Since there are no currently active contests, we have switched Climate CoLab to read-only mode.
Learn more at
Skip navigation

Please find below the judging results for your proposal.

Finalist Evaluation

Judges'' comments

SUBJECT: Climate CoLab Judging Results

Proposal: Space Solar Power for Global Energy Supply based on Low-Cost Access to Space

Thank you for participating in the 2015 Climate CoLab Energy Supply contest, and for the time you spent in creating and revising your entry.

The Judges have strongly considered your proposal in this second round of evaluation, and have chosen to not advance it as a Finalist for this contest.

We, the Judges and contest Fellows, are truly grateful for your contribution to the Climate CoLab and for your commitment to address climate change.

We encourage you to keep developing your work. Transfer it to the Proposal Workspace to re-open it, make edits, add collaborators, and even submit it into a future contest. You can do so by logging into your account, opening your proposal, selecting the Admin tab, and clicking “Move proposal”.

We hope you will stay involved in the Climate CoLab community. Please support and comment on proposals that have been named Finalists and vote for which proposal you would like to be nominated as the contest’s Popular Choice Winner.

If you have questions, please contact the Climate CoLab staff at

Keep up the great work. And thank you again for being a part of this mission to harness the world’s collective efforts to develop and share innovative climate change solutions.

2015 Climate CoLab Judges

Additional comments from the Judges:

Comment 1:

I would like to confirm previous comments that this highly innovative proposal has arrived a few years before it would be economically feasible.

Interesting, to be monitored, but as yet far away from economic feasibility for the cost of launch and the current challenges, technical and economical, of transmitting the energy.

Comment 2:

Space Solar Power is an interesting technology that I have been aware of for well over 20 years. In the past, I have discussed the topic with one of its early proponents, Marty Hoffert of NYU. I have always found the concept very interesting and SSP to be a worthy goal.

The proposal here focuses on one of the key barriers to an economical SSP system – cost of getting payloads into space. As such, it is a necessary step in establishing SSP. However, I wish the proposal contained more information on the entire SSP system. For example, it says it needs to launch the panels into Low-Earth-Orbit. It is my understanding that these panels would need to be put into Geosynchronous Earth Orbit. Is this the same as low Earth Orbit? Also, can we really get solar 24/7 (“uninterrupted power supply”) as claimed in the proposal, or would the panels be shaded by the Earth at night?

Besides getting the panels into space, getting the power back to Earth is another major challenge. The proposal did not discuss this aspect. It is my understanding, even if launch costs were in an acceptable range, this second key challenge still needs to be addressed.

Finally, there are many drivers for lower space launch costs. Several private firms are already trying to fill this niche. It would be nice to know how the program proposed here fits in with on-going activity. Does it complement it or does it duplicate it?

Comment 3:

Very innovative idea, well presented. Still have questions on feasibility and the energy recovery to substantiate the initiative.

Comment 4:

I think the proposal team underestimates the technical feasibility of the their proposed approach, as evidenced by their comment that the main barrier is the cost of launching the panels into space. There are many technical issues that would need to be addressed in a concerted R&D effort before this proposal could be considered feasible - the main one being the mechanism for wirelessly transmitting power from space to ground-based receivers. I think the team did a nice job on their proposal, but would like to see more focus on the technical approach before even worrying about the economics, which do appear far too high at this time.

Semi-Finalist Evaluation

Judges'' ratings


Judges'' comments

This proposal is interesting in its approach and bold in creativity to address the renewable energy challenge. While the premise is that it creates a viable solution for global clean energy based on design of reusable space launch system, the approach may have limited feasibility based on the cost - reward tradeoffs and the innovation required to practically execute the plan. However, the proposal was well written.

Perhaps this highly innovative proposal has arrived a few years before it would be economically feasible. The idea of having Solar Power in the space is an interesting one and it has to be monitored, but the cost are currently prohibitive, as mentioned by the author in terms of the huge upfront costs. While in the case of OffShore Wind energy we are talking of a small multiplier, here the value differ by a dimension, while the energy production would only be at best 3-4 times higher than in the most sunny area. In addition, many challenges, like transporting the energy to the final use point are quite difficult to tackle.

The scenario may change in a few years time (no less than ten in my opinion) but at the same time maybe other innovation may simply lower the threshold of competitiveness to a much lower level.

If the author can find ways to address these comments, it will aid in evaluating the merits of this proposal against the other semi-finalists.

Share conversation: Share via:

Supraja Sudharsan

Jul 14, 2015


1 |
Share via:
The judge's comments regarding costs of TSTO space launch system and its viability have been reviewed and the proposal accordingly revised. Compared to existing space launch technologies, reusable TSTO launch system reduces payload launch costs by 10 times compared to similar earth to low-earth-orbit technologies and >10 times when considering earth to geosynchronous orbit technologies. With expendable rockets (which is the existing technology) this cost can never be improved due to the high recurring costs associated with each launch. Therefore fully reusable launch vehicles with more frequent launches is the right alternative. Literature also indicates that a $500/lb(based on early 90s $) payload launch cost would make space solar power competitive in a number of markets, which can be achieved by the reusable TSTO system(explained in the proposal). While there are a number of variables including the amount of energy that needs to be harvested, efficiency of solar panels, number of launch sites utilized, launch rate, availability of funding and delegation of costs among partner countries,it remains that the TSTO system may be realized with existing technologies which would significantly reduce the RDT&E and other upfront costs.