Environment

Can space-based solar power save the climate?

Introduction

How shall we tackle climate change? This is still an unresolved question. Here, I will put forward an idea and argue its case.

Burning fuels creates carbon dioxide, which thickens the atmosphere. Consequently, an increasing amount of the Sun’s heat is trapped. So, to tackle climate change, we must stop burning fuels. However, fuel is needed for energy. Therefore, we need to find other sources of energy that do not adversely impact the environment.

Space-based Solar Power

What I think has the most potential in reducing global warming is Space-based Solar Power (SBSP) Figure 1. This technology involves placing solar satellites in space, where their energy production is unaffected by seasons, weather, the day and night cycle, and the filtering effect of the Earth’s atmosphere. The Sun’s energy for us is virtually unlimited (around 5 billion years to go).1 In addition, the satellites are placed nearer to the Sun in space than to the Earth, so they receive more of the Sun’s energy. The satellite then transmits power to the Earth using a laser or microwave beam.2 Transmission by microwaves has already been tested by NASA, and proven possible. In space, solar irradiance is 144% higher than in the Earth,2 which means there is a lot more power available up there! Japan has already been working on this idea for 30 years and invested over 20 billion dollars, hoping to finish their project by 2030.3 The Americans and the Russians are also at the breach, working on a similar idea. The problem with this solution is that we would need to make sure the laser or microwave beam is perfectly orientated toward its receptor on Earth, and would not hit planes or other satellites. Further development is needed before this method is actually feasible.

Figure 1: A SBSP satellite (from http://en.wikipedia.org/wiki/ File:Solardisk.jpg)

On 19 November 2009, two astronauts went into space to begin the installation of solar cells on the International Space Station (ISS). The two astronauts were part of the crew of the shuttle Discovery. More outings like this are scheduled to take place in the next few years, providing the space station with a greater supply of power. Soon, the station would be able to host not only three, but six astronauts permanently.4

The Pacific Gas and Electric (PG&E) wants to buy 200 MW of power in space from the firm Solaren. Solaren has been planning for 7 years to send a satellite to space, which is designed to gather power. A PG&E representative says, “We are convinced this technology is to be taken very seriously. It is astounding to see how much energy is available in space”.5 Another company called Space Energy is also developing this technology.

There is also the option of placing solar cells on our only natural satellite, the Moon. This idea involves building a solar plant on the moon using resources found locally. The stations would be built on the two quarters of the moon that are visible to us, as one of them is always facing the sun. Energy is retransmitted to Earth using microwaves or laser, but this only works when the solar cells are in a direct line with the station on Earth.

Nuclear

Other “less good” options include nuclear energy, which provides a reliable source of power that does not contribute to climate change and is relatively cheaper. However, it could be dangerous if the plant is not properly run. The nuclear waste produced as a side product is very radioactive but we have not found a way to safely dispose of this highly dangerous material yet. Moreover, the waste can be used to make nuclear weapons. If terrorists targeted nuclear power plants, catastrophic consequences would result. In addition, nuclear energy is non-renewable and the “ingredient” for nuclear power, Uranium, would run out sometime soon.

Solar

Obviously, building land-based solar power stations is another option. However, they can be affected by clouds, the filtering of the atmosphere, the weather, and the day and night cycle, which make them a lot less effective than space-based solar cells. Yes, they are cheaper and easier to set up, but in my opinion, it is not really worth it.

One breakthrough of solar power is the discovery of photovoltaic spray paint. This paint, which is made up of tiny particles of photovoltaic cells, can be sprayed on any surface. These sun-absorbing particles then all gather and conduct power. So, if a wire is connected to the “paint”, power can be transported to wherever it is needed. Nonetheless, this only collects 2% of the Sun’s energy directed at them, whilst the usual solar cells harvest 14% of

the Sun’s energy that hits them.6 Like solar cells, these are affected by the day and night cycle, the weather, clouds, etc. So, even if this method could be incredibly useful, allowing one to spray a fence with this paint and set up their own “solar power station”, it is not as effective as SBSP.

