1:1:E:2. Electricity

Aurora's electricity can be generated by a number of sources. Possible technologies include:

1. Internal combustion engine (ICE) generators

2. Photovoltaics (solar panels)

3. Fuel cells

4. Thermoelectrics

5. Tritium-photovoltaic / Betavoltaic generators - for very low-power electronics, like hardware monitors, probes, and, possibly, periodic radio beacons

1. Generation

Most of Aurora's electricity is anticipated to come from solar panels and ICE generators early in the program, and from hydrogen infrastructure as the station evolves.

Traditional ICE generators generally rely on hydrocarbon fossil fuels. These fuels must be kept warm during the winter to prevent them from freezing. At any given time, two generator buildings / power plants will be heated above the freezing temperature of their fuel, even if both aren't running. This allows a backup unit to be started quickly in the event of a failure, and generator cycling to reduce the wear on a single unit. The ICE unit of choice is a diesel generator. Diesel engines have long lifespans, and can consume a variety of fuels. Petroleum-based or renewable fuels can be used with no modification to the machine; this builds flexibility into the Aurora energy plan, and allows sources to be changed as the program evolves.

Hydrogen power infrastructure behaves generally the same as an ICE system, except that units won't have to be kept warm to activate at a moment's notice. Compressed hydrogen gas won't freeze in Antarctica, so a fuel cell, or even an ICE generator, can be started immediately. Hydrogen power is discussed in more detail in 1:1:E:3.

During the long days of the Antarctic summer, Aurora is projected to get most of its electricity from arrays of photovoltaic (solar) panels. These will provide electricity, electric heat, and, eventually, power for a hydrogen generation and storage plant. Aurora's electricity requirements, and therefore the size of the arrays, will depend on its crew compliment, scientific goals, and the station's overall size. Examples of array requirements based on differing parameters are given below. Since weather at the planned Aurora site is particularly turbulent, and blizzards are common, crew will have to be diligent about keeping panels clear; this will likely be one of the most time-intensive jobs at the station.

In essence, solar arrays must produce entire year's worth of station's required energy during antarctic summer, multiplied by EHE (electricity to hydrogen to electricity) efficiency multiplier. This will provide enough stored energy to run the station all year, with a built-in safety margin: the months during which the panels are active will have a higher thermodynamic efficiency than EHE, so less overall energy will be needed.

[GRAPHIC showing station configuration, and resulting solar array size / specs, based on hab heating requirement, hydrogen generation needs, life support needs, etc. TABLE relating different station configurations (number of modules, etc) to array surface area.]

Fuel cells are an attractive option for a number of reasons. Their simplicity, reliability, and high efficiency means low maintenance and long lifespan. Certain kinds (solid-oxide fuel cells) can be used with various types of hydrocarbon fuels as well as with hydrogen gas. The benefit of being able to use either hydrogen or propane, for example, with no modification to hardware, is obvious.

Bimetallic thermocouples, powered by combustion heaters, can act as backup power sources and provide insurance against failure of complex electronics. This, among other things, is discussed in the Emergency Procedures (1:1:EP) subsection.

:: For very low-drain devices, tritium

:: The most attractive [winter] power generation options are: diesel generators, and solid oxide fuel cells. Diesel generators can be operated on both petroleum-based and renewable fuels, without modification; SOFCs can use both gaseous fossil fuels and hydrogen that's produced on-site. If SOFCs are used, fuels can be changed over time without need for extensive infrastructure alteration. Investing in both diesel generators and fuel cells at the beginning of the program will likely pay off in the long run, since diesel generators can provide overwinter power early on - gradually giving way to increasing use of fuel cells - and provide a backup source of power when hydrogen is Aurora's main source.

2. Storage

Techniques for storing energy include:

1. Hydrogen

Hydrogen for energy storage is discussed in detail in 1:1:E:3, but the basic principle is as follows: electricity generated by solar panels during the summer powers machines that electrolyze water; the resulting hydrogen is compressed and stored, and the oxygen is vented. In the winter, this hydrogen can be burned for heat, fed through fuel cells, or power internal combustion generators.

2. Batteries

:: Lead-acid batteries can provide backup power, as well as smooth out power delivery during generator cycling. Lead-acid battery technology has been around for well over a hundred years, is extremely reliable, resilient, and long-lived, and makes up for its low power density

:: Also worth mentioning are NiMH rechargeable batteries, for small electronics. AAA will be standard, with adapters for larger sizes. Explain why.