Generate day energy and hunt asteroids at night

At the time they seemed the future of solar energy for their ability to follow the sun with oscillating mirrors. Today the solar concentration plants, which direct the light by heliostats towards a large central tower, They cannot compete with photovoltaic prices collapse. But when a door closes, sometimes a window opens to the universe.

Short. A pilot project in the United States has begun to take advantage of these gigantic mirrors when the sun falls for the Planetary Defense. For the day, heliostats generate energy concentrating sunlight in a tower connected to steam turbines. At night, they defend the planet of potentially dangerous asteroids.

The figures are devastating. The thermoelectric solar energy has lost the battle against photovoltaic by win. In 2023, the world installed the record figure of 345.5 gigawatts in solar panels, but the solar thermos I barely added 0.3 GW in total. And what is worse, since then construction is not started of no new plant.

Although Spain, the world leader in concentration technology, maintains its centrals working, other projects are canceled or reconvisaged. Morocco has replaced the Termosolar part of the MEGACOMPLEJO NOOR MIDELT by photovoltaic after qualifying it as “immature and face technology”. And iconic projects, such as the gigantic Ivanpah plant in Californianow face their closure for not being able to compete with the low price of photovoltaic kilowatt.

Save the planet, and incidentally investment. Given this panorama, what can be done with these huge and expensive infrastructure? John Sandusky, scientific researcher at Sandia laboratories, has been turning an idea for almost 20 years. “Heliostat fields do not have a night job. They are simply there, without using,” Explain in a statement. “We have the opportunity to give a night work at a relatively low cost to find objects close to Earth.”

The proposal is not to use heliostats to take photos of the sky. Its optical quality is not enough to form crisp images such as a telescope. The genius of the proposal, embodied in a Study of the late 2024 That has already been put into practice, lies in using what these mirrors do best: concentrate light. A lot of light.

How it works. The traditional method seeks in the long exposure images the steles that the asteroids leave when moving against the fund of fixed stars. Sandusky’s method is radically different and is based on frequency analysis.

Instead of aiming at a fixed point, the plant’s software causes the heliostats (mirrors designed to follow the sun) oscillate, sweeping a small portion of the sky at a constant and repetitive rate. The light of the stars, swept at this constant pace, generates a signal in the tower receiver with a specific and predictable frequency. It is the “tone” base of the sky.

If an asteroid crosses that field of vision, moves at a different angular velocity from that of the stars. This makes the light that reflects generates a signal with a slightly different frequency from that of the “tone” base. It is a tiny change, but measurable with current technology. And can be used to detect asteroids due to its speed relative to the stars.

From theory to practice. A team has demonstrated its viability using a single heliostat, and is already working to climb the project to a large solar plant to increase sensitivity and to detect smaller and more distant objects. Even tracking satellites and other objects in the cislunar space, to sell the idea to the space force.

Sandusky’s idea is a masterful example of lateral thought. Instead of building new and very expensive observatories, it reuses a multimillion -dollar infrastructure that would otherwise be inactive half of the time. A technology that fights to survive in the competitive energy market and that could find a second life, a second job.

Image | Pexels

In Xataka | It was inaugurated in 2014 as the largest solar thermal energy plant in the world. Will close after setting fire to birds