A look at electric horizontal grinders

This look at electric horizontal grinders is not intended to endorse or promote any particular product or manufacturer. Attempts were made to include input from all known North American manufacturers of horizontal grinders.

Increasing government regulations – particularly federal emission standards – and a lower operating cost compared to diesel powered machines, are driving demand for electric horizontal grinders, manufacturers say.

“We are definitely seeing an increase in the popularity in electric machines, and most of that is driven by cost of operation and cost of ownership,” said Jay Van Roekel, strategic business unit manager at Vermeer Corp., of Pella, Iowa.

Jason Morey, sales and marketing manager for Bandit Industries Inc., Remus, Mich., said he has seen a consistent demand for electric grinders in recent years.

“There hasn’t necessarily been a large increase, but that may change a little with this being the last year that we can do Tier 2 diesel engines above 750 horsepower,” Morey said. “Once the Tier 4 final rules go into effect, I think electric is an option that more people are going to consider.”

Machines that are not Tier 4 Final must be in production by December 31 in order to be sold in the U.S.

“Anything relating to biomass is going electric pretty much,” said Tim Griffing, sales manager, stationary line, for Continental Biomass Industries (CBI), of Newton, N.H. “With emissions regulations changing, if you don’t have to move the grinder, electric is the direction that everybody is aiming at. In my business it is increasing 5 to 10 percent a year.”

Manufacturers say electric horizontal grinders provide myriad benefits in stationary applications, but most see no potential for making the machines mobile for off-site work using portable generators in the near future. Hauling an electric generator that can power a grinder, they say, defeats the purpose of eliminating a diesel engine on the machine.

Electric grinding equipment, according to Art de St. Aubin, president and CEO of Rotochopper Inc., of St, Martin, Minn., is one of the most dramatic and under-utilized means of minimizing costs of mulch production.

“Electric grinders have many advantages over diesel grinders, some of them obvious – such as cost of electricity vs. diesel fuel and some of them subtle and more complex – such as uptime vs. downtime,” de St. Aubin said. “Costs for operating and electric grinder for 2,000 hours in a year can be as much as $50,000 less than operating a diesel processing the same product due to less expensive energy costs and lower maintenance costs.”

According to Paul Clark, electric systems engineer at Peterson Pacific Corp., Eugene, Ore., the relative consistent cost of electricity, compared to fluctuating diesel fuel prices, is a main reason why operators consider electric grinders.

“In some cases overseas, where diesel costs are really high, they will only consider electric,” Clark said.

Grinder manufacturers generally agree that an electric horizontal is likely to provide a lower production cost per ton than a diesel powered machine if you process material in a fixed location and have access to a three-phase power supply.

“It’s important for people to know that this technology has existed for some time,” said Pat Crawford, vice president of products at Diamond Z Manufacturing, Caldwell, Idaho. “It’s not some mysterious application. We did our first electric tub grinder back in 1990. It has been around and proven for a long time.”

Either electric or diesel grinders and shredders will do the same job on the material, said Todd Dunderdale, senior area sales manager for Komptech Americas, Westminster, Colo.

“The real question is customer requirements, such as space, permit needs or energy costs,” Dunderdale said. “Typically if a customer plans on running inside a building they go with an electric unit. For customers who desire to be mobile, then a track diesel unit is the best.”

Following is a look at what manufacturers of horizontal grinders for organic materials processing are saying about the electric option.

Ideal for stationary operation

Tim Wenger, vice president of CW Mill Equipment Co., Sabetha, Kan., said electric grinders are ideal for stationery grinding operations.

“Municipal operations, for example, are typically more centrally located in that wood waste is dropped off at a certain location,” Wenger said. “An electric machine is a big pro in that aspect.”

“If your work requires you to move the grinder to the product, a diesel is the correct choice,” said de St. Aubin. “Electrics are often chosen for facilities that wish to place a grinder in line with a conveyor that handles wood waste. You will often see them at the end of sorting lines in construction and demolition waste applications or in consumer waste applications. They are popular for processing green waste for compost, pallets for mulch, waste wood for animal bedding, among many other uses.”

