User:Nna4

William Maness on why alternative energy and power grids aren’t good playmates and his plans for beaming solar power from space.

In principle, sunlight is a near-ideal energy source since it’s essentially free, ubiquitous, and surprisingly powerful. In practice, however, even vast arrays of the most sophisticated photovoltaic cells, which convert sunlight to electricity, seem incapable of meeting all our energy needs. This is largely because they’re confined to the ground, where the Earth’s rotation and atmosphere eliminate and attenuate sunlight.

During the heyday of the Space Age in the late 60s, researchers conceived of solutions to this problem that relied on placing solar arrays, or “powersats,” in orbit. The powersats would beam the collected power down to Earth as microwaves, which can easily penetrate the atmosphere with scarcely any energy lost. Space-based solar power (SBSP) seemed feasible, except for one thing: Launching the necessary infrastructure into high orbit would be prohibitively expensive, especially when cheaper fossil fuels were readily available.

Today, as with many other alternative energy proposals, interest in SBSP has been rejuvenated by the rising direct and indirect costs of fossil fuels, and several SBSP companies have formed. Earlier this year, Pacific Gas & Electric, a major California utility company, signed an agreement to purchase hundreds of megawatts of power from Solaren, an SBSP company, beginning in 2016. Last month, another SBSP company, PowerSat Corporation, filed two patents for technologies that the company claims can shave billions of dollars off the launch costs for an SBSP system. Seed’s Lee Billings spoke with PowerSat’s CEO, William Maness, about the company’s technology and the revival of SBSP.

Seed:

How is space-based solar power different than solar power on the ground?

William Maness: Terrestrial solar power has some irksome limitations: It doesn’t work at night, it works poorly when it’s cloudy, and it’s really only cost-effective in a few places in the world. It works better in places like Phoenix than in places like Seattle. So the idea is to harvest the solar energy in high orbit where the sun shines 24/7. That constant sunlight is a big deal when you’re trying to supply power to utility companies for their customers.

Seed: What makes it superior to other forms of alternative energy?

WM: The way power is actually generated and handled in the world involves something called “dispatchable” power. Alternative energy is generally intermittent, and thus not dispatchable. Dispatchable means a utility can make a contract with someone that says, “On December 21st of 2011, I want you to carry 1,000 megawatts of my load for six hours.” So they make a financial contract, and these things are traded back and forth. This economic system behind [power generation] is the cornerstone of what keeps our lights on. 

SBSP gives you a continuous source of electricity that you can lay down independent of geography. You can put a receiver in New Jersey and a receiver outside of Seattle, and you can switch the power between those from our orbital system with essentially a flip of a switch.

Seed: Ideas for SBSP have been around since the late 60s. So why is it only commercially viable now?

WM: The costs of deploying powersats are falling, and the costs of fossil fuels are rising. When powersats were first envisioned, solar cells were these huge monolithic crystalline beasts that weren’t very efficient in weight per watt. Now, we’re printing thin solar cells on sub-micron aluminum and titanium. Solar cells have gotten much more efficient per unit at converting sunlight to electricity, and the weight’s gone way down. Weight—or, really, mass—is everything in space.

Meanwhile, the base cost and the burdened cost of fossil fuel is rising fast. The base cost is just how much it costs to extract and distribute fossil fuels, pretending that carbon emissions don’t mean anything and that there’s no penalty whatsoever for warming the entire world. Burden cost is when the political system says, “Wait a minute. You can’t do that!” and spanks you in terms of taxations and carbon-curbing measures.

Seed: Are you worried about fluctuations or manipulations in the price of fossil fuels causing problems for PowerSat?

WM: There will surely be further price manipulations. You see OPEC doing it all the time. But the market can only support this in the short term. The fossil fuel price cycle is fairly regular, but the cycle’s tightening every time it occurs, getting shorter and shorter in duration. We could easily weather another artificial lowering because we know what’s coming on the other side of it. The market’s fundamental feedstock is inflexible; there’s only so much fossil fuel. Powersats, once established, will always win over the long term because there’s essentially no cost for fuel—you get it for free from the Sun.

Seed: What about the high cost of launching payloads into orbit? That’s a lot of heavy lifting to do before you turn a profit.

