Grid Storage of Solar Power and Wind Energy

Wind Energy Growth in US

(8/15/12) By John Addison


Enough sunlight reaches the earth each day to meet all of our energy needs for one year including powering all transportation from electric cars to high-speed rail. Globally, over 70GW of solar power is installed and over 250GW of wind energy. Solar power has grown over 30 percent annually since the 1970s, and 85 percent in the U.S. for the first quarter of 2012, as technology improvements and manufacturing volume have lowered its cost to one percent of 35 years ago. In the past five years, the U.S. has added more renewable energy than coal and nuclear power.

The rate of continued growth will depend on the ability to store renewable energy. Depending on location and time of year, solar often generates significant electricity from noon until 3 pm, but we live in a 24/7 world. For example, as gasoline becomes more expensive, solar power captured during the day could charge 100 million electric cars in the middle of the night with cost-effective storage.

The electric utility industry primarily uses energy stored in coal, natural gas, and uranium. Needed is cost-effective storage of renewable energy that can compete with low-priced natural gas.

Xtreme Power Grid StorageEnergy storage is increasingly used at every point in the grid. Utilities use pumped hydro to dispatch power-plant scale energy during peak hours. Massive batteries and ultracapacitors smooth loads near substations, wind farms and utility-scale solar. Lithium batteries are used from data centers to net-zero buildings. Vehicle-to-grid pilots are underway.

Storage innovation is a priority for utility executives, renewable energy and smart grid innovators. It was a hot topic when I recently attended the InterSolar Conference attended by over 20,000 industry leaders, developers, and customers.

Value-Add Storage

Some forms of storage pay for themselves by shifting the delivery of electricity to peak hours. 125GW of pumped hydro is used globally for energy storage.

Reliability justifies other forms of storage. If a data center is down, it can cost millions of dollars per hour. On Wall Street, the cost can be millions per minute. Although lithium batteries cannot be justified for many mundane applications, data centers increasingly cannot afford less than 99.999% uptime.

Emerging forms of storage must add value in several ways to justify the investment: high-priced regulatory services, avoidance of other costs such as transmission lines, emission avoidance, avoidance of alternative costs to improve reliability. In the United States, aging generation, transmission, and distribution has failed to meet new demands for reliability and distributed generation.

Brian Carey, Managing Principal at PwC sees grid storage growing from $3 billion annually in 2012 to $160 billion in 2017. Jim Eyer with Strategen sees major opportunity not just with batteries, also with subsystems, power electronics, semiconductors, inverters, sensors, communications, controls, and software.

Storage Asset Classes and Innovation

Janice Lin, Executive Director of the California Energy Storage Alliance (CESA), organizes grid storage into asset classes including:

  • Gravitational
  • Mechanical
  • Thermal
  • Chemical

Gravitational. Today, the most cost effective way to store MW of electricity is mechanical – water is pumped uphill at night when demand for electricity is low, and released to fall at peak hours when electricity is most valued. Gravity works.

Mechanical includes flywheels and compressed air energy storage (CAES), promising technologies that struggle to be financially viable. New York State Electric & Gas may lead in using an existing salt cavern for 150 MW CAES. The project will be designed with an innovative smart grid control system to improve grid reliability and enable the integration of wind and other intermittent renewable energy sources.

Thermal. Software leader SAP at its LEED Platinum Newtown Square campus uses thermal storage. Beneath a main building is an ice storage unit featuring 16 Calmac containers that create 3,500 tons of ice each night and then melt down during the day. LA Community College is installing 5MW of thermal storage.

Chemical storage in batteries has been used with solar for decades, especially with off-grid projects. Megawatt flow and sodium-sulfur batteries are used near large generation or sub-stations to dispatch energy that once required firing-up dirty gensets and peaker plants. Ultrabattery is one company providing large-scale lead acid with integrated capacitor. Smart buildings to smart grids are using lithium batteries popular in everything from electric cars to the device you’re using to read this article.

Hawaii Leads in Renewable Energy and Advanced Storage

On the mainland, low-cost natural gas is a challenge for renewables, but there is no low-cost way to transport natural gas, or even coal, to Hawaii. Oil is used in many power plants. To meet its need for clean energy, Hawaii has a renewable portfolio standard (RPS) requiring 40% renewables by 2030. DOE RPS Data

Several islands, including Oahu, Maui, Kauai, Molokai, and Lanai, have installed megawatts of Xtreme Power’s integrated power management and energy storage systems, branded as Dynamic Power Resources (DPR).

Since 2009, Maui has used a one MWh DPR when the wind stops blowing to deliver electricity to the grid while a generator is brought online. Now Maui is adding 21MW of wind power and a 10 MW Xtreme Power system.

