The Energy Star list of FAQs: Energy Star has a long inventory of Frequently Asked Questions related to all aspects of energy efficiency.

Why should I invest in energy efficiency? The list of advantages to modernizing your buildings and introducing renewable energy into your mix is long and profound. You can reduce your energy operating costs, lessen the negative impact of your operations on the environment, improve your image with customers and peers, improve the working conditions of your employees, improve your response times, and do all this with guaranteed results!

Can I get some help improving my energy use? You bet. There are many state and federal programs that can help with financing and with technical needs. There are also a number of financing options that are very attractive. There are also ways of involving energy companies in helping you identify and complete energy projects that will allow you to share the risk, both financial and technical, with expert companies that will guarantee the outcomes.

What kind of improvements can I make? Investments in the way you use electricity include upgrading your HVAC systems, building envelopes, lighting, and your fleets. You can also step into energy production, particularly using renewable energy technologies. Combined Heat and Power systems conserves the heat of your plant equipment and uses it as an energy source. You can implement solar, wind, or biomass energy production. The most effective systems use more than one of these approaches in tandem to optimize efficiency.

What are municipal bonds? When municipalities desire to build new facilities such as schools, fire stations or libraries the project may be financed through the issuance of municipal bonds. Unlike corporate bonds, the interest on municipal bonds is generally exempt from federal and state income taxes. Because of this unique feature there is high demand among investors for municipal bonds. A municipal bond, just like its corporate cousin, pays interest to the owner periodically and will be redeemed on a certain date in the future.

Are there different kinds of municipal bonds? Municipal revenue bonds are issued by self-supporting agencies of a municipality such as a water system, sewer system or parking garage that charges the public for use of the facility. The agency will accumulate user fees and pay interest and principal to investors to retire the debt. General obligation bonds are issued by municipalities to fund projects that are not self supporting such as roads and bridges, court facilities and school buildings. Municipalities collect property and income taxes from their residents, accumulate the revenue and pay interest and principal to investors to retire the debt.

A general obligation bond bears the unconditional promise of the municipality to pay interest and principal, including the promise to raise taxes on the people if necessary. Most states have laws that restrict the amount of general obligation debt that can be issued by municipalities.

Lease revenue bonds are issued by municipalities when their general obligation bond limit is not large enough to allow a project to be financed in that manner. If a municipality is reserving its general obligation limit for other future projects it may elect to issue lease revenue bonds to finance current projects. Some states do not allow the issuance of general obligation bonds without a referendum. In those states, lease revenue bonds have become the method of financing infrastructure projects that will be paid for from property taxes. A lease revenue bond is not an unconditional obligation of the municipality. Rather, the revenue necessary to repay bond owners must be appropriated from tax revenue by the municipality each year.

How are municipal bonds issued? Municipal bonds are sold to investors by either "competitive sale" or "negotiated sale." Municipalities will usually contract with a financial advisor who will analyze the transaction and will make recommendations about such things as the term of the financing, credit rating agency selection, municipal bond insurance, etc.

In a competitive sale a financial advisor will structure the transaction and will advertise and market the transaction to potential purchasers throughout the United States. When the date for selling the bonds arrives the financial advisor will assist the municipality to accept bids for their bonds and will also assist the municipality to determine which bid is the best (usually the lowest interest rate) bid to accept. A competitive bond sale offers a municipality the opportunity to let the competitive marketplace determine the interest rate (value) of its bonds on the day they are sold. In a negotiated sale a financial advisor will still provide structural analysis for the transaction but will also help the municipality to select an underwriter in advance of the bond sale. Negotiating directly with an underwriter may offer some advantages such as allowing the municipality to delay issuing bonds if market conditions are adverse or, if a transaction is very complex, an underwriter may be chosen on the basis of their ability to sell that particular type of bond issue.

How long does a bond issue take? A municipal bond issue can generally be completed within six to eight weeks of a decision to move ahead. While there are many tasks to complete in order to close a bond issue, many of them can be telescoped together and completed simultaneously. For example, any state or local approvals can be sought at the same time that the plan of finance is submitted to a credit rating agency for evaluation. The legal documentation and preparation of other related paperwork can be done at this time as well.

