This is part 4 of a 4-Part Article about “Energy Storage” in the form of Ice-Assisted A/C.  This new HVAC technology incorporates Energy-Storage in the form of “stored” (cold) Thermal-Energy within ice.  The system makes the ice when overall electricity demand is low.  It then uses the ice to provide cooling (without the outside unit needing to run) during periods of peak electricity demand the next day.

photo of the ice bear commercial ice-assisted air conditioner

SHOWN:  An Ice-Assisted HVAC System

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Profressional Series gas & electric water heaters, and tankless water heaters.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience, and offer 24/7 Emergency Service.

This Is Part 4 Of A 4-Part Article

For Part 1 of this article, click here: Ice-Assisted A/C Part 1

For Part 2 of this article, click here: Ice-Assisted A/C Part 2

For Part 3 of this article, click here: Ice-Assisted A/C Part 3


Residential Demand Pricing Is Happening Now

The benefit of this technology is for residential electricity customers who pay an electricity “Demand Charge”.  Demand charges have been used in commercial for years, and are now becoming active for more and more residential customers.  One such plan (described below) is in effect in Arizona.   At present DFW does not have Residential Demand Pricing, but this may be subject to change.

The purpose of demand charges is to reduce electricity consumption during periods of peak demand.  In short, a demand charge is an additional charge that is based on the highest level of electricity usage during a pre-set time period.  For the plan described below, it’s the highest demand during a 1 hour period during the month.   A customer can reduce demand charges by minimizing their electricity usage during periods of peak demand.  Ice-Assisted A/C is a tremendous way to reduce demand charges.  Since residential a/c is the largest user of electricity in a home during summer, minimizing it’s usage during peak demand reduces electricity bills.

North Texas does not currently have demand charges.  As DFW continues to grow, electricity usage may exceed the power-grid’s ability to generate electricity.  If this occurs, there are only two solutions; reduce demand or build more peak-demand power plants.  Peak demand power plants are very expensive in relation to how little they are used.  Because they only generate electricity during periods of peak demand, the electricity they generate is very costly.  The cost of generating power is passed on to consumers, and rate hikes must occur in north Texas in order to pay for building more & more peak demand power plants.

For summer of 2018 ERCOT (Electricity Reliability Council of Texas) said their “reserve margin” (the difference between the system’s maximum electricity generating capacity and electricity demand) is the lowest it has been in many years.  Reserve Margins that were too small created the need for Demand Pricing in order to reduce electricity peak demand in other locations in the United States.   It’s fair to say DFW is prime for this type of charge too.

flag for state of arizona

logo for arizona public service utility company

In 2018 Arizona Public Service Implemented 4 Residential Electric Rate Plans

  • These electric rates are specifically designed to incentivize customers to minimize electricity usage during On-Peak (peak demand) hours.
  • On-Peak Rates Hours: 3 p.m. to 8 p.m. – Monday through Friday. **    All other hours are Off-Peak, including weekends & holidays.
  • Each residential customer must choose a plan. 

These 4 Plans Allow The Customer To Choose: 

  • The maximum monthly Demand Charge they are willing to pay
  • The cost per kWh associated with the Demand Charge they chose.
  • Those who choose higher demand charges pay less per kWh.
  • The highest level plan (with lowest kWh charges) Is Available Only For Those With Solar Collectors  PLUS  Electricity Battery-Storage At Their Home

graph compares effect of electricity demand charges

SHOWN: Blue Line: Electricity Consumption For A Home Without Electricity Demand Charges

Black Line: Electricity Consumption For A Home With Demand Charges

  • Demand Charges to fund the costs related to ensuring the power-grid has enough electricity generating capacity to meet periods of Peak-Demand.  For those who choose to minimize their home’s demand during periods of peak demand (and agree to pay the highest demand charge) they are rewarded with notably lower per kWh charges for electricity.

R-1: No Demand-Charge Plan

  • On-Peak:    24.3 cents per kWh.        Note: The average price per kWh in north Texas during 2017 summer was just under 13 cents per kWh.
  • OFF-Peak: 10.9 cents per kWh
  • On-Peak Hours Are Mon-Fri — 3-8 pm
  • No Demand Charge Applies

 R-2: Low Demand-Charge Plan

  • Demand Charge of $8.40 kW.    This is 1 single monthly charge that is based on the highest kW electricity demanded in 1 hour (during On-Peak hours) for the entire month.
  • The charge is $8.40 per 1,000 kW of usage during the customers peak electricity usage hour during the month.
  • Example: A 3 ton central A/C uses 3,500 watts.  It alone would create $29.40 demand charge.    Ice-Assisted A/C uses NO electricity during peak demand hours.
  • The Demand Charge is in addition to the price per kWh (shown just below).
  • On-Peak:  13.2 cents per kWh
  • OFF-Peak: 7.8 cents per kWh

