Wind Energy - Wind Turbine
Society has been harnessing the wind`s energy for hundreds of years. From old Holland to farms in the United States, windmills have been used for pumping water or grinding grain. Today, the windmill`s modern equivalent - a wind turbine - can use the wind`s energy to generate electricity.
A wind energy system transforms the kinetic energy of the wind into mechanical or electrical energy that can be harnessed for practical use.
Wind turbines extract the kinetic energy of the wind to produce electricity or into mechanical energy that can be harnessed for practical use, using a rotor fitted with aerodynamic blades.
Mechanical energy is most commonly used for pumping water in rural or remote locations - the ``farm windmill`` still seen in many rural areas is a mechanical wind pumper - but it can also be used for many other purposes (grinding grain, sawing, pushing a sailboat, etc.). Modern Wind turbines generate electricity for homes and businesses and for sale to utilities.
Wind turbines, like windmills, are mounted on a tower to capture the most energy. At 30 meters or more above ground, they can take advantage of faster and less turbulent wind. Turbines catch the wind`s energy with their propeller-like blades. Usually, two or three blades are mounted on a shaft to form a rotor.
A blade acts much like an aeroplane wing. When the wind blows, a pocket of low-pressure air forms on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind`s force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity.
The hub is connected to a gearbox and generator which are located inside the nacelle (the large part at the top of the tower where all the electrical components are located).
Today, wind turbines can range in capacity from under 100 watts (W) to several megawatts (MW). Turbines of between 100W and 10kilowatts (kW) have rotor diameters of 5-10 metres and towers of 6-15 metres in height. Commercial scale electricity wind turbines typically range from 0.6MW to 2.75MW and have rotor diameters of 44 to 80m, and hub heights of 40 to 80m. There has been a trend in recent years towards the use of larger turbines, at the upper end of this range, and commercial scale wind turbines are now capable of delivering large amounts of electricity at a competitive cost.
Wind turbines can be used as stand-alone applications, or they can be connected to a utility power grid or even combined with a photovoltaic (solar cell) system. For utility-scale sources of wind energy, a large number of wind turbines are usually built close together to form a wind farm. Several electricity providers today use wind plants to supply power to their customers.
Stand-alone wind turbines are typically used for water pumping or communications. However, home owners, farmers, and ranchers in windy areas can also use wind turbines as a way to cut their electric bills.
Small wind systems also have potential as distributed energy resources. Distributed energy resources refer to a variety of small, modular power-generating technologies that can be combined to improve the operation of the electricity delivery system. Such small on site and building-mounted systems offer many benefits for households and communities who want to generate their own electricity.
Biomass
The Carbon Cycle
Biomass energy has the potential to greatly reduce greenhouse gas emissions because using biomass as a feedstock releases about the same amount of carbon dioxide as burning fossil fuels. However, fossil fuels release carbon dioxide captured by photosynthesis millions of years ago - an essentially ``new`` greenhouse gas.
Biomass, on the other hand, releases carbon dioxide that is largely balanced by the carbon dioxide captured in its own growth (depending how much energy was used to grow, harvest, and process the fuel). In Nature there is an equilibrium which exists when the rate at which atmospheric carbon is fixed by photosynthesising plants such as trees matches that at which respiring organisms and combustion processes emit carbon into the atmosphere.
The recent rise in GHG CO2 levels present in the Earth`s atmosphere is mainly attributed to massive deforestation of our rain forests coupled with the release of carbon deposits from society`s combustion of fossil fuels.
Biomass has the environmental advantage in that it is a renewable supply of carbon fuel as biomass resources can be replenished at the same rate as they are consumed.
Carbon neutrality is reached when biomass we use as fuel releases into the atmosphere the CO2 that was absorbed whilst it was growing.
Even after taking into account the energy used for harvesting, transport and processing, the CO2 emissions from use of Biomass as fuel in a power station is significantly lower than the CO2 emissions for Fossil Fuel-fired power stations (the feedstock which also requires energy for its production, transport and processing).
Biomass does not add carbon dioxide to the atmosphere as it is utilised and a further advantage is that it can be used to generate electricity with the same equipment or power plants that are now burning fossil fuels.
Biomass is an important source of energy and the most important fuel worldwide after coal, oil and natural gas. The use of biomass can reduce dependence on foreign oil because bio-fuels are the only renewable transportation fuels available.
In the developed world biomass is again becoming important for applications such as combined heat and power generation. In addition, biomass energy is gaining significance as a source of clean energy for domestic heating and community heating applications.
Instead of burning the loose biomass fuel directly, it is more practical to compress it into briquettes (compressing the biomass through a process to form blocks of different shapes) and thereby improve its utility and convenience of use. Such biomass in the dense briquetted form can either be used directly as fuel instead of coal in traditional furnaces or processed in a gasifier. A gasifier converts solid fuel into a more convenient-to-use gaseous form of fuel called producer gas.
Advantages of Biomass Power
KP Renewables is developing the next generation of cost effective, environmentally friendly biomass power stations to recycle Carbon waste streams which will reduce our dependence on foreign oil, improve our air quality, and support rural economies through growing and using dedicated energy crops, such as fast-growing trees and grasses, that can grow sustainably on land that will not support intensive food crops.
Unlike renewable energy technologies such as Wind or Solar, Biomass power stations are not subject to the unpredictability of the weather and thus do not require back-up from fossil fuel power stations. Biomass power stations are base load plants, producing electricity on a predictable and constant basis.
