NREL’s just-released Renewable Electricity Futures study concluded the most abundant U.S. renewable resource is solar. The U.S. technical potential of utility-scale photovoltaic (PV) was estimated at 80,000 gigawatts. Concentrating Solar Power (CSP) was 37,000 gigawatts. Distributed PV was estimated at 700 gigawatts.

The U.S. needs about 1100 gigawatts of electricity production capacity, so the race is on between PV and CSP to capture the market that other utility-scale renewables don’t. BrightSource, SolarReserve and Abengoa, emerging forces in CSP solar power tower technology, are working on large-scale technologies. ESolar is going the other way.

“What is so unique about our technology is the modular nature of it and the scalability,” explained eSolar President/CEO John Van Scoter. “Instead of one-size-fits-all,” he said, “we can literally build these up just like building blocks and adapt to different customer requirements.”

ESolar’s Sierra SunTower in California has been in operation since 2009, and its Bikaner power tower in India has been in operation since last April. Its business partners include General Electric (GE) and Babcock & Wilcox, two major energy sector multinationals. And it has a roadmap for scaling its cost down and its reach outward.

The company has just completed phase two of a $50 million move, in partnership with the U.S. Department of Energy (DOE) and Babcock & Wilcox, to molten salt storage. “That will dramatically reduce the LCOE [levelized cost of electricity] delivered to the grid compared to steam-only non-storage systems,” Van Scoter said. “We chose to move the roadmap in that direction back in 2010 in order to be competitive,” he added.

The LCOE reduction is, Van Scoter acknowledged, to compete with PV. ESolar’s roadmap, he said, shows industry LCOE predictions for both crystalline silicon and thin-film PV. “Our objective is to compete straight-up with the best-in-class PVs on an ongoing basis but have the advantage of being dispatchable with storage.”

Van Scoter expects to beat PV with the company's first commercial deployment of a solar power tower with molten salt storage in 2014-2015. “We know where PV is going to be, so we can back into where the capex for the system has to be. We break down that capex for the individual sub-systems. And we are designing the cost for each of those individual sub-systems.”

Sierra SunTower is a two-tower, five-megawatt, first-generation project. It has been producing as would be expected, explained plant manager Joe Long. But, he added during a walk through the facility, “I can show you as many things that we would not do again as things we would.”

“Right now, our base module is roughly 4 megawatts electric, not 2.5 megawatts like you see at Sierra SunTower,” Van Scoter said, but “the basic concept and materials are all proven.” With 4-megawatt blocks, eSolar can, he explained, “build any size plant up to 200 megawatts.”

Phase three of the molten salt storage project will be a proof of concept plant they hope to have operative by the end of next year. “We have a number of sites right now that we are considering,” Van Scoter said. “Some are here in the states, some are overseas. We’ve seen tremendous interest in the Middle East and North Africa.”

It is possible the storage technology will be tried at Sierra SunTower, he explained, but added, “We would like to do something larger.”

ESolar has learned from its first-generation facilities. SCS5, a “next-generation heliostat,” Van Scoter said, has slightly larger mirrors and a smaller and more easily implanted base, but “will continue to be mass-produced and pre-fabricated in very low cost factories around the world.”

The company has also streamlined the system’s power electronics, cabling installation and robotic heliostat cleaning. The first two will reduce costs and the third, Van Scoter said, “will reduce water consumption by an order of magnitude.”

First-Generation Heliostats

Next Generation Heliostats

ESolar is talking to a variety of potential customers around the world “about projects ranging from twenty to more than 100 megawatts,” Van Scoter said. “With the exception of India and China, we are seeing pretty much across-the-board movement to dry cooling,” he added. “The molten salt system is designed for either, but we expect the vast majority of those to be deployed as dry-cooled systems.”

Adapting to dry-cooling technology “isn’t a concern,” Van Scoter said. “There are many people who can do it. And with General Electric as our partner -- they bring an incredible reach and capability.”

GE invested $40 million in eSolar after “nine months of due diligence,” according to Van Scoter. GE’s investment, he said, gave it a worldwide license, with the exception of India and China, to develop a breakthrough integrated solar combined cycle (ISCC) concept. The first, a 500-megawatt GE natural gas plant in combination with a 50-megawatt eSolar power tower facility, is expected to “get full notice to proceed in 2012.”

Van Scoter said ISCC could do for solar what the Prius did for cars. “I think it will drive volume. It will drive learning. It will drive cost. It then will ultimately drive stand-alone systems down to more competitive positions in time.”

That might happen sooner if eSolar brings its LCOE down while the China import tariff, the loss of the 1603 manufacturing tax credit, and expected stalls in major markets provide PV’s LCOE back-up.