Meeting Energy Demands While Facing the Challenges of Electric Grid Instability  

Photo courtesy of Propane Education & Research Council

 

Meeting the energy demands of buildings of all types, during normal operations and times of power grid interruptions, can be done in numerous ways, including the use of propane.

Energy use in commercial buildings continues to be a primary concern of owners and managers of all types of facilities. There are issues of cost and reliability for continuous operations and future growth needs. While there is increasing attention on providing all-electric buildings, the current practical aspects of doing that haven’t yet met the idealized goal. Most electrical usage is based on utility grid-supplied power which is remotely generated and has some inherent inefficiencies and environmental concerns based on the type of fuel being used. On-site power generation is an option, but it needs to be looked at in terms of all of the options and particular constraints of a building and its site. This course looks at the issues related to commercial building energy use and specifically investigates the use of propane energy as a clean energy solution. Understanding propane as a fuel and the way it can be used in different building systems can actually lead to a cleaner solution than an all-electric design. All of this can be done today, without compromising the comfort or operational needs of a building or facility.

PROPANE ENERGY

Building owners, design professionals, and others who may not have used propane in the past, often have some predictable questions such as the following:

• What is Propane? Propane is a gas, sometimes known as liquefied petroleum gas, or LPG, that is normally compressed and stored as a liquid. Whether it is stored and transported in either a liquefied state or as a gas, it is an energy-rich hydrocarbon that is used in a variety of ways to provide energy to buildings, vehicles, and appliances. Environmentally, it is a cleaner alternative than other hydrocarbons and has been designated as a clean energy by the EPA¹. Propane is nontoxic, colorless, and naturally odorless—Mercaptan, an identifying odor, is added to propane so it can be readily detected.
• Where Does Propane Come From? Propane can come from several sources. It is primarily a byproduct of domestic natural gas processing. Some propane is produced from crude oil refinement. Renewable propane is produced from plant oils, animal fats, and cooking oils. Once refined, there is virtually no difference between LP gases processed from these sources. Over 99 percent of the propane used in the U.S. is produced in North America. Notably, the US exports more than twice as much as is kept and used for our own purposes. Currently, about 30 billion gallons are produced in the U.S. per year with 10 billion gallons used domestically and 20 billion gallons exported.
• What is Renewable Propane? Renewable propane has the same features as conventional propane but with even lower carbon emissions when compared with other energy sources. Unlike conventional propane, renewable propane can be made from a variety of renewable feedstocks. More and more renewable propane is being generated from the seed oil of the camelina plant. Also known as camelina sativa or false flax, camelina is a member of the mustard family and a relative of cabbage, kale, and cauliflower, but is not a food crop nor does it compete with food production.

Photo courtesy of Propane Education & Research Council

Renewable propane is becoming a viable alternative in some parts of the country and more production is expected as demand increases.

Dispelling Some Myths about Propane

There are a number of misperceptions or misunderstandings about propane which are addressed as follows.

• MYTH #1 - Propane is not safe for the environment. Actually, propane is considered to be very environmentally friendly. Propane is stored as a liquid, but when released into the air, it vaporizes and dissipates which means it won’t contaminate groundwater, drinking water, marine ecosystems, or other sensitive habitats. When vaporized, propane produces virtually no ozone-harming effects and unlike natural gas, it is not a greenhouse gas in its un-combusted state. Propane has a comparatively low carbon intensity for each unit of energy produced compared to other energy and fuel sources. Renewable propane has even less carbon intensity.
• MYTH #2 - Propane is not energy efficient. As a fuel, propane is extremely energy efficient, especially when compared to other fuels. Liquid propane has a higher energy density than ethanol, methanol, and liquefied natural gas, meaning propane-powered equipment produces more usable energy than most other liquid alternative fuels, assuming comparable equipment efficiency. When compared to electricity from the utility grid, it is important to recognize that electricity is a secondary energy product, generated using a primary energy source. There are inherent efficiency losses in converting the primary fuel into electricity, then distributing it long distances over wires, and then converting it into useful purposes in a building or facility. This means that one unit of useful electricity in a building may require up to three units of energy from the primary source – not highly efficient. Using propane on-site to produce useful energy is inherently more efficient since transmission losses and conversion losses are minimized.
• MYTH #3 - Propane is not more advantageous than diesel or petroleum. In fact, Propane has been shown to have a lower carbon content than electricity, conventional gasoline, and diesel fuel. That’s why propane is listed as an approved clean alternative fuel under the Energy Policy Act of 1992.
• MYTH #4 - Propane is not as safe as some other fuel choices. Propane has actually been shown to be very safe to use. NFPA 58 Liquified Petroleum Gas Code specifically covers everything from highway transportation of LPG to the design, construction, and operation of propane-based systems. This code has been used and followed for decades and has helped to ensure a successful track record of safety across the United States for propane.

