis for large-scale customers such as sovereign utilities in emerging markets or large international industrial operations. The company’s most recent addition to our its genset technology is the APR Energy Gas Power Module, which operates off of a four-stroke-cycle CAT G3516C low-emission gas engine packaged in a modular fashion for fast-track transportation and installation at a project site. The Gas Power Module’s advanced control system allows for automatic operation, initiated locally or remotely by a SCADA system.

“Onsite power generation or distributed generation is incredibly important to the global power generation market, especially for large national utilities,” points out Sarah Strickland, spokesperson for APR Energy. “Distributed generation such as this provides an efficient and secure method of delivering additional electricity at a local level and can also help improve the overall efficiency of the customer’s electrical system by supplying Reactive Power [MVARs].”

As the local demand increases, more power modules can deployed to augment the installed capacity onsite.

“Ultimately, upon the installation of a more permanent power plant or improved transmission line, the temporary power solution can be relocated or decommissioned,” says Strickland.

Typical decibel levels for gensets versus other sounds

Tecogen manufactures natural-gas-fueled, engine-driven, CHP products. For the company’s first 25 years, its cogeneration units were of the type not available during a power outage.

“If the lights would go out, they would go stone cold dead, and there would be no danger to the utility line that might be doing repairs,” says Bob Panora, president and Chief Operating Officer of Tecogen. “This was done to appease utilities.

“If you were building a machine for a big project, you could afford the safeties that were required,” he continues. “But you couldn’t afford to do that for small equipment like ours.”

In the early 2000s, there emerged a market demand for equipment that could run during a power outage on the level of that brought on by Hurricane Sandy. Tecogen turned to manufacturing inverter-based, engine-driven CHP units, rolling them out in 2008.

“Utilities accepted inverter-based as a more safe type of interface, particularly if they are certified to the UL standard,” says Panora.

To that end, Tecogen developed the InVerde Ultra 100 CHP Module. The InVerde Ultra 100 is a natural gas-fueled CHP module rated at 100-kW continuous electrical output, while simultaneously producing 6.7 therms per hour of hot water. When all the recoverable heat is used, the overall efficiency reaches 90%. The InVerde Ultra 100 module features a low-emissions natural gas engine, which drives a water-cooled permanent magnetic generator (PMG).

The Tecogen’s CHP systems’ technology generates electrical power along with thermal power recovered from the natural gas engine, says Panora. While thermal power is typically lost during electrical production (in the form of waste heat), captured and recycled thermal power can be used for heating processes (such as increasing indoor temperatures or heating water), which can result in reduced energy costs.

Panora says he believes while having a generator set is a large investment, “it has a payback associated with the energy savings as a cogeneration system; so, in my mind, it validated what we were trying to do in the early 2000s with this product-that there would be more of a market demand for having a power outage capability in the future because of all of the things that have happened with storms and the vulnerability of the grid.”

Panora points out that because a Tecogen’s system runs on natural gas, it requires no storage.

“It burns very cleanly and you get much lower emissions levels from an engine operating on natural gas as opposed to diesel or gasoline,” he says.

“The downside of natural gas not having storage is that you could project a scenario where the natural gas supply was interrupted and you wish you had a 1,000-gallon tank of fuel onsite,” says Panora. “People could do that with propane with our equipment, but typically they don’t. They just run on natural gas.”

Panora says the system is cost-efficient.

“Because our systems are run every day as a cogeneration system, they are typically watched very carefully in terms of the savings,” he says. “The customer is looking for the savings very closely: the gas bills every month, how much heat did they recover, how much electricity are they generating.

“Typically there’s not much decay in the efficiency of the machine. When the engine gets old, you replace it and then you move on. You don’t see a maladjusted system operating because people are watching it too closely. The energy they’re generating each year is $100,000 worth of electricity and hundreds of thousands of dollars of fuel. The numbers are very large, so you don’t miss them.”

Carl Caridi would agree. He’s the property manager for The Americana, a 290-unit co-op in Bayside, NY, that host three 100-kW Tecogen cogen units. The American was constructed in 1968, and the mechanical room equipment was aging. Additionally, there was a leak of No. 6 fuel oil in the 25,000-gallon oil tank outside below the ground outside in the grassy area of the property.

Photo: Cottage Hospital/Glenn Dubock
Critical facilities-like Santa Barbara’s Cottage Hospital-depend on the reliable backup provided by CHP and gensets.

“We saw that as an opportunity to start to think about making changes, knowing there were going to be laws coming up in the future regarding the use of oil and also concerns about the cost of oil and the cleanliness of oil,” says Caridi. “We decided to look into cleaner energies and more efficient energies. Cogen was brought to our attention by NYSERDA (New York State Energy Research and Development Authority) and through other avenues of communication.”

In New York City, new regulations require that existing boilers must switch from No. 6 oil to a low-sulfur version of the No. 4 heating oil, or to an equivalent cleaner fuel, by 2015. Newly installed boilers must burn a less-polluting grade, such as low-sulfur No. 2 oil, natural gas, or an equivalent low-emission fuel. Boilers not replaced by 2030 need to be modified to meet the new regulations. Caridi hired a company, Energy Concepts, to provide engineering input and, in 2008, made the decision to change out the two original boilers from 1958 and swap them out for seven gas-fired modular boilers that run on natural gas.

