Space Power Grid Approach To Space Solar Power


Georgia Institute of Technology, School of Aerospace Engineering


Experimental Aerodynamics and Concepts Group




Presentations and Animations




STAIF paper February 2006: American Institute of Physics Conference Proceedings: Evolutionary Model for Space Solar Power


International Astronautical Congress October 2006, Valencia: The Space Power Grid


AIAA Paper 2008-7711 Space 2008, San Diego CA


SPESIF Huntsville February 2009: Millimeter Wave Issues


Atlanta Conference on Science and Innovation Policy, Atlanta, GA, Oct. 2009


US-India Power Exchange Paper, ISDC 2011, Hunstville


IEEE Aerospace Conference 2012: Millimeter Wave Architecture 2011


IEEE Aerospace Conference 2011: Design of a Millimeter Waveguide Satellite for Space Power Grid


IEEE Aerospace Confefence 2012: A Gigawatt-Level Solar Power Satellite Using Intensified Efficient Conversion Architecture


AIAA Joint Propulsion Conference July 2012: Intensified Conversion Architecture


Online Journal of Space Communications July 2012: A Five Nation Demonstration Experiment


ACM Jounal of Emerging Technologies 2012: Retail Beamed Power for a Micro Renewable Energy Architecture: Survey


Journal of Low Power Electronics2012: Architecture Based on Aerostat Power Beaming


IEEE Aerospace Conference, March 2013: Design of a Gigawatt Space Solar Power Satellite Using An Optical Concentrator System


MillimeterWave Space Power Grid Architecture Development 2012


ISDC2013: Five-Nation Wireless Power Transmission Demonstration


Space Technology Applications International Forum, Albuquerque, NM - February 2006


International Astronautical Federation Congress, Valencia, Spain, Oct. 2006


Atlanta Conference on Science and Innovation Policy, Atlanta, GA, Oct. 2009


AIAA Space 2008, San Diego CA. Poster Session


International MultiConference on Engineering and Technological Innovation, Orlando, FL June 2010


Space, Propulsion and Energy Sciences International Forum, Huntsville, ALA Feb. 2009


SDK Animation generated by Nicholas Boechler, 2006


SPG global animation


US-India Power Exchange Presentation, ISDC 2011, Huntsville


IEEE Aerospace Conference Big Sky Presentation - Architecture - March 2012


IEEE Aerospace Conference Big Sky Presentation - Waveguide Satellite - March 2012


IEEE Aerospace Conference: Big Sky Presentation - Girasol Satellite - March 2012


MillimeterWave Space Power Grid Architecture Development 2012


NEW! Space Power Grid and 5-Nation ISS Experiment Proposal Video: 6 minutes; Caution: 78 MB MP4


Komerath, N., Flournoy, D., "Five Nation Wireless Power Transmission Demonstration Experiments: The Space Power Grid Road Map to SSP". 2013 International Space Development Conference, San Diego, CA, May 2013.


Our latest efforts:

1. Papers at the IEEE AIAA Aerospace Conference in Big Sky, Montana.

One paper refines the design of the Girasol 1 GW converter satellite, and re-defines the Mirasol. We brought the Mirasol down to near the orbits of the Girasols, to minimize the need for large capture area on the Girasol, taking into account the divergence of sunlight (a large divergence!!). Thus the Mirasols are now quite low, and hence will be in shadow (night) some of the time. This increases the number of Mirasols needed to keep all the Girasol converters supplied 24 hours a day. The radiators of the active thermal control system on the Girasol have also been re-examined. A combination of graphene sheets and other materials brings down the mass of the active thermal control system considerably.

2. The other peer-reviewed paper at the Big Sky conference refines the overall SPG architecture based on these newer numbers and reduced uncertainty, and updates the list of assumptions.The specific power of the entire system is still well up there around 1.6 kW/kg. Thus the Net Present Value calculations presented at the 2012 meeting become even more conservative, with reduced uncertainty in the ability to achieve the required parameter values.

3. Our team has prepared a video summary of the project. We are working with a team guided by Professor Flournoy at the Ohio University.

