Is there a better way to employ fusion to make clean, green electricity for the Earth than giant machines, incredibly difficult temperatures to manage, neutron fluxes to dodge and shield? Researchers at the California Institute of Technology are reviving an old, heretofore implausible, concept: go into space and capture the Sun’s fusion energy directly with photovoltaics, beaming electricity back to earth.
Science fiction? At 6:55 a.m. Pacific Time on Jan. 3, a SpaceX Falcon 9 medium-lift rocket took off from Florida’s Cape Canaveral station, carrying 114 satellites for a variety of customers, among them Pasadena-based Caltech’s Space Solar Power Demonstrator (SSPD). That’s a 50-kilogram prototype that Caltech says, “will test several key components of an ambitious plan to harvest solar power in space and beam the energy back to Earth.”
The project, says Caltech, is “a major milestone in the project and promises to make what was once science fiction a reality. When fully realized, SSPP will deploy a constellation of modular spacecraft that collect sunlight, transform it into electricity, then wirelessly transmit that electricity over long distances wherever it is needed—including to places that currently have no access to reliable power.”
The SSPD package consists of three basic experiments:
- DOLCE(Deployable on-Orbit ultraLight Composite Experiment): A structure measuring 6 feet by 6 feet that demonstrates the architecture, packaging scheme and deployment mechanisms of the modular spacecraft that would eventually make up a kilometer-scale constellation forming a power station;
- ALBA: A collection of 32 different types of photovoltaic (PV) cells, to enable an assessment of the types of cells that are the most effective in the punishing environment of space;
- MAPLE(Microwave Array for Power-transfer Low-orbit Experiment): An array of flexible lightweight microwave power transmitters with precise timing control focusing the power selectively on two different receivers to demonstrate wireless power transmission at distance in space.
A box of electronics controls the three experiments.
There is nothing new about the idea of collecting the Sun’s energy and beaming it back to earth. As an article in CNET points out, noted science fiction writer Isaac Asimov raised the idea in a short story titled “Reason” in a 1941 edition of Astounding magazine. A Wikipedia article notes, “Various [space-based solar power] proposals have been researched since the early 1970s.” In addition to the US, solar power from space “is being actively pursued by Japan, China,[3] Russia, India, the United Kingdom.”
In the 1980s, when the space-based power concept was getting a lot of attention in the US, the Microwave News publication raised health concerns, arguing that bombarding the earth with microwave radiation could have widespread and harmful health effects. The publication also considers that power line non-ionizing radiation emissions could have harmful health effects, which the scientific community, including the National Institute of Environmental Health Sciences, has thoroughly debunked.
The chief problem for moving space-based electrical energy to earth, notes the Wikipedia article, isn’t the effects of the microwave beams but “the necessarily vast size of the receiving antennas would still require large blocks of land near the end users.” Ironically that same critique applies to large land-based solar power systems.
Caltech scientists have developed a technique to concentrate the diffuse sun energy (which in space will not be affected by weather or the Earth’s rotation), much as a magnifying glass on Earth can concentrate sunlight to make fire (something you former Boy Scouts or science geeks may recall). Caltech’s approach, which project co-director Ali Hajimiri explains in a fine YouTube video, uses the physical phenomenon of interference to focus the delivery of power from space to Earth, and even allows the movement of the energy delivery to different end points.
The Caltech project is just a beginning, and the experiments will take some time. “We plan to command the deployment of DOLCE within days of getting access to SSPD” from the spacecraft, says co-director Sergio Pellegrino. “We should know right away if DOLCE works.”
Additionally, Caltech says, “The collection of photovoltaics will need up to six months of testing to give new insights into what types of photovoltaic technology will be best for this application. MAPLE involves a series of experiments, from an initial function verification to an evaluation of the performance of the system under different environments over time. Meanwhile, two cameras on deployable booms mounted on DOLCE and additional cameras on the electronics box will monitor the experiment’s progress, and stream a feed back down to Earth.”
This test of a practical use of fusion energy, which doesn’t require taming fusion’s atomic reaction, has a potential for a far quicker practical application than the Earth-based approach that has been garnering such enthusiasm following the tiny steps at California’s Lawrence Livermore National Laboratory late last year.
–Kennedy Maize
ITER Fusion Project Faces New Delays
The multi-billion dollar, long-delayed, over-budget international project to develop practical fusion energy, the International Thermonuclear Experimental Reactor (ITER), faces new, potentially years’ long, delays, the project’s new director said late last year. Pietro Barabaschi – who in September became the project’s latest director general after a series of leadership scandals – told Agence France-Presse during a visit to the facility that the previous schedule for achieving a plasma, a necessary first step in proving that magnetic fusion using the “tokamak” technology to confine the enormous heat necessary for controlled fusion of hydrogen atoms is feasible, set for 2025, won’t be met.
Barabaschi said ITER would come up with a new schedule by the end of 2022, but as of this writing, ITER had released nothing about a new date. He said the 2025 “target wasn’t realistic in the first place,” and new problems would add “not weeks, but months, even years” to the schedule. The problems, as The Guardian reported, include “wrong sizes for the joints of blocks to be welded together for the installation’s 19 metres by 11 metres (62ft by 36ft) chamber,” and “corrosion in a thermal shield designed to protect the outside world from the enormous heat created during nuclear fusion.”
ITER, long a pipedream of fusion enthusiasts, got off the ground in 1985, when then Soviet leader Mikhail Gorbachev and US President Ronald Reagan agreed to a wide international venture to demonstrate practical fusion energy. The project was sited in the south of France in 2005. Over the years, the ITER supporting membership has changed. The US has been a partner, left the project, and rejoined over the years. The current membership consists of China, the European Union, India, Japan, South Korea, Russia, and the United States.
–Kennedy Maize
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