Electric powered grinders, Van Roekel said, “will do all the same things that our diesel powered machines will do. It is basically the same machine. It is used for pre-processing and product sizing, it can be initial grind or a regrind or even a final grind. They can be inside or outside, at a plant or a regional yard where material like green waste comes in. We see electrics used for more of a 24/7 type of an operation where they are working the same job and the same material day after day as opposed to a diesel that is going to go to a site for four to five hours for a day or two and then move to the next site.”

Originally, Van Roekel said, the market for electric machines was driven by efficiency of operation compared to diesel engines.

“Over time, we’re seeing regulations pushing more people toward electric power,” he said.

Operating a stationery electric grinder offers convenience and efficiency of maintenance, said John Snodgrass, who is in technical sales at West Salem Machinery, Salem, Ore.

“All of your parts and tools are centralized on site,” Snodgrass said. “That’s one of the big advantages of having the stationery horizontal grinder.”

According to Morey, “If you don’t need to move around, electric makes a lot of sense as long as you have the infrastructure to support it. Bandit is known for making mobile equipment, but out horizontal grinders can be put into a stationery electric application at any time.”

Cost savings

“Even at today’s diesel prices, an electric machine can be about $30 an hour cheaper to run,” said Clark, citing in part a recent analysis done by one of Peterson’s customers. “You have to take into account that there is an initial up-front capital cost because you’re adding more controllers and you may have to get more power capacity installed to your site. At today’s lower diesel prices, the electric machines will, in a reasonable time, break even, then you will start to see a gain in payback.”

Clark said the additional up-front costs to power a new site could range between $150,000 and $200,000, including costs from the local power utility and an electrical contractor.

“If you already have power, it’s relatively inexpensive,” Clark said.

Van Roekel said depending on hours of operation and maintenance practices, the operating costs of an electric grinder can be about half the costs of running a diesel machine.

“The machines themselves are comparably priced,” he said. “The extra costs come with your drive panel that controls the electric power to the motor. It could be a soft start panel or a variable frequency drive (VFD) panel with which the motor acts more like a diesel engine. Then you have the electric power lines that go to the grinder and the panel, so those are the additional install costs, but that it is soon made up for in the lower operating costs.”

Electric grinders offer cost savings associated with routine maintenance as well, de St. Aubin said.

“Besides savings on diesel fuel, electric grinders eliminate the costs and downtime associated with maintaining a diesel engine, radiator and clutch, including oil and filter replacement, coolant exchange, air filter replacement and clutch fluid and filter replacement where applicable,” he said.

Wenger agreed.

“The nice thing about an electric motor is not having to maintain the diesel engine,” he said. “You don’t have gas tanks and turbos and air filters and radiators and head gaskets. That’s one of the biggest reasons most of our customers have gone electric initially, and then years ago we had the fluctuating diesel prices.”

According to Snodgrass, the absence of road hauling equipment also reduces the cost of an electric machine.

“You need to have the brakes, the chassis and all of that other stuff to move a mobile unit,” he said. “You don’t have that on a grinder that is staying in one place.”

“As long as the (electrical) power is at a decent rate, then the electric machines are definitely cheaper to run,” Morey said. “You’re eliminating filters and diesel fuel and you’re going to have all the Tier Four emission components on these (diesel) engines, so there is going to be an even greater savings when it comes to the Tier Four compared to electric.”

Kollin Moore, electrical engineer with Morbark LLC, Winn, Mich., cautions, however, that the resale market for electric horizontals could be a limited compared to diesel machines.

Another disadvantages of an electric machine, Dunderdale said, is the need to have a mechanic who is proficient on electrics, “which is often hard to find.”

Longer life

“Far and away the biggest difference between diesel customers and electric customers is the quantity of hours that they put on the machine in a year,” Van Roekel said. “The electric powered machines run way more hours than diesel powered machines. It comes down to maintenance, but electric motor will last longer. We see an excess of 30,000 hours on many electric machines. We don’t assume that diesel will go more than 10,000 hours.”

de St. Aubin agreed.

“Besides reduced routine maintenance and downtime, electric grinders offer considerable savings on long-term maintenance and operation,” he said. “Electric motors also tend to have a longer life span. Electrics provide constant dependable performance with reliable uptime. They are extremely reliable machines with some still in service with more than 30,000 hours on them.”