Isn't A Bond Issue Expensive? No. The most important thing to keep in mind is the fact that municipal bonds represent the lowest interest rate option available to municipalities. There are costs associated with issuing bonds, but they are quickly outweighed by the lower interest rates available in the bond market.

Isn't Our Project Too Small For A Bond Issue? There is a persistent myth that only very large projects benefit from bond financing. Many people believe that bond issues only work well for those rare $50 million to $100 million infrastructure projects such as massive water and sewer systems. This simply isn't true. Many municipalities issue bonds for $1 million to $2 million to purchase fire and rescue equipment and construct municipal facilities such as fire stations, libraries, town hall buildings and to establish E911 systems.

 

Thank you to Joe O'Brien, Allentown, PA, at public-finance.com for some of these FAQ's.

ABSORPTION NATURAL CHILLERS Part of an HVAC system, absorption chillers use heat to drive the refrigeration cycle. They produce chilled water while consuming just a small amount of electricity to run the pumps on the unit. Absorption chillers generally use steam or hot water to drive a lithium bromide refrigeration cycle but can also use other heat sources.

ANAEROBIC DIGESTION Anaerobic digestion is a method of breaking down sewage, wherein micro-organisms break down biomass to produce methane and carbon dioxide. This can occur in a carefully controlled way in anaerobic digesters used to process sewage or animal manure. Many waste water treatment plants use anaerobic digestion to stabilize sludge generated during the treatment process. Microorganisms break down organic material, releasing biogas, a mixture composed of methane and carbon dioxide, trace gases, and water. Typically, plants flare biogas to dispose of it, but this renewable fuel can be used in fuel cells to generate heat and electricity. Using biogas in this way reduces emissions that otherwise would be generated by flaring and eliminates emissions that would be generated by using traditional power sources.

BATTERIES An early solution to the problem of storing energy for electrical purposes was the development of the battery as an electrochemical storage device. Batteries have previously been of limited use in electric power systems due to their relatively small capacity and high cost, however since about the middle of the first decade of the 21st century newer battery technologies have been developed that can now provide significant utility scale load-leveling capabilities.

BIODEISELS Transitioning to biodiesels can be done simply and easily. Unlike changing to solar, wind, or other renewable sources of energy, no special equipment or adaptations are needed to use biodiesels in vehicles or for home heating use. Existing cars, trucks, and home heating oil tanks can simply be switched directly to biodiesel. In standard diesel engines, biodiesel can be readily substituted for regular diesel fuel.

BIOMASS and BIOPOWER Biopower is made by the burning of biological waste, either plant, animal, or clean municipal waste, in a controlled way that steam powers a generator while capturing the carbon released in the burning. Sustainable, low-carbon biomass can provide a significant fraction of the new renewable energy we need to reduce our emissions of heat-trapping gases like carbon dioxide to levels that scientists say will avoid the worst impacts of global warming. Technology demonstrations lately have shown that there are even more efficient and cleaner ways to use biomass. It can be converted into liquid fuels in a process called "gasification" to produce combustible gases, which reduces various kinds of emissions from biomass combustion, especially particulates.

CHILLERS There are many types of Chillers! Part of an HVAC system chillers produce chilled water while consuming just a small amount of electricity to run the pumps on the unit. Absorption chillers generally use steam or hot water to drive the lithium bromide refrigeration cycle but can also use other heat sources. There are also direct-fired, helical liquid, centrifugal, and compressor chillers. In addition, there are air-cooled chillers and cooling towers.