R-3: Mid Demand-Charge Plan

  • Demand Charge of $17.44 per kW.   
  • A 3-ton, 3500 watt A/C alone would generate a $61.04 Demand Charge
  • On-Peak:    8.7 cents per kWh
  • OFF-Peak: 5.2 cents per kWh

R-Tech: Top Demand-Charge Plan (only available to those with solar + battery storage)

photo of home with solar panels on roof

  • Available ONLY To Customers with: 1. Solar Equipment + 2. On sight Battery Storage sized at 4 kWh or more.
  • Summer Demand Charge of $20.25 per kW.   
  • A 3-ton, 3500 watt A/C alone would generate a $70.88 Demand Charge.
  • On-Peak:    5.75 cents per kWh
  • OFF-Peak: 4.75 cents per kWh

Those with solar equipment + battery storage are able to use little or no electricity from the Power Grid during periods of Peak-Demand (depending on the size of their solar equipment and battery).  If their electricity needs exceed the solar equipment’s capacity, they tap into their battery storage for additional power.   If both the solar equipment and battery are at capacity, they buy additional electricity from the Power Grid.

  • No Demand Charge customers pay 24.3 cents per kWh (On-Peak rate).
  • R-Tech customers pay 5.75 cents per kWh (On-Peak rate).
  • No Demand Charge customers pay over 4 times the (On-Peak rate) per kWh that Tech Tier customers pay!

Upon Review These 4 Plans, One Can Easily Determine:

  • There is tremendous incentive to minimize electricity usage (during On-Peak hours) in the form of lower per kWh charge + Demand Charges.
  • Those who are most willing to reduce electricity use the most (during On-Peak hours) are rewarded with progressively lower per kWh charges.
  • Ice-Assisted A/C could help pay for itself over its lifetime — in the form of lower charges for electricity per kWh + lower Demand Charges. 
  • Those Who Put The Lowest Demand On The Power Grid Receive The Lowest Electric Rates (solar + battery storage customers).


Arizona Public Service’s On-Peak Rates Shows How Ice-Assisted A/C Can Dramatically Reduce Electric Bills  

  • Non-solar Arizona Public Service customers with Ice-Assisted A/C could cool their home with ice during the On-Peak demand hours of 3-8 pm on M-F.
  • They could be on the Mid-Tier electric plan that lowers their On-Peak (per kWh) charge by nearly 2/3  AND  Off-Peak (per kWh) rate by nearly 1/2.
  • Because they use Ice-Assisted A/C during On-Peak hours, their Demand Charge would be minimized, as central a/c uses 50% of total electricity use during summer.


How (cold) Thermal Energy-Storage Works With Residential Air Conditioning 

photo of ice energy ice bear 20 residential HVAC System

Shown: Ice Energy’s Ice Bear-20 Ice-Assisted Residential HVAC System

photo of the ice bear commercial ice-assisted air conditioner

Ice Is Made & Stored In An Insulated Tank Inside The Outdoor Unit

Thermal-Storage Technologies Enable Short-Term (cold) Energy Storage

  • The HVAC System makes ice during off-peak hours, while electricity rates and demand are lower.
  • During Peak-Demand, when electricity demand and costs are highest, ice provides the cooling (without outdoor unit running).
  • This lowers cooling costs AND reduces electricity usage during periods of Peak-Demand on the Power Grid

Ice-Assisted Residential A/C Is Starting To Become Available! 

Image result for A Santa Barbara CA based Ice Energy logo

A Santa Barbara, CA based Ice Energy manufactures the “Ice Bear 20 Residential Ice-Assisted HVAC System”.  Ice Energy, a leading provider of thermal-energy storage solutions launched the Ice-Bear-20 to provide an innovative way to store cold thermal energy.  While initial sales efforts will be focused on California, the unit is available “anywhere people want it,” said Ice Energy’s CEO Mike Hopkins.

Ice Energy’s Website Reads: Ice storage is a clean, reliable and least-cost energy storage solution.  With a reliability record in excess of 98%, Ice Bears benefit both electricity providers and their customers. Ice Bears lower cooling bills, improve the efficiency and resiliency of the Power Grid, and reduce carbon emissions. The residential Ice Bear 20 integrates with ductwork or ductless mini-split systems inside new or existing homes.

