The first part of this blog covered the growing trend of renewables curtailment. This second post will cover the solutions that are turning curtailment from a problem into an opportunity.
Many solutions have been proposed to address the integration of renewables into the energy sector. The first two, transmission upgrades and storage technologies, tend to get a lot of media attention. However, these can be seen as “necessary but not sufficient” options in the race to integrate renewables. Flexible gas generation technologies will also play a growing role in the grid of the future.
Transmission upgrades connect renewables to more loads and diversify generation resources. Germany, with 26% of its generation coming from intermittent sources in 2015, has been building out transmission to connect the windy south of the country to the industrial north. As in many global markets, transmission expansion is subject to NIMBYism, and in Germany’s case is being forced underground, which is more expensive. California, with 14% of its generation from intermittent sources in 2015, may be expanding its independent system operator (ISO) into a regional organization across the climatologically diverse Western Interconnection, though the decision has been delayed for further review. And China, generating just around 3% of its electricity from wind in 2015, still curtailed billions of dollars of wind power in recent years and is quickly pushing to interconnect it with load.
Storage technologies are growing quickly, as well. Hydroelectric storage is a cheap and clean technology that nonetheless sometimes battles drought-related, environmental, and even methane emissions concerns. Batteries, including lithium ion and other types, are rightly making news as costs fall and policies like incentives and storage mandates drive the market toward rapid growth. These and related storage technologies, including compressed air storage, are growing quickly and will become a major part of our electric grids.
Flexible gas-based generation solutions tend to get less media attention but will also be crucially important in the flexibility of the grid.
- A 2016 National Renewable Energy Laboratory (NREL) report suggested that for California to accommodate 50% of its generation coming from solar PV, a wide range of changes would need to take place. Notably, flexible thermal generators and combined heat and power (CHP) plants were mentioned as a key necessity, even if the amount of energy storage is boosted by more than 10 times what is outlined in the current mandate.
- A 2015 report by the Union of Concerned Scientists on California’s grid states that under a 50% Renewable Portfolio Standard (RPS) scenario, curtailment could be cut from 4.8% to 3.2% if natural gas resources are able to turn down to half-power.
- A 2015 report points out that Denmark was able to generate 39% of its electricity from wind thanks in large part to flexible district energy CHP resources. These district energy systems are in some way the core of Denmark’s grid and are expected to become electricity consumers rather than producers during times of high wind generation.
- A 2016 report funded by the German government suggests that power-to-heat will be more important than batteries in balancing that country’s grid in the future.
Most of these reports suggest that fossil-based sources will fuel this generation, though carbon-neutral biogas and hydrogen are taking strides to catch up too. These gas-based technologies have the dual benefit of boosting grid flexibility while (in most cases) decarbonizing heating, an area of growing concern. As a complement to the transmission and battery storage changes making headlines, these sources are set to become key contributors in the grid of the future.
Tags: Carbon Emissions, Combined Heat and Power, Energy Storage, Flexible Generation, Policy & Regulation, Transmission Upgrades
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