Whether you see it as a brash and impressive American feat of energy engineering in the tradition of Hoover and Grand Coulee dams, or a blight on nature in the tradition of, uh, Hoover and Grand Coulee dams, it’s here. Ivanpah is here.

NRG Energy made it official early today, announcing that the Ivanpah Solar Electric Generating System was “operational and delivering solar electricity to California customers.” The concentrating solar thermal power plant isn’t the first of its kind, but there’s never been anything approaching it in scale.

ivanpah solar
image via NRG Energy

Ivanpah covers some five square miles of the Mojave Desert, a few miles off Interstate 15 near the Nevada state line. The plant consists of three 450-foot-tall towers surrounded by a total of 173,500 “heliostats,” garage-door-sized pairs of mirrors that pivot and tilt to track the sun, focusing energy on boilers atop the towers where water is heated to produce steam that is used to turn turbines and produce up to 392 gross megawatts of power.

It’s a big achievement for the companies behind it – BrightSource Energy, the technology company; NRG, the huge power generation and retail electricity company; Google, an investor to the tune of $168 million; and Bechtel, which did the construction – and for the Obama administration and U.S. taxpayers.

The $2.2 billion project was aided by a $1.6 billion U.S. Department of Energy loan guarantee, and Secretary Ernest Moniz was scheduled to be in the desert today for a dedication ceremony. In remarks released beforehand by the DOE, Moniz used Ivanpah’s opening as a platform to defend and promote the administration’s aggressive approach to clean energy development through the loan program and other means.

“President Obama and the Department of Energy are committed to ensuring that all sources of energy are competitive in a carbon constrained economy,” Moniz declared. “This is why we have already invested more than $6 billion in carbon capture and sequestration technologies and recently announced up to $8 billion in available loan guarantees for advanced fossil energy projects that lower emissions. This is why we provided more than $8.4 billion in loans to the auto industry to allow our domestic auto producers to retool their American factories to produce cleaner and more efficient vehicles. And this is why we have committed more than $24 billion in loan guarantees for clean energy projects across the country – including right here at Ivanpah.”

With its size and government backing, Ivanpah will no doubt be heavily scrutinized. Here are four things to keep in mind in the weeks and months ahead.

1. There might be hiccups. There are smaller power tower plants operating in Spain, and BrightSource itself did a mini-Ivanpah of sorts in Coalinga, Calif., a few years ago, a 29-MW single-tower plant where the steam produced is used by Chevron for (irony alert!) enhanced oil recovery. Ivanpah goes a step further, producing electricity, which shouldn’t be complicated; steam is used to produce electricity the world around. Still, the federal loan guarantee program that helped build Ivanpah, Section 1703 of Title XVII of the Energy Policy Act of 2005, was intended “to support innovative clean energy technologies that are typically unable to obtain conventional private financing due to high technology risks.” Did you note the word “risk”? It will be interesting to watch how steadily and in what amounts Ivanpah’s three units are providing electricity to Pacific Gas & Electric and Southern California Edison. NRG said Ivanpah will produce enough electricity to power 140,000 homes. Coming through on that promise could drown out any carping about the cost of Ivanpah’s clean electricity, estimated to be at least twice that of conventionally sourced energy.

2. It’s in the desert, it uses water, it must be a water hog – but it’s not. Instead of cooling steam by sending it through pipes surrounded by water, Ivanpah relies on fans blowing ambient air. This results in some efficiency losses, especially on hot summer days when Ivanpah’s power might be most needed, and it takes electricity to run those fans, but the gains in water savings are enormous. Ivanpah will need fresh water only to clean the heliostats, about 100 acre-feet a year. BrightSource says that’s how much water a nearby golf course uses to keep the grass green on two holes.

3. It does not come with energy storage. Solar thermal, unlike PV, offers the enticing possibility of large-scale energy storage and producing power on demand. And, in fact, the U.S.-backed, parabolic-trough Solana Generating Station, which began operating last year in Arizona, uses molten salts to store heat and extend its generating capability. Likewise, another power tower plant that’s due to start up this year, 110-MW Crescent Dunes project near Tonopah, Nev., does come with molten-salt storage. BrightSource wants to do storage down the road, but for its first massive project, chose not to.

4. The big environmental issue might not be tortoises, but birds. Ivanpah’s developers have spent more than $20 million dealing with the endangered desert tortoises that called the plant site home [PDF]. But the bigger issue in the long run might be birds. Chris Clarke of the ReWire blog has led the reporting on the risk to birds presented by Ivanpah’s concentrated solar radiation. Even in the on-and-off powering-up phase over the fall months last year, plenty of dead birds were being found at Ivanpah, scorched by “solar flux.” A concern is that the plant attracts insects that migrating birds could be drawn to. The bird issue wasn’t completely unexpected – the L.A. Times’ Julie Cart noted, in a 2012 piece, that an early demo of power tower technology had a grim impact on many birds – but regulators have clearly been surprised and troubled by the scope of the problem thus far. So much so that a BrightSource plan to build two even taller power towers in Riverside County is now stalled. Beyond cost, birds could be the biggest stumbling block to more power towers popping up in the Southwest deserts.