Overall, propane is safely and efficiently used throughout the United States. It has been rated as a clean fuel by the federal government. There is a strong network of American producers and suppliers across the country that provide propane as a reliable, affordable, and abundant energy source.

Photo courtesy of Propane Education & Research Council

Propane is safely stored and transported without the environmental concerns of other fuels.

ELECTRICAL POWER GRIDS

Electric power is predominantly provided by established utility grids with electricity generated from power plants or other sources. While most people don’t see any sign of emissions, electricity from the grid is not necessarily the cleanest option for buildings—at least not until the electric grid is powered by 100% renewable, non-polluting, energy. Unfortunately, that remains a distant goal.

The U.S. Energy Information Administration (EIA) publicly reports annual data, with the latest numbers available from the year 2022 (October 2023 compilation). They identify three primary energy sources used by utility-scale electricity generation plants:

• Over 60 percent is still from fossil fuels including natural gas, coal, and petroleum products (2.5 trillion kilowatt hours generated).
• Just over 18 percent is from nuclear power (772 billion kilowatt hours generated)
• Only 21 percent is from renewables including wind, solar, hydropower, and biomass but has grown to exceed nuclear power (901 billion kilowatt hours generated).
• In addition, the EIA estimates that an additional, much smaller amount of 61 billion kilowatt hours was produced from small-scale solar photovoltaic systems in 2022. (Data source: U.S. Energy Information Administration, Electric Power Monthly, February 2024; preliminary data)

While the slow but steady growth of renewable energy is welcome news in light of efforts to reduce harmful emissions, the reality is that the grid is still over 60 percent powered by fossil fuels. This production of electricity from fossil fuels still contributes to global warming/ climate change, acid rain, and air pollution.

While full electrification of buildings is still a goal of many people in the interest of environmental improvement, the reality is that even electrification advocates admit full implementation will take over 20 years and cost about $20-$25 trillion. There is also considerable variation across the U.S. in terms of capacity, interconnectivity, and controllability. Further, the increased demand on the electric grid is currently causing issues with inadequate supply in many parts of the country. While the trend is definitely away from fossil fuels, the power industry isn’t there yet and it will take a while for the transition.

Carbon Intensity

Given the current reliance on fossil fuels, a discussion of the electric grid should also include a look at carbon intensity, which is a measure of how much carbon dioxide (CO₂) and other greenhouse gases are produced per unit of activity. It can be used to compare the carbon impacts of electricity, transportation fuels, or the production of a product. Most commonly, it refers to how many grams of carbon dioxide (CO₂) are released to produce a kilowatt hour (kWh) of electricity. Obviously, electricity that’s generated using fossil fuels is more carbon intensive, since the process by which it’s generated creates more CO₂ emissions than renewable sources.

