Technical challenges and solutions to building a 100 percent clean electricity system

1. Technical challenges: Variable sources of electricity

The sun doesn’t always shine, the wind doesn’t always blow, and managing these resources in a predictable way so as to always be able to deliver electricity when it’s needed is, indeed, a challenge.

2. The smart grid

The solution to intermittency is to build a smart grid. Please watch the video below to understand what a smart grid is.

The utility of the future is going to need to operate in part like a tech company. The keyword in "smart grid" is "smart." In fact, some people in the industry have moved on from this term and refer, instead, to "power grid modernization."

Power grid modernization involves reworking the electricity network to enable a two-way flow of electricity and data. Imagine a future where your washing machine is "talking" to the grid in real-time, and switching on automatically when there's excess (and therefore cheap or even free) solar power available somewhere in the system: Every country is going to need to build this sort of system over the next few decades.

A smart grid will need the following technological innovations throughout the system:

• Intelligent appliances that can decide when to consume power based on consumer preferences and grid balancing needs.

• Smart power meters that feature two-way communications between consumers and power providers.

• Smart substations that monitor and control a range of operational data.

• Smart distribution that is self-healing, self-balancing and self-optimizing.

• Smart generation that can learn and optimize clean energy generation, and automatically maintain voltage, frequency and power factor standards based on feedback from the grid.

Demand response

Traditional power systems are designed to serve whatever load there is. That is, people consume electricity as and when they wish, and utilities make sure they can provide the power that's needed.

A smart grid with high levels of renewable energy requires a change in approach. We want the use of electricity (the load) to more closely match or follow the supply. And of course, we want to implement this in a way that does not crimp a household or business' ability to carry out its tasks as needed.

Luckily, a new generation of communication and control technologies can enable major loads to continuously respond to changing renewable supply levels and other market signals. This is the idea behind demand response, which is also sometimes called demand flexibility or "flexiwatts."

A smart grid with flexible demand can do things like automatically turn on your washing machine or charge your electric car at times when the sun is shining and other loads are low.

Consider the picture below with two graphs showing how rescheduling some flexible household loads can greatly improve the match between solar resource supply (the yellow line) and household energy needs in Hawaii. Demand response enables better integration of renewables, prevents curtailment, and helps overcome the problem of oversupply.