Wind Power in Cold Storage

Solar Concentrator Molten Salt System


A molten salt system is a means to store thermal energy, thus mitigating the problem of an intermittent source for generating electricity at night or during cloudy weather. A Danish project wants to do slightly the reverse: store wind energy produced at night in refrigerated warehouses and to release this energy during daytime peak hours.

It is good to see solutions proffered for the Intermittency Issue rather than using it to justify business as usual. Thermal electric storage is one means of balancing the variability of solar or wind power with the peaks and valleys in the demand curve over a 24 hour period. Thermal electric storage also is a way to address seasonal variations in demand for heating or cooling.

“Electricity is expensive to store, but many of the things we make from electricity are not. I’ve been touting the possibilities of ice-storage systems for A/C for some time,” notes EP.

I first became interested in the concept when exploring a novel approach to providing a vaccine refrigerator in undeveloped areas. Whereas there already were “Camel Refrigerators”, i.e., refrigerators that ran on direct current from solar panels, the Solar Chill approach was using photo voltaic panels to run a DC powered compressor creating cold storage.

The Danish project is on a different scale:

The population of the Netherlands is about 16.5 million. The US has about 18 times as many people, and likely about 18 times as much refrigerated warehouse capacity. If Holland has 50 GWH of energy-banking capability available, the US might already have on the order of 900 GWH. That’s about 2 hours of average US electric consumption. We’d have to build out one huge amount of wind and solar power capacity to strain that.

Electric Thermal Cold Storage in Loveland, CO


“During periods of power surplus, the warehouses’ refrigeration systems will be run full-bore to chill them by up to 1�C; when power production lags demand, the warehouses will shut off their chillers and coast on their stored heat-absorption capability.” - Engineer-Poet

Roland Piquepaille1 writes, “According to Nature2, a European-funded project has been launched to store electricity created from wind in refrigerated warehouses used to store food.

As the production of wind energy is variable every day, it cannot easily be accommodated on the electrical grid. So the ‘Night Wind’ project wants to store wind energy produced at night in refrigerated warehouses and to release this energy during daytime peak hours. The first tests will be done in the Netherlands this year. And as the cold stores exist already, practically no extra cost should be incurred to store as much as 50,000 megawatt-hours of energy.

For more information, refer to Introduction to Cool Energy Storage (PDF)3

Electric Power Demand


Wind Power DER + Cold Store DSM would be of benefit to the HVACR (Heating, Ventilation, Air Conditioning and Refrigeration) customers that either invest in renewable energy sources or receive sufficient incentives to make use of such peak shaving.

DER (Distributed Energy Resources)
Autonomous generating, storage, and load control technologies that are typically located at customer premises and operated for the customer’s benefit.
DSM (Demand Side Management)
When a utility company has control over energy consumption on the customer’s side of the meter. Such programs include conservation / energy efficiency, load management, and load building.

A central concept of Demand Side Management is that an interconnected network of distributed energy resources can function either connected to, or separate from, the Grid. “Once the warehouse systems are out there, we can extend the concept as necessary to leverage the variable energy resources,” notes Engineer-Poet. Such interconnectivity relies upon sophisticated control and dispatch strategies.

NaS Batteries


NaS batteries from NGK Insulators, Ltd. can function as a power station to charge electric power in the base power source at low demand and discharge it at peak demand.

Unfortunately, electric thermal storage is unable to resolve all demands, which is why there is research into other massive demand-managed systems, e.g., CAES (Compressed Air Energy Storage), PHS (Pumped Hydroelectric Storage), or flywheel plus the storage of electricity in large scale flow batteries or high temperature sodium-sulfur batteries.

Besides expert control systems, such examples that use kinetic energy or pressurized fluids / gases require electric generators to again convert the stored energy back into electricity for local distribution. A linkage between electricity storage and electric motor / generator suppliers thus seems practical. For example, refer to recent investments into geothermal power4 by Raser Corporation, manufacturer of advanced motors and power electronics. It would be good to see enhancement of distributed energy resources with energy policy based upon greater efficiency and security.

Continue reading here: Combined Heat and Power from Rice Husks

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