Once again we want to report of some interesting pieces of science news. Continue reading Science round up 2
Though space and air flight are as distinct from each other, as air flight and ship transport are from each other, many people do group them together. Therefore we’ll discuss in this post the future of aviation on Earth.
Of all types of aircraft air-planes are the most well-known and together with helicopters the most popular ones. Most air-planes are powered by burning kerosene. Unfortunately petroleum, of which kerosene is made, is going to be depleted in a few decades. And given that simultaneously the amount of air traffic is increasing, flying will become more and more expensive.
For other modes of transportation the depletion of oil is less a problem, ships can be powered by wind, by using kites. Land based vehicles can be powered by electricity and can be recharged along the route. An electric plane is possible but a commercial air plane would need very heavy batteries, which would mean that fewer passengers and cargo can be transported at a flight.
An easy solution would be to replace petroleum-based kerosene by bio-fuels or synthetic fuels. Bio-fuels have they big disadvantage that the production of it will compete with food production, and hence will increase the price of food and lower people’s access to food.
Another option would be to reconsider airships. Since the disaster with the Hindenburg airships have fallen out general use, but modern version use inert helium rather than flammable hydrogen as buoyant. Only helium is on Earth are rare resource, and much of our helium reserves is wasted in, for instance, helium balloons at parties.
Fortunately there might be good news. With the prospect of oil depletion, more people are turning to fusion power as a method of energy production. And the primary waste product of fusion power happens to be helium. With more fusion power plants, also more helium will be produced. And hence more airships can be produced.
But wouldn’t be nice if we could use solar energy to power air planes? Well, NASA just did that, their Pathfinder planes are basically flying wings covered by solar arrays. But these are small, unmanned planes designed for research purposes rather than for transportation. For commercial air planes huge solar panels would be required.
The Canadian company Solarship has developed an aircraft which combines airship technology with solar energy. Their hybrid airship, while being heavier than air, gets a substantial part of its lift from buoyancy and therefore reducing its fuel consumption.
The people behind Solarship claim that the main benefit of their product is that increase the accessibility of many parts of the world, because no infrastructure is required for the operation of their airship. Though they intend to use their airship for cargo, it seems also to be usable for transporting people.
A totally different approach more suitable for mass transport along predetermined routes, is the vacuum tube train also known as “vactrain“. The idea is to drive maglev trains through long vacuum tubes, because it takes less energy to remove air from a tube than for a maglev to overcome air resistance. This approach would allow speeds up to 8,000 km/h. Vacuum tube trains might be powered by fusion power plants.
Some time ago we wrote about the feasibility of Space based Solar power (SBSP) for terrestrial use, in that post we argued that SBSP is an unlikely candidate for meeting terrestrial energy needs both because of expected negative reactions from the public and the presence of suitable alternatives. One of those alternatives we mentioned were so-called solar islands.
A few years ago we wrote a sceptical article about seasteading. One of our arguments against seasteading was about their economic suitability. We argued that seasteads had poor economic prospects, with the consequence of a lack of interest from potential investors. However, solar islands might change this.
As we have argued in an earlier post, the ocean might be a good place for producing synthetic fuels. According to this site seawater contains 15.1% CO2 against 0.03% in air, thus CO2 can easily be extracted from seawater. Energy provided either by solar islands or ocean thermal conversion, can be used to produce hydrogen gas. From CO2 we can produce CO, and from CO and hydrogen we can make synthetic fuels. These fuels can be exported to other places.
The off-shore production of synthetic fuels might be a raison d’être of seasteads. However, it’s doubtful whether the political ideals associated with seasteading can be realised if seasteaders would specialize them in synthetic fuel production. It will depend on who is providing the funding for these projects, if corporations or governments are the primary investors in seasteads then the pursuit of liberty might be jeopardized.
Soon we will discuss the colonization of Antarctica.
On march 11, 2011, Japan was hit by an earth quake and a tsunami which resulted in the Fukushima Daiichi nuclear disaster. Consequently the public opinion in Japan turned 180 degrees against nuclear power. Even their government began to consider a nuclear free future. But Japan is so heavily dependent on nuclear power, that last summer two nuclear power plants had to be restarted in the face of massive public opposition. The question of this post is what are the alternatives for Japan? I will discuss solar power, wind power and Ocean Thermal Energy Conversion (OTEC). [However, both wind power and OTEC are in fact indirect forms of solar energy since both winds and the oceans are powered by the Sun.]
