Solar and wind power curtailments are rising in California

wind and solar power

subscribe

SAN FRANCISCO -

The California Independent System Operator (CAISO), the grid operator for most of the state, is increasingly curtailing solar- and wind-powered electricity generation as it balances supply and demand during the rapid growth of wind and solar power in California.

Grid operators must balance supply and demand to maintain a stable electric system. The output of wind and solar generators are reduced either through price signals or rarely, through an order to reduce output, during periods of:

Congestion, when power lines don’t have enough capacity to deliver available energy
Oversupply, when generation exceeds customer electricity demand

In CAISO, curtailment is largely a result of congestion. Congestion-related curtailments have increased significantly since 2019 because solar generation has been outpacing upgrades in transmission capacity.

In 2022, CAISO curtailed 2.4 million megawatthours (MWh) of utility-scale wind and solar output, a 63% increase from the amount of electricity curtailed in 2021. As of September, CAISO has curtailed more than 2.3 million MWh of wind and solar output so far this year.

Solar accounts for almost all of the energy curtailed in CAISO—95% in 2022 and 94% in the first seven months of 2023. CAISO tends to curtail the most solar in the spring when electricity demand is relatively low (because moderate spring temperatures mean less demand for space heating or air conditioning) and solar output is relatively high.

CAISO has increasingly curtailed renewable generation as renewable capacity has grown in California. In 2014, a combined 9.0 gigawatts (GW) of wind and solar capacity had been built in California. As of July 2023, that number had grown to 17.6 GW. Developers plan to add another 3.0 GW by the end of 2024.

CAISO is exploring and implementing various solutions to its increasing curtailment of renewables, including:

The Western Energy Imbalance Market (WEIM) is a real-time market that allows participants outside of CAISO to buy and sell energy to balance demand and supply. In 2022, more than 10% of total possible curtailments were avoided by trading within the WEIM. A day ahead market is expected to be operational in Spring 2025.

CAISO is expanding transmission capacity to reduce congestion. CAISO’s 2022–23 Transmission Planning Process includes 45 transmission projects to accommodate load growth and a larger share of generation from renewable energy sources.

CAISO is promoting the development of flexible resources that can quickly respond to sudden increases and decreases in demand such as battery storage technologies. California has 4.9 GW of battery storage, and developers plan to add another 7.6 GW by the end of 2024, according to our survey of recent and planned capacity changes. Renewable generators can charge these batteries with electricity that would otherwise have been curtailed.

Related News

battery storage

Battery energy storage system eyed near Woodstock

TORONTO - A Quebec-based renewable energy company is proposing to build a battery energy storage system in Oxford County near Woodstock.

The Oxford battery energy storage project put forward by Boralex Inc., if granted approval, would be ready for commercial operation in 2028. The facility would be in the Township of South-West Oxford, but also would serve Woodstock businesses and residences due to the city’s proximity to the site.

Battery storage systems charge when energy sources produce more energy than customers need, and discharge during peak demand to provide a reliable, steady supply of energy.

Darren Suarez, Boralex’s vice-president of public affairs and…

READ MORE
ns power biomass

Nova Scotia Power increases use of biomass for generating electricity

READ MORE

ev charging

N.W.T. will encourage more residents to drive electric vehicles

READ MORE

ev charger

EV Boom Unexpectedly Benefits All Electricity Customers

READ MORE

bess

BESS: A Clean Energy Solution NY Needs

READ MORE