• Single-stage absorption units use low pressure steam or low grade hot water to drive the absorption cycle. These units are particularly useful for energy conserving applications such as heat recovery or process applications where a low cost heat source is available.
• Two-Stage absorption chillers use the efficient series solution flow cycle which improves the unit efficiency over 50% compared to single effect models, these units are ideal when medium pressure steam or 350°F (176.7°C) hot water is available. Absorption technology reduces the requirement for electric energy and can give owners flexibility where electrical demand and consumption are expensive or in short supply. Models available 111–1685 tons (390–5925 kW)
• Direct-fired absorption chillers offer customers a choice in how they consume energy to produce chilled water. The chiller uses natural gas or other fuels to fire the absorption refrigeration cycle. A direct-fired absorption chiller can be used as a primary component for hybrid plants or other applications where electrical demand and consumption are expensive or in short supply. The efficiency of the double-effect cycle used in these chillers makes them competitive with electric chillers in many regions of the world where electricity prices have risen dramatically over the last decade. All sizes also can act as a chiller/heater to supply chilled or hot water for conditioning the building during the summer or winter.
• Absorption refrigeration machines provide chilled water for either comfort or industrial water cooling systems. These chillers are engineered for lower life cycle costs and reliability through design simplicity
• Centrifugal chillers are among the quietest in the industry. And the Trane exclusive Adaptive Control™ microprocessor can keep the Trane chiller operating when others would shut down—often just when you need cooling the most. All of our centrifugal chillers feature multiple stages for a large operating envelope and surge resistance, and a flash economizer to save energy. Download the CAD templates for the equipment you need for your designs. Select refrigeration products.
• Compressor Chillers are ideal for comfort or process cooling applications, keeping the chilled water loop indoors without the need for performance-degrading freeze protection.
• Helical Rotary Liquid Chillers provide chilled water for both comfort and industrial cooling systems. These air- and water-cooled chillers can reduce your total cost of ownership because they are engineered for lower life cycle costs and reliability through design simplicity. Scroll Air-Cooled Chillers
• Air-Cooled Scroll liquid chillers provide for a wide range of comfort and process-cooling applications. These chillers are complete, factory-assembled liquid chillers that offer ease of installation with wiring and microprocessor controllers providing maximum operating efficiency. Compact chillers install easily and quickly into most building layouts, making them ideal choices for retrofit or new building designs.
• Cooling Towers -There are any numbers of companies that make cooling towers, but none of them has more new ideas than Trane. Our cooling towers are engineered to provide optimal cooling with minimum energy usage.

CO-FIRING Co-firing is an energy production method that mixes biomass with coal and burns it at a power plant designed for coal. Through gasification, biomass can also be co-fired at natural gas-powered plants. The benefits associated with co-firing can include lower operating costs, reductions of harmful emissions, greater energy security and, with the use of beneficial biomass, lower carbon emissions. It is also a renewable resource because plants to make biomass can be grown over and over. Co-firing is also one of the more economically viable ways to increase biomass power generation today, since it can be done with modifications to existing facilities.

COGEN SYSTEMS AND THE STIRLING ENGINE A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work. There are internal combustion engines and external combustion engines. In a conventional internal combustion engine, the fuel mixes with the internal workings of the engine, where it is burned to provide power. In an external combustion engine, like the Stirling, the combustion products do not mix with the working fluid. Some fuels, like those derived from a landfill biomass, contain ingredients that can damage the engine, like siloxane. Thus, a Stirling engine is ideally suited to landfill biomass.

The Stirling engine is currently exciting interest as the core component of micro combined heat and power (CHP) units, in which it is more efficient and safer than a comparable steam engine. It is noted for its high efficiency compared to steam engines, quiet operation, and the ease with which it can use almost any heat source. There are two types:

• In an Alpha type Stirling engine, there are two cylinders. The expansion cylinder is maintained at a high temperature while the compression cylinder is cooled. The passage between the two cylinders contains the regenerator, which creates electricity.
• In a Beta Type Stirling Engine, there is only one cylinder, hot at one end and cold at the other. A loose fitting displacer shunts the air between the hot and cold ends of the cylinder. A power piston at the end of the cylinder drives the flywheel and creates electricity.

COMBINATIONS The term 'combinations' can mean two things when talking about energy production; the first is a direct physical link between two different types of units, as in Cogen. This happens when you use a natural gas unit to make electricity, and then physically attach a heat capturing unit to capture the excess heat to make hot water. The second is the combination of different technologies in the same building, such as solar and HVAC improvements. The synergy of two different types of energy related projects is something to look and design for to get the highest performance.

COMBINED GENERATION - COGEN Any type of thermal power generation, like coal, natural gas, or petroleum, does not burn with 100% efficiency. Up to half of the energy used can be lost as excess heat, and that's not good for the environment and not good for your bottom line. When that excess heat is captured as used properly, the power plant can be made 89% efficient, a large and important increase. Combined Heat and Power systems are known as CHP or Cogen systems.

For example, if your municipality buys electricity and natural gas from the local utilities, you may burn the natural gas in a boiler and the hot water is used throughout the civic center, including for heating and the municipal pool. Now instead, buy only natural gas and make your own electricity on site, right there in your main boiler room. When making the electricity, excess heat is produced. Use that heat to heat your water. That's a cogen system, and it's much, much more efficient!

