POWER GRID & STORAGE??

Traditional fossil fuel dominated electricity systems typically comprise a small number of large generators, such as coal, gas and hydro plant, which can provide load following and frequency response capability and provide the grid with inertia. The level of inertia on the grid determines the rate at which frequency changes following a step change in generation or demand.

Power System Operation Slides - YouTube

Many renewable generators, particularly solar and wind, either have no inherent inertia, being inverter connected, or reduced inertia as a result of being small, light-weight and often non-synchronous, machines. UK electricity grid has seen the contribution from renewables grow from under 5% in 2004 to around 25% in 2016, that proportion continue to grow with current share is around 42.1 %.

In an electricity grid system, all synchronous generators connected to the grid rotate at the same grid system frequency. If there is an imbalance between generation and demand on the system, the rotational kinetic energy of the synchronous generators changes such that energy is conserved; it goes up when generation is greater than demand, absorbing energy through an increase in speed and therefore system frequency, and vice versa when demand exceeds generation. Thus, imbalances between generation and demand in power systems cause deviations in frequency from the target. Consequently, frequency is the primary control parameter used to ensure that generation matches demand at all times.

RKE of the synchronous machines is proportional to their inertia, the term ‘system inertia’ is then used for the aggregated inertia of all the rotating machines (generators, turbines, other mechanical components) coupled to the power system. Having a large amount of inertia on the system, predominantly provided by the large rotating masses of fossil fuel generation, helps to reduce the rate of change of frequency (RoCoF) in the few seconds required for primary frequency response (PFR) plant to begin adjusting its output. Thus, in a traditional grid system, the initial frequency disturbance caused by a power imbalance is 'damped' by system inertia and then responded to within a few seconds by generation plant and subsequently, if required, by dispatching fast response plant, such as hydro operating as spinning reserve, to balance the system.

In a normally operating network, the system inertia will affect the RoCoF and frequency minima and maxima during typical load variations. Thus a battery system responding automatically to frequency, such as under the EFR service, is likely to experience more volatile operation as system inertia reduces. Intuitively, the total installed battery capacity will also affect the depth of cycling and cycle count, and hence battery life, of individual installations; this is the point where battery storage come as crucial role in demand to tackle this issue. That will include sub-second response and inertia and will provide a route to market for fast-acting response.

Power grid storage plays a crucial role in the energy sector for several reasons:

1. Balancing and Stability: It provides important system services that range from short-term balancing and operating reserves, ancillary services for grid stability, and deferment of investment in new transmission and distribution lines.
2. Reliability and Resilience: It ensures uninterrupted power to consumers, whenever and wherever they need it. This flexibility is critical to both reliability and resilience.
3. Decarbonization: Energy storage is critical for mitigating the variability of wind and solar resources and positioning them to serve as baseload generation.
4. Environmental Impact: Storage can reduce demand for electricity from inefficient, polluting plants that are often located in low-income and marginalized communities.

Future of power grid storage, it is expected to play an even more significant role:

1. Deep Decarbonization: Energy storage is a potential substitute for, or complement to, almost every aspect of a power system, including generation, transmission, and demand flexibility. It enables electricity systems to remain in balance despite variations in wind and solar availability, allowing for cost-effective deep decarbonization while maintaining reliability.
2. Technological Advancements: The total installed capacity of pumped-storage hydropower stood at around 160 GW in 2021. However, grid-scale batteries are catching up and are projected to account for the majority of storage growth worldwide.
3. Emerging Markets: Developing economy countries are an important market for electricity system storage. Storage can reduce the cost of electricity for developing country economies while providing local and global environmental benefits.
4. Legislative Support: Major markets are targeting greater deployment of storage additions through new funding and strengthened recommendations.

Energy Storage - Example

There are several types of energy storage systems, each with its own unique characteristics and uses. Here are some examples:

1. Pumped Hydro Storage: This involves pumping water uphill during times of low energy demand and releasing it through turbines to generate electricity during periods of high demand.
2. Batteries: Advances in technology and falling prices have led to the development of grid-scale battery facilities that can store increasingly large amounts of energy. The world’s largest battery energy storage system so far is the Moss Landing Energy Storage Facility in California, US.
3. Thermal Energy Storage: This method stores energy in a thermal reservoir for later use, typically by heating or cooling a substance. It’s predicted to triple in size by 2030.
4. Mechanical Energy Storage: This type of storage harnesses motion or gravity to store electricity. For example, a flywheel is a rotating mechanical device that is used to store rotational energy.
5. Offshore Hydroelectric Storage: This is a form of large-scale energy storage that uses the sea as a reservoir.
6. Modular Plug-and-Play Batteries: These are scalable energy storage solutions that can be easily installed and expanded.
7. Virtual Energy Storage: This involves using software to control and optimize a network of distributed energy resources.

Energy Storage Cost

The cost of energy storage can vary significantly depending on the technology and scale of the system. Here are some key points:

1. Lithium-Ion Batteries: The cost of small-scale lithium-ion residential battery systems in the German market fell by 71% between 2014 and 2020, to USD 776/kWh.
2. Cost Structure: The cost structure of energy storage technologies includes the cost to procure, install, and connect an energy storage system, associated operational and maintenance costs, and end-of-life costs.
3. Levelized Cost of Storage (LCOS): The LCOS is a metric that determines the average price that a unit of energy output would need to be sold at to cover all project costs inclusive of taxes, financing, operations and maintenance, and others.
4. Future Projections: The Department of Energy’s (DOE) Energy Storage Grand Challenge (ESGC) is providing a standardized approach to analyzing the cost elements of storage technologies, engaging industry to identify these various cost elements, and projecting 2030 costs based on each technology’s current state of development.