During a wet, cold fall, your grain dryer can seem to guzzle more fuel than an oil tanker sailing at full speed.

Still, you don’t have to be stuck with a huge bill once your grain is dried to a desired level. Through sound purchasing decisions, you can slice fuel costs. Here’s how.

The natural way. You may need to purchase little or no extra equipment. For example, natural air drying can cut drying costs with a sparse investment, says Bill Wilcke, University of Minnesota extension agricultural engineer. This method uses bins with full-perforated drying floors and fairly large fans. Fan size runs approximately .75 to 1.0 hp/1,000 bu. of corn for bins that are no deeper than approximately 18 ft.

Natural air drying can work well, even in the upper Midwest. However, farmers must delay harvest until corn drops to 22% moisture. Natural air drying also requires several weeks of fan operation. In some cases, farmers may not be able to complete drying before winter. Thus, they must keep corn cold during winter and finish drying in early spring.

Although natural air drying uses no propane or natural gas, it consumes an average of 1 kW hr. of electricity/bu. of corn. Its cost-effectiveness depends upon propane or natural gas costs versus the cost of electricity, and how favorable weather is during the drying season.

“As farms get bigger, the key is not just energy efficiency,” reminds Charles Sukup, president of Sukup Manufacturing, Sheffield, IA. “It’s a combination of efficiency plus speed and what you sacrifice in yield losses by not getting the crop out on time. That’s where a stand-alone dryer and speed become important.”

Don’t overdry. That’s why companies still focus on speedy, high-temperature drying systems. “There probably isn’t any dryer company designing a new dryer model based solely upon energy efficiency,” says Warren Odekirk, sales and technical support manager for Growmark, Bloomington, IL.

However, some companies have designed dryers that reduce overdrying, which reduces energy efficiency and purges profits.

“Overdrying corn increases drying costs, particularly when fuel costs are high,” Wilcke says. “It also reduces grain-drying capacity and the number of bushels available for sale. The more water you remove, the less weight you have. Overdried corn is also more susceptible to cracking and breaking during handling.”

Thus, some firms have engineered driers to more uniformly dry the grain column inside the dryer. “This makes dryers use less energy,” Odekirk says.

For example, Sukup Manufacturing offers a quad metering roll system that consists of two metering rolls in each grain column. The inner metering roll runs faster than the outer roll and pulls grain closest to the heat through the dryer faster.

“This results in grain having a more even moisture content and less damage,” Charles Sukup says.

Some companies design dryers to reuse heat from the drying and cooling of grain. Beard Industries, Frankfort, IN, claims that its Superb Energy Miser dryer cuts the fuel costs of conventional dryers by 50%. That’s because the firm’s dryer reycles exhaust through the system.

Beard Industries is researching more ways to improve energy efficiency, says company president Bill Beard. “But for now, the cost of fuel isn’t high enough to make more changes economically feasible,” he says.

Computerized controls. Farmers who want to uniformly dry grain and save energy may check out computerized drying control systems. For example, Shivvers, Corydon, IA, sells a computerized drying control system — the CompuDry Command Center — for in-bin counterflow dryers. The system prevents overdrying by controlling the grain output moisture and automatically selecting the most efficient drying temperature, says Jim Ratliff, Shivvers sales manager.

Payback for the cost of such computerized control systems depends upon the situation, Wilcke says. “It sounds like these controls work pretty well, but they cost several thousand dollars,” he says. “Whether the controls will pay for themselves depends on how far off the moisture is from the target value without these more expensive controls, and how many bushels are run through the dryer each year.”

If a farmer overdries grain by one to two moisture points, most computerized drying controllers can pay for themselves in one to two years, Odekirk says. Here’s a two-step example Odekirk uses to calculate payback:

  1. Determine overdrying costs.

    Let’s say you overdry corn down to 13% instead of the targeted 15%. This gives you an additional 2.3% shrink in sellable weight. In other words, you lose 2.3 bu. for every 100 bu. that you sell. At a $2/bu. corn price, you lose $4.60/bu. for every 100 bu. that you sell. If you sell 60,000 bu., overdrying costs you $2,760.

