Today a lot of pressure is being applied to upgrade our energy production systems to renewable energy formats. Holding this back is the cost of implementing these systems too quickly. Here you'll find a collection that will aid you in understanding which of these technologies is most promising.
Old King Coal
Coal, which made the industrial revolution possible, is still the cheapest and most plentiful non-renewable energy source on this planet. This availability, however, comes at a steep price as the miners in pit mines are exposed to a very unhealthy and accident-prone enviroment. Strip mining has turned once lush mountainsides into open pits contaminated with industrial waste).
Much maligned because of the pollution that old plants created, coal is almost a dirty word in renewable energy circles. However, present technology enables very efficient and clean coal plants to be built. Being such a cheap and mature technology, it is the easiest for developing countries to exploit. Chances are, coal will still be an energy source long after oil is retired.
Black Gold or Black Death?
Oil is what made most 20th century developments possible. Cars, airplanes, and even plastic all owe their existence to the petroleum-based economy. It was easier to transport than coal, and very small engines running off of it could be made. The very advantages oil provided, as well as its concentration in fewer geographical places than coal, meant it played a bigger political role than coal ever did. While not as devastating to the environment as strip mining is, oil drilling has been known to create geological instability in some areas (earthquakes), and oil spills are second only to nuclear meltdown in the scale of environmental catastrophes.
Ownership of the world supply by a few countries and the fact that distribution is in the hands of very few powerful companies create a situation where the vested interests in favor of maintaining oil consumption are very powerful. Even though cars, ships, and even airplanes are becoming more fuel-efficient, the largest share is still consumed in electricity production, which uses up about 45% of global supply.1 While there is lots of oil left, despite what the doomsday criers say, the global economy is rapidly approaching a point where global demand will far exceed cheap supply.
We've Got Gas!
Although natural gas has long been considered a marginal source of energy due to the difficulty in transporting it over long distances, advances in gas pipelines and the development of liquid natural gas transport ships have led to it being much more widely used. Cheaper and more abundant than oil, many oil-fired power plants have been converted to natural gas. The USA has exploited its vast reserves to the point where it is the world's largest producer, although it also consumes all of it. It is much cleaner than oil, although it is (explosively) dangerous. Its value has enabled it to become a favorite political weapon of gas-exporting countries. For example, Russia often uses its gas wealth to coerce its neighbors by cutting off gas supplies and exploits its position as Europe's leading supplier to further its geopolitical agenda.
The "Old Renewables," Nuclear and Hydroelectric
Since the middle ages, water has been used for industrial purposes. Modern hydro plants have very long lifespans, and once built provide steady power very cheaply. Yet they do have their share of drawbacks. Hydro plants can only be built along rivers, and even then only on natural chokepoints that allow the construction of a dam, limiting their use to areas with the right geological ingredients.
Often considered not to be a renewable resource since it depends on uranium, of which there is a finite supply, nuclear energy does qualify as a renewable source of energy since spent fuel can be reprocessed and used again infinitely. Nuclear is arguably the most efficient form of power production anywhere, however it carries a great deal of baggage as the risk of nuclear meltdown has frightened people enough to ensure that nuclear makes up a disproportionately small share of the energy supply. (Except for France, where nearly 80% of electricity comes from nuclear sources.)
Solar Power, So Easy a Tree Can Do It
On paper, solar power appears to be the optimal energy solution, sunshine being remarkably abundant in many places. Solar-powered steam engines were developed as early as 1839, but failed to catch on due to the lower price of coal. The high cost of construction, maintenance, and the existence of clouds is what holds solar power back. The technology of generating electricity from solar sources has made major strides in recent decades.
Heliostat and updraft towers are cheaper to build and maintain than relatively delicate photovoltaic arrays. Heliostats using molten salt as the heat exchange medium have the potential to generate electricity in overcast conditions and even overnight, as the molten salt retains the heat generated during daylight hours well into the night. Solar power is best utilized in very sunny areas or countries with a lack of domestic energy sources. Most designs require a great deal of acreage to generate a worthwhile amount of electricity, so presently unproductive desert regions are ideal. Solar updraft towers, however, require less room and could be installed in more crowded areas. European countries are investing heavily in solar power, even if it is mainly to reduce dependence on easily cut Russian gas supplies.
Wind and Geothermal Power
Second only to sunlight in abundance is the heat of the earth's core. Accessing geothermal power economically is presently limited to areas where the crust is very thin (and prone to volcanic eruptions). Geothermal is, however, very clean and efficient where it can be implemented. Unlike wind and solar, a geothermal plant will produce energy 24 hours a day, under any conditions. Since hot spots under the earth tend to shift, it is necessary to build new ones every few decades, which is the main reason they have failed to catch on outside consistently volcanic areas. Wind power can be installed just about anywhere, as improvements in the technology allow worthwhile electrical production to occur in a light breeze. In most areas, however, the wind is too infrequent to make wind farms viable, and in the places where the wind is constant, like over the ocean, they are very expensive to build. Maintaining wind turbines is also very expensive. Despite this, some developed countries have still invested heavily in them to reduce dependency on foreign energy suppliers.