Works well but

Yup, they eat energy.

An electric dehumidifier includes a refrigeration cycle that is very similar to a window AC units and refrigerators. They cool the air in the basement to condense and collect water and remove humidity, heat the air as a required consequence of the refrigeration cycle and dump it back to your basement.

Two sources of humidity in basements include warm outside air that naturally cools due to below grade earth contact and water passing from the ground though the floors and walls and evaporating into the basement. Dehumidifiers do most of the work in the summer when higher temperatures outside enable air to hold more water content.

In the winter, cooler outside air contains less moisture by weight eventhough it may be raining and the relative humidity in basement will be less because the air is warmed relative to the outside. The lower moisture content in the winter also absorbs the water passing through the walls and floor.

From an energy perspective, you may want the humidity set NOT below 50%. This will keep humidity below the level mold desires, but prevents the dehumidifier from doing more work and eating more energy than needed. A cheap battery powered temp/humidy meter left in your basement will help. Sources that include the "mold triangle" (temperature, water & food) often separate fact from expensive hype.

If the dehumidifier doesn't keep up, consider adding a moisture barrier to the basement walls and floors such as Dry-lock and floor paints to ****** moisture entry. Moisture barriers act very similar with water as insulation does with heat. They don't eliminate the need for a dehumidifier, but they reduce the work they do and energy they eat.