We’ll be running various small-scale concurrent research projects here at the institute, but each year we’ll focus our attention on a specific problem. This year we will look at hot water. A formal research proposal, funding requests, and volunteer opportunities will be coming out this spring, but for now, I’ll be posting initial information and draft plans here. Of course all results and DIY instructions will be published on our website.
The Problem: Home and Water Heating Accounts for Majority of Domestic Energy Use
According to the 2009 Residential Energy Consumption Survey (US Energy Information Administration, latest available data), 59.2 percent of domestic energy consumption goes to heating the home (41.5 percent) and water (17.7 percent). While this is down from the 53.1 and 18.3 percent, respectively (71.4 percent total) used for the same purposes in 1993, it is still a majority of home energy use. Most of that energy comes from domestic electricity and natural gas: 9.3 percent of electricity goes to heat air and 9.8 percent goes to heat water, while 62.7 percent of natural gas goes to heating the home and 26.1 percent goes for heating water (source).
Individual households are using about 38.7 million BTU for space heating and 16.0 million BTU for heating water annually (source). A British Thermal Unit (BTU) is the amount of energy necessary to raise one pound of water one degree Fahrenheit. Space heating needs vary by season while hot water is a steadier utility.
The Solution: A Reservoir of Heat from Diverse Sources
While it is convenient to use electricity and natural gas for home air and water heating, these resources are finite (in the case of natural gas and electricity generated from coal, natural gas, or oil) and will likely increase in cost if history is any guide. Natural gas was steady earlier in the last century: $1.04 in 1930 through $1.03 in 1960 but shot up to $4.21 in 1980 and has remained above $4.00 until fracking lowered its price below that point more recently (source; all values in 2010 dollars [inflation adjusted here]); the only thing certain about future natural gas prices, though, is that they will eventually rise as the new sources begin to be used up. The cost of electricity has risen steadily from 2.6¢/kWh in 1960 to 11.5¢/kWh in 2010 (source).
On the other hand, sun and wind are continuous resources and their only associated cost is equipment and installation. Most places in the US have enough solar radiation to provide for their domestic use. The same is true of wind power, although it is not commonly used for domestic heat applications.
Detractors will argue (correctly) that the sun does not shine brightly enough every day and wind can be intermittent, but by using these two sources in conjunction with one another, the homeowner must only worry about times when neither the sun is shining nor the wind blowing, which is considerably less often than each individually.
Another common complaint about solar and wind energy products is the storage problem, that is, what types of batteries are used to store the energy from times of surplus for later use. In this case, energy would not be stored in the form of electricity but rather heat: a hot-water reservoir would serve as the “battery” of this system and any inefficiencies only serve to heat the house.
More to come on this project in the next few posts.