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SUMMARY
100 MW Wind Farm       No. WT No. FCU      Uplift tons     Solar sqm      C. Air cum
Using 3MW WT              33         6                  704,732.53       266,805.00     898,772.53
Using 7MW WT              14         8                   399,926.73      150,920.00     509,686.73

 

 

ENERGY STORAGE 

BACKGROUND

Electric power is a necessity and must be provided continuously and be dependable. Electric power supplies are summarized as follows:

Power plant capacities

  • Power plant capacities are planned and executed at least to cover peak power requirements plus ten (10%) overload and failure of the largest generating unit.
  • Although the total power plants capacity and respective transmission lines are planned to cover future power requirements up to ten (10) or twenty (20) years, the yearly increase in power requirements may exceed the estimated yearly increase.   Further planning may be done to provide space for additional generating units, for dual voltage of transmission lines and dual voltage transformers.
  • In addition, a power plant requires a minimum of three to five (3-5) years to be become operational depending upon size; thus reducing the planned period by three (3-5) years.   
  • Another problem is that the peak power requirements similar to a duck's curve, may be up to three times the average daily power requirements.
  • The individual unit generator sets failure may exceed a ten (10%) of the planned power requirements.
  • Countries with single power plants should have three (3) generator units; 1@ 33% and 2@66% of full load.  This would cover full load requirements in spite of failure of any generating unit.

Renewable Energy Systems

  • Renewable energy systems output are intermittent and are prone to power failures.
  • Wave energy depends on availability of sea waves.  There are a multitude of wave energy extraction systems that can be reviewed using the published data on the internet.  Failure of these systems is prevalent and no system compares with what we are proposing.
  • Tidal energy is available for a maximum of twenty out of twenty four (20/24) hours per day, due to the time duration when tide and ebb water flow reverse direction twice a day.
  • Solar energy is available for a maximum of 8 hours a day depending on clouds overcast and geographic location.
  • Wind energy is available for a period up to three (3) months per year Due to required wind speeds between (3 to 30 miles per hour.
  • Offshore wind turbine installation using fixed pylon support is limited to fifty (50) meter water depth, due to cost of materials and construction.  Floating wind turbine support to be investigated and provided as herein proposed.
  •  Land based wind turbines require large and expensive land together with land for access roads, transmission lines and right of way for installation, maintenance and operation.
  • A proper renewable energy extraction system to be provided.  The system must be a "Coordinated Offshore Energy Extraction" system (COEE) for extracting energy from; waves, tidal, solar, wind, thermal and deep sea cold water, all installed on a "Floating Construction Unit" (FCU) suitably moored to the sea bed, as detailed at www.renewableenergypumps.com  .

Household and Customer Behavior

Energy saving techniques are not observed by consumers of electric energy, such as simply to abstain from using high power consuming equipment during peak power demand hours. This applies to any equipment with a rating of one and a half (1-1/2) KW and above.  
Setting the thermostat outside the comfort zone temperatures for heating and/or cooling and opening doors and/or windows to obtain a comfort temperature zone.

Codes and Construction Practices

  • Buildings and homes to be provided with suitable insulation and to have windows and doors with minimum air seepage, to minimize heat transfer from and to the internal space and save on cooling and heating loads.  This applies equally to cold and to hot climates.
  • Although the NEC Electric Code and other Local Codes specify that high power consuming equipment to be connected through separate electric power circuits, this practice is not strictly adhered to and there is a mix between lighting, low power consuming equipment and power electric circuits.
  • Tariff Structure; tariffs should be set and enforced to penalize consumers for both the value of peak power used and for power consumption during peak demand hours.

CurrentLY Used Energy Storage Systems

There are many currently proposed energy storage systems, to name a few:

  • Water storage reservoir; pumping water to a high water storage reservoir for generating electric power from the hydro power plant using existing generator units.  Two questions come to mind:
  • The power plant capacity is limited and probably all units are working at full load.  Providing additional stored water does not help; it is only helpful when the water level in the main reservoir is low and not sufficient to operate the power plant at full capacity.
  • A study of the available space, foot print, available elevation of the water storage reservoir, constructability, cost and the resulting cost per KW of power generated.
  • Compressed Air Energy Storage (CAES); produce and store compressed air as energy storage (CAES) during reduced load demand, and feeding the compressed air at the gas turbine air inlet.
  • This requires nearby storage space to store the compressed air, piping and controls.
  • Using the compressed air would increase the efficiency of a gas turbine by a maximum of 10% due to reduction of power needed to compress the air inlet to the gas turbine.
  • Performance of presently operating projects does not encourage this type of energy storage.
  • The physical size of the storage reservoir and the cost of generated KW-Hour to be investigated.
  • Spinning Reserves; where generators are run at less than optimal full power.  The inertia of the generators and their readiness to provide immediately full load, compensate massive changes in load demand.
  • This entails running the equipment at reduced or no load for long time with ensuing wear and tear and fuel consumption for no useful power output.
  • Batteries as power packs; to store energy in battery power packs during low power demand for feeding electric power to the electric network during: power plant overload, during peak hours and/or during power failure.  Siemens and others had developed container size sets of batteries with a 1-MW capacity.
  • The test for this system is for how many hours these can provide 1-MW power.    Usually these systems are useful for a maximum of thirty (30) minutes, to cover transient power dips and are not suitable for longer periods.
  • Charging of these battery power packs may be done using solar system or from the electric network during low power demand.
  • Usually energy storage is required for long durations, for three (3) or more hours.
  • This system must be approved by the electric utility to which the battery pack to be connected to.  The question of grounded or floating DC bus and the quality of the resulting sine wave to be investigated.
  • The physical size and the cost of generated one KW-Hour to be investigated.
  • Batteries for public building and single family homes; these systems to be strictly used for providing hot water and for providing power locally during peak demand hours and not for feeding electric power to the network.
  • Charging of these battery power packs to be performed during off-peak hours using solar system.
  • There are a multitude of energy storage systems that can be searched on the internet.  Most are not worth mentioning.

