New LED exit signs are inexpensive, with prices typically starting at around $20. The U.S. EPA’s ENERGY STAR program website provides a list of suppliers of LED exit signs. Tritium exit signs are an alternative to LED exit signs. The advertised lifetime of these signs is around 10 years and prices typically start at around $150 per sign. Electronic ballasts. A ballast regulates the amount of electricity required to start a lighting fixture and maintain a steady output of light. Electronic ballasts can require 12% to 30% less power than their magnetic predecessors . New electronic ballasts have smooth and silent dimming capabilities, in addition to longer lives , faster run-up times, and cooler operation than magnetic ballasts . New electronic ballasts also have automatic switch-off capabilities for faulty or end-of-life lamps. Replacement of T-12 tubes with T-8 tubes. In many industrial facilities, it is common to find T-12 lighting tubes in use. T-12 lighting tubes are 12/8 inches in diameter . T-12 tubes consume significant amounts of electricity, hydroponic channel and also have extremely poor efficacy, lamp life, lumen depreciation, and color rendering index.
Because of this, the maintenance and energy costs of T-12 tubes are high. T-8 lighting tubes have around twice the efficacy of T-12 tubes, and can last up to 60% longer, which leads to savings in maintenance costs. Typical energy savings from the replacement of a T-12 lamp by a T-8 lamp are around 30% . Replacement of mercury lights. Where color rendition is critical, metal halide lamps can replace mercury or fluorescent lamps with energy savings of up to 50%. At a Basic American Foods facility in Shelley, Idaho, the production area lighting system was upgraded using metal halide lamps. According to the company, the improved color rendition and increased light levels offered by the metal halide lamps helped production workers better detect deffects in the plant’s potato products. Plant sanitation was also improved, because staff could better see debris on the equipment and floors . Where color rendition is not critical, high-pressure sodium lamps offer energy savings of 50% to 60% compared to mercury lamps . High-intensity discharge voltage reduction. Reducing lighting system voltage can also save energy. A Toyota production facility installed reduced-voltage HID lights and realized a 30% reduction in lighting energy consumption .
Commercial products are available that attach to a central panel switch and constrict the flow of electricity to lighting fixtures, thereby reducing voltage and saving energy, with an imperceptible loss of light. Voltage controllers work with both HID and fluorescent lighting systems and are available from multiple vendors. High-intensity fluorescent lights. Traditional HID lighting can be replaced with high intensity fluorescent lighting systems, which incorporate high-efficiency fluorescent lamps, electronic ballasts, and high-efficacy fixtures that maximize output to work areas. These systems have lower energy consumption, lower lumen depreciation over the lifetime of the lamp, better dimming options, faster startup and re-strike capabilities, better color rendition, higher pupil lumens ratings, and less glare than traditional HID systems . Daylighting. Daylighting involves the efficient use of natural light in order to minimize the need for artificial lighting in buildings. Increasing levels of daylight within rooms can reduce electrical lighting loads by up to 70% . Unlike conventional skylights, an efficient daylighting system may provide evenly dispersed light without creating heat gains, which can reduce the need for cooling compared to skylights.
Daylighting differs from other energy efficiency measures because its features are integral to the architecture of a building; therefore, it is applied primarily to new buildings and incorporated at the design stage. However, existing buildings can sometimes be cost effectively refitted with daylighting systems. Daylighting can be combined with lighting controls to maximize its benefits. Because of its variability, daylighting is almost always combined with artificial lighting to provide the necessary illumination on cloudy days or after dark . Daylighting technologies include properly placed and shaded windows, atria, clerestories, light shelves,and light ducts. Clerestories, light shelves, and light ducts can accommodate various angles of the sun and redirect daylight using walls or reflectors. More information on daylighting can be found at the website of the Daylighting Collaborative led by the Energy Center of Wisconsin .The use of on-site electricity generation appears to be quite limited in the U.S. fruit and vegetable processing industry. In 2002, only 5% of the industry’s electricity was generated at individual facilities . The use of on-site generation was confined almost exclusively to the fruit and vegetable canning sub-sector, where the extensive use of steam in blanching, evaporating, pasteurizing, and sterilizing applications makes combined heat and power systems particularly attractive. Self generation can be an attractive option for many facilities for reducing the energy intensity of utilities services. This chapter provides a brief overview of several self-generation measures applicable to the U.S. fruit and vegetable processing industry. Combined heat and power . For industries like fruit and vegetable processing that have simultaneous requirements for process heat, steam, and electricity, the use of CHP systems may be able to save energy and reduce pollution. Combined heat and power plants are significantly more efficient than standard power plants because they take advantage of waste heat. In addition, electricity transmission losses are minimized when CHP systems are located at or near the facility. Often, utility companies will work with individual companies to develop CHP systems for their facilities. In many cases, the utility company will own and operate the facility’s CHP system, allowing fruit and vegetable processors to avoid the capital expenditures associated with CHP projects while reaping the benefits of a more energy-efficient source of heat and electricity. In addition to energy savings, CHP systems also have comparable or better availability of service than utility generation. In the automobile industry, for example, typical CHP units are reported to function successfully for 95% to 98% of planned operating hours . Many large-scale CHP systems use steam turbines. Switching to natural gas-based systems is likely to improve the power output and efficiency of the CHP system, due to increased power production capability. Although the overall system efficiency of a steam turbine-based CHP system is higher than that of a gas turbine-based CHP system , the electrical efficiency of a gas turbine-based CHP system is superior . Furthermore, modern gas-based CHP systems have low maintenance costs and will reduce emissions of NOx, SO2, CO2, and particulate matter from power generation considerably, especially when replacing a coal-fired boiler . In general, the energy savings of replacing a traditional system with a standard gas turbine-based CHP unit is estimated at 20%-30% . However, hydroponic dutch buckets savings may be greater when replacing older or less maintained boilers.Additional advantages are that the amounts of power and thermal energy produced by the turbine can be adjusted to meet current power and thermal energy loads. If steam loads are reduced, the steam can then be used for power generation, increasing output and efficiency . Drawbacks include the additional complexity of the turbine’s design. The economics of a CHP system depend strongly on the local situation, including power demand, heat demand, power purchasing and selling prices, natural gas prices, as well as interconnection standards and charges, and utility charges for backup power. In some states, programs may offer support for installation of CHP systems .
