Transportation: - Vehicle/Grid
- Alternative Fuels
- Public
Electric: - Demand Reduction Technologies
- Generation Technologies
- Transmission and Distribution (T&D) Technologies
- Energy Storage Technologies
TRANSPORTATION
Vehicle/Grid Plug-in Hybrid Electric Vehicles
A plug-in hybrid electric vehicle (PHEV) combines the propulsion capabilities of a traditional combustion engine with an electric motor. The batteries in PHEVs can be recharged by using an external power source, such as a home electrical outlet. The most appealing way to charge PHEVs is to charge vehicles at night using the output of off-peak wind or geothermal energy.
PHEVs are gaining in popularity because of their ability to travel nominal distances using little to no petroleum-based fuel in their all-electric range. According to the Electric Power Research Institute (EPRI), half of the cars in the U.S. are driven just 25 miles a day or less. PHEVs can also be less expensive to operate than conventional vehicles because using grid electricity to recharge the vehicle is substantially cheaper than petroleum fuels (U.S. DOE Vehicle Technology Program). Some energy experts envision using PHEVs as a way to provide energy storage to the grid or to islanded microgrids.
PHEVs such as those produced by Hymotion achieve 135-150 MPG equivalencies and use proven battery technologies from A123. The Hymotion L5 Plug-in Conversion Module is a rechargeable Nanophosphate™ lithium ion battery that uses regular 120V grid power to recharge, providing the user with ~5kWh of rechargeable energy storage at full capacity.
President Barack Obama announced in March 2009 that the U.S. Department of Energy (DOE) is offering up to $2.4 billion in American Recovery and Reinvestment Act funds to support next-generation plug-in hybrid electric vehicles and their advanced battery components.
Back to Top Electric Vehicles (EVs)
Electricity can be used as a transportation fuel to power battery electric vehicles (EVs). EVs store electricity in an energy storage device, such as a battery. The electricity powers the vehicle's wheels via an electric motor. EVs have limited energy storage capacity, which means they must be plugged into an electrical source after a certain number of miles depending on the battery. Although electricity production may contribute to air pollution, EVs are considered zero-emission vehicles because their motors produce no exhaust or emissions. (U.S. DOE Alternative Fuels & Advanced Vehicle Data Center) In December 2008, Hawaii Governor Linda Lingle announced a plan to bring all-electric vehicles and an electric vehicle infrastructure by 2009 to the island of Maui through a partnership with Phoenix Motorcars.
Back to Top Alternative Fuels Biofuel-powered Vehicles
Land transportation vehicles that typically run on gasoline and diesel can also be powered by biofuels such as cellulosic ethanol and biodiesel. The largest U.S. renewable energy source every year since 2000, biofuels produced from biomass provide a renewable alternative for liquid transportation fuel. (U.S. DOE Biomass Program)
Biodiesel is made by transforming animal fat or vegetable oil with alcohol and can be directly substituted for diesel either as neat fuel (B100) or as an oxygenate additive (typically 20%-B20). In the United States, the fuel is usually made from soybean oil. In 2002, 15 million gallons of biodiesel was consumed in the United States. (The American Soybean Association)
Ethanol can be used either as an alternative fuel or as an octane-boosting, pollution-reducing additive to gasoline. The U.S. ethanol industry produced more than 3.4 billion gallons in 2004, up from 2.8 billion gallons in 2003 and 2.1 billion gallons in 2002. (Renewable Fuels Association and Renewable Fuels Association Ethanol Industry Outlook 2005)
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Hydrogen Fuel Cell Vehicles
A hydrogen vehicle is a vehicle that uses hydrogen as its on-board fuel for motive power. The term may refer to a personal transportation vehicle, such as an automobile, or any other vehicle that uses hydrogen in a similar fashion. (U.S. Department of Energy, Vehicles Technology Program) The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy (torque) in one of two methods: combustion, or electrochemical conversion in a fuel cell. In fuel-cell conversion, the hydrogen is reacted with oxygen to produce water and electricity, the latter being used to power an electric traction motor.
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Public Mass Transit
Mass transit, or public transportation, can consist of buses, subways, light rail, monorails, commuter trains, van pool services, paratransit for senior citizens and people with disabilities, ferries, and water taxis. Studies have shown that in densely populated areas public transportation is able to decreases energy consumption per capita due to a decrease in private vehicle use.
Back to Top Electric Demand Reduction Technologies Green Buildings
Structures can be designed and built to minimize environmental impact and energy use if they are built to certain specifications. The U.S. Green Building Council’sLeadership in Energy and Environmental Design (LEED), for example, is a third-party certification program that promotes a whole-building approach to sustainability by recognizing performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.
