Broadly the costs saving possibilities are determined by the current methods used for creating and maintaining the Controlled Atmospheres. By combining two or more of the options described below a payback of 1 to 4 years on the capital cost of a scrubber installation can be expected.

Currently using Slaked Lime for Carbon Dioxide control?

In general the capital cost of an Isolcell activated carbon CO2 scrubber can be paid for with 3 to 4 years of lime consumption. These scrubbers have been purpose designed to maintain oxygen and carbon dioxide levels as low as 0.5% in “standard” CA stores. Using a CO2 scrubber instead of lime also eleminates the costs associated with the lime handling, storage and disposal.

Currently using Dilution with Nitrogen for Carbon Dioxide control?

Using an activated carbon scrubber instead of an on site nitrogen generator for carbon dioxide control in a CA store will significantly reduce the nitrogen consumption. To date activated carbon scrubbers have injected a small amount of oxygen into the CA room each time the drum switched from air for regeneration back to the adsorption mode. Unless the CA stores were extremely gas tight this caused the oxygen to rise. Prior to the IS range of Isolcell scrubbers, a common solution to this problem was to install a large nitrogen generator which was used to dilute the oxygen that had been introduced. This also diluted the carbon dioxide and in regions where electricity was inexpensive the scrubbers fell out of favour and nitrogen was used for carbon dioxide control as well.

Reducing the nitrogen consumption reduces operating expenses in 3 ways:

1. Assuming that a nitrogen generator has not already been purchased a significantly smaller (60% to 70%) unit will suffice. The reduced capital cost of a smaller N2 generator is more than the capital cost of an equivalent duty carbon dioxide scrubber which can save anywhere from 20% to 40% of the initial capital outlay.

2. Less nitrogen consumption means less energy usage. This saving is dependant on a large number of variables and is best demonstrated by an example. Using a scrubber instead of nitrogen to control the carbon dioxide in a CA facility storing at 1.5% carbon dioxide for 6 months at an energy cost of $0.04 per kW hour will save approx. $0.60 per bin per season, while storing at 1.0% carbon dioxide for 9 months at an energy cost of $0.06 per kW hours will save approx. $2.00 per bin per season. If the reduced maintenance costs for the nitrogen generator are included it could almost double these savings.

3. Due to the energy saving that can be achieved, in many regions the utility suppliers will subsidize the capital cost of a carbon dioxide scrubber installation by as much as 75%.

Savings from replacing Post Harvest treatments with DCA

1. In the 4 to 8 months storage window DCA is a cost effective alternate to 1-MCP in conventional CA stores, with paybacks ranging between 1 and 2 years.

2. There is a growing demand from consumers for a grade of fruit which has no post harvest chemical treatments and Dynamic Controlled Atmosphere foots this bill.

3. Also DPA drenching for scald control is no longer necessary if a Dynamic Controlled Atmosphere system is installed.