Moore said electric motors typically last up to two or three times longer than diesel engines.

“If somebody has had a diesel machine for years and then they go electric one of the things they radically notice is that there are no longer any oil changes to do, you don’t have to change filters,” Clark said. “There is a lot of mechanical maintenance involved with diesel. With electric, once you get them set up right, you’re not touching those motors for maintenance for 10,000 to 15,000 hours depending on how much you’re grinding, so there is a tremendous reduction in overall maintenance cost when you go with an electric machine. I think the life span of an electric machine is longer, as the diesel has clutches and things that wear out pretty quick. With the electric machine, belts and consumables will wear out, but the drive train itself is fairly robust and maintenance free.”

Better performance?

Moore cited the following advantages of an electric horizontal grinder compared to a diesel powered machine: Cleaner, more efficient power source with no emission regulations to meet, quieter operation, less maintenance, less expensive to operate, lower capital cost and less chance of catastrophic fire.

“A more consistent end product is the result of the more consistent RPMs the unit runs at,” Moore said. “Diesel powered machines have a bigger variance in engine RPMs.”

Comparing the relative grinding power of comparably sized diesel and electric motors is one area where some manufacturers disagree. Most sources interviewed suggested that electric motors can provide more power directly to the rotor than a comparably sized diesel. Pat Crawford, vice president of products for Diamond Z, Caldwell, Idaho, disagreed.

“I disagree 110 percent,” he said. “Electric grinders do not perform exactly the same way as combustion engines with the horsepower and torque curves. A lot of people think that if you run a 1,000 horsepower diesel you can get away with 700 horsepower electric, but we go the other way. The reason is the fixed RPM with an electric motor. If you run a variable frequency drive (VFD), that would help the situation a little bit, but you still wouldn’t have the range of RPM utilization that you would have on diesel.”

Clark, however, said electric motors can deliver more power than their diesel counterparts.

“In some applications we can provide more grinding power with electric motors compared to our largest diesel motors,” Clark said. “An electric motor puts more direct horsepower on the rotor instead of losing efficiency through the clutch. Sometimes you need that extra power directed directly to the rotor. The other piece of it depends on the type of motor controller you have. You can, for short bursts of time, can deliver up to another 50 percent of the power of that motor. For example, you can turn a 600 horsepower electric motor into a 900 horsepower motor for short bursts of time if the rotor demands it without compromising the integrity of the motor.”

Morey agreed.

“With electric you can run a lower horsepower and get high horsepower capabilities,” he said. “In our experience it’s almost two to one from the feedback we get.”

According to Snodgrass, “With a 1,000 horsepower diesel, that is not 1,000 horsepower available to grind with compared to an electric where you get the full 1.000 horsepower.”

Griffing said electric grinders offer a better torque curve than diesel powered machines.

“I would say comparing a 600 horsepower CAT diesel engine with a 600 horse electric motor, the electric will increase your power at the rotor by a minimum of 25 percent,” Griffing said.

Dunderdale said the available grinding power is the most important question to consider.

“Buyers should be aware that an electric high speed grinder requires the same amount of horsepower that its diesel counterpart has,” Dunderdale said. “Typically a 1,000 horsepower grinder needs a 1,000 horsepower electric motor to run it since it is direct drive. However for our Crambo, for example, the 500 horsepower mobile unit is only 240 horsepower in the electric version because you don’t have the loss of power as you do with the diesel to run the hydraulics. There is far less electrical consumption from a 250 horssepower motor than from a 1,000 horsepower. Also when considering a 1,000 HP electric grinder, you must also have to purchase expensive soft starts in order to not overload the power supplier. This can be very expensive.”

Beefier machine

Engine comparisons aside, Griffing said because stationary electric grinders aren’t governed by Department of Transportation specifications like mobile units, the machines can be configured to meet the needs of an operation. That means they can have larger hoppers and longer discharge conveyors.

Wenger echoed that.

“Because they aren’t restricted by road hauling regulations, stationary grinders can be built to larger capacities,” he said. “When you install a 150,000 pound machine it’s going to last forever. When you take away the transportation aspects, it frees you up to build a grinder for more strength instead of transportation.”