Here's another cogen system, this time using your air conditioning. Say you replace your old air conditioner with a chiller unit that uses natural gas. An efficient, natural gas engine-based chiller can significantly reduce energy costs. You can get a wide range of sizes to suit your needs, and it can be installed in standard locations such as plant rooms or rooftops. You can get an efficient clean energy system to provide you with high-performance air-conditioning and improved comfort at your properties. The natural gas engine chillers offer you greater efficiency by supplying both cooling and hot water to supplement your existing boilers for domestic hot water applications, laundries and heated swimming pools.

If there is another re-processing step added to the power generation cycle, the system is called a tri-cycle plant, which usually have efficiencies above 80%. Why is there such a big difference in fuel efficiency between the electric utility and a combined heat and power system? The electric utility and CHP system each produce electricity and heat from one source of fuel. However, the heat produced at the electric utility is not used; it goes into the cooling water or up the smokestack along with greenhouse gases and other pollutants. Approximately two-thirds of the fuel's energy is wasted. Alternatively, while generating electricity, a properly sized combined heat and power system recovers nearly all of the heat it produces and deploys it on site.

ESCO One approach to developing on-site renewable energy is to work with an energy services company (ESCO) and develop a Performance Contract. The Performance Contracts are special in that they guarantee energy savings from the installed retrofit measures, and they usually also offer a range of associated design, installation, and maintenance services. An ESCO is a business that develops, installs, and arranges financing for projects designed to improve energy efficiency and maintenance costs over a seven to twenty year time frame. ESCO's generally act as project developers for a wide range of tasks and assume the technical and performance risk associated with the project. Services are bundled into the project's cost and are repaid through the dollar savings generated.

FUEL CELLS A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent. Hydrogen is the most common fuel, but natural gas and biofuels (gases from food processing and wastewater treatment) can be used as a source fuel. Fuel cells are different from batteries in that they require a constant source of fuel and oxygen to run, but they can produce electricity continually for as long as these inputs are supplied.

The energy efficiency of a fuel cell is generally between 40-60%, or up to 85% efficient if waste heat is captured for use. While the need to ensure the availability of hydrogen has been seen as a concern in the operation of fuel cells, some fuel cells are unaffected by such limitations because they use natural gas and biofuels (gases from food processing and wastewater treatment) as a source fuel. Furthermore, with system adjustments, these fuel cells can also operate with a wide range of alternate fuels, including ethanol and propane.

Direct Fuel Cells have even been shown to generate clean power from diesel fuel and coal gas, fuels traditionally considered to be high pollution sources. Fuel cell power plants generate more electricity per unit of fuel than almost any other distributed energy source. The downside so far has been that they can be more expensive, though that is changing rapidly. Efficiency is further increased when used in a Combined Heat and Power (CHP) application or in conjunction with other power technologies (solar, gas turbine).

GEOTHERMAL ENERGY Conventional geothermal energy draws on the earth's hydrothermal resources, its underground heated water and steam. After drilling into these reservoirs, geothermal plants extract heated water and steam from the earth's crust to drive electricity-generating turbines, a process called "heat mining." The various techniques currently used to produce geothermal energy include the following

• Dry Steam Dry steam plants draw steam directly from under the earth's surface to a turbine that drives a generator. The steam then condenses into water and is reinjected into the geothermal reservoir.
• Flash Steam Flash steam plants extract geothermal water exceeding 350°F under extremely high pressure. Upon surfacing, a sudden reduction in pressure causes a portion of the heated water to vaporize, or "flash," into steam. That steam turns a turbine, which drives a generator, after which the water is reinjected into the geothermal reservoir.
• Binary Cycle Binary cycle plants operate in areas with substantially lower-temperature geothermal water (225°F). Rather than using hydrothermal resources to drive a turbine, binary cycle uses the earth's heated water to vaporize a "working fluid," any fluid with a lower boiling point than water (e.g., iso-butane). The vaporized working fluid drives a turbine that powers a generator, while the extracted geothermal water is promptly reinjected into the reservoir without ever leaving its closed loop system.

