Rezachek & Associates'
Energy & Environmental Resources

Utility Integration of Renewables

Energy Storage

ASPES AG Aspes has been founded as a spin-off company by four former university researchers from the Technical University of Zurich ETH in 1987. Each of the founders accumulated more than ten years experience in kinetic energy storage. The main purpose of the company is the development of flywheels for energy storage and high speed composite rotors for different applications. Realized applications have been in the field of uninterruptable power supplies (UPS), manufacturing medicine, improving grid power quality and transportation.

Electrical Battery Storage Deep cycle, rechargeable, long-life battery banks are required in all photovoltaic applications for which there are energy demands other than during sunlight hours. Exceptions are certain grid-connected PV installations, where the utility grid acts in lieu of storage. Another exception is "PV pumped-water-storage" installations, which also acts in lieu of chemical storage batteries. In this configuration, water is pumped uphill, to be released only upon demand, when it is forced across the veins of a low-head-hydro, permanent magnet alternator, thereby creating on-site electricity.

Energy Research Corporation A leading developer of electrochemical power technologies. ERC is commercializing its fuel cells and batteries for various industrial and government customers.

Energy Storage Many renewable energy systems that are not connected to the power grid have some method of storing energy. Energy storage allows a system to operate even when there is no input or when the input is not capable of meeting all of the demands of the loads.

Energy Storage Energy storage involves methods and apparatus used to store heating, cooling, or power. In district energy applications these encompass a wide variety of applications, but all are designed to be recharged on a cyclical basis (usually daily, occasionally seasonally) and fulfill one or more purposes.

Estimated Use of Water in the United States in 1990 - Hydroelectric Power Water Use Water used for hydroelectric power generation is classified as an instream use and refers to the water used in the generation of electricity at plants where the turbine generators are driven by falling water. Estimates of water used for hydroelectric power generation may vary because of the way individual estimates are made of the quantities of water passed through the plants. If the water is passed through the plants only one time, then accurate estimates of water use can be obtained by streamflow measurements and gate openings. However, it is difficult to define and obtain net water use at pumped-storage hydroelectric plants because the same water is recycled a number of times. Pumped-storage plants usually generate electric energy during peak-load periods by using water previously pumped into an elevated storage reservoir during off-peak periods when excess generating capacity is available to do so. When additional generating capacity is needed, the water can be released from the pumped-storage reservoir through a conduit to turbine generators located in a power plant at a lower level.

First Hydro First Hydro is an independent generating company based in North Wales where it operates hydroelectric pumped storage power stations at Dinorwig, near Llanberis and Ffestiniog, near Blaenau Ffestiniog. Through these it competes effectively in the electricity market, selling energy and offering fast response services to the national electricity transmission system. The power stations provide flexibility and security to meet peak demand through the day and to provide rapid response to meet sudden demand changes. First Hydro helps to ensure that electrical demand throughout the country can be met consistently.

Hydro Power HANJUNG has focused on the production and installation of facilities needed for the construction of Pumped Storage Power Plants and the repowering of outdated power plants, while making moves into power plant markets in Malaysia and other countries in Southeast Asia.

Ludington Pumped Storage Plant A 27-billion-gallon water reservoir -- 2.5 miles long, a mile wide, and 110 feet deep -- sits along U.S. 31, four miles from Ludington, hidden by a steep, grassy hillside. Owned jointly by Consumers Energy and Detroit Edison, this pumped storage plant can generate enough electricity to serve a community of 1.3 million people.

Mt. Elbert Pumped-Storage Powerplant The power generated at Mt. Elbert derives from water originally pumped from Twin Lakes, which acts as the Mt. Elbert afterbay, and also from supplemental water delivered from Turquoise Lake to the forebay. The generators are designed to operate as a 170,000-horsepower electric motor which drives the turbines in reverse, and pumps water back up to refill the forebay. This pumping mode normally will be used during the very early morning hours, when power demands are low and surplus low-rate power is received from other generating stations. This pump-back storage principle is advantageous since the generating units can be started quickly and adjustments of power output can be made rapidly to respond to varying patterns of daily and seasonal power demands.

Pumped-Storage Hydro Pumped-storage plants allow for large-scale storage of electrical energy. They store water energy during off-peak hours by pumping water from a lower reservoir to an upper reservoir which is usually at a minimum of 100 metres height difference. When electricity is in high demand and is also expensive to produce using conventional plants, electricity is produced by allowing the water from the upper reservoir to flow back down through the same pump/turbine.

Research on Electricity Storage Technology Equipment such as pumped storage power generators, electric water heaters and ice thermal storage air conditioning systems are major pillars of power load leveling programs, and have already been brought into actual use. In recent years, compact sodium sulfate (Na-S) batteries with high energy storage efficiency have been researched and developed for power storage purposes. They intend to conduct operation tests on these batteries to research their peak shift effect (ability to be charged with electricity overnight, for use in the daytime), and ways of utilizing them effectively.

Solar Chemistry Section Solar energy is essentially unlimited and its utilization ecologically benign. However, solar radiation reaching the earth is intermittent and inconveniently distributed. It needs to be stored and transported from the sunny and uninhabited regions to the industrialised and populated places, where the energy is required. The thermochemical conversion of solar energy into chemical fuels provides a thermodynamically efficient path for storage and transportation. By concentrating the sunlight with parabolic reflectors and capturing that radiative energy in solar receivers and reactors, we can supply high-temperature process heat to drive endothermic reactions.

Source Energy and Environmental Impacts of Thermal Energy Storage -- Executive Summary A California Energy Commission program, Opportunity Technology Commercialization (OTCOM), is working to "effectively increase the market penetration of energy technologies offering compelling energy, environmental, diversity and economic development benefits. "OTCOM selected Thermal Energy Storage (TES) as one such technology. TES allows cooling made at night to be stored for building air conditioning during the day.

The All Vanadium Redox Battery The pursuit of efficient and environmentally safe energy storage systems has seen the Vanadium Battery become recognised as a top contender for energy storage solutions. Electrochemical systems such as batteries and fuel cells convert the energy of electrochemical reactions directly into low voltage, direct current electricity. Since conversion of heat is not involved, the thermodynamic efficiency can be at least twice that of a thermal power plant. Practical energy efficiencies reaching 90% are possible for electrochemical energy storage systems. The Vanadium Battery is a redox flow battery system and one of its advantages is that it offers the possibility of "instant recharge".

Thermal Energy Storage (TES) Technologies For Utility-Scale and Industrial Applications An emerging issue that may limit the usefulness of cogeneration is a daily mismatch between the demand for electricity and the thermal energy load to be supplied to an industrial facility. Increasingly, utilities are requiring cogenerators to provide dispatchable power (power supplied on demand) whereas the industrial thermal loads are relatively constant during the day. A Pacific Northwest National Laboratory-developed diurnal TES system proposed here will store thermal energy recovered from the exhaust stream of the gas turbine to meet daily variations in electrical and thermal energy demands.