When comparing large-scale energy usage across the grid and different fuel sources, the common energy measurement used is a joule which is equal to 1 watt of electricity per second. Hence, 1,000 watts generated in one second, (i.e. 1 kilowatt) is equal to 1,000 joules. However, one kilowatt hour (kWh) is by definition, 3,600 seconds of energy. Therefore, the conversion of kilowatt hours to joules means that 1 kWh = 3,600,000 joules. When dealing with larger amounts of kWh, it is useful to talk in terms of megajoules (MJ) which is simply a million joules – so 3,600,000 joules is 3.6 megajoules. Equivalent calculations and conversions can be done for other fuels too, to determine the number of megajoules in those fuels.

The corresponding information on the amount of energy produced is the amount of carbon dioxide (CO₂) or its equivalent that is emitted during the energy generation process. That is typically calculated as a measurement of grams. When data from different energy sources are used to determine the carbon intensity, it is typically expressed as grams of CO₂ generated (or equivalent) for each megajoule of energy produced—expressed as gCO₂e/MJ.

When this process is used on the electrical grid, we can get a sense of the carbon intensity of the grid compared to other fuels. Since different parts of the utility grid can access electricity created with different fuel sources, there are different carbon intensity scores that can be calculated for each state in the country. When these are averaged together the electrical grid has a comparatively high carbon intensity. Considering the various source energies used, the U.S. average carbon intensity score is around 130. By comparison, petroleum and diesel score around 91, while natural gas and propane range from 71-79. Renewable propane scores as low as 7 to 43.5.

By understanding the true nature of carbon intensity, it is easier to discern which sources actually contribute to decarbonization today and which ones still aren’t there yet. The use of alternative energies, like propane, provides lower carbon intensity now and offers the potential of even greater reductions as more renewable propane becomes available.

Costs Based on “Spark Spread”

All purchasers of energy usually want to know what the cost of that energy is and how it compares to other energy sources. When different types of fuels or energy sources are used, then some type of conversion needs to be done to compare the same energy output—the price of a million watt-hours (i.e., a megawatt-hour (MWh)) is not the same as the price of a million Btu (mmBtu) nor do they have an equivalent amount of energy. Therefore, in order to do an “apples to apples” comparison of the cost of using electricity compared to using propane, a conversion calculation is necessary. That calculation is referred to as the “spark spread” and is defined simply as the price difference in a particular market area between electricity generated by the local utility and that of propane fuel for equivalent amounts of energy.

In order to calculate the spark spread for a particular project, first the power price or cost of electricity per Megawatt hour ($/MWh) is needed—generally as published by the utility company. Then the propane cost is identified in terms of cost per million Btu ($/mmBtu)—generally available from a propane supplier. The propane cost is then multiplied by a conversion factor based on the heat rate of propane compared to electricity—i.e., the number of Btus per megawatt hour (mmBtu/MWh). The cost of the propane can then be expressed in cost per megawatt hour ($/MWh) and be compared to the electricity cost per megawatt hour ($/MWh). The difference between the two numbers is the “spark spread” and can be used to determine a fair comparison of what is really being paid for energy between the two energy sources.

In some market areas, where electricity is available from the grid at a higher price, then the spark spread of propane or other fuels can be quite favorable, meaning propane is more economical. If electricity is a lower price than propane, the spark spread may not be favorable. Of course, calculations are typically done only at current electricity rates. It is generally held that electric rates are expected to continue to increase as demand increases and improvements are needed for the grid. In that light, it would be easy to compare the projected spark spread if rates go up during the life of a propane system and determine the “crossover” point where propane becomes more favorable. Ultimately, the building owner or operator can use this information to determine which is the most economically favorable solution and a system can be designed accordingly.

Photo courtesy of Propane Education & Research Council

The carbon intensity of the electrical grid varies by state but is nonetheless rather high since coal and natural gas are still the primary fuels used for electrical generation.

Image courtesy of Propane Education & Research Council

The Spark Spread for a particular project is calculated as the cost difference between electricity from the grid and locally produced energy using propane.