Geothermal energy also depends on advanced hard-rock drilling technology. While oil and gas drilling techniques apply to geothermal drilling, temperatures above 250°F found in geothermal reservoirs complicate the process. The high heat increases the probability of well failure due to collapse, mechanical malfunction, and casing failure. Extensive research has gone into understanding the geological characteristics of geothermal reservoirs and how to adapt drilling technologies to these conditions.

For smaller geothermal systems, loops a buried near the building:

• Horizontal Loops Horizontal loops are the most common type of loop system, and are commonly used in rural areas due to the land space needed for installation. An excavator will dig several trenches about six feet deep in the ground, each one up to 300 feet long. Our green geothermal pipe is placed in the trenches which are then backfilled with soil.
• Vertical Loops Vertical loops are primarily used in urban areas because they require little land space for installation. A specially designed geothermal drilling rig bores vertical holes into the ground each ranging from 180 to 540 feet deep. Our green geothermal pipe is inserted into each vertical bore and then the holes are filled with bentonite grout.
• Pond or Lake Loops On properties that have a nearby lake or pond that is appropriate in size and eight feet deep, a loop system can be submerged at the bottom of the body of water. A single trench is excavated from the home to the water and typically two pipes are inserted into it. These two pipes connect to several green geothermal pipes that are submerged at the bottom of the lake or pond.

HVAC CONTROLS Controls include the following: Single Building Control Systems,Multiple Building Control Systems, Zone Sensors, Variable Frequency Drives, Thermostats, and Adaptive Frequency™ Drive Upgrades.

• Adaptive Frequency™ Drive Upgrades: Adaptive frequency drive (AFD) improves HVAC performance by providing safe, efficient inlet guide vane and compressor motor speed control combinations. This HVAC upgrade ensures the most efficient part load operation possible.
• Rebuilt HVAC Motor Upgrades: for some chiller models, remanufactured HVAC motors can be swapped in. The motors are usually been tested and proven reliable through a variety of rigorous methods.
• Refrigerant Purge Upgrades: purges are designed to remove air and moisture from low-pressure chillers while minimizing refrigerant emissions.
• Retrofit Starter Replacement Upgrades: retrofit starter replacements regulate the current flow to a chiller motor.
• Retrofit HVAC Control Upgrades: HVAC controls optimize chiller performance by allowing the chiller to adapt to changing load conditions.
• Engineered Conversion Retrofit Upgrades: Some companies offer a retrofit to re-engineer your chiller to optimize it for your specific operating conditions.

HYBRID COOLING Hybrid Cooling is an HVAC air conditioning model that utilizes a standard packaged chiller to produce ice during the night and store it in modular thermal energy storage tanks. The stored ice provides cooling the following day to meet the building's air-conditioning requirement.

NET METERING Net metering is a mechanism that provides a simplified approach for interconnecting and metering on-site renewable generating facilities, such as a solar PV system. It allows customers to use excess solar electric generation to offset utility-purchased electricity on a monthly or annual basis.

As a solar PV system starts generating electricity, it first goes to meeting the on-site electric demand at the home or business, slowing down the power being supplied by the grid. It is very common that later on in the day the solar PV system may produce more power than what is needed at the site, , at which point the "excess" electricity will automatically back feed through the bi-directional utility meter and onto the utility grid (Note: your utility may not have bi-directional meters and therefore require two meters, one to be wired in reverse, to record this information; they should provide a reimbursement for the second meter installation cost). At the end of a month, if a customer uses more electricity than a solar system generates, the customer is charged for the difference on the customers' utility bill. However, if the customer generates more electricity than is needed during a given month, the excess is carried forward at full retail value towards the following month's bill. If the solar PV system generates more annual electricity than the annual electric usage by the home or business, then the customer receives payment for the annual surplus based on the 'Price to Compare' for electric generation and transmission.

PERFORMANCE CONTRACTS An Energy Performance Contract is an agreement between a municipality and an energy services company, an ESCO, to customize a set of energy efficient projects that can be implemented outside of the capital appropriations process and then paid for over time, partly or in whole from energy savings that the projects produce. In this way the town shares the cost and savings with the ESCO. The ESCO is responsible for financial and operational outcomes, and the savings can be guaranteed in many different forms. Performance Contracts are special in that they guarantee energy savings from the installed retrofit measures, and they usually also offer a range of associated design, installation, and maintenance services.

