Energy Storage: What Is the Cheapest Solution?

There is some other obvious storage options being missed here:
1. One of the big power users is for cooling in the sun belt where solar will be most cost effective.  AC units that save money by making ice when power rates are low and then use the ice for cooling when power rates go up, are increasingly available.  (This turns out to be an old trick used to cool theaters back when AC units weren’t large enough to handle such a large load.)  Right now cheaper power is available at night when obody is using the coal generated power.  With more solar available, and as it continues to decline in price, the cheapest power will be available during daylight hours, inspite of increased use during this time and better load matching.  These AC units will then be making ice during the day for use in cooling during the night.  Essentially you’re storing power for cooling in the form of ice.  Very cheap storage used for one of the biggest power loads in the sun belt.
2. Molten salt storage in central tower type Concentrated Solar Thermal (CST) plants can be stored under ground and used later in the day at reasonable cost.
3. We have huge amounts of natural gas available in the shale deposits in the USA.  So forget storage and use solar and wind in combination with natural gas peak power plants.
If you’re going to get into this discussion then provide a table of options and reasonable estimates of their costs.  This article is very conjectural.  $1 million per megawatt for 15 minutes for Li Ion is a way-out-to-lunch number.

Lithium Ion gets lots of buzz because they are the best solution for cars - if they can keep them from exploding - and this means we should have lots of them lying around someday - assuming people buy a lot of cars and figure our how and where to charge them - I park in the street.

There are technologies that are suited for bulk storage and available now.  Besides the molten (600 degrees F) sodium sulfur, there is the VRB-ESS - flow battery technology, for about the same price.  No heat, no pressure, no emissions, 20 yr life, little O&M, unlimited deep charge cycles, and first used at wind farms.  More information at http://www.Utility-Savings.com.

When referring to energy storage, please use “kWh” or “MWh” not MW. We pay for electricity in kWh not kW. Both figures are needed, except for grid stabilization, where power over a short interval like 15 minutes is important.

The #1 take home message here is:  “Intermittent renewable energy will require more grid regulation”.  This regulation can either be from present regulation generators which supply AGC grid frequency control or spinning reserve or from batteries.  Batteries would do a wonderful, and mostly better job of regulation, and would replace the present generators for peaking and regulation, which are the most polluting of all generation sources.  To make a generator change output very quickly, you sacrifice efficiency, and increase pollution.  Not so with a battery.

The #2 take home message here is that batteries are presently too expensive.  That is changing, and changing quickly.  Between the several redox flow battery flavors being developed, Sodium-Beta batteries, and Metal-Air batteries, a reliable battery that meets the market is on the way.. but it’s not the big present battery corporations that are developing it.. this is an inflection point in technology where one or two of the 40 small companies I’m tracking will be a $Billion company in 5-10 years.  See http://www.silentenergy.com for more.

You’ve done a great job Uci with most of your articles, especially on PV, but your primary source here provided a lot of disinformation.  I’m writing an in-depth analysis of the energy storage options, which I’ll present at the ASME ES conference next spring.  The paper, ES2010-90377, probably won’t be available until shortly before the conference, but the abstract follows:

There is the general perception that increased grid-scale energy storage will facilitate expansion of renewables.  Most discussions of costs and competitiveness of storage options have addressed cycle efficiency and capital costs of energy storage in terms of both $/kW and $/kWhr.  However, likely number of cycles per year, marginal value of delivered energy, impact on GHG emissions, application-specific expected lifetime, discount rate, likely trends in the markets, and other factors have seldom been addressed, at least for grid-scale applications. 

The levelized costs of delivered energy from the leading technologies for grid-scale energy storage are calculated using a model that considers likely number of cycles per year, application-specific expected lifetime, discount rate, duty cycle, and likely trends in the markets.  The expected capital costs of the various options evaluated – pumped hydrostorage, underground pumped hydrostorage (UPHS), hydrogen fuel cells, carbon-lead-acid batteries, advanced adiabatic compressed air energy storage (AA-CAES), lead-acid batteries, lithium-ion batteries, flywheels, sodium sulfur batteries, ultra capacitors, and superconducting magnetic energy storage (SMES) – are based on recent installation cost data to the extent possible.  The marginal value of the delivered stored energy is analyzed using recent grid energy prices from regions of high wind-energy penetration.  The above list is in order from most competitive to least competitive.

Grid-scale energy storage is expected to lead to significant reductions in GHG emissions only in regions where the off-peak energy is very clean.  These areas will be characterized by a high level of wind energy with cheap off-peak and peak prices.  At the expected daily price differentials, the only conventional options expected to be commercially viable are hydro storage and UPHS.  The market value of energy storage for short periods of time (under a few hours) is expected to be minimal for grid-scale purposes.  Only low-cost daily storage is easily justified both from an economic and environmental perspective.

A lesser-known energy storage option, Windfuels, is also briefly reviewed.  Here, excess off-peak electrical energy is used to synthesize standard liquid fuels, such as gasoline and jet fuel, from CO2 and H2O.  Simulations have shown that innovations should make it practical to reduce CO2 to CO at 90% of theoretical efficiency limits.  When combined with other process advances, it should then be possible to synthesize hydrocarbons and alcohols from point-source CO2 and off-peak clean grid energy (wind or nuclear) at system efficiencies in the range of 52-61%. The cost of the tanks for storing energy in jet fuel, ethanol, and diesel is only $0.02/kWhr.  The cost of storing vast amounts of energy in batteries, compressed air, or flywheels would be several thousand times greater.

Thanks for sharing it, FDDoty—looks like a comprehensive analysis. Would love to read the paper when it’s available.

what a excellent water reservoir with good battery back up.hope that u will read this blog for using this product…..

Grid-scale energy storage is expected to lead to significant reductions in GHG emissions only in regions where the off-peak energy is very clean.  These areas will be characterized by a high level of wind energy with cheap off-peak and peak prices.  At the expected daily price differentials, the only conventional options expected to be commercially viable are hydro storage and UPHS.  The market value of energy storage for short periods of time (under a few hours) is expected to be minimal for grid-scale purposes.  Only low-cost daily storage is easily justified both from an economic and environmental perspective.

How does flywheel storage compare? I know of one firm which has commercial applications in evaluation by power companies. look at Beacon corp.