US electric grids: Flexibility for grid reliability – EPRI report


The new report, released this February, analyses the impact on the US electric grid of changes in natural gas prices, load growth, energy policy and the penetration of variable generation.

It also gives recommendations for stakeholders to meet up with the system’s research and development needs.

Distributed energy resources

System flexibility is highlighted as a key area for stakeholder focus with a major driver in increasing the deployment of distributed energy resources including solar and wind.

In regard to the penetration of variable generation, the study highlights that consumers, energy suppliers and developers are increasingly adopting distributed energy sources due to decreasing capital costs and incentives.

[quote]The US alone recorded 10GW generation from solar PV in 2013, which is less than 2% of the total installed generation capacity.

However, the report recommends stakeholders put aspects of PV into planning and implement coordinating system modifications to avoid adverse outcomes as currently the system is connected to the grid, benefiting from its electrical support, flexibility and reliability but not integrated with the grid’s operation.

Generation costs and environmental impacts

By incorporating distributed energy resources into the US grid’s central control systems, utilities will meet their energy goals at the same time addressing economic and environmental impacts.

For instance, PV and wind can produce energy at a marginal cost due to subsidies and the absence of fuel costs.

This would in return reduce carbon emissions caused by the burning of fossil fuels as this would allow dispatching of thermal units.

On the other hand, fluctuating fuel prices are driving the demand for flexibility in the electric grid system.

From 2002 to 2012 the price of natural gas for power generation ranged from approximately US$3.50/MMBtu to US$9.00/MMBtu.

To date, the future of natural gas is uncertain following the US Energy Information Administration (EIA)’s prediction that by 2040 natural gas prices will range from US$8.50/MMBtu to US$17.50.

Such uncertainty will likely continue to negatively affect the generation mix.

Customer choice

EPRI predicts consumers will drive demand for grid flexibility as they shift from passive to active buyers with the installation of residential solar PV panels, and buying plug in electric vehicles, appliances and equipment that enable them to better manage electricity use.

Such developments of more active consumers will result in more variable load, requiring a flexible system to respond.

However, the report recommends stakeholders to implement solutions including:

  • Viable cycling of conventional generation
  • Implement polygeneration
  • Address customer behaviour and adoption by implementing energy efficiency programs and enhancing network communications for connectivity, fast reaching loads and distributed storage
  • Power system balancing and operation
  • Power system planning