Power grids across the world are speeding up the transition to renewables to meet net zero targets. But the success of this transition relies on adopting new approaches for traditional grids designed originally to serve large-scale fossil-fuel generation.Kristina Carlquist, Head of Synchronous Condenser Product Line, ABB Large Motors and Generators, outlines some of the challenges and opportunities that arise.
Renewable energy resources like wind and solar are transforming how we power our lives, they are clean, sustainable and growing fast. However, their increasing penetration in the global energy mix is creating new challenges for existing power grids that were never designed to handle renewables. The reason is that most of the world’s grids were originally constructed at the start of the 20th century, over 100 years ago. And they were designed to serve large, centralized power stations, first burning coal and later with gas-fired or nuclear plant, with the energy flowing in one direction from the center out to the edge.
These traditional networks have served their purpose and provided an exceptional level of reliability, decade after decade. But renewable energy is very different. It is decentralized almost by definition, since wind and solar power resources are generally located far from population centers, out in the countryside or on remote hillsides or even out at sea. That means that they must feed their electricity into multiple points across the grid, often at the very edge, where the infrastructure was only designed to deliver electricity, not to receive it.
Furthermore, wind and solar power are intermittent. When the wind doesn’t blow or clouds cover the sun, output can drop in an instant, with other generation or energy storage systems having to come online immediately to make up the balance. That means grids now need to be able to handle complex, multi-directional flows of electricity.
There is also another, often overlooked, factor which is that the traditional power stations have turbines – large spinning masses that play an important role in providing services to help keep grids stable should there be a sudden change such as an increase in load or plant dropping offline. In contrast, renewable energy is often converter-based. That means some intermediate processing is needed before the electricity is fed into the grid – in the case of solar panels they produce direct current (DC) that has to be changed into the alternating current (AC) used by the grid. This conversion step is why wind and solar resources are currently unable or limited in their capacity to provide grid stability services, such as inertia and fault current contribution.
When talking about renewables, hydroelectric power is an important exception. This long-established method of generation, going back to the 19th century, uses water to spin a turbine, so it can help keep the grid in balance.
These challenges certainly do not mean that renewables necessarily weaken power grids. Instead, grids need to adapt and evolve to use generating resources effectively wherever they come from, while maintaining the reliability essential to keep the lights on. The good news is that proven technologies, are available today to support this evolution, with many examples already in place and making an important contribution.
The bottom line is that the energy transition should not be seen as a threat, rather it is a huge opportunity. By using the right solutions, we can make power grids both strong and sustainable. In our next article we will cover the topic of grid stability, what it is and why it matters to our day-to-day life.
