People have been harvesting plants and animals from the ocean for food for thousands of years. Harvesting food from the ocean is a multi-million dollar industry. Almost 75 million fish are harvested every year. Fishermen have become a lot better at locating and taking fish from the ocean with more improved technology, such as sonar and drift nets. Recently, people have been worried if we are over fishing the ocean which means that we are taking more fish than can naturally be replaced. Now, the fishing industry is working on preventing over fishing.
It has become more difficult to supply the amount of fish that we need. So to solve this problem, we are keeping different types of fish in fish farms where fish are separated in holding ponds. When the fish grow old enough, they are packaged and harvested for shipping. The fish are protected by huge nets, so their predators do not eat them. Types of algae, known as seaweed, can also be harvested from the ocean. Kelp can be harvested and used for thickener in jellies, ice cream, and other smooth gel-like products. Seaweed is rich in protein.
Oil and natural gas are major sources of energy from the ocean. Oil and natural gas are nonrenewable resources, so they can't be replaced quickly. The process of oil and natural gas forming began when dead organisms on the ocean floor were covered by sediments. Then this material was crushed and buried under the surface by the sediment on top, while heat was generated, then the plant/animal matter finally turned into oil or natural gas. They are both trapped under layers of impermeable rock. Petroleum engineers must drill through this impermeable rock, in order to reach them.
People desalinate ocean water in places of the world where fresh water is limited. Desalination is the process of evaporating sea water so that the water and and the salt separate. As water cools and condenses, it is then collected/processed for human use, but it can still be very expensive. Countries with a good amount of rainfall rely on the water provided by precipitation, so they don't need expensive desalination plants, but some countries located in dry areas need desalination plants to provide enough water.
Scientists are very fascinated by mineral nodules that lye on the ocean floor. Nodules are formed from dissolved substances in sea water that stick to solid objects such as pebbles. Manganese nodules can grow from the size of a marble all the way to the size of a soccer ball. Nodules are mainly made of manganese, so they can be used to make certain types of steel, and also contain iron, copper, nickel, and cobalt. They can also be made of phosphates, which can be used in fertilizer. It is believed that 15% of the ocean floor is covered with nodules, but those nodules are found in deeper parts of the ocean, which will make mining difficult and expensive.
The ocean can create many types of energy resources just by its continuous movement. The ocean rises and falls (as tides) from the gravitational pull of the sun and the moon. Tidal energy is energy generated from the movement of tides. Tidal energy can be a great alternative energy source. When water in a high tide rushes through a narrow coastal passageway, sometimes the water's force can be powerful enough to generate electricity. Tidal energy is a clean, inexpensive, and renewable resource, but it is only in a few areas where the coastline has shallow and narrow channels. A renewable resource can be replaced quickly.
When the waves crash on the shore at the beach, it is known as an energy resource called wave energy. Wave energy is also a clean, renewable resource. Computer programs are now able to analyze the energy of waves. Researchers have been able to find areas where wave energy can generate enough energy to make it beneficial to build power plants. Wave energy in the North Sea can make enough power for parts of Scotland and England.