In 2014, energy technology featured prominently in the headlines. Our recent report Top 22 Technologies and Trends of 2014 gives details about the most buzz-worthy technology topics. Here, we present the top 5 of our total 22.

5. The Battle of the Electric Water Heaters Rages On

In 2014, the debate over a US Department of Energy (DOE) ruling on electric water heaters continued. The proposed rule could potentially ban electric resistance water heaters (ERWHs) over 50 gallons in size, supplanting them for heat pump water heaters (HPWHs). Some proponents of the rule, including the Northwest Energy Efficiency Alliance and HPWH manufacturers, claim that HPWHs work just fine for demand response (DR) and other storage services, and that the energy-efficiency improvement over ERWHs offers a large societal benefit. On the other side of the debate are some rural utilities, grid operators with large penetrations of renewable energy, and manufacturers of grid-interactive water heaters that claim that ERWHs work better for storage and grid-balancing applications. It’s not clear how the DOE will rule, and the industry awaits its April 2015 decision. We’ve yet to find persuasive evidence that HPWHs can work effectively for DR or grid stabilization. Until we see a comparison of how the societal benefits of the improved efficiency of HPWHs stack up to the energy storage and grid-balancing capabilities of ERWHs, we maintain that both technologies are valuable for their respective purposes.

4. Tesla’s Gigafactory: A Paradigm Shift for Li-Ion Batteries

The expense and low availability of batteries for electric vehicles (EVs) have limited the growth of the EV market. To help drive down the price of lithium-ion (Li-ion) batteries and ensure that production will be high enough to satisfy demand for its EVs, Tesla Motors announced that it would build a $5 billion Gigafactory near Reno, Nevada, to produce the batteries. The company estimates that by 2020 it will be producing enough Li-ion batteries to power 500,000 EVs annually—that’s more than the current combined production of all Li-ion manufacturers worldwide. At this scale, Tesla speculates that it will be able to reduce the per-kilowatt-hour cost of Li-ion batteries by at least 30 percent starting in 2017.

The Tesla Gigafactory will likely be around 10 million square feet in area, or the equivalent to 174 football fields.

This image is an artist's rendering of Tesla's Gigafactory.

3. Laundry Gets an Energy Makeover

Laundry technologies may not be as sexy as some of the other technologies, but we couldn’t help but marvel at the innovative products we saw in 2014. Residential ozone retrofit products, already established in commercial settings, are showing early promise in field trials. Also in 2014, the first-ever Energy Star–qualified clothes dryers hit the market. Fourteen gas, heat pump, and conventional electric models, all from LG, are available.

According to its manufacturer, the WashIt residential ozone laundry retrofit device can yield a simple payback period of less than a year through a combination of water, energy, bleach, softener, and detergent savings.

This is a photo of the WashIt residential ozone laundry device.

On the commercial side, polymer bead and liquid carbon dioxide clothes-washing products emerged with the potential to save water and energy. In commercial drying, two new technologies caught our interest: the DrySmart retrofit moisture sensor, which claims gas savings of 15 to 30 percent, and a modulation device called BiO-Therm that limits gas burner output to only what’s needed. All of these new technologies may not pan out, but we’re excited by the innovation in this energy-intensive and often-neglected application.

2. Google Buys Nest: The Acquisition That Launched a Thousand Protocols

It almost seems like ancient history, but it’s been less than a year since Google acquired thermostat company Nest Labs for $3.2 billion. The move marked the beginning of an all-out race to own the smart home industry. By the end of 2014, there were a nearly infinite number of protocols, alliances, start-ups, new widgets, and hype. Here are some highlights:

1. LED Tubes Now Viable for Some Applications

Look up at any ceiling in a commercial building and you’re likely to see lighting fixtures filled with fluorescent tubes. Putting the most-efficient tubes and ballasts into these fixtures has long been a goal of utility demand-side management programs, and putting in tubular LEDs (sometimes called TLEDs) has long been a goal of LED lamp manufacturers. But until recently, testing by the DOE of these TLEDs has yielded disappointing results in terms of quality, quantity, and light distribution. This year marked the first time the DOE found that some of the products may be viable alternatives to fluorescent lamps. However, the DOE urges caution, noting that though some good products are available, there are still a lot of bad ones. And even with the good ones, performance will vary with the type of fixture they’re installed in.

Want to know more about the 17 other technology trends we tracked in 2014? Check out the full report.