Technology

Space race to power the final frontier

 By Amanda Saint

There is currently a big buzz around space-based solar power (SBSP) in R&D departments and space agencies around the world. The reality of affordable, safe SBSP seems to be getting closer by the day, and there are a number of different systems in development that have the potential to deliver SBSP within a couple of decades…

One of the biggest issues that’s had to be resolved in harnessing SBSP, other than the prohibitive costs, is getting it safely down to earth. The different solar systems that are now in development seem to be addressing this problem.

In the UK, a system designed by scientist Ian Cash is currently with the British Interplanetary Society for review. Called the HESPeruS (Highly Elliptical Solar Power Satellite), it’s still at the concept stage, but Cash says it has cost parity with new nuclear and also delivers advanced power collection options compared to many of the systems being designed for SBSP. This is through a rigid, modular and essentially flat design that rotates just once per year so its panels are permanently facing the Sun. The way the power reaches earth is also more advanced, with the collecting antenna being where Cash believes the HESPeruS has the biggest advantage over other designs. He said: “It’s perhaps unique in having a transmitter diameter (aperture) greater than its solar collecting surface.”

This means it can beam more power down to earth, and do it more easily than other systems. The launch of the HESPerus is dependent on the success of the Skylon reusable space plane,which is being built by British company, Reaction Engines. All the signs are good that this will soon be a reality as the European Space Agency gave it the seal of approval in late 2014. The first space plane is expected to go into test flights in 2019. If all goes according to plan with both of these projects, we could expect to see the HESPeruS delivering SBSP to the UK within 15-20 years.

A project in the MENA regions, which is a joint development between India and UEA, has put together a proposal for a phased development plan that would also have SBSP delivering power within 20 years, with the added bonus of it creating clean drinking water at the same time. The first phase involves land-based solar farms that double as desalination plants.

The SBSP system proposed for this project is based on the SPS-ALPHA design, which resembles a bee hive. It has three parts: a large array of solar panels pointing towards the earth; a large sunlight interceptor reflector system that sits between the array of solar panels and earth; and a truss that connects the two together. The energy created will be beamed to earth using microwaves.

Space based solar power...
...and a demonstration Experiment

The Japan Aerospace Exploration Agency (JAEA) has already advanced to the technology demonstration stage and the SBSP team is preparing for the world’s first demonstration of 1kW wireless power transmission technology. The plan is that their SBSP will be up and running in the early 2030s.

The lead researcher on the project, Yasuyuki Fukumuro, believes that his design has the most advanced solution for getting the power to earth. He said: “When transmitting power by microwaves, a significant technological challenge is how to control the direction, and transmit it with pinpoint accuracy from a geostationary orbit to a receiving site on the ground. Transmitting microwaves from an altitude of 36,000 km (22,369 mi) to a flat surface 3 km (1.9 km) in diameter is like threading a needle. In my opinion, Japan currently has the most advanced technology to do this.”

This is because the JAEA design uses laser beams rather than microwaves and also uses the solar power its harnessing in space to power the lasers themselves, meaning the SBSP station needs less equipment and so is lighter weight.

In the US, NASA is carrying out feasibility studies of launching SBSP satellites, also based on the SPS-ALPHA design, using reusable Space X Rockets, which received certification from the Space and Missile System Center in May 2015. Unfortunately, shortly after that, an unmanned test launch of the rocket exploded on take-off. So whether NASA thinks it’s feasible remains to be seen when its time for contract renewals.

But whether that project goes ahead or not, the reality of SBSP is without a doubt getting much closer. Now that the issue of energy transfer has been addressed, there’s the cost to think about.

about the author
Amanda Saint
Journalist and content writer, specialised in engineering and technology with a focus on environmental sustainability, urbanisation and biotechnology.