The Ice Bear sits outside the home.  It has a refrigerant line going into the home, just like a conventional central a/c.  During periods of low electricity demand, the Ice Bear 20 uses its built-in cooling system to make ice.  During Electricity Peak-Demand times, the Ice Bear 20 uses only the ice to cool the refrigerant (which cools the home).  The residential Ice Bear 20 also serves as a traditional Heat Pump Residential HVAC System.   It heats and cools like a regular Heat Pump + also serves as a (cold) Thermal Energy Storage unit.

diagram of how ice energy ice bear residential a/c works

Diagram Of Ice Bear 20 Residential HVAC System Connected To The Coil Inside The Furnace (just like conventional central a/c) 

photo of the ice bear commercial ice-assisted air conditioner

Shown: The Ice Bear Ice-Assisted A/C Thermal Energy Storage

Building upon Ice Energy’s patented system, the Ice Bear 20 is designed to provide homeowners with an; affordable, reliable, earth friendly energy storage cooling & heating system.  The Ice Bear 20 includes the same components as any residential Heat Pump + the additional thermal-energy storage components.

The Ice Bear 20 is a residential a/c  with up 4.3 tons of capacity (a 2,000 square foot home in DFW needs a 3 ton central a/c).  When the system is not being used for cooling, it freezes water in an insulated tank.  It can freeze the tank water in 4 hours.  Then on command, the system switches from conventional AC to using the ice to cool the house for at 4  hours.

To See A Specification Sheet For Ice Bear 20, Click Here: Ice Bear 20 Specification Sheet

The Ice Bear 20’s Thermal-energy storage component is a 265 gallon insulated storage tank filled with tap water.  Inside the tank are coiled copper tubes which are used both to freeze the water.  During “ice only” cooling cycles, the refrigerant passes through these same coils to cool itself.   To provide AC, the Ice Cub uses a low power pump to circulate refrigerant through the ice and into the evaporator coil (evaporator coil is located inside or above the furnace).

photo of ice created by the ice bear ice assisted commercial air conditioner

Shown: Refrigerant Coils Surrounded By The Ice They Created

By producing ice during the night, and using the ice the next day, the Ice Cub moves some of its electricity neds to times when electricity demand and costs are low.  It cools with the ice during the day (when electricity demand and costs are highest).

The Ice Cub Operates In Multiple Modes:

  • Cool the home like a conventional AC unit.
  • Create & Store (cold) thermal energy by freezing water in the ice tank.  All water is frozen in 4 hours.
  • Ice-Cooling can occur for 4+ hours without using electricity.  A battery provides up to four hours of blower-fan operation.
  • When heating is required, the Heat Pump shifts into reverse and operates as a heat pump to provide heating for a home.

The Ice Cub A/C provides 4 hours of Ice-Cooling at any time.  This can provide a notable savings for anyone who pays residential “demand” electricity charges.

Click Here To See Details On Ice-Assisted A/C — On Ice Energy’s Website:

With The Growth Of Wind & Sun Electricity Generation Energy-Storage Is Vital 

Energy Storage:

  • Increases the spread of renewable energy.
  • Maximize the potential of wind & solar by storing excess electricity for use at other times.
  • Improve air-quality as less demand (particularly Peak-Demand) will need to come from fossil-fuel power plants.
  • Maximize the existing power grid.
  • Create a better balance between needs of electricity consumers and the producers of electricity.

Grid-Connected Energy-Storage Is Coming Of Age

As of April 2017, 2.5% of delivered electric power in the U.S. is cycled through a storage facility (24.2 GW of power in energy storage).*5   Energy storage can be installed at many points within the power-grid.  This article focuses cold thermal-energy storage at the location of electricity consumption.  Additionally, Energy Storage can refer to a wide range of technologies and approaches to manage electricity demand and supply.

*5 Source:

Additional Current Forms Of Energy-Storage

The Ice Bear provides (cold) thermal energy-storage.  There are other forms of energy storage used in various locations in the world.  These energy-storage solutions solve the problem of variable outputs of wind & solar energy.   Storing the electricity generated by wind and solar is key to making these renewable resources able to power homes and business customers 24 hours a day.

Energy storage systems provide a wide array of technological approaches to matching electricity supply and demand.  Energy-Storage Systems redirect the focus of solar and wind renewable energy away from when electricity is supplied to when the electricity is needed.

