Cédric Philibert is a senior analyst in the Renewable Energy Division of the International Energy Agency (IEA). He leads the division’s policy analysis on concentrating solar power (CSP) and is the lead author on the IEA renewable energy Technology Roadmaps.
In this solar point of view, he points out four ways that are being used to enable a steadier power supply from renewable energy resources.
by Cédric Philibert
Renewable energy has shaken up the power landscape in a brilliant way. More than 100,000 MW of global capacity was installed last year alone, and its pricing is becoming far more competitive against fossil fuels. Indeed, as prices continue to fall, the potential for renewables is only really limited by uncertainty due to the power supply being largely dependent on the changing weather. This would paint a rather worrying picture for the future viability of renewables, if it weren’t for the fact that there are legitimate measures being taken to tame its volatile nature.
Today, I’d like to point out four ways that are being used to enable a steadier power supply from renewable energy resources.
Aside from the technological complexity, energy storage is, in theory, accomplished through a simple and easy mechanism - on a sunny or windy day, energy storage systems stock the excessive energy supply and release it when demand is high.
Presently this back-up capacity is largely supported by one storage method, pumped hydro, representing 99% of the energy storage capacity in the world - no other means of storage operates on such a large scale. But this may well change in the coming years as cost savings can be achieved through the smart use of various energy storage technologies. For example, high capacity grid scale energy storage batteries are being implemented that are able to manage the variability of the renewable power contributions to the grid and regulate grid frequency.
Taking a Holistic View of Regional Power Systems
Another way to stabilize power output is to look at all the power systems in a region as a whole, continuously building pieces complementing and therefore strengthening the entire power network. With such a holistic view of regional infrastructure, power plant owners can build new power generation facilities to match the macro demand of the region, not just a specific community.
For instance, in California, government incentives are provided to solar operators who build solar farms orienting west. Although less power will be produced compared to southern-oriented solar farms, they will provide additional valuable capacity to feed the increasing demand in the afternoons, when other solar farms are in the shade.
While we have made great strides in forecasting, we only need to watch the evening weather forecaster’s embarrassment at getting it wrong again to realize that we are not there yet. The good news is that we’re actually not far off. The evidence of its effectiveness comes from Spain, where a 35% reduction in errors has been achieved in forecasting output a day in advance.
Advanced software, coupled with more reliable weather forecasts, will enable operators to better manage machines to improve the power output. For example, in the event of abundant wind, operators are informed to “open the full gear” of the wind turbine in order to fully capitalize on the wind. In the event of overly strong wind, operators are, conversely, warned to shut down machines to prevent them from being damaged, saving maintenance and repair costs and reducing downtime in the long term.
For this to become a more widespread reality would also require a more reactive market, able to respond to the forecast in the same way.
Grid Interconnection allows us to dampen the volatility through a more diversified power mix: solar generated in the south is used in the north; wind from the west powers the east, etc. When power plants are scattered over a vast region, provided that they are well interconnected, one plant can always generate power and compensate for the shortcomings of another. The better interconnected the region, the more predictable the power output it will be.
While we will never be able to control the weather, we can get a better view of the future, which in turn makes renewable energy a more reliable and sustainable energy source as we transition towards a cleaner energy future.