Hydrokinetic power is an emerging and promising clean energy resource with great potential for untapped power generation from oceans and rivers around the world. Although it is still largely unexploited and unknown, this source of renewable energy is getting increased attention since it does not emit greenhouse gases, it is capable of providing continuous power, unlike wind and solar sources, and it can be placed into flowing water with minimal infrastructure or impacts on wildlife and water quality. However, the design and research of hydrokinetic devices are still not as evolved as other renewable energy technologies; thus standard designs and best practices remain under development. To date, fully permitted pilot projects have already been deployed on-site.

Hydrokinetic conversion devices generate power by using submerged or partially submerged turbines. These devices are generally categorized as either rotating devices or wave energy converters. Rotating devices are deployed within a stream or current, thus capturing the energy from the flow of water across or through the turbine. This energy powers a generator without impounding or diverting the flow. Rotating devices work similarly to wind energy conversion devices, thus are commonly referred as underwater mills. On the other hand, wave energy converters create a system of reacting forces in which two or more bodies move relative to each other. One of these bodies, the displacer, is acted on by the waves. The second body, the reactor moves in response to the displacer.

According to estimates, the amount of energy that could feasibly be captured from U.S. waves, tides and river currents is enough to power over 67 million homes.

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[1] Hydrokinetic energy refers to the kinetic energy possessed by a body of water because of its motion.

[2] Hydrostatic energy is the potential energy possessed by a body of water because of its position or elevation above a reference or datum, commonly referred as “head”.

 Sustainable Site Development: discourages development on previously undeveloped land, minimizes building’s impact on environment, promotes smart transportation options, encourages the use of existing infrastructure, community resources, and access to open space.

 Water Savings: encourages the reduction of potable water use inside and outside the building.

 Energy Efficiency: promotes a variety of energy saving strategies, from efficient design to the use of renewable sources, and building commissioning.

 Material Selection: encourages the reduction of waste and use of local materials and resources.

 Indoor Environmental Quality: promotes the improvement of indoor air, access to daylight and acoustics, and the overall health of occupants.

LEED stands for Leadership in Energy and Environmental Design. It is an internationally recognized green building rating system developed by the U.S. Green Building Council (USGBC). Through its voluntary program, LEED provides third-party verification of practical and measurable green building strategies. Consequently, it encourages the adoption of sustainable building practices.

LEED certification is available for all building types. The USGBC developed different LEED rating systems applicable to the type of project worked on. The current LEED 2009 rating systems are LEED-Building Design & Construction, LEED-Interior Design & Construction, LEED-Operations & Maintenance, LEED-Homes, and LEED-Neighborhood Development.

LEED is a point based system where building projects earn points or credits for satisfying specific green building criteria in the five key areas mentioned before. The number of credits successfully accumulated and earned by a project determined the certification level achieved by the project. There are four levels of LEED certification:

Certified (Minimum points)

Silver (Second highest points)

Gold (Third highest points)

Platinum (Maximum points)

According to the USGBC, buildings in the United States are responsible for 39% of CO2 emissions, 40% of energy consumption, 13% water consumption and 15% of GDP per year.

• Orientation
• Structure
• Distance to transmission lines

Orientation

The orientation of solar panels to the sun affects the efficiency of the system. East facing panels are 81% efficient. South facing panels are 87% efficient. A complete residential solar system is 83% to 85% efficient. In Rhode Island, solar panels are exposed to the sun’s photons for about 4.23 hours each day in average, therefore proper orientation is crucial to maximize a solar system.

Structure

Not all structures can support solar systems. If the solar panels are to be installed on a roof, the structure must be able to support panel and rack weights, and ballast if applicable. The structural effect to the building due to the increase sail from the solar panels must be analyzed to prevent any building structure failure. Finally, wind loads pushing behind the panels and snow loads in winter are other elements to consider and study.

Distance to transmission lines

In the case of commercial solar “farms”, generated electricity must be fed into the electrical grid. Proximity and access to transmission lines are key; building new transmission lines can be very costly.

In essence, a customer’s electric meter can run both forward and backward in the same metering period, and the customer is charged only for the net amount of power used. By definition, true net metering calls for the utility to purchase power at the retail rate and use one meter. States have adopted a number of variations on this theme.

As part of the Energy Policy Act of 2005, all public electric utilities are now required to offer net metering on request to their customers. Utilities have three years to implement this requirement.

Net metering is a financial incentive for customers who install renewable energy systems.

• Customers tend to see lower bills with net metering. The payment system does not have to be disrupted as the utility company does not have to account separately for electricity produced by customer-generators. In general, net metering customers do not produce more electricity than they consume during billing periods; the customer only pays a reduced bill.
• Net metering participants are more aware of energy consumption, and tend to consume less energy than is generated. Studies, including some sponsored by utilities, have shown direct, measurable benefits for having generation located close to the end user.

Merchant power, where the power is generated for sale to the ‘grid’ and sold at a wholesale rate, is typically done on larger wind facilities, rather than servicing local point loads. In New England, this wholesale rate is about $.055 per KwHr, which is the ISO’s ‘avoided cost’.

You can find specific information about net metering in your State on the Interstate Renewable Energy Council website www.irecusa.org/index.php?id=90

Federal and State governments offer several tax incentives and funding opportunities to assist
with the development of wind power and to help alleviate the up-front, capital cost.

Small Wind Systems Tax Credit

Under present law, a federal-level investment tax credit (ITC) is available to help consumers purchase small wind turbines for home, farm, or business use. Owners of small wind systems with 100 kilowatts (kW) of capacity or less can receive a credit for 30% of the total installed cost of the system. The ITC, written into law through the Emergency Economic Stabilization Act of 2008, is available for equipment installed from October 3, 2008 through December 31, 2016. The value of the credit is now uncapped, through the American Recovery and Reinvestment Act of 2009.

The Production Tax Credit (PTC) Extension

In October 2008, Congress acted to provide a one-year extension of the Production Tax Credit (PTC) through December 31, 2009. Under present law, an income tax credit of 2.1 cents/kilowatt-hour is allowed for the production of electricity from utility-scale wind turbines. This incentive, the renewable energy PTC, was created under the Energy Policy Act of 1992 (at the value of 1.5 cents/kilowatt-hour, which has since been adjusted annually for inflation).

Rapid Depreciation

Double-declining balance, five-year depreciation schedule (I.R.C. Subtitle A, Ch. 1, Subch. B, Part VI, Sec. 168 (1994) (accelerated cost recovery system)) is another federal policy that encourages wind development by allowing the cost of wind equipment to be depreciated faster. States also offer their own incentives and grant programs.

Visit www.dsireusa.org to learn more.

• Wind speed
• Topography and accessibility
• Surface roughness
• Distance to transmission lines

Wind Speed

Wind speed is the most important factor in choosing a turbine site. Small increases in wind speeds make a significant difference in power output. A wind turbine at a 16-mph site can produce over 50% more electricity than the same turbine at a 13-mph site.

Topography and accessibility

Good wind sites are generally higher than the surrounding areas. Steep hills and cliffs can create wind turbulence that reduces energy output and leads to higher maintenance costs, while gradually sloping hills can increase wind speeds. Sites also need to accommodate access roads for construction and maintenance equipment.

Surface roughness

Tall obstacles such as buildings and trees can slow the speed of wind and create turbulence at low altitudes. Siting turbines in open fields or in the ocean reduces the effect of surface turbulence, while taller towers can be used to get turbine blades above turbulent areas.

Distance to transmission lines

In the case of commercial wind turbines, generated electricity must be fed into the electrical grid. Proximity and access to transmission lines are key; building new transmission lines can be very costly.