Geothermal Systems

Save Money as You Save the Earth

Geothermal systems not only give homeowners the satisfaction of doing their part in building a cleaner energy future, they also save them money on heating and cooling cost every month, rain or shine.

One of the best energy sources underground isn’t a fossil fuel, it’s the earth’s natural heat. Geothermal systems tap into the consistent temperature beneath all of us to warm a house in winter and cool it in summer.

Today, over 700,000 homes in the United States use a geothermal heating and cooling system, including over 8,000 DTE Energy customers in Michigan. Still not convinced geothermal systems are a dependable energy generation technology? Geothermal systems have a national customer satisfaction rating of over 90 percent.

Geothermal Benefits

Every day, geothermal systems save homeowners on their heating or cooling costs. In fact, operating costs savings range between 30 and 60 percent.

Environmentally Friendly
No fuel, no fumes. Geothermal systems take advantage of the heat already stored in the earth. It doesn’t get more natural than that.

Winter, spring, summer and fall, geothermal systems help homeowners maintain an even temperature and humidity level throughout their homes.

With no open flames and no soot, geothermal systems are completely compatible with living in a secure and future-focused home.

Not only does a geothermal system assist with heating and cooling, it also contributes to water heating as well.

Geothermal systems are as reliable as the sunrise. This proven technology operates on few moving parts, has no outdoor equipment and requires little maintenance.

Properties featuring these geothermal systems have increased value and generally produce higher cash flow.

Compared to traditional heating and cooling units, geothermal systems are as much as four times more efficient than conventional systems.

Geothermal Heating Cycle

A geothermal system consists of three components: a heat exchanger to collect the heat from underground, a compressor to enhance the heat, and a fan to distribute the heated or cooled air through a standard duct system. Here’s how it works.

A. Ground Loop
An environmentally safe water and antifreeze solution is pumped through a system of looped polyethylene piping buried underground. As the solution circulates, it absorbs the earth’s heat.

B. Pump
This pump forces the water and antifreeze solution through the buried loop system.

C. Refrigerant Loop
Liquid refrigerant flows through this tube, headed toward the evaporator.

D. Evaporator
As the liquid refrigerant flows through the evaporator (at this point, it’s in a tube within a tube) and absorbs the heat of the ground water, it changes from a liquid to a gas.

E. Compressor
In the compressor, gas from the evaporator is pressurized, raising the gas to a temperature of 180 degrees Fahrenheit.

F. Refrigerant Loop Outlet
The 180 °F gas is conveyed from the compressor to the radiator.

G. Radiator
As the heated gas from the refrigerant loop circulates through the radiator, the radiator fins absorb the heat of the gas through conduction.

H. Distribution Fan
This fan pulls air over the radiator fins, which have absorbed heat from the compressed gas. The warm air is then distributed throughout the house, via the house’s ductwork system. As the gas in the loop system loses heat, it changes back to a liquid and the cycle starts all over again.

Geothermal Energy Rate

DTE Energy is pleased to support the adoption of geothermal systems with a special geothermal option that could save you approximately 50 percent off the regular heating and cooling rate. See our Rate Options to learn about all the wide range pricing choices we offer.

The Geothermal Rate Is a Time-Of-Use Rate
Your geothermal rates varies depending on the time of day. You’ll pay a higher rate during on-peak hours (11 a.m. to 7 p.m., Monday through Friday) and a lower rate during off-peak hours.

The average home uses 75 percent of its energy during off-peak hours. If after installing a geothermal system your on-peak hours comprise more than 25 percent of your usage, consult the dealer who installed your system.

Seasonal Rates Apply to the Geothermal Rate
The geothermal rate is also a seasonal rate, meaning you’ll pay one rate during the summer (June through September) and a different rate during the winter (October through May).

Qualifying for the Geothermal Rate
Residential and business customers must meet specific requirements to qualify for the geothermal rate. In addition to installing a geothermal system, customers must have a licensed, independent, electrical contractor install the wiring for a separate geothermal meter (D1.7).

Qualifying homes or businesses must have either geothermal ground source heat pumps or a split system with a natural gas, propane or an oil booster (if the geothermal heat pump is designed to operate at least 80 percent of the time). Air source heat pumps qualify for rate code 086, with a D1.1 meter. This is the same rate as the interruptible air conditioning rate. DTE Energy does not interrupt during the heating season (October through April).

Contact DTE Energy customer service at 800.477.4747 to request installation of the meter once the wiring is completed. Refer to the D 1.7 meter and rate code 036 when speaking to your customer representative.

Items Measured on the Geothermal Meter
Your Geothermal Rate will be applied for energy used by your furnace, fans, motors, electric water heater, electric resistance heat and well pump (if it is on an open loop geothermal system).

Learn More Before You Dig

Geothermal systems are an easy to operate technology, the perfect way for many homeowners to reduce their environmental impact without sacrificing comfort.

Whether you’re considering a system for a new or existing building, speak with one of our service planners before you start. Your DTE Energy expert will check to see if your existing electrical equipment can handle the extra load, allowing you to build your geothermal system for maximum returns.
How Geothermal Systems Work

As a Michigander, we don’t need to tell you the outside temperature varies in our home state from sweltering to freezing (with seemingly little in between). What you may not know is that no matter the season or the weather, the temperature underneath us is always warm.

Geothermal systems tap into that steady supply of underground warmth, usually 50 degrees Fahrenheit, and transform it into an endless supply of renewable energy. Best of all, it does it with proven, easy to maintain technology.

The key to harnessing geothermal energy is an electrically powered water source heat pump (similar to your refrigerator). It is connected to a continuous loop of polyethylene pipe filled with an environmentally-friendly liquid solution buried in the ground outside the house.

During the winter, the solution goes through the loop and absorbs heat from the earth, which is used to create warm air (or hot water for radiant floor heating). During the summer, the hot air from the house is fed into the ground through the piping, where it is cooled and then returned to the house.