Tri-generation. Many new CHP systems offer the option of tri-generation, which provides cooling in addition to electricity and heat. Cooling can be provided using either absorption or adsorption technologies, which both operate using recovered heat from the co-generation process. Absorption cooling systems take advantage of the fact that ammonia is extremely soluble in cold water and much less so in hot water. Thus, if a water-ammonia solution is heated, it expels its ammonia. In the first stage of the absorption process, a water-ammonia solution is exposed to waste heat from the co-generation process, whereby ammonia gas is expelled. After dissipating the heat, the ammonia gas—still under high pressure—liquefies. The liquid ammonia flows into a section of the absorption unit where it comes into contact with hydrogen gas. The hydrogen gas absorbs the ammonia gas with a cooling effect. The hydrogen-ammonia mixture then meets a surface of cold water, which absorbs the ammonia again, closing the cycle. One food company that has successfully implemented absorption technology is the Ghirardelli Chocolate Company, a California based manufacturer of chocolate products. Ghirardelli’s manufacturing facility in San Leandro, California, uses an on-site electricity generating system, which is powered by four 350 kW natural gas-fired reciprocating engines. In 2003, the company installed a single-stage 145 ton absorption chiller that runs entirely on heat from the engines’ exhaust and jacket water. According to the company, the combined area of the buildings being cooled by the absorption chiller is approximately 35,000 square feet . In contrast to absorption cooling, adsorption cooling utilizes the capacity of certain substances to adsorb water on their surface, from where it can be separated again with the application of heat. Adsorption units use hot water from the co-generation unit. These systems do not use ammonia or corrosive salts, but use silica gel . Adsorption units were originally developed in Japan and are now also marketed in the United States. The thermal performance of absorption and adsorption systems is similar, with a coefficient of performance between 0.68 and 0.75. The capital costs of both systems are also comparable. However, the reliability of an adsorption unit is expected to be superior and its maintenance costs are expected to be lower . Back pressure turbines. At many facilities, steam is produced at a higher pressure than is demanded by process requirements. Often, steam pressure is reduced for process use by passing steam through pressure reducing valves, essentially wasting thermal energy. A back pressure steam turbine can perform the needed pressure reduction while converting this otherwise wasted thermal energy to electricity for use throughout the facility. According to the U.S. DOE, back pressure turbines can be considered wherever a pressure reducing valve has constant steam flow of at least 3,000 pounds per hour and when the steam pressure drop is at least 100 psi . Morning Star Packing Company, a manufacturer of tomato paste and other canned tomato products located in Williams, California, uses back pressure turbines to generate 100% of facility electricity needs . In the mid- to late- 1990s, the company installed three 1 MW back pressure turbines at a cost of around $847,000, including capital costs and installation expenses. Reported electricity cost savings have totaled nearly $500,000 per year. The company projected that over the 20-year lifetime of the back pressure turbines, they expect to save almost $9 million in total energy bills and realize a compound annual rate of return of more than 60% .Photovoltaic panels. Photovoltaic panels convert sunlight directly into electricity and can provide a reliable and renewable source of electricity to facilities with ample sunlight. Photovoltaic panels, which are typically mounted on the roof of a facility, convert electricity to DC current, which is subsequently sent through an inverter and transformer and converted into AC power. The AC power can be fed directly into a facility’s power supply. While the capital and installation costs of photovoltaic systems are currently somewhat high , manufacturers can often receive substantial rebates and tax credits from state and federal agencies that can help make photovoltaic investments more economically attractive. Inverters typically last 10 to 20 years, while photovoltaic panels can typically generate power for 25 to 40 years . Kettle Foods, a producer of all natural snacks based in Salem, Oregon, installed a 114 kW photovoltaic power system on the roof of its processing plant and headquarters in 2003. Reportedly, the system saves the company $8,400 in energy costs each year, while also avoiding around 2,500 tons of CO2 emissions. The initial capital and installation costs totaled $675,000, but the company received over $400,000 in clean energy incentives, Oregon energy tax credits, and U.S. federal energy tax credits, which helped to make the project more economically viable . Over the 40-year life of the system, the company estimated a 7% average rate of return and a net present value of $55,000. However, the project has also helped reinforce Kettle Foods’ image as an environmental steward and has reportedly led to good corporate publicity.