Electricity grids were once laid out like trees: Power stations were connected to a transmission network or “trunk” through which energy flowed to local distribution networks or “branches” and then on to homes, businesses and other end users.
Power flowed in a single direction and this centralized system was very reliable — when customers flicked a switch, their lights came on.
Today, the system is being transformed into a complex spider’s web of connections. Instead of power being mostly produced by giant coal, gas, hydro or nuclear power stations, it now comes more and more from large-scale renewables and smaller generators such as solar panels connected to the edge of distribution grids, called distributed energy resources, or DERs.
The cost of generating electricity using these renewables is moving close to parity with traditional methods in many places, and this is a primary reason many states, including California, Hawaii and New Mexico, now feel empowered to introduce goals to eliminate emissions from power generation sources and switch to 100 percent renewable energy.
When the fuel is free and non-polluting, it’s little wonder that renewables appeal to bill payers and policymakers alike. Yet not every state, nor the federal government, is convinced that renewables are the way to go.
Generally, there are two major challenges seen as standing in the way of renewables cleaning up our generation resources: reliability and resiliency.
The first challenge is reliability — the sun doesn’t always shine and the wind doesn’t always blow, so renewables are, by their very nature, intermittent.
Today, many DERs are being connected at the very edges of the grid, and they operate in a less predictable way, making it much harder to balance supply and demand across the grid. This balance is absolutely essential to keeping the grid reliable, as even a relatively small imbalance can lead to a cascading loss of power across a wide area.
Reliability is an absolute must for grid operation; it’s unthinkable to homeowners or businesspeople that they may face a power cut if the sun isn’t shining or the wind isn’t blowing at the right moment. The economic consequences of an unreliable grid would be immense.
The new systems that are used to help solve the reliability problem are called DERMS, or distributed energy resource management systems.
These new systems combine distributed, autonomous computing right at the point of connection of the DER to the grid, together with the traditional centralized control system. Autonomous systems are needed since events happen far too quickly and in too many locations at once to rely on human operator decision making.
The use of these systems helps to solve the reliability issue, and they have the added benefit of enabling far more renewables to be safely connected to the existing utility distribution infrastructure than traditional utility systems would allow. This means that the renewable goals can be obtained without the huge costs of “beefing up” the distribution systems to take this power.
Some added good news is that, in addition to the new control systems technology that is making the introduction of increasing levels of DER possible, the cost of batteries is collapsing. The obvious solution to the intermittency problem is to “smooth out” power spikes and ebbs by using stored electricity. Batteries are changing the landscape.
Batteries also have the advantage of being quick, as they can switch from discharge to charge within seconds, and soon electric vehicles will mean there are millions of portable batteries available to help balance the grid. The additional function of the DERMS is then to optimize how all of this works, and great progress is also being made in that area.
The conundrum of the grid operator keeping the grid reliable in the face of massive intermittent new generation at the grid edge is rapidly being solved. Regulators can sleep soundly at night knowing that the technology now exists to make their visions of a totally clean grid a reality.
The second major challenge is resilience, not simply in the face of natural disasters such as hurricanes but also when confronted by cyberattacks or other acts of terrorism. The deployment of massive amounts of DERs and intelligent, communicating computing resources at the grid edge brings with it a massive increase in the opportunity for someone to “hack” the system.
It’s not just rival national governments that are a threat either; a smart kid with a laptop in her bedroom could be equally as daunting a menace. Having more and more devices connected to the grid — especially computer-loaded EVs — also presents more opportunities for hackers to access the control systems that manage the power network.
Modern smart grids run with DERMS can be separated into their constituent microgrids, making them not only more resilient to this natural threat, but also faster to restore if something does happen.
To some extent this model sacrifices the huge economies of scale a massively centralized system presented, but grid resiliency in the face of increasing natural threats (storms, etc.) and human-created cybersecurity threats are now an overriding concern. To counter the cyberthreat issue, DERMS must be designed and built from the ground up in ways that fully mitigate this threat.
Once the economics are in place, as is quickly happening, then reliability and resilience become the essential questions that need to be answered to satisfy politicians and regulators at every level that we really can move to a clean-generation grid. Fortunately there are armies of engineers in companies around the world, and in our federal labs, racing to find solutions, and many of these are available now.
Anyone who isn’t yet fed up of hearing the “solar-plus-storage” mantra soon will be. After all, who wouldn’t want to power their home or business and commute vehicles using free, inexhaustible and nonpolluting power from the sun or wind?
Ultimately, the driving factor for the adoption of a 100 percent carbon-free grid will be consumer demand. Consumers are also voters, and the direction of travel is becoming increasingly clear for our politicians.
Pete Maltbaek is general manager for North America at Smarter Grid Solutions, a provider of DERMS software.
Source: Greentech Media