Storage or New Generation?

If we hope to continue our strong economy, we must build new generating and distribution capacity or make the existing system we have more efficient.  This is not a future decision; we need to be executing this decision now.

Our choice for new generation is nuclear or coal.  Enough said.

We have several technologies available for storage.  We can effectively double our existing electrical supply by storing power generated at night and using it during the day.

Our existing electric energy system was built to deliver energy “on demand” at the moment it is needed.  As a result we have an inefficient generating, transmission and distribution system sized to provide energy during the highest demand minute, during the highest demand hour, during the highest demand day, during the highest demand month of the year.  Since air conditioning is the biggest variable demand on the system, this peak in demand occurs on the hottest weekday afternoon of the year when the country is in full production.

In addition to moving energy from off-peak to on-peak, energy storage also acts as a shock absorber, taking the excesses out of energy production and reducing the surprise brownouts and blackouts.  Surprises increase prices.  Storage provides instant supply to satisfy instant demand.

Coal and nuclear plants like to run wide open.  When forced to run at half power some older coal plants loose as much as 40% efficiency.  Emissions go up when these plants run partially loaded.

Renewable energy, specifically wind, generates 2/3 of its power in off peak times.  This energy needs to be stored until the next day’s peak.

Transmission and generation infrastructure improvement through storage will increase use of existing assets and will help improve the financial performance for its owners.

Storage will reduce the pressure to expand existing right of ways or build new right of ways in congested areas.  No one wants more land going to overhead high voltage power lines.

Proven Storage Methods

Pumped Hydro….. pumps water to a lake at a higher elevation from a lake at a lower elevation during off-peak hours.  The pump drives a generator to produce electricity during on-peak hours.

• System cost $2000. kW
• First installation was the 32 MW Rocky River facility in Connecticut built in 1929.
• 60% to 75% efficient.
• Does not reduce transmission and distrinution needs.

CAES….. Compressed air energy systems.

• Off peak power is used to compress air and store it under ground.
• The compressed air is used to eliminate the compressor in a gas turbine increasing output 60%+ or 3 times the generating capacity of a standard gas turbine.
• Capital cost $450/KW.
• Does not reduce transmission and distribution needs.
  

TES……  Thermal energy storage uses off peak electric energy to produce cold water or ice.  The cold water or ice is used to produce air conditioning during off-peak hours.

• There are currently 7000 installations, displacing 5 GW of peak load.
  
• Retrofit cost is $250 to $500 / peak KW shifted.
  
• Systems installed during new construction reduce cost 20% to 60%.  (EPRI)
  
• Large systems such as Unicom Thermal Technologies, in downtown Chicago with 66,000 tons are possible.  Small residential systems are now available.
  
• Shifting peak demand load has proven to be less expensive than building new power facilities.
  
• Utilities generally support TES because it increases their profits significantly more than building new generation.  More of these profits need to end up in the hands of the consumer to encourage more TES.
  
• Major problem is the up front capitol for installation.
  

Thermal cooling storage if integrated into the design of a new building can result in the reduction of the cooling infrastructure equipment size requirement; sometimes by 40 to 60%.  Typical payback can be less than 3 years.

The primary barriers to TES are obtaining rebates and on peak pricing differentials that reflect the true costs of on peak power.  The electric utilities are determined to keep the lion’s share of the savings.  Up front capital to finance the residential and small commercial systems is not readily available.