This article is part one of a short series for October’s National Energy Awareness Month by National Geographic Geography Intern Hannah Dempsey.

We live in a time where oil is a highly politicized, billion-dollar industry. Where mountains are destroyed so we can pick at the coal buried underneath. Where climate change threatens our coffee beans.

Pick a reason: politics, money, or the environment, we need a crazy amount of renewable energy.

Solar, wind, and hydroelectric all have advantages and disadvantages, but I think these energy sources get enough attention. For National Energy Awareness Month, I want to talk about the unsung renewable energy options.

First up: tidal energy.

What exactly is tidal energy?

Tidal power is extremely predictable and vastly underused (as predictable as the tides). We are still hunting for the technology to efficiently capture the natural rise and fall of the ocean’s tides. This technology needs to both withstand battering waves and, most importantly, be economically viable.

There are a few different ways we can capture tidal energy, but the general principle is changing tides run through turbines or turn paddles to generate electricity.

Currently, there are only a handful of operational tidal power stations. The largest station is in South Korea and produces 254 megawatts (that’s a little less than half of the average coal plant and 10 megawatts can power about 10,000 American households); the oldest was constructed in 1966 in France and still produces up to 240 megawatts to this day. The other tidal power stations live in Canada, China, Russia, and the United Kingdom.

Why aren’t we utilizing tidal energy?

There are several barriers to the proliferation of tidal energy, the first and most obvious being access to the ocean. Landlocked countries need to rely on more traditional hydropower technology with rivers rather than the ocean’s tides. (NASA has an excellent tide map project here.)

Second, the technology is still somewhat experimental despite pilot projects in Australia and Scotland and the aforementioned existing power stations.

Lastly, the investment needed to make tidal power a reality is absolutely massive. Tinkering with prototypes is expensive, and no one wants to commit to a project they aren’t sure will pay off—such as this investment by China in 2014 that still hasn’t manifested into a power plant.

Other concerns like the quantity of produced energy, dangers to marine life, and environmental effects from ocean level manipulation remain in the minds of scientists and policymakers, and should certainly be addressed with further research.

The promise of carbon-free and a potentially limitless amount of energy production will hopefully provide an impetus for coastal countries to supplement their energy production with this truly alternative energy.