Wind and solar technology are becoming increasingly cost-effective.
Renewable energy is derived from resources that are naturally replenished or extremely abundant. Two of the cleanest forms of alternative energy are solar and wind power, both of which harness and convert an external element into electrical power. As concerns of resource-depletion and environmental degradation become increasingly prevalent, these alternative forms of power are becoming more and more attractive. Furthermore, as investment increases and technology improves solar and wind power are beginning to look feasible as supplemental energy sources. There are various types of machines that harness solar or wind power.
Solar Cells
The basic unit of all machines designed to convert solar energy to electricity is the solar cell (or photovoltaic cell). Many solar cells grouped together make up a solar panel (a photovoltaic panel). Electrical power is generated through the photovoltaic effect. The photovoltaic effect is the creation of a voltage or a corresponding electric current in a material upon exposure to light. Simply put, the photovoltaic effect is when voltage is created in a material as it is exposed to light. Power is generated by solar cells and stored in a battery. The amount of electricity produced is dependent on the size of the solar cell network (these can be massive networks of solar panels linked together), the intensity of the light source and the angle at which the sunlight comes into contact with the cell.
Solar Machines
While solar cells are the basic building block of solar power, there are a multitude of machines that can be powered by it. Theoretically anything that runs on electricity could be powered by solar energy, but in reality the machine must carry a certain quantity of solar cells and be in contact with direct sunlight. The solar powered machines with the most media exposure are vehicles. Solar powered cars, which use photovoltaic cells to power either all or some of the vehicle's functions, are not available to most consumers, but are mostly built as engineering exercises or in the course of government-funded research. Solar powered boats, however, are commercially available. As solar cells and panels become smaller and more efficient it is speculated that the range of cost-effective solar powered vehicles and machines will increase.
Horizontal-Axis Wind Turbines
Horizontal-axis wind turbines (HAWTs) have the rotor and the generator at the top of a tower, facing directly into the wind. This is the most common form of wind power turbine and also the most immediately recognizable due to its windmill-like appearance. The rotor blades themselves essentially resemble a propeller. Large wind turbines generally have a wind sensor that works in tandem with a servo motor that keeps the blades facing directly into the wind. Wind farms are medium voltage power networks with multiple wind turbines working simultaneously. Power is then transferred to a base station where a transformer converts it to high voltage electricity.
Vertical-Axis Wind Turbines
Vertical-axis wind turbines (VAWTs) are a type of wind power machine that mounts its rotor shaft vertically with the majority of the machinery at the base. Rather than resembling a windmill, many VAWTs resemble helixes or double helixes (though there is wide variation between different models) and are therefore omnidirectional. The primary advantage of these over more traditional wind turbines is that they can be more densely packed together. Horizontal-axis wind turbines tend to reduce the velocity of wind as it passes through the blades and therefore designers must spread them out from each other, whereas VAWTs do not produce this effect. VAWTs tend to fare better in low-to-medium wind conditions. Similarly, as the main components are closer to the ground, VAWTs are easier to maintain.