PROPANE ENERGY SYSTEMS

Keeping in mind all of the foregoing, propane can readily be used in buildings either as a stand-alone fuel source or as part of a hybrid energy strategy. As a stand-alone solution, it has often been used in locations that don’t have natural gas available (i.e. rural or edges of metropolitan areas). Lately, it has also been used where natural gas usage is being restricted by local regulations for environmental protection and/or in the interest of reducing fossil fuel use. In both of those cases, propane can help serve these locations with cleaner solutions for space heating, hot water production, cooking, or other residential and commercial uses. In order to help compare costs, even beyond the spark spread, most equipment manufacturers have an economic impact calculator to review the cost-benefit of using their product and the corresponding reduction in grid demand.

In addition to conventional space heating and appliances, there are also innovative propane-powered products available like Combined Heat and Power (CHP), propane cooling, power generation, and even snow melt systems to provide safety and comfort and ensure continuous building operations. Such ongoing operations help building owners limit their liability in the event of power outages—often a genuine economic advantage.

Since propane has been in use for a long time in this country, there are comparable codes and standards for propane equipment just like any other mechanical equipment used in buildings. Propane equipment manufacturers hold certifications for performance and quality control from recognized testing organizations such as UL, CSA, ETL, AHRI, etc. Local and national building codes (e.g., the International Construction Codes – ICC) recognize propane as a fuel source and it can be readily used to meet safety and energy efficiency requirements in those codes. All of this points to the fact that when safe, proven, and cleaner energy solutions are the challenge, propane is a viable solution.

In the following sections, we explore some of the specific energy systems that are being successfully used in buildings and facilities of all types.

Photo courtesy of Propane Education & Research Council

The economics of using propane can be assessed for every building project.

Photo courtesy of Propane Education & Research Council

Hybrid systems effectively combine on-site propane-fueled components with other building mechanical systems.

Hybrid Systems

While propane can be used as a stand-alone system, it is also possible to use it as part of an overall hybrid energy strategy. This can allow building electrical systems to be more appropriately sized and reduce total costs. For example, a recent innovation in hydronic heating systems is to use a propane tankless water heater that is attached to an electric heat pump to replace the need for electric resistance backup heating in colder temperatures. This is accomplished by the use of a hydronic coil custom fit to match a heat pump air handler plus a circulating pump and a control module. The pump moves hot water from the tankless water heater to the hydronic coil, then the heat pump air handler fan blows air across the hydronic coil to heat the building. The results of this type of system commonly include:

• Improved comfort since hybrid heat pump solutions can deliver heat faster and more consistently than all-electric systems.
• Greater affordability compared to all-electric systems—hybrid heat pump solutions are cheaper to run than all electric systems using electric resistance backup heating. They have been shown to reduce operating costs by up to 35 percent.
• Increased efficiency since hybrid heat pump solutions are energy efficient, requiring less electricity use and less overall energy consumption while still improving heating performance.
• Design flexibility for architects and owners considering additions of on-site generation from solar or wind when possible. On-site generation is more efficient since it reduces or eliminates the transmission losses found in the grid. The size of the solar system may or may not be limited by the site or the available access to the sun, meaning a supplemental or hybrid system using propane may make the most sense.

A hybrid propane/ electric heat pump solution can make installation more cost-effective due to the reduced electrical peak and running loads. All of these results will vary, of course, based on the particular details of a building’s location and design and should be reviewed and assessed accordingly.

COMBINED HEAT AND POWER CASE STUDY

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Energy System: Combined Heat and Power (CHP) Units

Application: Industrial and Institutional Facilities

The Challenge: Today, two-thirds of the fuel used to generate power escapes as waste heat, usually through cooling towers.

