Open Thread – Watts Up With That?

GRID-SCALE BATTERY SYSTEMS IN NEW ENGLAND TO COUNTERACT SHORTFALL OF ONE-DAY WIND/SOLAR LULL
https://www.windtaskforce.org/profiles/blogs/grid-scale-battery-systems-in-new-england

Wind Methods Paired with Grid-Scale Battery Methods 

Wind output is completely different from different electrical energy turbines, as a result of it’s unpredictable and extremely variable; its intermittency will not be the principle downside. 
Wind gives desultory power, MWh, however not dependable capability, MW. 
Dependable capability is completely needed, sin qua non, for any fashionable grid system, to match provide to demand, with excessive precision, always. 

Grid-scale battery methods are more and more paired with wind methods to scale back the hostile results on grid stability, because of the variability of wind output, MW. Throughout gusty wind situations, the output of a wind system has giant variations, which may adversely impression the soundness of frequency and voltage of the grid.

For instance, a utility, or grid operator, might require a 30 MW wind system have an output variability not exceeding 2 MW/min, up or down, to keep up grid voltage and frequency variations inside prescribed ranges. See URL. 

The battery methods should be able to charging and discharging to satisfy the utility-required ramp charges, whereas additionally not overheating the batteries.

Overheating would shorten the battery helpful service life, and will trigger fires, that burn at excessive temperatures and take a very long time to extinguish.

Battery methods are rated for delivering an influence stage of, say 10 MW for 4 hours = 40 MWh, as AC at battery voltage, from 100% full to 0% full. The battery possible can be about 60 to 70% full, when a wind down ramp would happen.

A most 2 MW/minute downward wind ramp is allowed by the utility; if exceeded, wind output curtailment can be required, by feathering the blades. The battery discharge can be 2 MW x 3 minutes/60 = 0.6 MWh, if the down ramp lasts 3 minutes.

Roundtrip battery system losses, A-to-Z foundation, are about 18% for brand spanking new li-ion methods, 20% or extra, for older methods

The MW and MWh of the battery system can be based mostly on the capability of the wind system, MW

On common, the battery must be charging and discharging to at all times keep a sure cost stage to be prepared for any up and down wind ramp.

In Hawaii, a number of battery methods caught fireplace, as a result of they have been charging and discharging too quickly, i.e., they have been undersized and/or didn’t have satisfactory cooling methods.

NOTE: EV batteries, in case of 1) quick charging at a charging station, 2) quick discharging throughout accelerating and going uphill, 3) frequent “vary driving”, corresponding to make lengthy journeys on daily basis (charging to 95%, discharging to five%, as an alternative of the beneficial 80%/20%), all of which would scale back battery life, on account of overheating and cell harm; sizzling summer time days and chilly winter days are disturbing for batteries.

NOTE: This Nationwide Renewable Power Lab, NREL, report mentions above points. NREL is a authorities, pro-wind entity, which tends to see wind by means of rosier glasses than personal enterprise.
https://www.nrel.gov/docs/fy14osti/59003.pdf

Photo voltaic Methods Paired with Grid-Scale Battery Methods

Variable clouds are the principle cause for speedy adjustments of photo voltaic output, along with the traditional day by day cycle. See picture
Photo voltaic output might lower by 60% inside just a few seconds, on account of a cloud passing over photo voltaic methods.

The time taken for the cloud to move depends upon cloud peak, solar elevation and wind velocity. 
These elements must be thought-about relating to solar energy output forecasting and integrating the variable output into the grid.
The graph reveals photo voltaic output profiles for ZIP codes in California. The additional north, the much less photo voltaic.

For instance, ZIP code 920 reveals a downward spike from about 115 MW to 65 MW, or 50 MW in 10 seconds, or 300 MW/minute, at 1 pm, which might considerably have an effect on frequency and voltage stability on the grid. 

For at the very least a decade, California has been mandating utilities to put in grid-scale battery methods on their distribution methods. 

The prices of such battery methods usually are not charged to photo voltaic system homeowners to perpetuate the fantasy “photo voltaic is aggressive with fossil”
 https://www.windtaskforce.org/profiles/blogs/large-scale-solar-plants-require-large-scale-battery-systems