PROPANE-BASED 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 storm events, wildfires, or other natural disasters being intensified by climate change. 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 for them to function safely again in light of these concerns.

Photo courtesy of Propane Education & Research Council

Propane-powered generators can start automatically and provide reliable back-up electricity during a power outage.

Photo courtesy of Propane Education & Research Council

Propane powered combined heat and power systems offer a complete energy solution to address all of the energy needs of a building.

Stand-by generators have been used in many commercial buildings for years with the interest of providing emergency power for critical operations in a community. Homeowners have followed suit in recent times as residential-sized systems have become available and more affordable. These generators improve homeowner resilience by keeping electricity available during a power outage and helping to avoid a loss of critical operations at home too. 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 house is using propane for other reasons, then the propane storage tank for the home can be sized to accommodate all of the needs accordingly–a separate storage tank isn’t required. Overall, propane generators are very straightforward to install and easy to operate and maintain.

COMBINED HEAT AND POWER SYSTEMS

In many building situations, particularly large homes or smaller light commercial applications, the owners see the value in having a combination of space heating and electrical power being 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 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.

Although CHP systems are more common in commercial and industrial applications, 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.

Overall, propane-powered CHP systems can be designed as an environmentally friendly, affordable, and reliable energy source that won’t go down with the electric grid.

CONCLUSION

Architects face a lot of choices and decisions in the quest to design buildings that are architecturally compelling and perform well in terms of energy use and environmental impact. While many options are available, there are also trends suggesting that all-electric solutions are preferable. However, as discussed here, the current realities do not yet seem to match up with ideal goals. Further, some building situations are not conducive to only grid provided electricity. Given the comparatively better environmental performance of propane compared to other options, and the emerging availability of renewable propane, systems that use this fuel are worthy of consideration. Design professionals can readily specify propane systems today in buildings where energy efficiency, resiliency, and reliability are part of the project requirements.

Net-Zero-Energy-Ready Case Study

Photos courtesy of Propane Education & Research Council

Project: Net-Zero-Energy-Ready Home
Location: New Fairfield, Connecticut
Designer: Chris Trolle/BPC Green Builders

The Challenge: To create a net-zero-energy-ready (ZER) LEED Platinum home in a rural lakeside location in Connecticut.

Energy Conservation Solution: Chris Trolle is co-founder of BPC Green Builders. He points out “With each of the [Zero Net Energy or Zero Energy Ready] homes we do, we focus on a very robust thermal envelope.” This project features a highly insulated, airtight envelope incorporating double-wall construction with R-33 blown cellulose insulation, an R-72 roof, and triple-pane low-e windows.

Energy System Solutions: Although ZNE construction relies heavily on the efficiency of the building envelope, the home’s performance can benefit from optimizing systems as well. First, the house meets all of the criteria to install a 9-kilowatt (kW) solar photovoltaic (PV) system to meet the electricity needs of the house. An electric-powered air-source heat pump heats and cools the space while an energy recovery ventilator brings in fresh air, all with nearly zero duct leakage. For heavier loads of winter space heating and domestic water, a hybrid approach was incorporated to supplement the electrical components. “The fuel the client chooses to use is based on their budget and local availability,” says Trolle. Since propane is a cleaner alternative to fuel oil and can be used nearly anywhere, including beyond the natural gas grid it was the fuel choice in this case. To keep the home warm during the coldest part of Connecticut’s winters, a 90 percent AFUE propane boiler with an appropriately sized propane tank serves an in-floor radiant heating system on the first level. Propane also provides domestic hot water heating. Instantaneous gas combination boilers are an energy-efficient option for space and water heating “with a very compact unit,” Trolle says. Because of their size, these tankless units can be located close to the point of use to reduce energy lost while transferring hot water throughout the home.

Results: All of the energy-related features help the home earn a code-recognized Home Energy Rating System (HERS) score of 39. At the time it was completed, adding a 9kW PV system would have brought it down to a HERS score of 2.

Off-Grid House Case Study

Photos courtesy of Propane Education & Research Council

Project: Off-Grid Home
Location: Barters Island, Maine
Owner: Patricia Seaward

The Challenge: To create an off-grid home in rural Maine in order to both protect the environment and meet the energy needs of the home. Independent by nature, the owner, Patricia Seaward chose an off-grid lifestyle after a career working at the Maine Department of Environmental Protection. She commented, “Once I received a quote from Central Maine Power, I realized that the components for solar electricity were only a few thousand dollars more than being grid-tied. I rationalized where I worked and decided that I could lead by example. It was more the philosophy, doing my part for the environment, that attracted me.”

The Solar Energy Solution: Seaward hired Albert Monaco, an electrician experienced with solar generation, to design her home’s off-grid, battery-based system. Monaco, owner of Oyster Creek Electric and Solar Options in Alna, Maine, installed a 2.5-kW solar photovoltaic array to power the home and charge the batteries. But for peace of mind, and with the size of her roof limiting the number of solar panels that could be installed, both Monaco and Seaward knew the home would need a source of back-up power. “Because of the days being so short in our winters, on some days you can’t produce enough power [with the solar panels],” Monaco says.

The Back-Up Energy Solution: Seaward considered wind-generated back-up power, but the cost was prohibitive. Therefore, to keep the home running year-round, Seaward turned to propane back-up power as the most cost-effective and environmentally friendly option. “My job at the Maine Department of Environmental Protection entailed working with homeowners whose wells were at risk or contaminated by various petroleum products,” she says. “As I live on the top of a hill, any petroleum spill could impact more than my property.” Her neighbors would have little use for their water wells if they were contaminated, and diesel fuel has the potential for contamination from spills and leaks that are retained in the soil. Propane doesn’t spill, pool, or leave residue, so it’s not harmful to soil or water in the unlikely event of a tank leak. Monaco installed a 2-kW propane generator with the start mechanism tied into the voltage of the batteries. When the batteries are depleted to a certain voltage, the generator automatically kicks on until the batteries are replenished to 80 percent.

The Results: When the power’s out in their neighborhood, Patricia Seaward’s neighbors grind their coffee beans at her house. Her coffee grinder, and the rest of her off-grid home in Barters Island, Maine, keeps running in any weather condition thanks to the two resilient sources of power: solar and propane.

Peter J. Arsenault, FAIA, NCARB, LEED AP is a nationally known architect and a prolific author advancing better building performance through better design. www.pjaarch.com, www.linkedin.com/in/pjaarch