Xtreme solar project HawaiiOn the island of Kauai, 3MW of solar generation is supported with a 1MWh Xtreme DPR to control the variability of the solar PV generation and act as a source of spinning reserves, while providing frequency and voltage ancillary services. The configurable control system allows utility KIUC to change desired ramp rates and service priorities in real-time.

On the island of Oahu, a 10MWh energy storage system supports 15 MW of wind generation. The storage system is one-third of the cost of installing new transmission lines. However, a recent fire at the facility raises questions about the safety of Xtreme’s dry cell system. A competitor NGK experienced an explosion in Japan of its sodium-sulfur battery. These incidents raises questions about the safety of megawatt-scale batteries.

Xtreme is one of the industries most promising companies with over $50 million of venture investment from Dow Chemical, Fluor, BP, Sail Venture Partners, Bessemer Venture Partners, Dominion Power, Spring Ventures, POSCO, and Skylake Incuvest.

Green Utility SMUD Takes Advantage of Multiple Storage Technologies

The Sacramento Municipal Utility District (SMUD) is one of the nation’s leaders in renewable energy, grid storage, smart grid, and customer use of electric vehicles. SMUD Board of Directors approved a plan to reduce greenhouse gas emissions 90% over 1990 by 2050. With its growing population and shift to electric transportation, this goal will not be easy to achieve.

Yet, SMUD is already a major user of wind, solar, and hydropower. Residents and commercial customers have 2,700 solar installations; 10,000 are expected by 2016. Commercial roofs could add 1 GW of solar; brownfields, 2.5 GW. By 2020, it plans on 37% of generation from renewables; by 2050, 95% RE and 5% baseload natural gas.

SMUD is challenged with an extreme peak of 4,000 MW during about 40 hours of extreme summer temperatures when air-conditioners are blasting. Unfortunately, there is little wind during these hours. The extreme peak hours are typically in afternoons; solar power peaks a few hours earlier. Needed is large-scale energy storage.

Large-scale energy storage would allow SMUD to dispatch power-plant quantities of electricity when needed. 400MW of pumped hydro is being evaluated at Iowa Hill, but the cost could run $700 million. Compressed air (CAES) is being considered in Solano where wind farms are already cost-effective. The CAES would need to be integrated with a natural gas power plant to make economic sense.

At Substations, 500kW 6-hour zinc bromine flow batteries are being evaluated with potential partners including Premium Power and National Grid.

Anatolia SolarSmart Homes includes 2kW of solar PV on all homes. It is adding fifteen 10kW/8.8kWh residential energy storage and three community energy storage systems. Partners include GridPoint, Sun Power, Navigant, NREL, and SAFT. SMUD Press Release

Globally, community and residential energy storage (CRES) systems use a range of technologies including flow, lead-acid and lithium batteries. Driven by the expansion of distributed solar photovoltaic capacity, the adoption of electric vehicles, and spread of dynamic pricing programs, the CRES market will experience sharp growth over the next 10 years, according to a recent report from Navigant Pike Research.  The firm forecasts that the global market for these systems will grow from $19 million in 2012 to more than $872 million in 2022. Total worldwide installed capacity for community and residential energy storage systems will reach 780 megawatts in 2022.

Highways have the potential of being transformed from black asphalt and baking motorists, to cool shaded freeways of the future. SMUD proposes a 1.4MW of PV and CPV on two sections of US50 with 500kW of lithium battery storage, with A123 as a potential supplier. Subject to regulatory hurdles, look for Sacramento Solar Highways in the future.

A dozen years ago, the Sacramento area was leading in adoption of hybrid cars. Now it is home to advanced development of electric and hydrogen vehicles by most automakers. Zero-emission laws from California’s Capitol in Sacramento have spurred development. In 2012, thousands of electric vehicles and hundreds of public chargers are used in the Sacramento area.

Vehicle-to-home and vehicle-to-grid are being tested using electric car lithium batteries that could be used for backup power, regulatory services, and during peak demand.

Grid storage will increasingly be used as we expand that installation of renewable energy. The sun does not always shine and the wind does not always blow. Utilities and regulators, will often continue to invest in better interconnects and transmission as a better way to make RE available. If high voltage lines interconnect larger regions, then a mix of wind, solar, geothermal, hydropower, and renewable bioenergy is predictable and available for millions of energy users.

The high growth of distributed energy distribution near load centers does not depend on new long-distance lines. Distributed generation does require reliable power management. Here grid storage is the clear winner.

John Addison will be presenting at the Advanced Energy Solutions (AES) Conference in San Diego, California, October 23 to 25.

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About Author: John Addison

Founder of the Clean Fleet Report, author of Save Gas, Save the Planet. John writes about electric cars, renewable energy, and sustainability.

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