Back to Top Solar Water Heating
Solar water heaters—also called solar domestic hot water systems—can be a cost-effective way to generate hot water for your home. Solar water heating systems include solar collectors, such as flat-plates or evacuated tubes, and often storage tanks. . There are two types of solar water heating systems: active, which have circulating pumps and controls, and passive, which don't.
Back to Top Energy Efficiency
Homes, commercial and institutional buildings, and industrial facilities could be made more energy-efficient with efficient lighting and HVAC systems, high insulation factors, daylighting, controls and motion sensors, and efficient practices among building tenants such as cycled air conditioning as part of a demand response program.
Building codes and standards could be passed to ensure that new buildings meet strict energy utilization standards, such as those instituted by the State of California or the International Building Code.
Back to Top Solar Thermal Absorption Chiller Air Conditioning
Modern evacuated-tube and concentrating parabolic collectors can generate hot water or other fluids that can drive an absorption chiller—common in the cogeneration industry—to cool commercial, institutional, and industrial buildings. (U.S. DOE Solar Energy Technologies Program) This load-following, peak-shaving technology suite essentially provides renewable air conditioning for buildings, with only minimal electric use, at the same time that the grid is most vulnerable to congestion and outages—on hot afternoons.
Back to Top Sea Water Air Conditioning
SeaWater Air Conditioning (SWAC) takes advantage of available deep cold seawater instead of energy-intensive refrigeration systems to cool the chilled water in one or more buildings. The main components of a basic seawater air conditioning system are the seawater supply system, the heat exchanger or cooling station and the fresh water distribution system. The seawater intake brings in water at a temperature lower than the temperature maintained in the chilled water loop. Once the seawater passes through the heat exchanger(s), it is returned to the ocean through another pipeline. (Makai Ocean Engineering)
Back to Top Generation Technologies Photovoltaics
Photovoltaic (PV) devices can be made from various types of semiconductor materials, deposited or arranged in various structures, to produce solar cells that have optimal performance. There are three main types of materials used for solar cells: silicon, polycrystalline thin films, and single-crystalline thin films.
PV applications include stand-alone, with battery storage, hybrid power systems, grid-connected, etc. (U.S. DOE Solar Energy Technologies Program)
Back to Top Solar Thermal Organic Rankine Cycle Generators
Solar thermal, using the concentrated heat of sunlight to heat a fluid with solar collectors, can drive an Organic Rankine Cycle generator in the 50 kW to several MW size range. Arizona Public Service and Solargenix installed a 1-MW solar thermal ORC generator a few years ago; some Hawaii-based companies are offering similar products in 2009.
Back to Top Large-scale Concentrating Solar Power plants
Concentrating solar power (CSP) technologies use mirrors to reflect and concentrate sunlight onto receivers that collect the solar energy and convert it to heat. This thermal energy can then be used to produce electricity via a steam turbine or heat engine driving a generator.
One way to classify concentrating solar power technologies is by how the various systems collect solar energy. The three main technology systems include Linear Concentrator Systems, Dish/Engine Systems, and Power Tower Systems. In a CSP system, if the receiver contains oil or molten salt as the heat-transfer medium, then the thermal energy can be stored for later use. This allows CSP systems to be a cost-competitive option for providing clean, renewable energy. (U.S. DOE Solar Energy Technologies Program)
Back to Top Hydroelectric
Water flowing in streams or through pipes can be used to produce electricity. With 80,000 megawatts of generating capacity, hydropower is the nation's largest renewable electricity source. There are three types of hydropower facilities: impoundment, diversion, and pumped storage; some hydropower plants use dams and some do not.
There are two main types of hydro turbines that convert hydropower to electricity: impulse and reaction. The type of hydropower turbine selected for a project is based on the height of standing water—referred to as "head"—and the flow, or volume of water, at the site. (U.S. DOE Wind and Hydropower Technologies Program)
Back to Top Wind
Wind energy is the world's fastest-growing energy technology--today, the U.S. has more than 6,300 megawatts of wind generating capacity. Industry and government partnerships have focused on developing wind energy technology for Class 6 sites — the best wind sites. However, many Class 6 sites are located in remote areas that do not have ready access to transmission lines. In addition, as more and more sites are developed, prime Class 6 sites that are easily accessible are becoming scarce.
Wind turbines are currently capable of producing electricity at 4.5 to 5.0 cents/kWh in the low wind speed areas — or Class 4 wind sites — that are broadly available across the United States. However, these turbine designs are not well suited to low wind sites and have only limited potential to achieve lower costs of energy. (U.S. DOE's Wind and Hydropower Technologies Program)
Back to Top Wave Energy
Hawaii's ocean energy potential is significant. Inventors and researchers worldwide are developing devices to convert the energy found in waves and ocean currents into electricity. According to a study completed in 1992, the annual wave energy resource off the northern shores of the Hawaiian Islands far exceeds the electricity demand of all but one of the major islands--Oahu. (Hawaii Department of Business, Economic Development, and Tourism)
The testing of one type of wave energy device is taking place in waters off Oahu. The U.S. Navy has initiated an at-sea demonstration of the 20-kW PowerBuoy ™ (Ocean Power Technologies, Inc.)
