Solar power is clean, abundant, and becoming cheaper and more efficient all the time. Unfortunately, however, the sun isn't always there when you need it—like when it's cloudy, or it's raining, or it's nighttime. In this Science Update, you'll hear about an ambitious plan to get around that problem.
Solar power from the moon. I'm Bob Hirshon and this is Science Update.
As the world's population continues to grow, the need for low-cost, sustainable sources of energy grows along with it.
One scientist says the answer to this dilemma might be found in space. David Criswell is Director of the Institute for Space Systems Operations at the University of Houston. He says building solar power stations on the moon could be a way to fulfill the energy needs of the whole world.
And as I look over all of the many options for doing this, I do not see any conventional options that can do it. That's the basic reason for considering the moon. It intercepts about a hundred times more solar energy than you need for a prosperous earth.
Criswell says the collected solar energy could be converted into low-intensity microwaves that get beamed back to earth. Then, receivers placed all over the world could convert the microwaves to usable electricity.
And the system actually uses on earth a very small amount of area compared to conventionally ways of generating that same amount of power.
Criswell says the basic technology to do this has been around since the 1970's. So, if people were to accept the idea, the system would be straightforward to build. For the American Association for the Advancement of Science, I'm Bob Hirshon.
Making Sense of the Research
This idea may sound pretty far-fetched, and there's no question that it would take some serious money and resources to implement it. But Criswell argues that in the long run, it will be cheaper than the power we use now. And it will definitely take some creative thinking to meet the world's energy demand of 20 terawatts (the amount of energy used by 200 billion bright light bulbs) by 2050. Neither our current supply of fossil fuels nor any current earth-based renewable energy technology is up to the task.
Why collect solar power on the moon? The answer is that all the factors that make life impossible on the moon (no atmosphere, wind, rain, fog, clouds, or weather of any kind) make it an ideal place to collect solar energy. The moon is exposed to sunlight constantly, except briefly during a rare lunar eclipse. If that energy could be harnessed, as Criswell describes, and sent back to earth in microwave form, it could supply energy far more efficiently than solar panels in even the driest earth desert.
Of course, this idea involves building solar panels on the moon, which means we would have people on the moon all the time (about six months to a year per person, Criswell suggests), to build and maintain the repair equipment and arrays. It also means shipping manufacturing equipment up to the moon. Criswell argues that most of the necessary materials can actually be extracted from the lunar landscape, with help from some start-up equipment and supplementary supplies. However, it would still involve an initial outlay of resources by the government and a decision on the role, if any, that NASA would play in the project.
There are other obstacles to overcome. For example, the project would involve building about 10,000 large receivers all over the world. Many comparable global energy proposals would actually require more equipment, but it's still a lot of work. Plus, many poorer countries and communities would have to build rectennas and power grids in order to benefit from this technology. This can be seen either as an obstacle or as an opportunity for workers in these countries to upgrade their skills.
On a more minor note, many communications systems, from cell phones to emergency response systems, broadcast on frequencies that would overlap with this system's microwave energy, and would have to be re-allocated to new channels. (Criswell says the microwaves won't cook humans or animals—they're well below hazardous levels.)
Despite these hurdles, the project offers the hope of powering the world cleanly through the twenty-first century. And although the World Energy Council has challenged all decision-makers to provide affordable and clean power to the world, few leaders or organizations have risen to the occasion. The Lunar Solar Power project would not be a simple undertaking, but even many skeptics admit that the technological knowledge is available to pull it off. Even if this project never gets off the drawing board, a real solution to the world's escalating energy needs will need to be just as ambitious.
Now try and answer these questions:
- Why put solar panels on the moon?
- Describe briefly how Criswell's system works.
- Why can't the world's energy needs be met by existing technologies? What are some of the problems with the way we use energy now?
- What are some obstacles to implementing ambitious, revolutionary energy technologies? Consider scientific, social, cultural, political, and financial barriers.
- How can the global community respond better to serious energy and environmental problems? What opportunities do you see for change?
A detailed article about Criswell's plan appeared in the April/May 2002 issue of The Industrial Physicist.
The Great Energy Debate is a lesson plan by National Geographic's Xpeditions that encourages students to analyze a number of issues concerning energy production in the United States.
The National Renewable Energy Laboratory is the U.S. Government's leading lab for researching and developing alternative energy sources.