Thursday, March 15, 2018

Back to Earth: Rebuilding Puerto Rico

I like talking about space and the future but real life and present day immediate problems beg to lower my gaze back to sinful Earth.

From the special IEEE Spectrum report.

On September 19 2017 as Hurricane Maria started churning through Puerto Rico, engineers of Puerto Rico Electric Power Authority (PREPA) helplessly stared at the computer monitors that displayed real-time conditions on the grid. One after another, transmission lines were failing, and the team hastily debated their course of action. In this fragile state, the network wouldn’t be able to absorb an oversupply of power, excess voltages, or swings in frequency. They could inject test currents into the downed lines, to see which ones could be restored, or else reduce the level of electricity being put on the grid, to protect the remaining transmission system. Hour after hour, the urgency was rising.
By nightfall on the 19th, the crew knew their efforts were futile. Winds topping 280 kilometers per hour had begun toppling transmission towers, snapping concrete power poles, entangling lines, and battering power plants. The PREPA engineers at their workstations watched in dismay as small outages spread and bloomed like a virus. Finally, at 2 a.m. on 20 September, all went into total blackout. All of Puerto Rico was now in the dark.
Four hours later, Maria barreled into the island as a Category 4 hurricane. The storm tore a diagonal 160-km-long path from the island’s southeast to its northwest, demolishing tens of thousands of homes, washing away roads and bridges, stripping the limbs from lush green palms, and leaving in its wake a littered and jarringly lifeless landscape. Unofficial tallies after the storm suggest that about 1,000 people lost their lives.
In the months to come, Puerto Ricans—who are, after all, citizens of the United States, a country of unquestioned technological preeminence—would discover how breakable their modern society actually was.

Water treatment facilities couldn’t provide drinking water, markets and restaurants couldn’t refrigerate food, banks couldn’t operate ATMs or conduct transactions. Cellular and Internet access was gone. Street lights and traffic lights stopped working. Schools, hospitals, and stores closed indefinitely, factories and businesses shut down.

After the storm cleared step one was to figure out the exact scale of what had happened, all over the island. The control center was running on a diesel generator, but island-wide communications were down. That meant the usual way of gauging conditions on the grid—using automated remote terminal units at substations to collect and send data to the central supervisory control and data acquisition (SCADA) system—didn’t work. PREPA’s grid reaches nearly every home, business, school, and hospital on the main island, as well as on the smaller islands. For months, the utility was unable to say just which customers were still in the dark. At first they relied on outage reports coming in via satellite phone and from amateur radio operators. 

Under normal conditions, Puerto Rico’s generating capacity exceeds 5,800 megawatts, but peak demand is only around 3,000 MW. About half of the electricity comes from PREPA’s 10 oil-fired power plants. Much of the rest is produced by a pair of natural-gas power plants and a coal plant. Renewables—including seven solar farms, two wind farms, and seven hydropower sites—supply just 2.4 percent of generation.
Puerto Rico's grid is lopsided: seventy percent of its power generation is in the south, while 70 percent of power demand is in the north. This is the biggest problem for PREPA. Hurricane Maria sliced straight through the middle of the vital connections between North and South. 
The transmission system consists of 4,000 km of line divided among three voltages. The backbone is a 230-kilovolt ring around the island, with two South-North corridors dividing the island into western, central, and eastern loops. This feeds an extensive 115-kV network that delivers power to population centers. Finally, a 38-kilovolt “subtransmission” network serves remote areas, as well as islands via underwater cable; it also supplies power to PREPA’s 51,000 km of distribution line.
Even four months since the hurricane the scenes of destruction were still evident. Steel lattice transmission towers lied in broken piles. High-voltage wires wraped around treetops. Where there was a wind farm, only the masts of turbines are sticking out, their blades shorn off, stuck up like fat white flagpoles. Near the beach town of Humacao, a large solar farm has been reduced to fields of broken glass and twisted metal.

Blue square tarps dot the landscape; these temporary roofs are all that shield the buildings’ occupants from the elements. After the storm, 200,000 Puerto Ricans decamped for the mainland United States in search of jobs, medical care, simply for normal life.

As of late February, the US Army Corps had brought in nearly 1,000 emergency generators. Truck-size 1-MW units went to hospitals and other critical facilities, while 25-MW units went to damaged power plants. The unit also received nearly 4,500 km of wire and more than 37,000 wood, concrete, and galvanized steel poles; another 13,000 poles were slated to arrive this spring. At first, supplies barely trickled onto the island, in part because inventories across the United States had been depleted by the disastrous 2017 hurricane season and wildfires in California.

Back in January PREPA announced a milestone: One million customers—roughly two-thirds of its residential, commercial, and industrial users—had their lights back on. The utility continues to boost generation. Most of that power however is coming from oil-fired units and a natural-gas fired plant. Other sites, though, sit idle.

If  Puerto Rico's grid recovery has been slow and contentious, modernizing the island’s electric system will likely take many years, billions of dollars, and a lot of creative thinking.

The restoration of Puerto Rico’s power grid is a timely object lesson on the vulnerabilities of modern electrical networks and on the emerging technological options for minimizing those vulnerabilities. Power experts are now not just repairing Puerto Rico’s grid but doing so with an eye toward a future that portends storms of increasing intensity and frequency. Grid operators around the world are considering the merits of microgrids, utility-scale energy storage, and distributed and renewable generation. But for Puerto Rican officials trying to rebuild their shattered electrical infrastructure, these possibilities are of much more than abstract interest.

There are a number of new ideas, and most share a common theme: a shift away from traditional centralized power plants and toward more distributed systems. For that to happen, government agencies have to agree on the plan. Microgrids, for example, still can’t connect to the main grid. The Puerto Rico Energy Commission is only now finalizing the rules to allow that to happen. But even the micro-grids are prone to disasters, although damage would be limited.

Here is the solution which could limit the scale of any disaster virtually to a point. Autonomous Mobile Energy System (AMES) can be delivered to any place which urgently needs energy, rapidly deployed and provide an uninterrupted source of clean energy regardless of external conditions 24/7.  

In case of disaster the module can be folded back into the transport configuration and withstand hurricane of category 4 and maintain its power ready to start generation again the moment the storm subsides. Ten thousand modules deployed each at the place of energy consumption would not require transmission lines therefore would not be affected by the grid being out. Moreover failure of any one module would not affect any others therefore the damage is minimized to negligible amount.

Such approach is also practically hacker- and terrorist attack-proof - a single module is not an attractive target comparing to the centralized grid or a pipeline.

And additional bonus - it does not require huge investment to start incrementally generate energy and contribute to the global problem.

Sustainable future is in distributed on-site clean energy generation.

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