“We went from two boilers the size of Civil War submarines, to seven boilers the size of file cabinets,” says Caridi. He also swapped out one absorber unit for two more efficient absorber units.

“It took us two to three years to do this-soup to nuts-and we’re very happy we did it,” notes Caridi. “We’re experiencing significant savings in our energy usage. We’ve confirmed an energy reduction of 37% from NYSERDA, and we make 80 to 85% of our own electricity now with the cogen.

“We pay a little bit more money for gas because everything runs on natural gas now, we pay a lot less money for electricity, and we pay no money for oil,” he continues. “Our savings are anywhere from $20,000 to $30,000 a month from what we were paying before the project began.”

The co-op was offered the option of a black start feature.

“Should we have a power outage here in New York or in our Borough of Queens, the automatic transfer switch would allow us to switch over to the cogens,” says Caridi. “The cogens were designed to power up an elevator bank, common area lighting, and some important pumps and motor equipment in our mechanical rooms.”

The Americana does not need storage now for the natural gas fuel.

“We have three gas meters, including the original gas meter for the cooking stoves, so we’re always receiving gas in the building for the cooking stoves. We have a separate gas meter for our boilers and our cogens. It’s a constant flow. As long as we don’t have a gas leak in our pipe, we’re OK.”

Another consideration in choosing generator sets is addressing the emissions. Using onsite power generation often means being a “good neighbor,” not only in considering emissions, but sound as well. Universal Acoustic and Emissions Technologies provides acoustic and emissions treatment products for generator sets, primarily standby power applications. One such product is QuietShield, an acoustic product designed to silence the engine noise coming through the generator set.

The company has another line, GreenShield, an emissions product for gensets used to treat the emissions to remove harmful chemicals. In some cases, it might be an oxidation catalyst for the control of carbon monoxide, a diesel particulate filter, or a combination of both. Ron Jake, marketing manager, points out there are new regulations coming out on an ongoing basis that require modification of gensets; his company helps clients hit target requirements.

With respect to sound attenuation, “there might be a regulation or a requirement to want to be a good neighbor and have that genset be as quiet as possible,” says Jake. “They’ll give us their sound target-typically, it is 85 decibels or so, or someplace within so many feet of where that generator set is going to be located. Working from that target, we figure out how much noise reduction there needs to be, and we size a silencer appropriately for that reduction.”

In attenuating the sound of gensets, the primary concern is the insulation inside the enclosure, notes Chris Murray, director of business development for Soundown. One of the biggest challenges in the genset market is the tightening of noise requirements, especially for export, he notes.

“Being a good neighbor as far as the airborne noise surrounding the site is important if the genset is external to the building,” says Murray. “If it’s internal to the building-such as a cogen plant, it’s not being obtrusive to other operations in the building. As internal and external sets get more sophisticated, and lower noise and lower vibration levels are required, controlling those levels is probably the biggest challenge.”

Soundown offers noise and vibration engineering for a variety of markets, including generator sets, beginning with an analysis and design of quiet gensets, including specification of components for exhaust handling, the enclosure, and the isolators. The company also offers a full range of mountings from under 50 pounds per point, up to 50 tons per point.

“We can do generators as little as a few kilowatts, all the way up to gigantic multi-megawatt sets with isolation, and, in our engineering side, we can also specify components that make it come together as a completed system,” says Murray.

Hennig Enclosure Systems designs and manufactures enclosures for sound attenuation and weather that can be used with generator sets as well as fuel tanks.

“We manufacture a skin-tight variety up to reach in and walk-in,” says Greg Champion, vice president of sales and marketing, says of the enclosures. The company also manufactures a variety of fuel sensors that help end-users monitor the level of fuel in the tanks, which are used primarily for diesel.

Champion says the three most common fuels he sees being uses for generator sets are diesel, natural gas, and “dirty gas.”

“The most common we see are diesel-operated generators. The rule is if it has anything to do with life safety, as in hospitals or nursing homes, the genset for backup power has to be diesel,” he says of the type of generator sets required in specific applications. “It can’t be natural gas, because if there is an earthquake in California, that natural gas line might be ruptured.”

Natural gas-operated generators require no storage tank, as the natural gas line is plumbed to the genset. They are common at facilities where life safety is not an issue.

“The third we’re seeing more and more is “˜dirty gas’, the methane that comes off of landfills or a large dairy farm from the manure-no storage device needed,” says Champion.

Miratech Corporation provides catalysts, silencers, and controls for gensets. Clary notes three of the company’s technologies are attracting particular attention: diesel particulate filters, SCR (Selective Catalytic Reduction) catalysts and silencers and acoustic technology. The driving factors behind the demand for such products as offered by Miratech include regulations and nuisance compliance with neighbors, Clary says. End users include hospitals, data centers, and financial institutions-any facility requiring backup power with a need for acoustic and emissions control.

Clary says his company’s experience to date is that there has not been a great deal of attention paid to fuel consumption.

“It’s been more of a reliability issue,” he says. “If generator sets are being used in storm avoidance situations or for prime or peak shaving, it becomes much more important in which case they typically start looking at either a dual-fuel gas/diesel application or going to gas, because gas is so much cheaper than diesel right now.” 
About the Author

Carol Brzozowski

Carol Brzozowski specializes in topics related to resource management and technology.

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