PROPOSED ENERGY STORAGE SYSTEMS

  • Energy storage is required to provide dependable and continuous electric power supply.   The main utilization is to cover peak load requirements where it may exceed three (3) times the average load, where large generating units may fail, or where the full capacity of the energy source is not available such as low level of water in a reservoir for hydro power plants and to compensate for the intermittent availability of renewable energy systems.
  • The tests for choosing the proper energy storage system are; availability of space, constructability, time duration of the stored energy supply, performance and the bottom line cost of generated one KW-Hour using the stored energy system.

Energy storage systems are proposed under two categories:

  1. at the Micro Level to be provided at the consumer level, and
  2. at the Macro Level to be provided at the public utility level.   The proposed systems are summarized as follows:

MICRO CONSUMER LEVEL

  • Building Insulation; buildings and homes to be provided with suitable insulation to minimize heat transfer from and to the internal space, to save on cooling and heating loads.  This applies equally to cold and to hot climates.
  • Tariff Structure; tariffs should be set and enforced to penalize consumers for both the peak value of the power used and for power consumption during peak demand hours. This would lead consumers to find ways to reduce power consumption during peak demand hours.
  • An incentive to be provided for renewable electric power generation or for providing hot water for domestic use using solar systems.  Excess solar electric energy being stored in batteries, after providing hot water.  Water being a good eutectic medium for storing thermal energy.
  • Setting the thermostat; outside the comfort zone temperatures for heating or cooling, and opening doors and windows to compensate for room temperatures outside the comfort zone. This practice is abundant among teen agers.  An educational system of information to be provided by the public electric utilities as to the proposed comfort temperature zone settings during each of summer and for winter periods.
  • Codes and Construction Practices; Although the NEC Electric Code and other Local Codes specify that high power consuming equipment to be connected through separate electric power circuits; this practice is not strictly adhered to and there is a mix between lighting, low and high power consuming equipment, namely equipment with ratings of one and a half (1-1/2) KW and above.
  • Building Management System (BMS); to be enforced for buildings and for single family homes.  Among other functions, this is necessary to control high electric power consuming equipment and prevent their operation during peak demand hours.
  • A programmable DCS system to be provided to prevent operation of high power equipment during peak demand hours. This is a simple matter and should be enforced.  It consists of a programmable timer and one or more contactor.
  • Ice Storage (Calmac Systems); Ice-makers are cheap; they could be added to window A/C units with ease.  Large, costly batteries are elite playthings.

MACRO UTILITY LEVEL

  • Water storage reservoir; pumping water to a high water storage reservoir for generating electric power from the hydro power plant using existing generator units.
  • Spinning reserve generators where the inertia of the generators and their reserve capacities handle massive changes in the load demand. At that point the reserve generators would have started up and taken over the load demand.
  • Ice Storage (Calmac Systems); an ice storage system should be provided, where space is available to produce ice during off-peak hours and to reduce the size of air-conditioning equipment.  The system uses the chilled water (glycol) by melting the stored ice to cool the air for air conditioning.  This has the following advantages:
  • Reduces the required air-conditioning chiller capacity to approximately forty to fifty (40% to 50%) percent, and would provide air-conditioning during peak demand hours or during utility power failures where the emergency generator is in operation. A mere ten (10%) percent of electric power is needed to operate circulating pumps and fan coil units to provide hundred (100%) of air-conditioning load. This would operate the air-conditioning system at full capacity during off peak hour demand
  • In the United States, according to DOE, roughly 35% of our electricity is consumed in the commercial building sector.  Of that 35%, about 15% is dedicated to HVAC (air conditioning load).
  • In a place like California, residential and commercial air conditioning can represent over 30% of summertime electric loads.
  • Large Scale Solar Systems: Used to provide electric power and store energy in large battery packs of the order of 1-MW for use during peak load hours.
  • Thermal energy storage; performs the same function as an electrical battery. This thermal storage system will never break down, wear out or catch on fire.
  • As the load on the grid increases, the stored thermal energy is used to reduce demand on the grid.
  • Examples are: industrial process heat, building heating, greenhouse heating or domestic and industrial hot water heating.
  • Interconnect all renewable energy sources to the main transmission network.
  • Provide a Central Energy Control Center, to manage power transfer and generation and to make the renewable energy sources as the prime sources of energy to make conventional power plants operate at minimal load.

 

 

 

 

 

 

sayntrazi@hotmail.com

Hion Joon Kim

hjk5607@yahoo.co.kr