Biofuels

Biofuels are preferable to petroleum but they still emit harmful greenhouse gases, though a lot less than petrol. In addition, there are too many petrol-only cars on the road to switch to biofuels and there are not many petrol stations that have a pump suited to biofuels. Biofuels have low energy efficiency as the level of energy they generate is much less than the amount needed to grow the crops. Another problem is that switching 5% of the nation’s petrol needs to biofuels would involve diverting 60% of the existing crops for biofuels’ production.7

Wind

Wind power has certain benefits. Besides the fact that it is a renewable source of energy, the wind turbines can be built on farmland, leaving the land below available for farming, and they can be used as tourist attractions. However, in my opinion, it does not help matters enough.

Wind power is unreliable as wind is not always available. Wind turbines are expensive to build and many people find them ugly. They are usually noisy when operating and can possibly affect television reception. Moreover, they can be harmful to birds.

New wind turbine projects include M.A.R.S. or the Magenn Air Rotor System Figure 2. This is an easily transportable helium- filled balloon placed at an altitude of 300 m. The contraption is a sort of cylinder, which spins under the influence of wind, facilitated by the flaps on the sides.8 There is no need to mention that the cables could be a nuisance, as the high-tension cables would get tangled up easily. Storms or lightning could also be very dangerous for objects on the ground, as the wires connect the balloon to the ground.

Figure 2: A Magenn Air Rotor System (from http://www.magenn.com/)

Another idea is being developed by Makani Power and Kite Gen Figure 3. This involves a kite that collects energy in three steps. Firstly, the kite rises, unraveling a cable that is connected to a generator on the ground. This process generates electricity in the generator. Once the cable is fully unraveled, the kite tilts, so it no longer catches the wind. Lastly, the cable is rewound, bringing the kite back to the ground. This step only uses up 12% of the power generated in step one. Like M.A.R.S., the cable could be dangerous, and storms are to be watched out for. Also, if more than one kite is flying in a certain area, the cables may get mixed up and cause inconvenience.

What is the craziest thing one can do with a wind turbine? Sending the contraption into the jet stream. Although it seems unbelievable, it is being considered by Sky Wind Power. Four rotors, connected to each other, make up the wind turbine. The device rises into the jet stream like a helicopter, where it tilts and starts collecting energy. Electricity is conveyed back to the ground level via a 10 km cable.9 Along the same lines, Joby Energy has developed the same sort of idea, but with 96 inter-connected rotors, 175 m long, and weighing 100 tonnes. It is estimated to be capable of producing up to 30 MW of power.10 These two projects are not developed yet and would definitely encounter some problems like the immense tension the 10 km cable would have to withstand, especially when there are powerful storms in the jet stream and wind speeds can reach 400 km/hour. Controlling the ascent would also be incredibly difficult. Yes, there is also the problem of cables getting tangled up and the danger of lightning.

Hydroelectric

Hydroelectric power is already producing over 20% of the world’s electricity.11 The generators in the dams can produce electricity constantly. No pollution is caused and water can be stored above the dam, in wait for peaks in demand. The disadvantages of these dams are the high construction costs and that they could flood large areas upstream which would affect wildlife and the local population. Moreover, finding a suitable site to build a dam can be difficult. If the dam breaks, floods can be very dangerous to the people living in downstream areas.

Figure 3: A Makani kite (from http://www.metaefficient.com/news/ google-wants-to-make-clean-energy-cheaper-than-coal.html)

Geothermal

Heat from below the ground can be used to generate power. In places like Iceland and New Zealand, geothermal power can be a very important source of energy and it has a number of advantages. It is a renewable energy and is non-polluting. No fuel is needed and power stations do not take up much space. Once the station is built, the cost of generating power is almost free. However, there are certain disadvantages too. Very few sites are suitable for building geothermal power stations and the construction cost is high. For years these sites may run out of steam. Also, dangerous minerals or gases may be given off from below.

Two Children Per Couple Policy

Another idea to reduce global warming is setting a policy which only allows two children per couple.12 This would reduce birth rates and therefore reduce the natural increase. With fewer people, there would be a smaller demand for power. However, this does not really solve global warming, but delays it, stops our growth and would not help us find better energy sources.

