Nice Grid Offers a Glimpse into the Future for Solar PV Plus Energy Storage

On a sunny winter day in Nice, France, 40 journalists from all over the world boarded busses to tour what serves as one possible example of a future networked electricity grid. Alstom Energy, the 9th largest electrical equipment supplier in the world, according to Bloomberg New Energy Finance, had put together a media tour in order to showcase what steps it is doing to understand the grid of the future.

According to Patrick Plas, SVP of Grid Power Electronics and Automation with Alstom Energy, the project sets out to address four challenges facing the grid side of the energy industry today. “There is an increasing demand for energy, which is then translated into investment in generation and investment in infrastructure.”  By 2023, he said, North America energy demand is expected to increase by 27 percent (22 percent in the US), with Latin America growing by 78 percent, Europe growing by 22 percent and Asia, the Middle East and Africa growing by triple digits – 156, 115, and 110 percent respectively.  “The growth is huge” and this is the first challenge in front of today’s electricity grids.

In the Nice Grid the post office roof is covered with solar panels. Credit: Xavier Ferrandez/Alstom.

That growth represents a $12 trillion market for both generation and infrastructure. Plas said that by using the smart grid model that number could be knocked down by 20 percent, with those savings being captured through demand-side management, which reduces the need for additional generation assets to be built.

The second challenge facing the grid today is blackouts or energy security. As weather events continue to wreak havoc on populations from the Philippines to Australia to New York City, leaving communities without power for days on end, major industry power players like Alstom are actively working to create a more stable and secure grid.  By using the micro-grid model, a community that is normally grid-tied is able to function as its own power “island” in the event of a larger power outage.  In places like hospitals and military bases, its importance cannot be underscored enough.

The third challenge said Plas is the increase in renewable energy generation assets in a utility’s portfolio, growth that will not be curtailed anytime soon. Wind and solar power are growing but utilities have concerns about how to control for overcapacity, power surges or drastic drops in power supply such as what occurs when a cloud passes over a large solar array. “So renewables, which are more and more contributing to the electricity generation, are a growing part of this [interest in] smart-grid technology,” said Plas.  “We need to manage our way through this increase in renewables,” he added.

Finally the last challenge relates to the volatility of the cost of energy. “It’s not a mere rising price of energy,” he said, even though electricity costs are expected to increase by 15 percent in the next few years, “but as well this volatility which is an issue.”

“So all in all to face these challenge, we need to make sure that we supply reliable power, and that this power is affordable, and of course that it includes more and more renewables,” he concluded.

Enter Energy Storage

Incorporating energy storage along with renewable energy into micro-grids is a growing trend all over the world.  The market for micro-grids plus energy storage will grow from $662 million in 2014 to more than $4 billion in 2024, according to a recent study by Navigant Consulting.

Cities currently occupy just 2 percent of the planet yet they are home to 50 percent of the world’s population and use 75 percent of all global energy produced.  Cities are responsible for 80 percent of of CO2 emissions. Today 3.5 billion people live in cities and that number that is expected to rise to 6.5 billion by 2050.  Alstom Energy defines smart cities are cities in which investment in human and social capital, energy infrastructure (electricity and gas), traditional methods of communication (transport) and digital communications (with very high speed connections) promote sustainable development and greater quality of life along with careful management of natural resources through a process of participatory governance. Image credit: Alstom

Navigant said that incorporating energy storage into a micro-grid offers the same benefits that energy storage provides the traditional grid: “resource optimization (fuel, PV, wind), resource integration (PV, wind), stability (frequency, voltage), and load management.” Since low-carbon energy is our future and climate change is our reality, it makes sense that companies all over the world are exploring how best to marry renewables and energy storage in secure, stable grid environments.

Indeed another report issued in early 2014 from the Abell Foundation echoes the findings of Navigant. Distributed generation including solar energy plus energy storage makes for a more resilient grid, the study says. It outlines how cities can use clean energy to create a more reliable electric system during power outages.

Stability and Renewables Are the Focus of Nice Grid

Despite all of these market predictions and perceived need for micro-grids and energy storage, utilities are faced with more questions than answers about how such a grid will function. Who will own and operate it? How the business model will work? Will customers become more active in their personal energy use? To answer these questions and more, a consortium of companies including Alstom, Armines, Daikin, EDF, ERDF, RET, Saft, Socomec, NetSeenergy and Watteco, have embarked on a project that attempts to put it all together. 

The four-year project, which officially began in late 2011, has four objectives and two main features, according to Christophe Arnoult, Project Manager with ERDF, the state-owned electricity distribution company in France.  “The first objective is to optimize a distribution network with a massive contribution from renewable energy [that is] decentralized and intermittent,” he explained.  “The second objective is to model how reactive the average low-voltage customer is likely to be to signals concerning his way of consuming energy.” The idea is to see if it is possible to “move the customer from a pure consumer attitude towards a more proactive ‘prosumer’” he explained.

Arnoult said the third objective is even more experimental.  “We will have pockets of network fully equipped with solar generation…and batteries, why not push the system to the limits and see whether it is feasible to operate a small part of the low-voltage network for a small period of time as an independent network [that is] drawing its power only from renewable sources?”