The Energy Solution: We now have the ability to capture waste heat to create more electricity or to warm nearby buildings with combined heat and power (CHP) systems. CHP units generate electricity and capture the heat that would otherwise be wasted to provide useful thermal energy, such as steam or hot water, that can be used for space heating, domestic hot water, and industrial processes. CHP systems can be located at an individual facility or building or can be a utility resource or part of a district energy system but are typically located at facilities where both electricity and thermal energy are needed. CHP is currently used in over 4,400 facilities across the U.S. including factories, hospitals, colleges, and commercial buildings.

CHP and Sustainability: CHP systems are known for their energy efficiency and environmental benefits because the heat and power are produced on site, eliminating efficiency losses from the power plant. Because they operate efficiently, CHP systems combust less fuel to provide the same energy services. This efficient energy generation reduces various types of emissions, including greenhouse gases (GHGs) such as carbon, criteria pollutants (six common outdoor pollutants regulated by the EPA), and hazardous air pollutants. In addition, they can complement renewable resources such as solar and wind and allow facilities to utilize these intermittent renewable resources while maintaining reliability.

CHP and Resiliency: A 2022 report from the North American Electric Reliability Corp. (NERC) found that large portions of the country are at risk of blackouts as higher temperatures lead to more demand for energy. As much as 44 percent of commercial and industrial companies report power losses at least monthly. While combined heat and power units are used primarily for their energy-efficiency benefits as replacements for high-efficiency water heaters or boilers, some CHP units are available with black start capabilities that allow them to provide standby power when the electric grid goes down, making them effective upgrades to a building’s power resilience. In this mode, they act as a backup source of power for a building’s energy needs, including electricity, heat, hot water, and cooling for residential, commercial, and industrial applications, depending on the model and setup. During a grid outage, CHP systems function in “island mode,” automatically separating a host facility or microgrid from the utility grid and providing consistent power and thermal energy to the facility or facilities connected to the microgrid.

Facility Example: The Southeast Propane Alliance Technical Education Center (SEPATEC) is the leading propane industry trade school for North Carolina, South Carolina, and Georgia. It provides concentrated, career-focused, and hands-on propane training to students looking to start a career in the propane industry. SEPATEC’s 10,000-square-foot state-of-the-art facility in Graham, North Carolina has classrooms and a training area called Propane Village. It features equipment and tools like electrical boards, tanks, gauges, and valves for hands-on learning.

A combined heat and power system was recently installed at SEPATEC, providing another opportunity for hands-on training while allowing the facility to generate its own power. Technically, the CHP was installed as a backup power system, but in reality, it is their primary source of electricity. The CHP is tied to a 1,000-gallon propane tank, which provides space and water heating for the entire facility. The exact run time is dependent on the amount of electricity used, but a 1,000-gallon tank will generally provide about two months of standalone power generation. Going forward SEPATEC’s CHP unit will be a powerful training tool that also provides resilience, reliability, and affordable on-site power generation.

Results: CHP systems have transformative potential in commercial construction. They not only enhance energy efficiency but also significantly cut down on waste heat and emissions, providing both electricity and thermal energy right where it’s needed.

Combined Heat and Power Systems

In many building situations, the owners see the value in having a combination of space heating and electrical power generated from the same equipment. Combined heat and power (CHP) systems have been engineered and fabricated to produce both heat and electricity at peak efficiency. These CHP units use a generator to produce electricity, while also capturing heat that can be used to warm air and water. The result is reduced energy expenditures, eliminating efficiency losses between power plants and buildings, leading to a lower carbon footprint. Essentially, they create an onsite, environmentally friendly, affordable, and reliable energy source independent of the electric grid. Just as with onsite emergency generators, propane offers the same cleaner, quieter, solution for CHP compared to systems that rely on gasoline or diesel fuel. Where resilience and independence from other energy sources are needed, propane-fueled CHP systems can be a viable alternative.

