Macrogrids Or Microgrids: Which Is The Key To The Renewable Energy Revolution?

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There is a lot of discussion about whether macrogrids or microgrids will be the key to the renewable energy revolution. Some argue we need a vast array of high voltage transmission lines to carry electricity from solar farms on a sunny afternoon in Arizona to meet the needs of New Yorkers coming home after dark following a long day at the office. Others maintain local microgrids are better because they avoid the rather frightening expense of building more transcontinental transmission lines.

The issue, of course, is time shifting. The demand for electricity tends to ramp up just when production from most solar power plants is decreasing. Traditionally, utility companies have fired up so-called peaker plants in the late afternoon to handle the surge in demand, but bringing those facilities online is expensive and comes with a big increase in carbon emissions. However, renewables can’t be turned on and off to suit the needs of utility companies. We need new strategies to maximize how most of the renewable energy available gets put to good use.

Bill Gates Backs HVDC Macro Grids

Breakthrough Energy, an organization created and funded by Bill Gates, is supporting something called the Macro Grid Initiative, a plan developed by the American Council on Renewable Energy and Americans for a Clean Energy Grid.

“To respond to the challenge of climate change, we need ambitious investments in our electrical grid. Solar, wind and other renewable energy sources are booming, moving us toward a carbon-free future,” says Gina McCarthy, CEO of the Natural Resources Defense Council, according to PV Magazine. “But we need a way to connect all this clean energy to our homes. Modernizing our outdated transmission network will create jobs, grow our economy — and allow responsibly sited, cleaner energy to thrive.”

Reforming US transmission planning and cost allocation procedures will enable more inter-regional transmission lines to deliver power where it’s needed, allowing grid operators to balance the power supply better at lower cost, says Gregory Wetstone, head of ACORE. 15 states between the Rocky Mountains and the Mississippi River account for 88% of the country’s wind potential and 56% of the country’s utility scale solar potential, he says, but only 30% of the projected 2050 electricity demand will be in those states.

“We need to help people understand why a Macro Grid is so essential to America’s economic and environmental success. We need to connect the dots that in order to deliver more low-cost clean energy, we need greater interconnection between the nation’s electricity markets,” Wetstone says.

“Our priority areas include an expanded nationwide and eastern grid with a focus on the power market regions of MISO, PJM and SPP; developing and advocating for a fully planned and integrated interregional transmission system; promoting a new FERC transmission planning rule; and enlisting the help of state leaders to advance the next round of regional and interregional transmission planning,” Wetstone said.

Proponents says enhanced transmission lines would ensure grid reliability in the face of new patterns of electricity demand and supply. Increasing transmission development at the “seams” between regions could save consumers more than $47 billion and result in a return on investment of  $2.50  for every dollar spent. Additionally, a nationwide, high voltage direct current network optimized for the nation’s best wind and solar resources could deliver 80% carbon emission reductions from the grid by 2030 without adding costs to consumers’ electric bills.

We Need More Mini Grids, Says California

Pacific Gas & Electric, the largest utility company in northern California, admitted liability this week for more than 80 deaths from forest fires ignited by its transmission equipment. Over the past 3 years, California has been afflicted with numerous brush fires that raged across vast swaths of the state, wiping out entire communities as they raced across the landscape. The Los Angeles Times reports the state’s investor owned utilities — Pacific Gas & Electric, Southern California Edison, and San Diego Gas & Electric — sparked 2,000 fires between 2014 and 2017, all because of defective equipment.

This week, energy regulators in the Golden State made it easier for utilities to develop localized microgrids with battery storage  to combat the forest fire threat while increasing the viability of renewable energy systems.

“The California Public Utility Commission’s order promises substantive changes in transparency and planning that should support collaboration with communities and tribes,” Michael Burr, founder of the Microgrid Institute, tells Forbes. “While these changes are steps in the right direction, they don’t actually require California’s investor-owned utilities to use distributed energy resources for local resiliency — or to back up the grid if the power goes out. It will be up to the commission and customers to hold utilities accountable for achieving the purposes of the order, and not just checking the boxes it requires them to check.”

The commission’s rule making, released last week, is a direct response to state law that requires the deployment of microgrids and in a way that does not shift the costs to customers. “The use of microgrids, coupled with the (commission’s) work to hold utilities accountable for creating and implementing wildfire mitigation plans will help make communities more resilient in advance of the 2020 wildfire season,” said the commission’s president Marybel Batjer, in a press release. The three utilities are expected to build several dozen microgrids and will give progress reports to the commission.

A microgrid uses locally produced renewables to power a local community. The time shifting problem is largely taken care of by battery storage installations, but some gas-fired peaker plants may be used as well. The theory is that local microgrids will avoid the resiliency problems often associated with long distance transmission grids when pylons or wires collapse during earthquakes or severe storms. Think of the havoc caused by Hurricane Maria in Puerto Rico or the collapse of transmission lines in Victoria and South Australia due to heavy winds some years ago — an event that led directly to the Hornsdale battery facility supplied by Tesla.

“In general, utility customers will continue pushing to connect privately-financed solar, wind and storage projects to the utility’s grid and the challenge will be for the utilities and our regulatory agencies to keep up with the pace that technology and the markets are setting,” Michael Powers, founding partner of Stellar Solar in San Diego tells Forbes. “If we are serious about fighting climate change and meeting the clean energy goals that communities have set, we need the utilities and agencies to become more nimble and resilient, too.

Can’t We All Just  Get Along?

Society doesn’t need to choose between macrogrids and microgrids. There is a need for both in the energy environment of the future. Microgrids can function independently if the connection to the utility grid is interrupted, but need to be interconnected to the larger grid to ensure constant service at all times since even the best human-designed systems can fail. HVDC transmission lines are vulnerable to quakes and storms and maybe even cyber attacks.

Arguing about macro versus micro is like arguing whether battery storage is better than pumped hydro. The truth is that both have a role to play in the renewable energy future. There are instances where gravity storage may be the best answer.

The factor that is driving all these debates is that renewable energy facilities cost less to construct and can become operational in far less time then coal, gas, or nuclear generating installations. As costs continue to fall, there will be more money available to provide the resiliency we need to complete the renewable energy revolution while lowering the cost of electricity consumers pay.