The partners will study whether or not it will be possible to fully detach from the high-voltage transmission line and operate the Nice Grid completely on solar power and batteries. And the 4th and last objective, of course, is to understand how to put together a profitable business model behind all of this innovation.


The Electrical Structure of Carros — A “Smart City” by the Sea

The city of Carros, population 11,000, is located just outside Nice, France, which lies on the Mediterranean ocean. There are 5,900 residential electricity customers and 136 industrial electricity customers and total installed capacity for the city is 2.5 MW. In France baseload power is supplied by hydro (30 percent) and nuclear (70 percent). Peak demand for the residential customers is 30 GWh and for the industrial customers it is 20 GWh.

The city was selected to be part of the pilot program due to its location on the periphery of France’s transmission grid, its abundant sunshine and its broad consumption needs: there are apartment dwellers, residential homes and industrial facilities all within the small city limits. 

As part of the test project, the consortium is seeking 550 residential customers and 11 industrial customers to participate in voluntary load shedding.  A portion of those will also be equipped with solar PV.

Three Levels of Energy Storage

Interestingly, in the Nice Grid grid, energy storage capacity in the form of batteries will be installed in three different levels on the network offering the grid operator maximum flexibility according to Alstom. “Flexibility through energy storage is no longer a concept,” said Davy Theophile, Conversion Solution Director with Alstom in a presentation about about the Nice Grid energy storage system.

The centralized 1-MW battery (already in place) stores 560 kWh of energy and is located at the point between the high-voltage transmission line that transmits power to the region and the distribution network that sends power to the customers.  This battery, which can provide 30 minutes of energy storage is is used for peak shaving, explained Theophile. The battery plus voluntary load shedding or demand response reduces the need for ERDF to purchase additional power when demand spikes occur.

The second level of storage is at the residential homes.  ERDF is currently recruiting residential customers to be equipped with 3-kW PV systems and 4-kW/4-kWh batteries. They anticipate that about 50 residents will participate.  These residential batteries will absorb excess energy in order to manage overvoltage situations that may occur. “So this may happen on a summer afternoon on a sunny day when people are at work or at the beach. Then you may have more production than consumption in some parts of the low-voltage grid,” explained Marc Delprat, Smart Grid Pilot Program Director for Alstom.  One way to control for that will be to encourage consumers to use more energy during those times — perhaps run their appliances in the afternoon instead of the evening.  (In France, residential consumers are subject to peak rates and off-peak rates.  Off-peak rates begin at midnight and grid operators see a spike in demand at that time as residents turn on their electric water heaters at midnight.) One of the aims of the Nice Grid is to see if consumers will shift their behavior at the request of the grid operator.  If there is still an over-voltage situation, the batteries will absorb the excess energy.

The third level of energy storage is located at three industrial buildings, which will be equipped with PV systems and 33-kW/100-kWh batteries. There will be a larger 250-kW/600-kWh battery also part of this system, and together the batteries will be used for islanding and load shedding.  These batteries will balance the micro-grid in the event that Nice Grid is detached from the main high-voltage transmission line.  “To our knowledge this is a world premier — to experiment with such islanding scenario without any kind of rotating device,” said Delprat. “We are doing that only with solar production and battery storage so this is completely carbon free energy,” he added.  Overall the storage system should allow for 4 hours of grid independence. See the sketch this page for a breakdown of the energy storage system.

Who is In Charge?

Controlling all of this is the Network Energy Manager (NEM), provided by Alstom, otherwise known as the “brain behind the grid,” according to executives with the company.  The NEM collects the solar production and load forecast, imports regional load reduction requests and then calculates local grid constraints and grid constraints and identifies the risks of overvoltage.  With this information, it publishes power adjustment needs to the suppliers and computes an optimal schedule of “flexibilities” according to Alstom.  (Flexibilities include both demand response and energy storage.)  Finally the NEM communicates the activation schedules for the flexibilities and the cycle begins again.

The total cost of the project is €30 million. The EU provided €7 million and the French Agency ADEME provided €4 million as part of its Future Investments Program. The rest of the cost was born by the project partners.  The total cost of the energy storage system is about €1.3 million. In total the system will provide about 1,660 kWh of energy storage at a cost of €800 per kWh.

Why Go Through all of This?

In speaking with executives about the Nice Grid there is a sense that a great experiment is underway, driven by an urgency to get in front of the transformation of the electricity grid. Alstom is currently involved in more than 30 smart grid demonstration projects all over the world.  The company says that it uses these projects to test functionality and different combinations of innovative technological solutions. Of the Nice Grid, ERDF’s Arnoult explained that his company is concerned about the “dramatic increase of solar generation connected to the DSO grid,” and the potential harm it could do.  “We are studying a potential solution to turn this constraint into an opportunity,” he said.

Overall, it seems that rather than recoil from the grid of the future, or fight it tooth and nail, these European energy companies are stepping into the great unknown and testing all sorts of different potential solutions to address all foreseeable challenges.  And for that, they should be applauded.

[Editor’s note: Want to hear more on this topic? Sign up for our upcoming webcast: Solar and Energy Storage: The Power Behind the Microgrid by clicking on this link.]

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