Propane CHP provides energy for critical building systems and infrastructure in hospitality, healthcare, education, business, etc. without any sacrifice. On-site generation frees up the grid and still provides the energy needed for operations and vital systems. The technology is emerging for residential uses too. Units in the 1–3-kilowatt range can provide heat and power for a standard 1,800-square-foot home. Larger homes with greater demands including a pool, or multi-family dwellings would require a unit of 3-10 kilowatts of power. CHP systems can also be designed to work in tandem with other energy sources, including traditional electricity and renewable energy sources like wind and solar, and still provide back-up power and heat as needed.

PROPANE GENERATORS CASE STUDY

Photo courtesy of Propane Education & Research Council

 

 

Photo courtesy of Propane Education & Research Council

 

Energy System: Propane-Powered Electric Generators

Application: All building types

The Challenge: Severe weather events, including hurricanes, tornadoes, wildfires, extreme heat, and major winter storms are growing in frequency and intensity. This significantly affects the country’s electrical grid and distribution infrastructure right at the same time electricity demand may increase (e.g., heat waves increase electricity demand for cooling). Drought can reduce the amount of surface water available for cooling power plants, which reduces the electricity they can generate. High wind events, flooding, and wildfires can take down infrastructure. Data from North American Electric Reliability Corp. (NERC) shows there were 64% more major power outages during the decade from 2011 to 2021 than from 2000 to 2010. Between 2000 and 2021, about 83% of reported major outages in the U.S. were attributed to weather-related events.

Resiliency Concern: It is vital that commercial buildings are able to maintain operations during such weather/ power outage events, not only for life-safety reasons but because a loss in business or product can have major financial implications. A loss of refrigeration, heating, and air conditioning is a significant safety hazard for some, but it can also result in lost inventory, equipment, and infrastructure. Power generation that is independent of the electric grid can provide power and resilience during these severe weather events. Resilience is the ability to function after or during an ongoing natural disaster or accidental power outage.

Energy Solution: Specifying a commercial propane standby generator offers building owners or operators a degree of resilience and peace of mind that they can fulfill orders, maintain inventory, and provide ongoing customer service in the face of catastrophe. A propane standby generator can save a business thousands of dollars by keeping the doors open and the lights on. It allows businesses such as retail stores, manufacturing plants, healthcare, and hospitality facilities to resist hazards brought on by major disasters as well as keeping employees engaged and productive during what would otherwise be downtime. Related to serving customers, patients, or clients, a propane generator allows the necessary services and products to remain available. Altogether, a generator can directly reduce the magnitude or duration of a disruptive event.

Specifying Generators: There are several options for commercial-grade generators, including fuel type and delivery system. Backup generators are powered by either liquid (gasoline or diesel) or gas (propane or natural gas). The availability of these fuels and the ability to replenish the supply after a natural hazard are key considerations. Diesel is the most common fuel used for backup generators, but it has some downsides. Diesel degrades over time and requires the addition of fuel additives to prevent degradation. Diesel generators require more maintenance and are more expensive. They also have greater emissions than propane-powered generators and importantly, diesel and gasoline rely on electric pumps for distribution, which can be compromised in a power outage.

Environmental Aspects: Propane generators can also help to meet carbon reduction goals and limit emissions, as propane is significantly cleaner than gasoline and diesel and is considered a clean alternative fuel by the U.S. Environmental Protection Agency (EPA). In addition, propane is methane-free, emits extremely low levels of nitrogen oxides and virtually no particulate matter, and is becoming more available in its renewable form made from cooking waste products and plants.

Results: “Keeping the lights on” is an age-old adage for every business that now must be taken literally, as power outages and severe weather events are expected to increase in frequency and intensity unless there is a significant change in carbon emissions. Propane power generation via standby generators could be the factor that makes or breaks a business after a severe weather event or power interruption from the grid.