Tidal

There are three main ways of harnessing tidal power: offshore turbines, tidal barrages and tidal reefs. The advantages are that once a station is built, power is free and can be produced reliably. Also, tides are easily predictable.

Offshore turbines are underwater “propellers” out at sea that rotate due to tides and subsequently generate power. The problems with these are that the turbine has to be joined to the floor so that it does not move, and therefore, is only suitable in shallow waters. In addition, they are expensive to build and may cause harm to marine life.

Tidal barrages are like hydroelectric dams, except that they are placed across an estuary and harness tidal power instead of gravitational potential energy. The disadvantages are that they are expensive to build, may disrupt the tides, and stop fish and boats passing through. Tidal reefs are like tidal barrages, except that sections can be opened to allow ships and fish to pass through. They affect the tides much less than tidal barrages. However, they are more expensive than tidal barrages. Tides can only be harnessed for 10 hours each day, when the tides are moving in or out.

Pumping Gases Out of the Atmosphere

The last idea is to pump heat-trapping gases like nitrogen out of the atmosphere, but this idea has not been developed yet. There is a lot of nitrogen in the atmosphere, and pumping it out could reduce global warming.

I do not think this can effectively solve the problem of climate change, but would only buy us some time. Nonetheless, we should work on it more to make this method viable.

Conclusion

To conclude, although SBSP is not the perfect solution, I believe it is the best option open to us. Now, we have the technology, and when the demand for power rises, all we have to do is make some more satellites! Global warming will then be a thing of the past. Also, if satellites could be “wired” to cars, instead of transmitting power to a station, it would be possible for cars run to on space-based solar energy!

References

  1. Vieru T. How to Make the Planet Sustain Life for Longer. Softpedia Jun 13, 2009. http://news.softpedia.com/news/ How-To-Make-the-Planet-Sustain-Life-for-Longer-114106.shtml Last cited on 2011.
  2. Available from: http://en.wikipedia.org/wiki/Space-based_ solar_power Last cited on 2011.
  3. Available from: http://www.dorffer-patrick.com/article-centrales-solaires-de-l-espace-a-la-terre–38547867.html Last cited on 2011.
  4. ‘Travauxd’installation des nouveaux panneauxsolairessurl’ISS’. Euronews, March 20, 2009. Available from: http://fr.euronews net/2009/03/20/travaux-d-installation-des-nouveaux-panneaux-solaires-sur-l-iss/ Last cited on 2011.
  5. Tolman B. ‘Des panneauxsolairesdans l”espace pour acheminer de l”énergierenouvelable sur Terre ?’. Paperblog Apr 22 2009. Available from: http://www.paperblog.fr/1838392/des-panneaux-solaires-dans-l-espace-pour-acheminer-de-l-energie-renouvelable-sur-terre/ Last cited on 2011.
  6. Available from: http://en.wikipedia.org/wiki/Photovoltaics Last cited on 2011.
  7. West L. ‘The Pros and Cons of Biofuels: Can biofuels cure America’s addiction to oil?’. Available from: http://environment. about.com/od/fossilfuels/a/biofuels.htm Last cited on 2011.
  8. Available from: http://www.magenn.com/ Last cited on 2011.
  9. Available from: http://www.skywindpower.com/ww/index.htm Last cited on 2011.
  10. Vance E. ‘High Hopes’. Nature Vol 460, Jul 30 2009. http://www.jobyenergy.com/img/news/high_hopes.pdf Last cited on 2011.
  11. Available from: http://home.clara.net/darvill/altenerg/hydro. htm Last cited on 2011.
  12. Rebecca S. ‘Limit families to two children to combat climate change.’ The Telegraph, Jul 24 2008. Available from: http:// www.telegraph.co.uk/news/2454215/Limit-families-to-two-children-to-combat-climate-change.html Last cited on 2011.

About the Author

Jamie Faure is an academic scholar at The King’s School Canterbury. His hobbies are sports, strategic games, gymnastics and Origami. His favorite subjects are Chemistry, Physics, Maths, French and CDT.

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