Can We Get Enough Energy from the Moon?

The elements may well hold the key to the future of energy production on Earth. Already, sophisticated solar projects and imposing wind turbines have dropped drastically in costs, making them an ever more attractive alternative to polluting fossil fuels. Wave power and hydro-electric dams are also contributing to a rapidly growing renewable sector.

However, another important natural phenomenon has gone largely neglected with regards to its energy generating capabilities: the moon. Tidal power is the only renewable power source which depends upon this lunar celestial body, and as yet has remained an untapped fount of reliable energy until now… though the tide may finally be turning.

The pros and cons of tidal power

Since it is dependent on the gravitational pull that both the sun and the moon (although especially the latter, due to its closer proximity to the Earth) exert on our oceans and seas, tidal power is an incredibly predictable source of energy. Indeed, we can say with near certainty exactly how the tides will behave far into the future.

However, this does not mean that the energy source is not intermittent. Indeed, tidal generators can only function for between six and 12 hours per day, meaning that it cannot be relied upon to provide a constant source of energy. This unreliability is further exacerbated by the occurrence of neap tides, which happen in between the spring tides of new and full moons and are considerably weaker, thus generating less power than the rest of the time.

Most prohibitively of all, designing, installing and maintaining equipment that can withstand the barrage of the ocean’s pull is a pricey business. Indeed, Swansea had hoped to host the world's first tidal power station in a project worth an estimated £1.3 billion, though the idea was eventually scrapped last month due to excessive costs. However, there are plenty of other projects waiting to take its place.

Answers to the tidal conundrum

The first ever large-scale multi-turbine array was launched in 2010 off the northern coast of Scotland in the Pentland Firth by MeyGen Limited and is currently capable of producing 252MW, with more capacity scheduled to be added in the coming years. Elsewhere, plenty of other companies are dipping their toes into the tidal energy market with a range of different designs and styles. These include:

• Horizontal axis turbine. Working in a similar fashion to a standard wind turbine, the force of the tide turns the turbine blades and generates power.
• Vertical axis turbine. Adopting the same principles as the horizontal axis turbine, a vertical axis turbine dispenses with blades in favour of a double rotor with scooped paddles.
• Venturi effect device. With the use of a funnel, the power of the tides is concentrated into a tunnel containing a turbine to achieve maximum power.
• Tidal kite. Tethered to the ocean floor, a kite flies in a figure-of-eight and directs water through the turbine installed under its wing.

While many of these designs are still in their infancy and face considerable teething problems regarding their cost and intermittency, the sheer dependability of tidal power makes it an attractive proposition for the future. Indeed, experts estimate that if properly funded, it could provide up to 750W by 2050 (along with that generated by wave power). If correct, the moon could contribute no small amount to a definitive transition away from fossil fuels and towards clean sources of energy.