Source: propane.com/2024/09/12/propane-generators-and-chp-systems-provide-protection-and-peace-of-mind-during-severe-weather-events/

PROPANE-BASED EMERGENCY GENERATORS

Power outages from the grid have become more of a concern to a growing number of people around the country. Some of these concerns are based on an increase in weather-related events like storms, wildfires, or other natural disasters. Other concerns can arise from chronic problems with portions of the grid that need updating or modernization. This can also be the case as more homes are built farther from municipal power lines or where electric power is less reliable or completely unavailable. Either way, there is a need for buildings that are designed to increase the resilience of the people who occupy them and allow them to function safely again in light of these concerns.

Stand-by generators have been used in many commercial and residential buildings for years with the interest of providing emergency power for critical operations in a community. These generators improve resilience by keeping electricity available during a power outage and helping to avoid a loss of critical operations. Such generators can also be the primary electricity source where an “off-grid” solution is needed. Where desired, they can be paired with an on-site solar or wind system to provide electricity beyond the capability or availability of the sun or wind.

When considering the options for powering such an on-site generator, propane generators can be considered based on a number of notable attributes. First, they are normally designed to turn on automatically when the power from the grid is interrupted. Second, they have more advantageous characteristics compared to diesel or gasoline-powered generators. Most notably, propane burns cleaner than diesel and gasoline and a propane-powered generator has been shown to be more reliable than gasoline generators. Third, they run quieter than gasoline or diesel generators - many propane generators operate at less than 60 decibels which is about the volume of a normal conversation.

Selecting propane as the fuel means it can be stored on-site without deteriorating over time. If the rest of the building is using propane for other reasons, then the propane storage tank can be sized to accommodate all of the needs accordingly—a separate storage tank isn’t necessarily required. Overall, propane generators are very straightforward to install and easy to operate and maintain.

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Propane can be used for a full range of hot water needs.

EFFICIENT PROPANE HOT WATER SYSTEMS

Propane can be an efficient means to produce hot water in many residential and commercial settings. In addition to hybrid heating and CHP systems, propane can also be used in a stand-alone domestic hot water system in either of two common ways:

• Propane tank type water heaters: his option has been commonly used to heat water using a gas burner instead of an electric heating element. Typically, propane tank water heaters can use the same connections, space, and venting as natural gas models. Of most interest to building users, propane heats water more efficiently than electricity and can cost up to a third less to operate over time.
• Tankless water heaters: This type of on-demand water heater avoids storing and reheating hot water by eliminating the tank. They operate by quickly heating water in a coil over high-output propane burners, then immediately circulating the heated water through the piping to the plumbing fixtures where it is being called for. By heating water only when needed in this way, it can reduce energy usage by up to 50 percent in some cases. That means the initial investment for a tankless propane water heater is typically offset within three years through lower operating costs. The cost is further reduced in many states that offer a rebate on the installation of propane appliances and by federal tax credits that are available for the installation of most propane tankless water heaters.

Tankless propane water heaters typically last for 20 years or more while tank-type water heaters are known to have a comparatively shorter expected useful life. Relatedly, a tankless propane water heater frees up 93 percent of the space used by a tank-type water heater. Finally, propane tankless water heaters provide an endless supply of hot water that is not restricted by tank capacity. Locating the tankless heater close to the fixtures requiring hot water can also reduce water usage where owners or occupants are “waiting for the hot water to reach the fixture.”

When looking at domestic hot water systems, the best results can be obtained by considering all available options, reviewing propane piping requirements, and verifying the needed controls for the solution selected.

AGRICULTURAL CASE STUDY

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Energy System: Gas Driven Chillers

Application: Indoor Agricultural Facilities

The Challenge: Indoor growing facilities, such as cannabis cultivation is surprisingly energy-intensive─about 10 times as much per square foot as for an office building. Energy is needed not just for the electric lighting to help the plants grow which accounts for up to 30–40 percent of the total energy use. Rather, the largest energy use, often making up 50–60 percent of the demand, is for cooling and dehumidification. That’s because cannabis plants are sensitive to moisture and can grow mildew if the air is too humid. This high energy demand for dehumidification equates to high energy costs for cannabis-growing facilities and may even require expensive and time-consuming electrical infrastructure upgrades.