Wind and Solar power
These are the “classical” kinds of alternative energy sources. Both options require a lot of space, and the intensity of solar radiation depends on altitude (lowest at the poles, highest at the equator). Japan is roughly located between 30 and 45 degrees north, which is a good point to start with. Currently Japan, together with Germany and China, is one the biggest producers of photo-voltaic cells. Yes, solar power is clearly a major alternative for Japan, but there are some other issues. First Japan is a mountainous country and has high population density, so relatively few land area is available for massive solar farms. To some extent this can be solved by placing solar arrays on roof tops, however this will only be a partial, but very important, solution for Japan’s energy problem.
Another important potential energy source is wind power. There are two main problems with wind power. First it is notorious because it is very irregular, secondly in order to be efficient wind turbines have to place at a minimum distance from each other. This means that in a given area only a fixed number of turbines can be placed. As we know in Japan land is a scarce commodity, although this can be solved by placing wind turbines at sea. In theory Japan has the potential to meet its entire energy demand through wind power alone, but then they have to deal with the irregular supply of energy. Some kind of grid energy storage is needed. Note that solar power has the disadvantage that it is not available during the night.
What is Ocean Thermal Energy Conversion?
Surface water of the oceans has a higher temperature than water a thousand meters below the surface, this difference in temperature represents a difference in energy (as heat), which can be used to power a heat engine. The basic idea is to heat a working fluid with the heat from surface water, subsequently this working fluid is vaporized. Then we can use this to drive a turbine, which produces electricity. Thereafter we let the working fluid condense by cooling it with cold water, which we have pumped up from a thousand meters below the surface of the ocean. In a closed cycle we let the fluid flow back to the evaporator, while in an open cycle we “dump” it somehow into the environment. A more detailed explanation how OTEC works can be found here.
Other proposed applications of OTEC are for instance mariculture, desalination and mineral extraction. Regardless whether these applications are practical, we should ask our selves where the best location for OTEC power plants are. This map shows that Japan is relatively close to one of the best (i.e. the locations with the highest difference between surface water and at a debt of a thousand meters), and this spot also covers a large area. Therefore this area contains an enormous amount of power.
Traditional power lines are impracticable, so energy has to stored somehow. One way to do this, is by producing hydrogen through electrolysis. But hydrogen has some severe drawbacks. First the very low density of hydrogen gas requires either storage under high pressure or liquefaction to very low temperatures, which might cost more energy than can be delivered. The storage problem of hydrogen is one of the greatest obstacles for the transition to a hydrogen economy.
An alternative for hydrogen would be the production of synthetic fuels through the Fischer-Tropsch process from hydrogen and carbon monoxide gas. CO gas can be obtained by electrolysis of CO2 from the atmosphere or sea water. There is also current research of creating fuels directly from water and CO2. Both methods will produce hydrocarbons, like methane gas [main component of natural gas], or alcohols like methanol. These synthetic fuels can easily be transported and because the synthesized fuels are chemically similar to “mineral” gasoline, they do not suffer from the transition paradox. This is the problem that no one will buy hydrogen cars if there are no hydrogen gas station, but no one will build hydrogen gas station if no one drives hydrogen cars.
Once the synthetic fuel is produced, it can be transported by tankers to where it is needed. This also solves another problem: the energy production can now be fine tuned to the demand. During peak hours more fuel is burned, and when energy demand is low we can simply turn off some generators.
Ocean Thermal Energy Conversion is an option, which deserves consideration if Japan really wants to phase out nuclear power. Unlike wind power OTEC is a reliable and predictable source of power. In combination with synthetic fuels it also offers the possibility to make Japan self-sufficient in respect of its energy supply. Of course Ocean Thermal Energy Conversion in combination with the production of synthetic fuels is not only a solution for Japan, but it is also interesting for emerging economies like China and India.
The next link is a critique of the hydrogen economy, and prefers an “electron” economy.