Friday, July 27, 2007

A Refrigerator-Freezer Strategy for Energy Efficiency, Saving Money, and Eating Healthy

At first glance it might seem that a small refrigerator is a better “green” choice than a larger one, but for most households this is simply not true. While a small refrigerator probably uses less energy than a larger one, you’ll also find yourself making more trips to the grocery store. You might save a few dollars on your electric bill to operate the smaller fridge, but you’ll spend much more than that on gasoline for the extra trips to the store.

A properly-sized refrigerator and a chest freezer is the best overall strategy for most families. A top-loading freezer is inherently energy-efficient because the cold air doesn’t “fall out” when the door is opened as it does with any freezer that has a side door. Adding to their efficiency, a typical chest freezer doesn’t have other energy-consuming features such as a light or a fan.

Not only does a chest freezer allow you to stock up on long-lasting items from the grocery store, it also allows you to preserve items grown in your garden during the summer months. Growing your own food not only cuts your grocery bill, home-grown foods are usually healthier and tastier than the same items when purchased at the grocery store. Since I’ve started using a freezer, I’ve increased the size of my garden. This ensures that I’ll have plenty of fresh produce and plenty to save in the freezer. And since I save seeds, my home-grown produce is almost free! If you’re not into gardening, you can stock up on locally grown food in the summer by visiting a farmer’s market.

If you’re about to purchase a refrigerator or freezer, be sure to look for those that have earned the “energy star”. If you’re replacing one that is over ten years old, you might save 50% or more on your electric bill. A 21 cubic foot energy star-rated refrigerator might use 430 kWh per year, or about 1.2 kWh per day. At ten cents per kWh, it will cost about $43.00 per year to operate. Actual results depend not only on your electric rate, but also on how you use it and where it’s located in your home. A small energy star-rated chest freezer might require 300 kWh per year, costing you about $30.00 per year to operate. The basement is a better location for the freezer than the garage because it’s cooler there, causing the compressor to run less frequently. The heat that the freezer produces is often desirable in a cool basement.

A small photovoltaic (PV) system can be used to provide backup power in order to prevent your food from spoiling during an extended power outage. I chose a PV system instead of a generator because it is quieter, less expensive to operate, and I don’t have to store fuel. As a bonus, my PV system provides power to the freezer on a continuous basis, cutting my electric bill. Since my PV system is not large enough to power both the freezer and refrigerator, I’ll use the PV-powered freezer to produce ice which can be used to keep refrigerated food from spoiling during an extended power outage. When I’m able to enlarge the PV system, I’ll add the refrigerator to the load. Currently, I have 340-Watts of solar panels, and 420ah of battery capacity. The PV system is able to meet the energy requirements of the freezer, except when cloudy conditions persist for several consecutive days. When that happens, I run the freezer on grid-supplied power until the batteries are recharged by one or two days of sun.

Transitioning into a future where fossil fuels are declining does not necessarily mean that we will have to do without comforts that we’ve become accustomed to, but we’ll have to do things differently. Recent innovations, like compact fluorescent lights and energy efficient appliances, show that we’re able to adjust to these conditions without giving up anything. This trend is likely to continue, radically changing the vehicles we drive and other products we use. Changing your food preservation strategy is a good, healthy way to begin your journey into the future.

My Garden - July 2007
Solar John

1 comment:

Damon Hart-Davis said...

Hi SJ,

You may be interested to know that on a smaller scale my main home Internet-facing server for Web/mail/etc is now powered off-grid when there is 'excess' solar power (more than 50% battery capacity remaining and the sun is shining, basically) leaving some juice for off-grid lighting.

You can see the off-grid stats at:

Your battery SOC article was VERY helpful in designing this system!