Energy System Solution: Due to the high electrical cost, some growers are turning to innovative, cost-saving alternative technology: chillers driven by propane or gas. The system uses a propane- or gas-powered engine to drive the compressor in a chiller machine to create chilled water while the waste heat from the engine is recovered to create hot water. Powering these energy-intensive chillers with more affordable propane or natural gas instead of electricity can reduce utility costs by 50 percent, according to manufacturers of this equipment. Perhaps just as importantly, these systems can help growers quickly and affordably retrofit industrial buildings for growing cannabis when the existing electrical infrastructure is insufficient.

Building Example: A cannabis grower in Douglas, Massachusetts, converted an old factory building that made envelopes to more lucrative cannabis cultivation. Many old buildings of this type are electrically constrained and at the mercy of the electrical utility to upgrade. This grower had been told it would take 18 months to 36 months to upgrade the power, but growers don’t have that kind of time to wait. The current situation in the cannabis market is such that in three years, the price is expected to be cut in half. So, time really is money in this business.

Instead, of waiting to upgrade the building’s electrical power capacity, the Douglas grower brought in a gas driven chiller unit that eliminates the need for additional power from the utility. Since the closest natural gas lines were eight miles away, the facility used an existing on-site 30,000-gallon propane tank to fuel the gas driven chiller.

Broader Agricultural Applications: Gas driven chillers have long played a role in institutional buildings such as universities and hospitals for comfort cooling. Its application in agriculture and food and beverage business is foreseen to play a larger role in facilities that use process cooling all the time. Gas driven chillers have a proven track record of running 24/7, 365 days a year with a really high degree of uptime and reliability. That is typically what process-cooling customers really want to see. Cannabis cultivation is leading the way as a smart application for gas-driven chilling because these facilities need cooling year-round. Growers of lettuce, leafy greens, and herbs are also using these types of systems, although their plants aren’t quite as dependent on dehumidification as the cannabis plant.

Resilience Aspects For businesses seeking to enhance resilience, gas-driven chillers can help reduce not only the amount of electrical infrastructure they need but also the size of their backup power generation equipment. Given their intensive energy demand, many cannabis growers are installing 2-megawatt or 4-megawatt generators to protect the crops they’re growing, which may be worth up to $10 million at any given time. By shifting some of the electrical demand to propane or gas, businesses can cut the size of the generator in half, saving millions of dollars by purchasing a more affordable unit.

Environmental Aspects: Powering the chilling with high-efficiency propane can also help to reduce greenhouse gas emissions in many parts of the country where the power grid comes from plants burning fossil fuels such as coal. A hybrid-drive chiller that can run on propane, gas, or grid power has also emerged on the market. While this adds additional resilience by allowing the unit to run on electricity if there’s a fault in the engine, it also allows the operator to choose whether the system runs on propane or electricity based on energy costs or carbon footprint considerations. If the grid electricity becomes 100 percent renewable in the near future, the hybrid unit can switch over to all-electric. If not, then operators have the option to still run it efficiently using propane or gas.

Results: By proving the real-world performance and efficiency of gas-driven chilling, cannabis growers may provide the innovative spark that spreads the cost-saving technology throughout the building industry.

Source: propane.com/2022/06/08/cannabis-growers-are-adopting-an-energy-saving-innovation-bwp/

CONCLUSION

All buildings need energy and owners often look to architects and other design professionals to advise them on the best way to purchase and use that energy. By considering propane systems as a primary, hybrid or secondary energy source, then all options can be reviewed and compared. Based on that, propane is often specified in projects where energy efficiency, resiliency, and reliability are part of the project requirements.

Peter J. Arsenault, FAIA, NCARB, LEED AP is a nationally known architect who has authored nearly 300 continuing education courses focused on advancing building performance through better design. www.pjaarch.com, www.linkedin.com/in/pjaarch