Snodgrass agreed.

“Grinders that are going over the road have some limits on things like width and weight,” he said. “If you don’t have to take your grinder on the road, a stationery machine can be much wider with a larger diameter rotor. You can get into tremendous capacities,”

Operating requirements

“Electric driven grinders can be used anywhere there is enough power to drve them,” Griffing said.

Manufacturers generally said minimum requirements generally include three-phase power with a minimum of 460-480 volts at 60 hertz. Having adequate electrical power at the installation site is important, and not always simple to achieve, some manufacturers noted.

“A lot of people assume that because they have a lot of power or voltage coming to their facility that they are set,” Crawford said. “But they may already be using most of their capacity. You can have three phase, 480-volt power available, but you also need to have sufficient amperage. Everybody has the voltage, but not everybody has the amperage.”

Required amperage, Crawford said depends in the horsepower of the motor.

“Lower horsepower machines don’t need that much amperage,” Crawford said. “But you have to consider that in-rush – what it takes to start the motor – can be eight times what it takes to operate the motor.”

Power to electric grinder motors is controlled using one of two types of controller: a soft starter or a variable frequency drive (VDF). A soft starter helps to protect a motor

“With soft start panels you tend to lose a little bit of power, but they are less expensive,” Van Roekel said. “If you’re regrinding it really doesn’t require the full horsepower anyway. It depends on the application. So soft-start is good for some jobs. If you’re doing more taxing work, you may want to look at the VFD panel. The VFD panel is something we believe is the secret to good productivity.”

Clark said Peterson’s machines required between 1,000 and 2,500 amps depending on the size the motor.

“If you’re going to use an electric machine, you need to be sure that you have a power supply that can handle it,” Morey said. “If you don’t have a big enough power supply then there is going to be a problem running the machine.”

Wenger said power drops can damage motors.

“Most problems we’ve had with the electric tubs, particularly on starting, have been from power drops, especially in the summertime,” he said. “People generally say 460 volts is the requirement, but sometimes the voltage in that system can fall to 440. When voltage drops, amperage goes up and that can trip out the power. I tell people to have the utility top the power up into the 505-volt range to protect against drops in voltage, and that usually takes care of the problem. It’s not a big deal – they just adjust it at the transformer.”

Clark said Peterson recently had a customer who was experiencing low voltage.

“It looks like the power company didn’t plan fully for situation,” he said. “It causes the motors to work a little harder and they get hotter. The way you handle that is to work directly with your electric utility company and tell them what you are planning to do so they can plan accordingly.”

Michael Spreadbury, Peterson’s marketing manager, added, “That is a conversation you need to have very early on the purchasing process. You need to get the utility involved and you need to talk to your local electrical contractor.”

Having access to sufficient power, Spreadbury said, is not always a given.

“If the infrastructure isn’t there it isn’t going to happen,” he said. “A customer in the Midwest would die to have electric. But the power company just will not put in the infrastructure.”

According to Griffing, “One downfall of the electric driven grinders is having enough power available to your site. Not all sites are close enough for the amperage required to operate large horsepower motors.”

Wenger agreed.

“Location and proximity to power is a consideration,” he said. “Some of these mulching operations can be in remote locations, so the ability to get adequate power can be a hindrance. It might cost a couple hundred thousand dollars to get lines run to you if you are a distance away.”

Market trends

“The shredder/grinder market has grown over the last couple of years and is forecasted to continue to grow,” Dunderdale said. “We have seen an increase in the number of stationary machines typically because larger facilities are now being planned because of industry consolidation.”

Tightened regulations in engine air emissions will increase the cost of diesel machines, making electric motors more attractive for the appropriate applications, manufacturers agree.

“Due to emissions standards becoming more strict, electric drive is becoming more popular,” Griffing said.

“The increased costs for Tier 4 diesel powered machines will be substantial,” Crawford said. “I think you’ll see machines that are not Tier 4 Final on the market through the first quarter to the first half of next year, but we’re already seeing a pickup in demand for electrics.”

Peterson also expects stronger interest in electric machines.

“With onset of Tier 4 and the significant price increases that it is going to entail, we are going to see more and more applications where, of the machine does not have to move, we’re going to be quoting more electric machines,” Spreadbury said.