POWER SYSTEMS An Electric Power Systems is a set of components that transform other types of energy into electrical energy and transmit this energy to a consumer. The production and transmission of electricity is relatively efficient and inexpensive, although unlike other forms of energy, electricity is not easily stored and thus must generally be used as it is being produced.

A modern electric power system consists of six main components:

1. Power Station The power station of a power system consists of a prime mover, such as a turbine driven by water, steam, or combustion gases that operate a system of electric motors and generators. Most of the world's electric power is generated in steam plants driven by coal, oil, nuclear energy, or gas. A smaller percentage of the world's electric power is generated by hydroelectric (waterpower), diesel, and internal-combustion plants.
2. A set of transformers to raise the generated power to the high voltages used on the transmission lines. In a typical system, the generators at the power station deliver a voltage of from 1,000 to 26,000 volts (V).Transformers step this voltage up to values ranging from 138,000 to 765,000 V for the long-distance primary transmission line because higher voltages can be transmitted more efficiently over long distances.
3. The transmission lines.
4. The substations at which the power is stepped down to the voltage on the distribution lines. At the substation the voltage may be transformed down to levels of 69,000 to 138,000 V for further transfer on the distribution system.
5. The distribution lines. Another set of transformers step the voltage down again to a distribution level such as 2,400 or 4,160 V or 15, 27, or 33 kilovolts (kV).
6. The transformers that lower the distribution voltage to the level used by the consumer's equipment. Finally the voltage is transformed once again at the distribution transformer near the point of use to 240 or 120 V.

PV SOLAR CELLS PV Solar Panels generate electricity by the Photovoltaic Effect. Discovered in 1839 by 19 year old Edmund Becquerel, the photovoltaic effect is the phenomenon that certain materials produce electric current when they are exposed to light. Solar cells are made by sandwiching two different types of silicon together, creating a junction.

The light from the sun is made up of packets of energy called Photons. Each photon carries an amount of energy corresponding to its wavelength of light. When a visible light photon strikes a solar cell it can do one of three things: pass straight through, be reflected, or be absorbed. If the photon is absorbed, its energy is absorbed and positive and negative charges move within the cell. This movement making an electrical circuit and provides usable electricity.

STIRLING ENGINES A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work. There are internal combustion engines and external combustion engines. In a conventional internal combustion engine, the fuel mixes with the internal workings of the engine, where it is burned to provide power. In an external combustion engine, like the Stirling, the combustion products do not mix with the working fluid. Some fuels, like those derived from a landfill biomass, contain ingredients that can damage the engine, like siloxane. Thus, a Stirling engine is ideally suited to landfill biomass. The Stirling engine is currently exciting interest as the core component of micro combined heat and power (CHP) units, in which it is more efficient and safer than a comparable steam engine. It is noted for its high efficiency compared to steam engines, quiet operation, and the ease with which it can use almost any heat source. There are two types: In an Alpha type Stirling engine, there are two cylinders. The expansion cylinder is maintained at a high temperature while the compression cylinder is cooled. The passage between the two cylinders contains the regenerator, which creates electricity. In a Beta Type Stirling Engine, there is only one cylinder, hot at one end and cold at the other. A loose fitting displacer shunts the air between the hot and cold ends of the cylinder. A power piston at the end of the cylinder drives the flywheel and creates electricity.

SUPPLEMENTARY EQUIPMENT Any electric-distribution system involves a large amount of supplementary equipment to protect the generators, transformers, and the transmission lines themselves. The system often includes devices designed to regulate the voltage or other characteristics of power delivered to consumers. To protect all elements of a power system from short circuits and overloads, and for normal switching operations, circuit breakers are employed. These breakers are large switches that are activated automatically in the event of a short circuit or other condition that produces a sudden rise of current. Because a current forms across the terminals of the circuit breaker at the moment when the current is interrupted, some large breakers (such as those used to protect a generator or a section of primary transmission line) are immersed in a liquid that is a poor conductor of electricity, such as oil, to quench the current. In large air-type circuit breakers, as well as in oil breakers, magnetic fields are used to break up the current. Small air-circuit breakers are used for protection in shops, factories, and in modern home installations. In residential electric wiring, fuses were once commonly employed for the same purpose. A fuse consists of a piece of alloy with a low melting point, inserted in the circuit, which melts, breaking the circuit if the current rises above a certain value. Most residences now use air-circuit breakers.