4. Over the past year two peer-reviewed papers appeared in journals of the electonics world, trying to build interest in developing efficient, high power millimeter wave converters by pointing out the state of those technologies and the opportunities when power beaming becomes a routine affair. See the papers in the Journal of Low Power Electronics and the ACM Journal of Emerging Technologies. These were expanded from papers presented at peer-reviewed IEEE conferences.

5. Our initial paper on the 5-nation collaborative project to jump-start the Space Power Grid, appeared in the Journal of Space Communications and can be seen here:

Brendan Dessanti, Narayanan Komerath, Don Flournoy, "Visualizing Wireless Transfer of Power: Proposal for a Five-Nation Demonstration by 2020". Journal of Space Communications, Fall 2012.

6. Our latest work presented at the ISDC 2013 conference: please see the last item under 'papers" and the last two under "presentations". We are working towards defining an ISS-based experiment to resolve the mysteries/superstitions around millimeter wave (around 220 GHz) beaming, and the joys of working together across nations and the world. This starts us on the roadmap towards building first a Space Power Grid to boost the business cases of renewable power plants around the world, establish retail and wholesale power markets with speed-of-light transactions for the power exchange (with 2000 km orbits, that's a loong 13 MILLIseconds at the very least!). This will lead up to a viable, global Space Solar Power architecture that may use high-intensity sunlight and Brayton Cycle (solar dynamic) conversion to millimeter wave power. Or maybe something a lot more exotic, like direct conversion to millimeter waves from sunlight.

We are now trying to refine the design of those experiments and start the long process of getting the right people to talk to each other and think how to make it happen in detail (hint: Anyone at NASA, JAXA, ISRO, any Space Agency who will help us negotiate those mazes of standards and regulations and protocols, please???) Contact komerath at gatech dot edu Thanks!

OK, So how realistic is any of this?

Ours is the first architecture that goes all the way from inception to full-scale global Space Solar Power and defined realistic parameters for economically viable development. In other words, we do not stop at "the first demonstration after which private industry will rush to pick up the project" nor is the objective limited to "flags footprints and ticker tape parades". We aim to replace terrestrial fossil-based power generation with Space Solar Power. We do not project that Space Solar Power will be "too cheap to meter" or anything of the sort. In fact it may not become cheaper than today's fossil or nuclear-based power for a long time to come, but it will get there eventually.

We project that the Specific Power can be taken to over 1.6 kW per kg in orbit, compared to the levels of below 0.2 kW per kg projected for older GEO-based, low-GHz microwave beaming, Photovoltaic conversion architectures. The outstanding obstacles are given below:

1) Millimeter Wave conversion to and from 220GHz remains to be proven at high efficiency and high specific power. This is an area of rapid R&D progress so there is every reason to be optimistic. Demonstration experiments are needed in this area.

2) Efficient transmission through the dense, moist lower atmosphere can be done using waveguides tethering aerostats, which contain the transmitter/ receiver antennae. There is no breakthrough required here, just some imagination in applying aerostat and waveguide technology to this problem.

3) Eventually, the scale-up to 4 Terawatts requires 4000 1-GW satellite pairs, at a specific power of about 1.6 kW per kg - you can do the numbers to calculate the mass that must be put up. To do this within a couple of decades, runway-launched, air-breathing routine space access is required with year-round, regular launch and landing operations at the rate of about 1 per day from numerous locations around the world. This is in fact the harder problem, but any move to a serious Space economy will require this.

Some people tell us that our efforts are "academic" because we base them on technologies that are rapidly developing, rather than calling for a rush to a short-term public-funded (hugely expensive!) "demonstration". But our counter to that is that if the architecture does not make sense from simple laws of physics and simple commonsense, and does not have a viable map to where SSP can really impact terrestrial power supply, it is not going to make sense to national lawmakers who have excellent staffers, and certainly not to the taxpaying public.

We base our hopesand our architecture calculations on hard numbers and careful examination of technology, not on wild hopes of a sudden collapse in the cost of space launch, or sudden infusions of hundreds of trillions of tax dollars into architectures that are clearly not realistic as seen from simple technical considerations such as the antenna sizing equation.

There is no great hurry to launch the first full-scale demonstrator: it is still at least 15 years away. We can focus our efforts on getting the technology right and the business plan viable, before asking the taxpayer to fund the Gigawatt-level space stations.