Solar power can be used to generate electricity in multiple ways, most commonly through photovoltaic(PV) and concentrated solar power (CSP). High profile CSP projects like California’s Ivanpah facility use an enormous chunk of real estate to focus sunlight on three “power towers.”
To improve security, reliability, and scalability, the power industry is moving towards distributed generation and microgrids, where small generators are placed in many locations. While a power tower typically generates tens or hundreds of megawatts, AORA’s Tulip offers a 100 kW distributed solar thermal option that’s suitable for microgrid applications and for small communities in developing nations. It’s also modular, so more units can be added as the need arises and the budget allows. Let’s see how it compares to its bigger cousin.
One AORA Tulip system uses less than a half-acre of land and 50 heliostats (mirrors) per tower, and generates 100 kW of electricity. By contrast, Ivanpah sits on 3500 acres of land and uses 300,000 mirrors to produce 377 MW of electricity. If we scaled up the AORA to the same acreage, we’d have 7000 Tulips producing 700 MW of electricity.
Here’s how the Tulip works:
Strength in Numbers
Distributed generation means that power is generated closer to the point of use. It’s estimated that nearly 10% of the electricity that’s generated is lost over transmission lines. Small power plants in many locations can reduce that waste, since electricity doesn’t have to travel as far. Even with a large-scale facility in one location, using many small towers rather than a few large ones will improve reliability. When one Ivanpah tower goes down for repairs, the facility’s output is reduced by a third. On our hypothetical scaled-up facility, the result of one Tulip being taken offline is almost negligible.
Power at Night
Like many CSP generators, the Tulip’s turbine can also run on natural gas, biofuel, diesel, or propane, allowing the unit to produce energy at night and on cloudy days. While some CSP plants divert the concentrated heat to molten salts, which store the heat so it can be used to run the turbine when sunlight isn’t available, AORA doesn’t offer a storage option for the Tulip. Instead, it delivers 170 kW of thermal energy that can heat water or buildings, run absorption chillers, assist in biofuel production, and desalinate water.
Each Tulip system costs about $550k - about $5.50 per watt of electricity. Ivanpah’s price tag was $2.18B, roughly $5.78 per watt. As a bonus, the Tulip provides heat. Both are expected to last around 25 years.
Prototype Tulip power plants - one in Israel and another in Spain - have been operational since 2009 and 2012 respectively. Two more are slated for construction in Ethiopia beginning in mid-2015.
When it comes to wind power, I say “Go big or go home.” Large turbines are more efficient and ultimately more cost-effective. The same rule doesn’t hold true for solar, however, even in the concentrated solar power game. It looks like small and scalable could be the better option. Will the long-term cost of ownership be comparable? It’ll take a few years to determine that.
Images and video courtesy of AORA