Back to Top Ocean Thermal Energy Conversion (OTEC)
OTEC makes use of the difference in temperature between the warm surface water of the ocean and the cold water in depths below 2,000 feet to generate electricity. As long as a sufficient temperature difference (about 40 degrees Fahrenheit) exists between the warm upper layer of water and the cold deep water, net power can be generated. Almost all of the major U.S. OTEC experiments have taken place in Hawaii. The Natural Energy Laboratory of Hawaii Authority (NELHA) has been recognized as the world's foremost laboratory and test facility for OTEC and OTEC-related research. On June 2, 2006, plans for a 1-MW OTEC facility at NELHA were announced. (Content from Hawaii Department of Business, Economic Development, and Tourism) Some energy experts believe that if it could become cost-competitive with conventional power technologies, OTEC could produce billions of watts of electrical power. (U.S. Department of Energy, Renewable Energy Consumer Guide)
Back to Top Ocean Current Energy
Marine and hydrokinetic devices offer the potential to capture energy from ocean currents. In fiscal year 2008, funding was provided to DOE for research on a wide range of advanced water power technologies. As part of its commitment to develop clean, domestic energy sources, DOE is collaborating with industry, regulators, and other stakeholders to investigate emerging water power technologies and further improve conventional hydropower systems.
Back to Top Stationary Fuel Cells
Fuel cells convert the chemical energy of hydrogen to mechanical energy through electrochemical conversion where the hydrogen is reacted with oxygen to produce water and electricity. Near-term fuel cell systems can run on natural gas or liquid petroleum gas. The longer term potential is for systems to run on renewable/alternate fuels.
Back to Top Waste-to-Energy Plants
Municipal solid waste (MSW) is one of three major waste-to-energy technologies (the others are anaerobic digestion and biomass). MSW can be directly combusted in waste-to-energy facilities as a fuel with minimal processing, known as mass burn; it can undergo moderate to extensive processing before being directly combusted as refuse-derived fuel; or it can be gasified using pyrolysis or thermal gasification techniques. Each of these technologies presents the opportunity for both electricity production as well as an alternative to landfilling or composting the MSW. In contrast with many other energy technologies that require fuel to be purchased, MSW facilities are paid by the fuel suppliers to take the fuel (a "tipping fee"). Another MSW-to-electricity technology, landfill gas recovery, permits electricity production from existing landfills via the natural degradation of MSW by anaerobic fermentation (digestion) into landfill gas. Anaerobic digestion can also be used on municipal sewage sludge. (California Energy Commission)
Back to Top Biomass Combustion Plants
Power from biomass is a proven commercial electricity generation option in the United States with about 9,733 megawatts (MW) in 2002 of installed capacity. Most of today's biomass power plants are direct-fired systems that are similar to most fossil-fuel fired power plants.
The biomass fuel is burned in a boiler to produce high-pressure steam which is introduced into a steam turbine connected to an electricity generator. (U.S. DOE Biomass Program)
Back to Top Algae to Fuels
The record oil price increases since 2003, competing demands between foods and other biofuel sources and the world food crisis have ignited interest in algaculture (farming algae) for making vegetable oil, biodiesel, bioethanol, biogasoline, biomethanol, biobutanol and other biofuels. Among algal fuels' attractive characteristics: they do not affect fresh water resources, can be produced using ocean and wastewater, and are biodegradable and relatively harmless to the environment if spilled. Algae cost more per pound yet can yield over 30 times more energy per acre than other, second-generation biofuel crops.
One biofuels company has claimed that algae can produce more oil in an area the size of a two-car garage than an football field of soybeans, because almost the entire algal organism can use sunlight to produce lipids, or oil. DOE estimates that if algae fuel replaced all the petroleum fuel in the United States, it would require 15,000 square miles (40,000 square kilometers), which is a few thousand square miles larger than Maryland.
As of 2008, such fuels remain too expensive to replace other commercially available fuels, with the cost of various algae species typically between US$5–10 per kg dry weight. But several companies and government agencies are funding efforts to reduce capital and operating costs and make algae oil production commercially viable.
Back to Top Biofuel-powered Turbine and Engine Generators
Many modern turbines and generators can operate on some biodiesel blend, usually capped at B20, or 20% biodiesel, on the engine side.