Currently Energy-Storage Is Within 5 Main Categories

  • Thermal – capturing cold or heat for later use.
  • Batteries – batteries that store energy until it is needed.
  • Pumped Hydro-Power – large water reservoirs as stored energy.  They are filled when electricity demand is low and drained to provide electricity during peak demand.
  • Compressed Air Energy Storage. It works much like pumped hydro power (above).
  • Flywheels – mechanical devices that harness rotational-energy to deliver instantaneous electricity

You can learn more about each of these technologies with *10 Sources below.

*10 Source:

tesla electric cars logo

Battery Energy-Storage

“New research suggests that, due to falling costs, solar power with battery energy-storage is now cost-competitive with natural gas peak-demand power plants (power plants that operate only during electricity peak-demand periods).  Research focused on specific markets in the USA suggests that 10 GW of natural gas peak-demand plants could be taken offline by 2027 with the continued growth of battery storage.  Battery Energy-Storage is vital to manage in the variable electricity supply that comes with solar and wind power. *2

image for tesla's power pack commercial battery

Tesla’s (all-electric cars) 2017 Earnings Report said the company plans to at least triple the amount of energy-storage (batteries) production in 2018, as compared to 2017.   Tesla states “It’s clear there is a huge opportunity for Tesla in large-scale energy storage.”   Tesla has built large battery farms on the Hawaiian island of Kauai, the island of American Samoa, in Connecticut, and on multiple sites in California.*3

In 2017 Tesla installed 100 MegaWatts of Energy Storage in the world’s biggest Battery Farm adjacent to a wind farm near Jamestown in South Australia.  In a letter to Shareholders, Tesla said the success of the South Australia project has led to “an increase in demand” for the Tesla Powerpack.   Tesla confirms their new ‘Powerpack 2’ with “twice the energy storage density.”

photo of tesla power pack installation in Nova Scotia

Shown: Photo Of Tesla Power Pack Batteries Installation In Nova Scotia


Tesla’s Residential Energy-Storage System  

graphic shows and identifies Tesla's Power Wall Home Energy Storage System

Tesla also has the PowerWall, a rechargeable residential battery system that stores energy from solar or wind and/ or from the power grid and makes it available on demand.  It can power your home during the night or back up your home in the event of a power outage.  Tesla’s Powerwall is compact and easy to integrate into your home.

Self-Powering your Home

  • With Powerwall you can use much more of your solar energy (electricity) by storing the excess energy during the day and using when needed.  This can up to double the amount of solar energy available to directly power a home.
  • No Solar Collectors On Your Home?  You can buy power from power-grid at night (when electricity demand and charges are lower).   Then use the stored electricity during the day (when electricity demand and charges are higher).  *

* NOTE:  This system saves money only if you have: higher daytime electric rates and / or are on a Demand-Billing or Time-Of-Use rate structure from your electricity provider.  None of these apply to north Texas at the time this article was written (May 2018).

See Tesla’s calculator to determine how many Power Walls are needed and their approximate cost.  See The Calculator At This Link: Tesla Power Wall Cost Calculator

Example: A 2,000 square foot home with central air conditioning requires 2 Power Walls.  Their installed cost = up to $15,500.00  The recommendation is designed to power the home for 24 hours during an electricity outage (35 kWh).  Telsa’s battery is designed for daily use.   A general guide is that the battery will need to be replaced after 10 years.

photo of tesla power wall installed on a home

Shown: Tesla’s PowerWall Home Energy-Storage System (the gray box near the center of the wall)

*2 Source:

*3 Source:

Water Energy-Storage: Pumped Hydro-Storage

diagram map of the tennessee valley authority

Shown: Map Of The Entire Tennessee Valley Authority (TVA) Project To Generate Hydro-Electric Power With 25 Dams on Rivers

 photo of fontana dam, part of the TVA project

One Of The 25 Dams Within The TVA.  The Fontana Dam Is Located On The Little Tennessee River Near Fontana Village, NC

Photo Source:


diagram of pumped hydro energy storage at tennesee valley authority facility

Shown: Diagram of The Tennessee Valley Authority (TVA) Pumped Hydro Energy-Storage Facility At Raccoon Mountain Storage Plant Near Chattanooga, TN.

How Pumped Hydro-Storage Works

Pumped Hydro-Storage stores energy in the form of gravitational-potential downward energy of water.  During times of low electricity demand, water is pumped upward from a lower elevation to a reservoir at a higher elevation.  During periods of high electrical demand, the stored water is released downward through turbines that produce electric power.


Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Profressional Series gas & electric water heaters, and tankless water heaters.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience, and offer 24/7 Emergency Service.