A Power Purchase Agreement, or PPA, is a long-term agreement to buy power from a company that produces on-site electricity. EOS Ventures, using its own source of capital, builds renewable energy technology installations (solar and wind) on our customer's site and maintains and operates the installation (also known as “facility�). This installation, or facility, generates reliable, long-term clean energy for use by our customer. EOS has established a variety of PPA options, spanning in duration, to meet the unique needs of each of our customers.

Wind energy is the energy contained in the movement of air, known as wind. The sun heats the earth at different rates and at different times. The difference in temperature throughout the earth generates pressure differences that in turn drive the movement of air. Air has mass and when a mass is put in motion it contains what is called kinetic energy, much like a baseball thrown by a pitcher.
Wind energy has been used for centuries to drive pumps and mills by taking the kinetic energy and converting it to mechanical energy through the use of windmills. This same concept is used to convert kinetic energy into electrical energy through the use of wind turbines.

Answer provided by Sustainable Energy Developments

A wind turbine is a machine that harnesses the kinetic energy in the wind and converts it to electrical energy. Mechanical energy created by its rotating blades turns a generator that creates electricity. A typical wind turbine consists of the following features:
Rotor Blades – rotate in response to the wind and are attached to the rotor hub
Rotor Hub – connected to a gearbox and generator inside the Nacelle
Generator – converts mechanical energy into electricity
Nacelle – houses the mechanical and electrical components of the turbine
Tower – used to elevate the nacelle, hub, and blades so to reach greater wind

The size of wind turbines varies and is directly related to its designed electrical output. For example, the electrical output of a 10kW turbine at maximum windspeed can produce 10 kilowatts of electricity. Utility-scale turbines used for wind farms and utility-scale onsite projects can vary from 100kW to 5MW and have rotor diameters of 21m to 100m respectively. Tower heights of these turbines can also vary from 40m to 90m. Smaller turbines used in residential and agricultural applications are typically less than 100kW and have rotor diameters less than 21m. Towers heights

The amount of electricity produced by one turbine depends on its size and quality of wind resource. For example, a 1MW turbine, if placed in an appropriate wind resource, can generate approx 2.5 to 3.5 million kWh annually, enough electricity to supply approx. 250 to 300 homes. However this number is only a helpful way to translate electrical production into familiar terms. A wind turbine is not always generating power and therefore cannot constantly supply electricity to a home. Similarly, a 10kW turbine with sufficient wind resource can generate approx 10,000 kWh annual, enough energy to supply a single home (depending on usage over the course of a year).

On-site generation also known as “distributed generation� is the generation of power near the location where it will be consumed. Most of the electricity an average person uses is part of a “centralized� system where large amount of power is produced in a small number of locations (power plants) and transmitted to end users. More and more people are realizing the benefits and merits of moving towards the decentralized or onsite generation model of power production. On-site wind power generation can be anything from a 10kW wind turbine to help produce power for your home to one or more megawatt size wind turbines helping to power a manufacturing facility.

First it is important to realize that it would be difficult for the electric grid to remain stable solely with distributed generation, so centralized generation is still a very important and a critical part of the overall system. That being said some of the advantages of distributed generation are:

1) Less electricity wasted in the delivery process- With centralized power production, the electricity produced needs to travel through miles of transmission wires before it arrives at your location to be consumed. No matter what, a portion of that electricity is lost traveling through those lines. With distributed generation system, the power is produced near where it is consumed so electric line losses are minimized.

2) Taking control of your power generation- Energy flows in electric grid to the area of least resistance. Regardless of who you “purchase� electric supply from the actual electrons could come from any number of nearby power plants. (Think of the electric grid as a pool of water… suppliers dump water in and consumers scoop water out with little choice of who’s water you are actually taking) With On-site generation you actually know exactly where a large portion of your power is produced and how it is produced. By knowing that the wind turbine on your property is actually powering the lights in your home or business, you ensure your energy consumption is from a clean source.

3) Long term savings – The installation of an on-site wind turbine requires a large upfront cost and a small amount of operations and maintenance costs throughout its lifecycle. Over time the wind turbine will pay for itself in energy savings, and you will pay significantly less money in the long run than if your purchased your power the traditional way, exclusively from a utility.

Renewable energy sources such as solar and wind produce power intermittently, meaning their output varies greatly hour-to-hour and day-to-day. With a properly matched wind turbine there will be times when it is producing no power (not enough wind) and times when it is producing significantly more power than needed (plenty of wind). Without net-metering any power that is produced above what you need is sold back to the utility at wholesale pricing. With net metering, any excess power essentially turns your electric meter backwards and you can receive that energy back on non-windy days at a net cost of zero. Another way of thinking about it the electric grid can serve as battery backup where excess energy is stored for future use. The availability and specifics of net-metering depends on your local market and the size of the generator.

Generally the need for a feasibility study depends on how big the project is and what degree of confidence is needed for the investment to be made. In addition, most funding agencies will require some form of feasibility study before a project will qualify for large design and construction grants.

Traditional fossil fuel-generated electricity requires consistent input of a fuel; typically oil, gas, or coal. These non-renewable resources must be located, extracted, transported, processed, burned, and the waste treated and removed. Each of these processes cost money throughout the life of the generating plant. Wind turbines simply use the force of the wind as fuel, and only require periodic maintenance. As fossil fuel resources decline and their costs increase, proven technologies such as wind energy have become an attractive long-term electricity solution. If we look at all forms of electricity generation stripped of the apparent and hidden subsidies, the wind power is competitive.

With advances in the engineering and manufacturing of wind turbines, the noise generated by wind turbines has been greatly reduced. Any noise generated is usually from the mechanical components, electric power conditioning, and the blades moving through the air. All modern wind turbine manufacturers design their wind turbines with particular attention to minimizing noise. With smaller machines, less than 100kW, turbine noise is primarily generated by the rotation of the rotor blades. Siting the turbine at appropriate distances from occupied buildings also minimizes any potential disturbance from turbine noise.