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  • Writer's pictureJeff Mathias

Fuel Switching and Energy Storage Design.

Fuel switching and battery storage.

One of the common trends in the residential building community is what I term “fuel switching”. The concept of fuel switching is the movement away from fossil fuels like natural gas, propane, diesel and gasoline in favor of electric sources. This is being done in the fight to reduce global warming and reducing carbon that is released when fossil fuels are burned. New research shows that one of the biggest greenhouse gases causing global warming is methane (EPA). Methane is released during the harvesting of natural gas and the leakages in the distribution systems of natural gas. These can be over one hundred times worse for global warming than what comes out of a car’s tailpipe. So how does switching to electric appliances help reduce our carbon footprint? In Sonoma County, our generation company, Sonoma Clean Power, is taking major steps to increase the usage of renewable energy to reduce the reliance on fossil fuels. They offer electric plans which are over 90% carbon free to their standard customers, with an option for 100% carbon free and renewable at an additional cost (Evergreen). The idea is that as they move closer to 100% carbon free, the improvement is seen by all their users, and has a more significant impact. If you are planning on adding a energy storage system to your home, ensure your future decisions for fuel switching are considered into the mix when sizing your system. Let’s look at some examples of fuel switching some common appliances in a home and see how these changes could affect battery storage.

  • Change hot water heating from natural gas-propane (NG-P) to electric heat pumps or electric water heating.

Many propane (NG-P) water heaters have a pilot light requiring no electrical needs. New NG-P water heaters and on-demand water heaters require a very small electrical usage for the gas igniter. When calculating storage needs of an all-electric water heater, it is important to consider the electrical requirements because the surge and kilowatt usage of heating water with electricity can be significant. The two primary types of electric water heating are standard electric element water heating and newer electric heat pump water heating. I would highly suggest heat pump water heaters because even though the upfront cost maybe higher, they are significantly more efficient than standard electric water heaters. While all devices vary, heat pumps typically use a third as much energy (1,500-2000 watts per hour) as the older electric technology (3,500-5,500 watts per hour). If you want hot water in an outage, make sure your storage system can handle this increased load for whichever water heater you select.

Change space heating from forced air furnaces to heat pumps and mini-splits. Many homes have a forced air furnace run by natural gas and propane (NG-P). When we tie these appliances to battery storage, we need to include the igniter (a small load) and the blower fan (usually a medium load). Fuel switching space heating requires a little thought. A whole house heat pump that replaces a gas furnace and uses the existing venting to heat or cool the home (they can also replace A/C). These units are usually 40-70-amps which is too large for most storage systems. If you want a whole house heat pump, an alternative heating source (wood or NG-P fireplace, space heater or mini-split) needs to be designed into the system for when the power is out. At my home I have installed a mini-split (not vented) heat pump that runs on 20-amps and is very efficient. Mini-splits can be installed as a supplemental heater (like in my home) or multiple splits installed for the whole homes heating needs. Because these units are usually 20-amps or less, a single mini-split can often be backed up with the proper storage design.

  • Change a gas stove to an induction stove.

NG-P stoves and ovens are being replaced with electric ovens and induction cook-tops. These electric substitutes are 40-50 amps and not the best options for battery storage. The primary cooking devices we connect into the battery storage in these situations are the microwave and kitchen plugs (to use an induction hot plate). Many of my customers have come up with some very creative solutions during an outage including using the barbeque more and propane cook stoves.

Change a personal car or motorcycle from gas or diesel to electric. Electric transportation, while still a small percentage of total transportation, is growing fast and makes sense for both the environment and when homeowners have solar. Most electric vehicles (EV) have timers that allows them to choose the most efficient time to charge, usually in the early morning. If we tie the EV chargers to our storage system and the power goes out while we are sleeping, the entire home storage battery could be transferred into the vehicle. One solution we use in our design, is to install a garage or outside 110 v plug so that we can trickle charge the EV, usually after the home storage is fully charged by the solar. Also since most EV chargers are 30-100-amps, most are to large for storage systems.

  • Change those personal 2-stroke power tools, weed-whackers, chain saws and leaf blowers to the electric or manual counterpart.

Since this is usually a minor electrical load it can be easily designed into any home storage system.

  • Changing out your gas clothes dryer to an electric dryer or manually hanging clothes.

Usually electric clothes dryers are not put on storage systems, as hanging clothes is an easy option. It is possible with a properly sized system and a little manual control (turning off other unneeded loads) to have a clothes dryer as part of the design. All-electric appliances and electric transportation are becoming the trend. Cities like Berkeley and Santa Rosa are no longer allowing gas appliances for new home building. Many auto makers are transitioning to all electric models over the coming decade. And more and more research points to the harmful effects of methane on our environment. I think it is safe to say, the move to electric appliances powered by renewable energy and away from fossil fuels in our homes and vehicles is a question of not if, but when. These are important parts of the design process. In preparation for these more environmentally sound power sources, we must anticipate the need, be creative and design our storage systems accordingly. And with the newly pass Inflation Reduction Act, there are many new rebates and credits to help reduce the up front costs.

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