Geopolitical events are accelerating a state of rapid change for the energy industry. Prices for fossil fuels are likely to rise in the near term as fallout from Russia’s invasion of Ukraine, resulting in an accelerated transition to electricity to replace and reduce fossil fuel use. The existing electric grid is relatively small, delivering only about 20% of total energy. Expanding the electric grid will require considerable time, as large T&D projects may require more than 20 years to complete.
Reducing GHG Doesn’t Always Mean a Switch to Renewables
Generally, the industry suggests switching from fossil fuels to renewable resources. The real issue is emissions, which can also be addressed by reducing demand or increasing the efficiency of use. The average efficiency in the delivery of useful work from primary energy is less than 35%, which is one actionable opportunity to reduce emissions in the near term.
Electric utilities have found a transition to renewable supply to be challenging. The target, to replace coal fired electricity generation has been largely achieved through the use of natural gas. While it may seem counterproductive to replace one form of fossil fuel with another, the emission reduction resulting from a transition from coal to natural gas is large. Coal produces about double the emissions produced by natural gas for the same energy. In addition, natural gas combined cycle plants are twice as efficient as the coal fired generation that they replace. Emissions may be reduced up to 75% using this technology—an excellent example of reducing emissions by increasing efficiency. Best of all, the technology used is off the shelf.
The Grid Should Take Lessons from Telcos for Grid Modernization
Prior to about 1982, growth in electrical energy use was 6-8% annually, doubling every 10 years. Utility companies became accustomed to this rate of growth. The T&D and generation systems grew, using new technology. At any time prior to 1982, half of the existing generation and transmission system was less than 10 years old. In 2022, more than 70% of T&D lines are aging out of commission.
One key technology that advanced transmission protection systems has been the availability of telecommunications. These systems made it possible to identify and isolate faults quickly, in order to maintain system stability. The transmission grid has become a system that can reliably and efficiently deliver energy and capacity in either direction between any two connected points. As these systems delivered large amounts of energy, the cost of modern telecommunications was relatively small and was easily justified.
The distribution system, however, did not capture similar benefits. Concepts used up to 100 years ago remain common. The protection system to identify and clear faults has been largely based on detecting overcurrent, much like a fuse. The design has created a one-way concept, to deliver power to customers from a central source. This structure has been a major barrier to the use of distributed resources. Today, new technology is available that can easily overcome this issue. Implementation will be essential if the concept of distributed energy is to become widespread.
Smart meters have been an early step in providing distribution system communications. In the past, utilities learned about power loss issues from user calls to say that their lights were out. The smart meters now send a last gasp to report that the power has failed and there will be no further data. Utilities can now identify both the location and scope of losses immediately. This data often provides clues to the problem location. Smart meters deliver large amounts of other useful information. But smart meters are a small start for potential valuable changes.
Cutting-Edge Technology Is a Must
While communications have enabled optimal operation of the transmission system, the distribution system, based on old technology, has not modernized significantly. What opportunities could be available from the distribution system that would help with the transition to a future with lower emissions? Answers to this question would be useful to fully understand and identify opportunities.
A conventional distribution feeder may have load limits based on the length of the feeder. A short feeder, (<1-2 miles) will have a limit based on the conductor or wire used to deliver the power. Above the thermal limit, the wire will become hot. Lines longer than about 2 miles generally limit on low customer voltage. The low voltage limit may be reached with the line current operating at a fraction of the thermal limit of the wire. There may be an opportunity to increase feeder capacity by managing the receiving voltage.
At the same time, the feeder delivers two quantities that are needed by most customers; these are real and reactive power – or Watts and VARs. Watts must come from a generator, but VARs can easily be created anywhere. But both Watts and VARs consume line capacity. Eliminating the delivery of VARs and creating them at the load site is an option to increase the feeder capacity.
VARs can be created by a generators, capacitors, inverters, or specialized solid state devices called Static VAR Compensators (SVCs). The SVC may be a costly but effective solution.
Generac Grid Services learned a lesson some time ago. Devices dedicated to providing one service may be effective, but expensive and not cost effective. A battery used for day/night storage is an example. While costs have fallen dramatically, a battery that captures solar energy by day, to be used during the night delivers a marginal benefit at best. However, if the battery can be used to also mitigate demand peaks for a local utility, or provide fast frequency support, the system becomes fully feasible.
Modernization of the distribution system has many features that may be opportunities for innovative solutions that will address several needs and improve operations at the same time. A few examples may be as follows:
- Systems used for backup sources may be able to be used to deliver reactive power at customer sites–raising feeder capacity and managing local voltage.
- Backup sources may be used to deliver peak capacity reduction for utilities, reducing the need for expensive peak capacity and reducing delivery losses.
- Managing local demand levels to provided needed flexibility for grid management in matching supply and demand.
It is apparent that the small electric grid will need to transition rapidly to become a major means of delivering energy to customers. The available time to achieve this change is too short to allow traditional means of expansion to be used. This is an opportunity for innovation and thought to achieve cost-effective results that can support rapid change.