SOLAR CELLS How a PV Solar Cell Works PV Solar Panels generate electricity by the Photovoltaic Effect. Discovered in 1839 by 19 year old Edmund Becquerel, the photovoltaic effect is the phenomenon that certain materials produce electric current when they are exposed to light. Solar cells are made by sandwiching two different types of silicon together, creating a junction.

The light from the sun is made up of packets of energy called Photons. Each photon carries an amount of energy corresponding to its wavelength of light. When a visible light photon strikes a solar cell it can do one of three things: pass straight through, be reflected, or be absorbed. If the photon is absorbed, its energy is absorbed and positive and negative charges move within the cell. This movement making an electrical circuit and provides usable electricity.

TELPs The Tax exempt Lease-Purchase Program is a flexible and convenient means of financing capital needs, from computers to modular classrooms. The program provides short to medium term, tax exempt, fixed rate financing and is a proven alternative to traditional loans, bonds, and internal funding. Tax Exempt Lease-purchase agreements are suited to energy efficiency projects. This is because they often include 'non-appropriation' language, which ties the repayment of the financing to the availability of funds from the current year's operating budget. If energy funds are not appropriated in future operating budgets, then the financing agreement is considered terminated without creating a default.

THERMAL ENERGY STORAGE Thermal energy storage comprises a number of technologies that store thermal energy in energy storage reservoirs for later use. They can be employed to balance energy demand between day time and night time. The thermal reservoir may be maintained at a temperature above (hotter) or below (colder) that of the ambient environment.

The applications today include the production of ice, chilled water, or eutectic solution at night, or hot water which is then used to cool / heat environments during the day. Thermal energy is often accumulated from active solar collector or more often combined heat and power plants, and transferred to insulated repositories for use later in various applications, such as space heating, domestic or process water heating.

WASTE MANAGEMENT SYSTEMS A Waste Management Facility can include a tipping hall, a furnace, a dry-scrubber, a baghouse, an ash conveyor, and even a generator.

Tipping Hall - trucks disgorge their loads and the material is presorted for goods that can be recycled or that cannot be incinerated. This location requires storage pits, front end loaders, and air management for dust and odor.

Furnace - The waste is lifted out of the storage pit by overhead cranes and dropped into a refuse feed hopper. At the bottom of the feed chute, hydraulic rams push the refuse into the boiler where it is burned under controlled conditions. The heat generated by burning the refuse converts water flowing through tubes in the boiler into steam. The floor of the furnace contains moving grates that push the burning refuse through the boiler. When refuse passes through the boiler, the resultant ash is discharged into a quench tank. The quench tank, which is filled with water, cools and eliminates dispersion of the ash. A Thermal DeNox system, which injects ammonia into the boiler's bum chamber, is used to control nitrogen oxides.

Dry Scrubber - After leaving the boiler, the combustion gases travel through a state-of-the-art pollution control system. The dry scrubber neutralizes acid gasses, such as sulfur dioxide and hydrochloric acid, by spraying a lime slurry into the exhaust stream. In excess of 95% of sulfur dioxide and hydrochloric acid are removed in this process. The reacted lime and ash are removed from the bottom of the scrubber.

Baghouse - The baghouse operates like a gigantic vacuum cleaner. As the air is drawn through the baghouse, particulate matter and fly ash are trapped in the bags. Each boiler has a baghouse that contains ten modules with bags made of fiberglass. The baghouse is cleaned by blowing air, in the reverse direction, through the bags. The particulate and fly ash are removed from the bottom. This process removes 99.5% of the particulate matter in the airstream down to sub-microscopic levels. After leaving the baghouse, the cleaned exhaust gases exit through a 265-foot tri-flue stack. Emissions are monitored by a combination of continuous monitors and periodic stack sampling.

Generator - The steam generated from burning the refuse is used to drive the turbine-generator producing electricity. Some of the electricity produced is used to operate the facility and the remainder is sold to Southern California Edison (SCE) for distribution to its customers. The steam used to drive the turbine-generator is then sent to a condenser where it is converted into water and recycled back through the boilers.

Ash Conveyors - The ash from the furnace, dry scrubber, and baghouse is treated and transported to the landfill where it is used as road base material.