Making green by going green
Sept. 4, 2012
by Dan Malovany
New technology continues to emerge to make bakeries not only more sustainable, but also more efficient. Heat pumps can produce both chilled and hot water. Ovens and oxidizers can take heat and use it to cool offices through heat exchangers and absorption technology.
Over the last 29 years, Scott Houtz has seen it all. The president of Air Management Technologies, an energy and environmental services company based in Lewisburg, PA, Mr. Houtz is a member of the American Society of Heating, Refrigeration and Air Conditioning Engineers, and the Association of Energy Engineers. He has been involved in the baking industry for the past 17 years and is a member of BEMA and the American Society of Baking. Here, in Baking & Snack’s ongoing coverage on the critical issue of sustainability, he outlines a few ways to make your bakery more green, efficient and profitable.
Baking & Snack: How can industrial heat pumps be used in commercial bakeries?
Scott Houtz: Industrial fluid-to-fluid heat pumps, when properly applied, provide a two-sided benefit. In bakeries, they can be used to produce chilled ingredient water and, at the same time, reject this heat to produce hot water that can be used for sanitation, basket washers or pre-heating boiler feed water. Some models can produce heat in excess of 190°F while simultaneously providing low-temperature glycol and using environmentally friendly refrigerants like carbon dioxide and ammonia.
How can heat recovery systems on oven oxidizers be used to cool offices?
The baking industry has a unique opportunity by using waste heat from the oven as a sustainability measure that is far less costly than harnessing solar energy or wind power. Cooling with absorption technology has been around for many years. Specifically, the heat is used to generate cooling to offices and other parts of a facility. The systems are low-maintenance because they have only one moving part and use lithium bromide (salt), a natural refrigerant.
Chilled water is produced in the absorption chiller and circulated to air handling systems, which distribute cool air to office areas. This chilled water can also be used for processes requirements provided the required temperature is above 45°F. The chiller is compact. A 4,000-sq-ft office can be cooled by a unit a little larger than a refrigerator, which can be retrofitted into existing systems.
What are the current environmental issues revolving around refrigerant management?
The Clean Air Act of 1990 has eliminated the use of refrigerants with ozone depleting substances (ODS) in new equipment since 2010 and has also set strict limits on the amount of refrigerant that can be manufactured to support existing systems containing ODS. This has caused prices to escalate, and many bakeries are now scrambling to find ways to replace existing refrigerants. Unfortunately, some of these alternatives may provide decreased efficiencies and capacities. It is important to have a refrigeration engineer evaluate the conversion and determine the potential impacts before a retrofit takes place.
The new concern pertains to a refrigerant is global warming potential (GWP), which assigns each refrigerant a value with carbon dioxide as a reference base of 1.
Some concerns exist in the baking industry that government agencies may regulate GWP in the future and prompted many companies to examine future direction of refrigeration system purchases. Consider the comparison with 134a, a “chemical refrigerant” with a GWP value of 1,430, and ammonia, a “natural refrigerant” ammonia with a GWP of less than 1. On the surface, the decision may seem simple, but it becomes more complex when you now examine their safety ratings. The 134a refrigerant has an A1 safety rating indicating low toxicity and flammability, while ammonia has B2 safety rating, which suggests high toxicity and medium flammability.
To assess what is the best direction, a good first step is to take an inventory of all refrigerating systems. Whether you’re looking at an existing facility or building a new facility, it’s important to evaluate the type of refrigerant, its charge volume and the equipment’s age. Through proper consultation and planning, many bakeries can measure their environmental exposure and reduce their risk by more than 75% in some cases. With the proper information, baking companies can make informed decisions about what type of refrigerant to use. Even with all this information, there will always be preferences based on a company’s past experience, but common ground can be found by all to keep refrigerant inventories as small as possible.
What are phase change materials, and how can they be used in a bakery to make it more sustainable?
Phase change materials (PCMs) are used for storing thermal energy. Think of them as ice packs in your home freezer. These materials hold significant amounts of thermal energy in a small space through latent heat, then release this energy as needed at higher temperatures. Often in bakeries, ice water and mixer refrigeration systems can benefit from PCMs. By design, mixers experience variable loads (on-off) when they are cycling or when ice water is batching numerous times each hour. PCMs can help level out capacity fluctuations.
In cases where existing mixer suffers from capacity shortfalls during certain peak time periods, such as when operating a liquid sponge, a heat exchanger can actually store energy over time and provide the reserve capacity as needed. Other benefits include energy savings by reducing electrical peak demand and enhancing chiller operation by allowing longer run times that will increase efficiency and operation.
What is the ROI for these various “green” systems, especially considering today’s natural gas prices?
Natural gas prices have dropped significantly in the US during the past few years, prompting electric companies to reduce their rates depending on their source of energy generation they use. Having been in the energy field for more 25 years, we have seen fluctuations with energy projects when utility prices are low, but this hasn’t been the case except with traditional retrofit measures driven solely by energy savings.
We have actually seen our energy-related business increase substantially and feel this is mostly due to implementing innovative solutions where capital has already been allocated to replace systems, and then working with the differential cost between doing the “traditional” approach compared to energy efficient “green” approach. Sometimes the most efficient approach can even represent a lower cost. One example is the oven/oxidizer heat recovery system, which costs about the same as a traditional steam boiler system but doesn’t require a boiler room. In addition, it is simple to operate with less maintenance and requires no chemical treatment. Energy savings could amount to more than $100,000 per year, depending on conditions.
Other opportunities that exist with low-cost natural gas prices include using it as a fuel source to generate electricity with micro-turbines, fuel cells and other measures that also provide added waste heat benefits. The overall return with this type of measure increases as natural gas prices decrease and electric prices increase, which is the forecast moving forward.
Bakeries should also be diligent to not leave money on the table. In some areas of the country, utilities and government agencies offer various energy efficiency incentives available through grants, rebates and other financial incentives. Visit www.dsireusa.org for more information.