reliable- humans can predict the power output of a geothermal power plant very accurately
In the future, geothermal energy is expected to grow
In the U.S., low temperature geothermal energy is available everywhere
When you harness geothermal energy, there is no involvement of fuel/fuel burning, which means less cost fluctuations(Think of a fluctuation as a "up and down swinging change") and stable electricity prices
of course....RENEWABLE! It can also sustain its consumption rate.
Cons
construction of geothermal plant can cause instability of Earth's crust(this means that Earth's crust is not stable), and in turn, sometimes cause an earthquake(this happened in Iceland, year: 1997)
greenhouse gases tend to be closer to geothermal reservoirs, so geothermal reservoirs are known to contain traces of toxic heavy metals like mercury, arsenic, and boron
geothermal plants that do not have a closed loop system do emit emissions that would be harmful to the environment if they were released in much larger amounts, but luckily, geothermal emissions' effects are "tiny" on the environment in comparison to nonrenewable plants
most efficient reservoir is dry steam, but they are unluckily very rare