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Modeled after the Defense Advanced Research Projects Agency (DARPA), the Energy Department’s Advanced Research Projects Agency-Energy (ARPA-E) funds game-changing energy technologies that are typically too early for private-sector investment.

From new wind turbine designs and transportation fuels made from bacteria to innovative energy storage solutions and smaller, more efficient semiconductors, ARPA-E projects have the potential to change the way we generate, store and use energy. The program continues to invest in technologies that could radically improve U.S. economic prosperity, national security and environmental well being.


#AskEnergySaver: Home Water Heating
Did you know: Water heaters account for nearly 17 percent of a home’s energy use, consuming more energy than all other household appliances combined. For more about water heaters, check out our <a href="/node/612476">Energy Saver 101 home water heating infographic</a>. | Photo by Eric Grigorian, U.S. Department of Energy Solar Decathlon.

Answering your questions about water heaters -- from the best type of water heater for you to low-cost actions you can take to cut your water heating bill.

Estimating Costs and Efficiency of Storage, Demand, and Heat Pump Water Heaters
A water heater's energy efficiency is determined by the energy factor (EF), which is based on the amount of hot water produced per unit of fuel consumed over a typical day. The higher the energy factor, the more efficient the water heater.

Calculating the efficiency and operating cost of your water heater can help you decide which model is right for your household.

Reduce Hot Water Use for Energy Savings
One easy energy lifehack: fix leaky faucets to save money and energy.

Fixing leaks, using low-flow fixtures, and buying energy-efficient appliances can help you save on water heating bills. Here are some simple steps you can take.

Solar Water Heaters
Solar panels heat water that is delivered to a storage tank.| Photo courtesy of David Springer, National Renewable Energy Laboratory

Solar energy isn't just for electricity. Learn how a solar water heater works.

Tankless or Demand-Type Water Heaters
Diagram of a tankless water heater.

Looking to save money and energy? A tankless water heater might be the right choice for your small household.

Storage Water Heaters
Consider energy efficiency when selecting a conventional storage water heater to avoid paying more over its lifetime. | Photo courtesy of ©iStockphoto/JulNichols.

Installing a storage water heater? Learn about selecting, installing, and maintaining a storage water heater.

Drain-Water Heat Recovery
Diagram of a drain water heat recovery system.

Did you know that you can use heat from water that you've already used to preheat more hot water -- and reduce your water heating costs?

Swimming Pool Heating
You can reduce the cost of heating your swimming pool by installing a high-efficiency or solar heater, using a pool cover, managing the water temperature, and using a smaller pump less often. | Photo courtesy of ©iStockphoto/herreid

Own a swimming pool? Find strategies to reduce the cost of heating your pool.

Living Comfortably: A Consumer’s Guide to Home Energy Upgrades
A weatherization worker drills holes to blow cellulose insulation in the interior walls of this home. | Photo courtesy of Dennis Schroeder, NREL

A four-step guide to making your home more comfortable, energy efficient and healthy.