New technologies known collectively as the “smart grid” are making it possible for utility companies such as San Diego Gas & Electric Co. to embark on the first large-scale changes to the electrical grid in a century — changes that promise lower costs and bring greater energy efficiency.

But as energy companies rely less on a traditional infrastructure of power lines and substations, and more on wireless sensors and automated computer-based systems, the issue of cybersecurity becomes ever more important, said Jessie Knight, chairman and CEO of SDG&E, during a keynote address at the Cybersecurity Symposium on Oct. 25 at the Sheraton Harbor Island.

“While we are all well aware of the many benefits our dependence on technology brings, it also makes us more vulnerable to cyber threats,” Knight said.

Possible threats include hackers and computer viruses that can interrupt power supply, to customer data breaches from manufacturers of “smart” appliances that communicate seamlessly with the grid, Knight said. “Much of this is hypothetical, as the smart grid is still in its infancy, but we must start planning and building the grid securely so our customers will be sure to have the reliable power they need,” he said in prepared remarks.

SDG&E’s smart grid plan spans through 2020 and costs about $3.5 billion, including cybersecurity measures, Knight said.

The smart grid will allow consumers to more easily view their energy usage, which is expected to improve their consumption habits. It also will better integrate solar power, wind power and other renewable sources — and ensure that ample power is available to consumers, even if the sun isn’t shining or the wind isn’t blowing.