Whether we learn to stop burning fossil fuels as a way to mitigate global warming or we simply use them all up, we will have to find truly sustainable supplies of energy for our future. Nuclear power is always a possibility but seems to be going nowhere as nobody but nobody wants the radioactive wastes.
Solar energy in all its direct and derivative forms is the odds on leader. Solar thermal for powering turbines to generate electricity and Photovoltaic energy production are direct applications of solar power. Important but derivative is wind. Wind is the result of the Coriolis effect (more about this later) and uneven heating of land and water which creates the movement of air from regions of high pressure to low pressure. Wind driven wave action of some coastal areas also can be exploited.
Hydropower is also derived solar power. Solar heating causes water to evaporate from the surface of the earth. The water vapor can then condense and return to the surface as rain. Rainfall can be captured in reservoirs and used to generate power.
Geothermal power, heat from the interior of the earth, can be tapped to generate power where cracks in earth’s mantle make sufficient heat close enough to the surface as to be practically accessed.
Even the moon can provide power. It’s gravitational attraction drives the tides and in prime locations this power source has been tapped. The Bay of Fundy in Nova Scotia has tidal changes as high as 50 feet.
Ocean currents are an as yet untapped source of power. They are driven by several factors. The Coriolis effect is a force exerted by the rotation of the earth. Combine the Coriolis effect with the temperature differential between the equator and the poles and and differences in salinity between the two and you get a gyre.
The north Atlantic gyre is a circulation of water involving the gulf stream flowing north up the east coast of the United States, across the north Atlantic then down the western coast of Europe and back east across the Atlantic. The flow rate if the gulf stream is only about 2 miles an hour. This seems slow compared to wind speeds of about 12 to 15 miles per hour need for practical wind turbine power production.
The much slower movement of water still can provide significant amounts of power as water is about 800 times as dense as air, and power production is directly proportional to fluid density. All that is needed for power production is the placement of turbines anchored in place amid an ocean current.
Another current which could be used to produce power is a similar ocean gyre in the Pacific Ocean. The north Pacific equivalent of the gulf stream is called the Kuroshio current. It flows northward up the east coast of Japan and circulates in a clockwise pattern around the north Pacific.
An abundance of sustainable energy supplies exist around the world. Accessing multiple sources of sustainable supplies can assure all the power we need without using fossil fuels. The energy needs of humanity can be accomplished without utilizing fossil fuels and all the baggage their use entails.