Back to Top Transmission and Distribution (T&D) Technologies Advanced Metering Infrastructure and Smart Grid Technologies
Meeting Kauai’s sustainable energy goals will depend to a large degree on the interconnection and operational integration of renewable generation to the transmission grid. Peaking generation that runs only a small number of hours every year, primarily during the summer months, is typically less efficient than most base load power plants. This means that peaking units contribute disproportionately not only to greenhouse gas emissions but to local air pollution because they operate during hot summer afternoons when local air quality can be poor. Advanced metering infrastructure (AMI) provides two-way communication between customers and their electric utility, giving utilities detailed information about electrical loads and power outages while giving customers the option to adjust their energy use in response to real-time utility rates. AMI is a necessary underpinning for more sophisticated approaches to demand response. AMI is a step toward "Smart Grid", which is a concept that involves adding internet-like communication technologies and control technologies to the nation's electrical grid. KIUC has begun its AMI initiative.
Back to Top Microgrids
A microgrid, or local energy distribution network, offers integration of renewable or distributed generation technologies with local electric loads, which can operate in parallel with the grid or in an intentional island mode to provide a customized level of high reliability and resilience to grid disturbances. This advanced, integrated distribution system addresses the need for application in locations with electric supply and/or delivery constraints, in remote sites, and for protection of critical loads and economically sensitive development.
Back to Top Energy Storage Technologies Pumped Hydro
Pumped hydro offers a technically feasible way to “firm up” or make more dispatchable renewable energy technologies. When the demand for electricity is low, a pumped storage facility stores energy by pumping water from a lower reservoir to an upper reservoir. During periods of high electrical demand or lower renewable energy resource, e.g. solar insolation, the water is released back to the lower reservoir to generate electricity. In Okinawa, Japan, a pumped hydro installation has been operating for years using sea water.
Back to Top Batteries
Battery storage was used in the early days of direct-current electric power networks, and is appearing again. Battery systems connected to large solid-state converters have been used to stabilize power distribution networks. For example in Puerto Rico a system with a capacity of 20 megawatts for 15 minutes is used to stabilize the frequency of electric power produced on the island. A 27 megawatt 15 minute nickel-cadmium battery bank was installed at Anchorage Alaska in 2003 to stabilize voltage at the end of a long transmission line. Many "off-the-grid" domestic systems rely on battery storage, but storing large amounts of electricity in batteries or by other electrical means has not yet been put to general use.
Batteries are generally expensive, have high maintenance, and have limited lifespans. Battery technologies for large-scale storage include: Rechargeable flow batteries that can be used as a rapid-response storage medium. Vanadium redox batteries and other types of flow batteries are beginning to be used for energy storage including the averaging of generation from wind turbines. Vanadium redox flow batteries are currently installed at Huxley Hill wind farm (Australia), Tomari Wind Hills at Hokkaidō (Japan), as well as in other non-wind farm applications. (Environmental Health Perspectives) Sodium-sulfur (NaS) batteries could also be inexpensive to implement on a large scale and have been used for grid storage in Japan and in the United States. NaS battery has a high energy density, high efficiency of charge/discharge (89—92%) and long cycle life, and is fabricated from inexpensive materials. Because, however, of the operating temperatures of 300 to 350 °C and the highly corrosive nature of the sodium polysulfides, such cells are primarily suitable for large-scale non-mobile applications the day to assist in stabilizing the power output of the wind farm during wind fluctuations.such as grid support.
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Flywheels
Mechanical inertia is the basis of this storage method. A heavy rotating disc is accelerated by an electric motor, which acts as a generator on reversal, slowing down the disc and producing electricity. Electricity is stored as the kinetic energy of the disc. Larger flywheel speeds allow greater storage capacity but require strong materials such as steel or composite materials to resist the centrifugal forces (or rather, to provide centripetal forces). The ranges of power and energy storage are technically and economically achievable, however, tend to make flywheels unsuitable for general power system application; they are probably best suited to load-leveling applications on railway power systems and for improving power quality in renewable energy systems.
Back to Top Hydrogen
Hydrogen is not a primary energy source, but a portable energy storage method (an energy carrier), because it must first be manufactured by other energy sources in order to be used. Hydrogen may be used in fuel cells which convert chemical energy directly to electricity. Hydrogen production requires either reforming natural gas with steam (having carbon dioxide as a by-product), or, for a possibly renewable and more ecologic source, the electrolysis of water into hydrogen and oxygen. Hydrogen can be used as a storage medium, and could therefore be significant factor in using renewable energies. With intermittent renewables such as solar and wind, the output may be fed directly into an electricity grid. At penetrations below 20% of the grid demand, this does not severely change the economics; but beyond about 20% of the total demand, external storage will become important. Therefore, these renewable sources may be used for the electricity to make hydrogen, then they can be utilized fully whenever they are available.
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