WM: It takes big, expensive rockets to get into low-Earth orbit (LEO), where the space shuttle goes. What most people don’t know is that to get from hundreds of miles up in LEO to 22,000 miles up in geosynchronous orbit (GEO), where a powersat wants to be, only requires about a third as much energy as it took to get to LEO in the first place. That’s doesn’t seem like a big deal until you realize that the propellant for that final leg of the trip has to be launched from Earth. In 2000 I came up with a proprietary idea to make this problem go away; it’s called the “solar-powered orbital transfer,” or SPOT. SPOT uses the solar collectors on the spacecraft to power ion thrusters, which gradually lift the system to GEO. SPOT can reduce the launch mass of an SBSP system by 67 percent. On a 2,500-megawatt system, that’s roughly $1 billion worth of cost savings. So even if our competitors get contracts with utility companies, they still have to come play with us.

The other key proprietary idea we have is called BrightStar. Classical SBSP proposals call for a single huge transmitter to hit a small spot on the Earth, the receiving station. BrightStars are smaller satellites, each one about 1/300th the size of a classical transmitter, guided by a pilot signal from the ground and working together in a phased array to form a beam. So we don’t have to ever build and launch this huge, honking, monolithic antenna—we just send up a cloud of solar satellites.

Seed: How many total satellites do you need for the first big stage of supplying power to utilities?

WM: Our baseline design is a 2,500-megawatt receiving station, which is only about 5 percent of our total costs. That would require about 300 BrightStars weighing 10 tons apiece, or 600 BrightStars at five tons each. We’re talking to several different launch service providers, including SpaceX and Lockheed Martin, but hundreds of launches is daunting. It’s a chicken and egg problem: You don’t have a cheap space access because you don’t really have recurring payloads, and you don’t have recurring payloads because you don’t have cheap space access. PowerSat can change that. We bring to the table credit-worthy customers with billions to spend, the utility companies, and say, “Please build us a way to launch these things efficiently.” If they build it, we will come.

Seed: So what’s the timeline of your plan?

WM: In the next 18 months, we’re aiming to do a 10-kilowatt ground-based wireless power demonstration, followed by a 1-megawatt ground-based demonstration a year after that.

The 10-kilowatt demonstration will only beam power over 300 yards or so and wouldn’t have much commercial purpose. We’ll be scaling up the engineering lessons we learn from that system and porting them to the 1-megawatt demonstration. The next step after the 1-megawatt ground station is launching a single BrightStar. One of these alone can’t form a beam tight enough to do anything useful on the ground, but it can transmit power sufficiently to be measured, and we can demonstrate our solar-powered orbital transfer.

Seed: What are the other big hurdles facing SBSP and PowerSat?

WM: We’ll need to find a suitable site for building the receiver station and get approval for it. From above, the receiver looks like an ellipse roughly a mile wide, between 1.5 to 2 miles long. But it’s not as environmentally disruptive as a terrestrial array of solar cells. Picture something that looks a bit like chicken-wire mesh strung up on utility poles between 30 and 50 feet off the ground. Anything underneath it doesn’t get substantial microwave impingement since the receivers above are catching the energy. If you put one of our receivers up over some pastureland, it can remain pasture. Rain and sunshine go right through it, so it doesn’t have major environmental effects. 

The only real disruptive effect is on cell phones or wireless internet communication. Directly beneath the beam, that stuff won’t work, so you don’t want to do this in the middle of an urban area. You’d also want to have a no-fly zone around the receiver, which is already done for other power production facilities.

The bigger problem is, there are only a couple of good windows for microwave transmission in the atmosphere. One’s at 2.45 gigahertz, which is exactly the frequency that cell phones and wireless internet use. Another is at 5.8 gigahertz, which also has a lot of communications sitting on it. Ultimately SBSP has to have a dedicated chunk of the spectrum, which would require dealing with the international body that does frequency allocation on a planetary scale. They’d need to say that power transmission would occur on exactly 2.45 gigahertz or 5.8 gigahertz, with a slot of 5 kilohertz to either side of it. We don’t want to drift from that. If we do, we lose a substantial amount of electricity to heat, which generates a lot of effects we really don’t want to deal with. So this would mean that new cell phones and wireless devices would need a filter built into them that would work around that frequency. The filter wouldn’t be expensive. The problem of frequency allocation is probably the biggest regulatory issue facing us now.

Seed: What’s the toughest part of talking with people about SBSP?

WM: I’ve spent the last eight years of my life fighting the “giggle factor.” When politicians or investors hear about SBSP, they get a little smile on their face, probably thinking about when they saw it in SimCity 2000. It drives me nuts because this isn’t science fiction. Powersats are no more science fiction than satellite television. What this is about is enabling the continued, controlled growth of our society and our standard of living in a way that doesn’t destroy the planet. I don’t want anyone to have to think about where their electricity comes from. But in order to get there, people like me have to think a lot about what happens behind the scenes when the lights get switched on.