Wenger said sales and inquiries for electric grinders increased a few years ago when diesel prices bumped upward.

“Now, with the changes in the emissions regulations, people are taking a closer look at electric power,” he said. “We make a lot of electric tub grinders, but any of our diesel horizontals can be made with an electric engine.”

According to Moore, Morbark has seen the demand for electric grinders slowly increasing, especially during times when the price of oil has been elevated.

“Regulatory influences, whether they are about emissions, dust or noise, are definitely switching people over to the electrics,” Van Roekel said. “The bulk of Vermeer’s horizontal grinder sales are diesel powered, but electric machines have been reducing the gap over the past five years.”

Making it mobile?

New technology has made many electric products more mobile. Horizontal grinders are unlikely to be one of them, manufacturers agree.

“To make an electric machine mobile you would need a pretty big diesel generator, which isn’t cheap,” Van Roekel said. “You’re kind of defeating the purpose if you’re running a 1,000 horsepower generator and then you have to move the panel with it to control the motors. You’re still going to have the noise and air emissions from the generator.”

That, Wenger said, is one of the few downsides of an electric grinder.

“They are not mobile at all,” he said. “You would need a 2,000 horsepower generator to power up a 1,000 horsepower grinder. You’re better off just getting a 1,000 horsepower diesel engine. I had a customer who wanted to take an electric grinder from town to town to town to do custom grinding and he pitched the towns to provide the electricity. That would have necessitated each town to set transformers of adequate size to power the machines. It wasn’t going to happen. The economics just aren’t there.”

De St. Aubin said that portable configurations using quick-connects are available, but power availability is essential.

“The site must have adequate three phase power available,” he said.

Griffing said quick-connects at adequately powered sites allows an operator to move an electric to two or three different locations.

“It works great, but you need to have soft starts at each of the facilities,” he said.

Wenger added that one customer has two locations powered up on his site so he can move an electric tub grinder back and forth.

Snodgrass noted a similar situation.

“I have seen yards where they have a semi portable situation,” he said. “They will have a crude pad and the ability to get power to it so they can process X amount of tons and when they are finished they can pack it up. The control panel is a part of the unit, so they can pack it up and move it to another part of the yard. It isn’t something that you would run for a week – you probably would run it for a year at a site. But generally, if you are dragging a generator around you are defeating the purpose.

Converting to electric

Wenger said converting an existing diesel powered horizontal grinder to electric is simple.

“We are quoting a project like that now,” he said. “I customer in California has a diesel grinder and they were not able to get an air quality permit. Our quote is pull off the 1,000 horsepower diesel engine and put on a 500 horsepower electric. It is a pretty simple conversion. It’s not a bad things to do. When a diesel engine goes bad, instead of a new $60,000 diesel engine you can put the money toward a conversion. It is probably going to cost you $100,000 by the time you buy the motors and starters. But you’re going to make that up in lower operating costs.”

Griffing said diesel-to-electric conversions are becoming increasingly popular.

“We’re seeing more and more of it now, especially in California with the regulations getting stricter,” he said. “If you’re not going to be moving it you might as well convert it. To buy a new diesel engine or have one rebuilt, they’re about the same price to convert, so you’re better off going with the electric.”

What to consider

Before making the decision to install a horizontal grinder, you need to know your local codes, Van Roekel said.

“There will be some safety regulations,” he said. “If you are under a roof there will be some kind of rules to prevent an explosion or a fire problem. It is high voltage, so you need to lock-out-tag-out and other proper safety and maintenance practices. Don’t try to eliminate maintenance schedules. A 24/7 operation is not going to want to turn it off very often, but you still need to clean the machine and check the cutters and screens.”

Moore noted that local laws may have restrictions relative to operating hours and start up times.

Before purchasing an electric grinder, Wenger said, be sure to do your homework.

“Talk extensively with everyone involved, be it the contractor who is pouring the concrete where the electric machine is going to set or the local electric company,” he said. “Are there certain times that the grinder should not operate as to not interfere with electric power elsewhere else, and make sure all of the people involved in the preparation for the grinder are in contact. Communication is key.”