  2. Calculate energy savings.

    Assuming energy costs are $0.01/point of moisture, overdrying costs you $0.02/bu. If you dry 60,000 bu., energy savings are $1,200. Thus, if a computerized drying system cost $3,960, you could pay for it in one year.

Solar surge

Low and stable energy prices have mothballed solar power as an energy source for nearly two decades. Yet, recent rises in fuel prices have sparked some folks to reexamine solar grain drying.

University of Saskatchewan researchers and Canadian farmers recently built a solar-powered grain dryer that dries approximately 3,000 bu. of wheat from 17 to 13% moisture over four days.

A solar collector transfers warm air via a centrifugal or axial-flow fan mounted in the outlet duct into the grain dryer. “It worked, even under cloudy weather,” says Edwin Arinze, a University of Saskatchewan researcher. Arinze figures the dryer will easily pay for its $3,000 construction cost, based on recent natural gas prices.

But using solar energy to power large-scale, high-temperature dryers likely won’t work, says Warren Odekirk, sales and technical support manager for Growmark, Bloomington, IL. Solar energy cannot provide sufficient heat for dryers that push hot air at high rates — such as 80 cu. ft./min. (cfm)/bu. — to dry corn. “They may work better in a low-temperature or natural air system, where the amount of air pushed through grain is just 1 to 3 cfm/bu.,” he says.

Yet, natural air drying can work well with no supplemental heat, points out Bill Wilcke, University of Minnesota extension agricultural engineer. In fact, adding supplemental heat could potentially overdry corn and add the solar collector construction and maintenance to drying expense, he explains.

Biomass boom?

During the energy-sparse days of the late ’70s and early ’80s, researchers studied biomass fuels such as wood, hay and crop residues to dry corn.

Biomass fuels showed potential because they were renewable and energy dense. Scientists believed that biomass fuels might help stabilize fluctuating external energy prices and even enable farmers to sell fuel. However, energy prices stabilized and research funds evaporated before biomass drying systems became operational.

Now rising energy prices are once again sparking interest in biomass fuels.

Bill Wilcke, a University of Minnesota extension agricultural engineer, says that, if you are considering using biomass fuels to dry corn, you should first answer these questions:

  • Can you harvest biomass ahead of corn harvest, or will it consume time and labor best spent to harvest corn?

  • What’s the biomass fuel’s expected moisture content? Will you need to dry biomass before you burn it? Remember that the higher the fuel moisture content, the lower the net energy production per wet pound of fuel.

  • Do you need special equipment and facilities to harvest, transport and store the biomass fuel? Or can you adapt equipment and facilities that you already own? If you have to buy special equipment, don't forget to include the cost of that equipment in your cost per British thermal unit (Btu) calculations.

  • Is the fuel difficult to use? Does the fuel flow on its own and can the fuel supply system be automated? Or will it consume considerable labor to supply the burner with fuel?

  • It may be easy to build an automatic fuel supply system for a fuel in pellet or granular form, but it would be more difficult to establish an automatic system that consumes logs or large bales.

  • Can you buy a burner that burns your biomass and will it supply the required number of Btus per hour? Several companies produce small biomass burners, but few firms produce the larger sizes needed for heated-air corn dryers.

  • If you decide to build your own burner, remember that it can be difficult to develop a design that provides optimum air amounts for complete combustion, is easy to feed, can withstand high temperatures for long periods of time and conveniently removes ash, clinkers or slag.

  • Will biomass removal reduce soil quality and increase erosion potential? For example, using all the cobs from a crop of corn may not boost soil erosion. However, removing all corn stalks may significantly raise soil erosion.

  • Is there a positive net energy balance for using biomass fuel? How much do you gain after you subtract energy required to grow, harvest and transport the biomass fuel from the energy produced by burning biomass?

  • Is the biomass more valuable as food, feed or an industrial feed stock than it is as a heating fuel?

  • Is use of the biomass fuel cost-effective? When you consider the costs for equipment, labor and other inputs for producing, harvesting, transporting, storing and burning the biomass product, is the cost per Btu competitive with other alternatives?

For more information on any of these topics, contact Wilcke at 612/625-8205 or send him an e-mail at wilck001@umn.edu.