Saving Some Green

Installing an energy curtain, which can reduce heating costs by up to 50 percent, has a good chance of being federally funded.

The estimated greenhouse fuel bill for the coming season keeps getting larger, so what can you do? Here's a simple process to help you save money this season.
 

Conduct an energy audit
First, have an energy audit done of your facilities, which identifies how energy is being used and pinpoints energy-saving technologies or changes in management. You can hire an energy consultant to conduct an audit or there are some self-help materials to guide you through the process.

There are several tools that will allow you to do a first-pass audit. The first tool is new and part of the USDA's energy tool library. The Energy Self Assessment tool is a web-based energy calculator (www.ruralenergy.wisc.edu) that was developed by the University of Wisconsin for the USDA and provides a comprehensive audit based on your own greenhouse particulars. The tool highlights energy-saving technologies and management practices and provides the estimated base line energy consumption and the expected savings for each technology.

Virtual Grower, (www.ars.usda.gov/services/software/download htm?softwareid=309) a tool designed by USDA-Agricultural Research Service, is a downloadable program that calculates the energy use for a greenhouse and predicts the stage of plant growth based on the environmental conditions.

Horticultural researchers Erik Runkle and Matthew Blanchard and agricultural engineers John Bartok and Ron Lacey, have put together a collection of web links to information on greenhouse energy conservation (www.hrt.msu.edu/energy).

Calculate energy savings
From the audit you should identify a list of low- or no-cost items to conserve energy, a list of equipment that can reduce energy consumption and the estimated energy savings for each. Implement the low-cost items immediately, as they will provide savings with little investment which equals a big return on investment.

Once you've identified the individual options you want to invest in, re-calculate the energy savings estimates if you are choosing more than one technology to be installed at the same time. In a greenhouse, individual energy efficiency measures are not additive, so you must look at groups of efficiency measures to determine the true return on investment.

For example, a grower installs an energy curtain and a high-efficiency boiler (96 percent annual fuel utilization efficiency). The energy curtain is estimated to save 40 percent and the boiler will save 25 percent, respectively. If the greenhouse uses 10,000 gallons of liquid propane gas per year, installing the energy curtain will reduce consumption to an estimated 6,000 gallons. Based on the individual estimate, the boiler would save 2,500 gallons of LP gas. However, with the energy curtain installed, the greenhouse is only using 6,000 gallons instead of 10,000 gallons of LP gas, so the savings by the boiler is reduced to 1,500 gallons (25 percent of 6,000 gallons). The sum of the individual estimates is a 65 percent savings, but the grouped options save only 55 percent, which is still a great reduction in energy costs.
 

If you are considering burning cord wood, look for a boiler that meets the EPA 2010 emissions standard.

Determine payback
Before making a decision on equipment investments, obtain installed-cost estimates from vendors to determine the return on investment for each option. This lets you rank the options from largest to smallest benefit to your business.

Simple payback is a quick way to get a snapshot of an investment. By definition, simple payback is the investment divided by the annual savings generated by the investment. The result is the number of years required to pay back the investment. Simple payback may not account for maintenance costs, interest costs and non-energy operating costs, but it is easy to calculate as an investment barometer. A net present value analysis would be a better option to account for all costs and equipment life.

The investment cost used for calculations may be the total investment or an incremental cost. If you are considering a "must-buy" decision, then you likely have a choice of conventional equipment or high-efficiency equipment. Since you are going to make a purchase, the true cost of buying the high-efficiency equipment is the additional cost of the equipment compared to the cost of standard equipment.

For example, if a standard unit heater costs $2,500 and a high-efficiency heater costs $3,000 and an existing heater has to be replaced because its heat exchanger has a hole in it, then the incremental cost of purchasing the high efficiency unit is $500. If the high efficiency heater uses $250 less fuel per year to heat the greenhouse, then the simple payback is $500 (incremental cost) divided by $250 (energy savings) — or a two-year payback.
 

Obtain funding
You've identified some energy efficiency projects that will reduce your costs and save energy, but how can you fund them along with all the other items on the wish list for improving your operation? There are several options.

If you use natural gas, check with your gas utility to see if the company offers grants for energy conservation. There is also a national database (www.dsireusa.org) for energy efficiency and renewable-energy grants and incentives at the federal, state and utility levels. Click on your state and scroll through the programs available for your state and utility or click the icon for the federal incentives at the top of the home page. If you use LP gas or oil for heating, a federal grant may be your only option.

For greenhouse growers located in rural areas, the 2008 Farm Bill includes a program called Rural Energy for America Program (REAP). This program offers competitive grants and guaranteed loans for renewable energy and energy conservation projects. Applications for grants are typically due in March or April each year. Applications are scored on quantity of energy saved, environmental benefit, commercial availability, technical merit, size of business, return on investment, etc. Within the REAP program is also a grant program for energy audits. Resources for the REAP grants can be found on the USDA Rural Development website (www.rurdev.usda.gov/BCP_Reap.html) and Farmenergy.org (www.farmenergy.org) under "Application Tools."
 

Potential greenhouse projects
Projects including energy curtains, high-efficiency heat equipment, double-wall glazing and boilers that burn renewable energy products have a good chance of being funded by the USDA REAP program. If you are considering switching to a renewable energy source, remember that reducing the energy use of your greenhouse first will reduce the size and expense of the boiler equipment.

Caution: The typical outdoor cord wood boiler has very low efficiency (30 to 40 percent based on EPA data) and many municipalities are restricting their installation due to excessive smoke emissions. Check your local government for regulations. Pellet boilers or furnaces are a much better option because the fuel is metered in as a greenhouse requires heat and don't produce much smoke.

If you are considering burning cord wood, look for a boiler that meets the EPA 2010 emissions standard. A list of boilers that meet requirements can be found online as well (www.epa.gov/burnwise/owhhlist.html). A boiler meeting this new standard will likely be about twice as efficient as the old style outdoor wood boilers. If cord wood is your choice, make sure you consider all costs. Even though you may have your own wood lot, it still takes time, labor, equipment and energy to harvest the wood.

Scott A. Sanford is senior outreach specialist, University of Wisconsin-Madison, Biological Systems Engineering; (608) 262-5062; sasanford@wisc.edu; www.bse.wisc.edu; www.uwex.edu/energy.