Solar cell technology has improved so much that energy generation can achieve efficiencies of around 10% and produce fully amortized power at $0.14 per kWh as much as many domestic users or a small companies would pay for grid supplied power today (2012). While wind power is more a supplementary generation that requires larger storage systems it can often be combined with solar. Bio mass is another feasible way of generating methane to drive combustion engines to generate electricity or burn it to create heat.
However, solar and wind depend on meteorological conditions to be suitable for the technology to work and efficiencies vary widely from region to region. Each climate region has its own challenges and requires its individual solution to create energy in a sustainable way.
Arctic and Subarctic Regions
We have not considered the arctic or sub-arctic regions as regions where more sustainable techniques can be applied. Those regions already use state-of-the-art techniques and mainly require heating in an environment where sun is scarce and wind may be blowing stronger than conventional turbines can sustain.
During times when sun and wind are usable the temperature differences and prolonged freezing as well as the abrasive effect of frozen water embedded in strong winds makes solar panels and wind turbines not a very viable option as they would have to be protected from the elements during adverse weather conditions or constantly maintained, those adverse conditions may exist for 2/3 rd's of the year.
Methane from biomass may be a small contributor where sufficient animal and human food and feces can be available for the digestive process of a biomass reactor. However, the buildings to house such a reactor might be quite expensive as the process works best between 68°F and 90°F and will therefore have to be a rather large thermos flask.
Equatorial Belt
This is the general region covering Latitude 27° South to 27° North. Basically, the area of the world where it would be the rarest of days when the temperature would drop below the freezing point. Although warm for most of the time, the tropical and wet regions have their challenges as neither wind nor long periods of sunshine exist for long periods of the year. In the rainy season, days are often overcast or having half a day of rain and half a day of hazy sunshine and that season lasts usually for several months.
Right on the Equator
This is the region 0° to +/- 5° latitude where there is hardly ever any wind and year- round it is between 25°C and 33°C so cooling and de-humidification are the only requirements. From a Solar Generation point of view this region has its challenges. Although not particularly wet, it is often hazy and in the wet season where half of the day's sunshine is often lost to rain. However, the lowest temperatures will never reach freezing point, and dust is not that big an issue especially as it rains from time to time helping to clean the solar panels. It is a possible region for solar generation but storage capacity has to be higher and solar PV acreage has to be higher to deal with the worst months in the seasons where average daily sunshine may be as low as 5 hours a day for a whole month. Wind speeds, unless a typhoon comes by, are generally low and do not yield a lot for wind generation.
Tropical Region
This region is for example around Panama and El Salvador between 10° and 15° North is very wet in the summer from July to end of October leaving an average of only 4.5 hours of usable sunlight. It requires the generation capability to be double the size of dry regions. Average low temperatures will never reach freezing point so no special, only rudimentary anti-freezing methods have to be employed.
Fully Sustainable Region
The most sustainable region for indoor climate control is between the latitude of 25° to 37° North and South of the Equator. This is due to the fact that those regions are Humid Continental, Semiarid, Arid or Humid Subtropical or in other words a reasonable mix of sunshine all year-round with reasonably clear skies and small amounts of cloudy days.
Assisted Sustainable Region
This is the latitudal region between 37° and 45° covering Humid Subtropical, Semiarid, Arid and Mediterranean climates or in other words a reasonable mix of sunshine all year-round with reasonably clear skies and small amounts of cloudy days. However, because temperatures may reach freezing or below and substantial supplemental heating is required from time to time we call it "assisted sustainable". The best method of assistance is Natural Gas as the most cost efficient for heating, followed by electricity followed by propane and solid fuels.
Biomass Generation
With new technology becoming available to reduce the constant need to monitor and react to adverse developments in the reactor, this technology should get more consideration from now on. As biomass is normally available, in the arctic and sub-arctic regions to some degree, and available in abundance where human, animal or agricultural concentrations occur, therefore a digester / methane reactor is very feasible. However, economy of scale has to be considered as those systems require substantial and constant monitoring to maintain their efficiency. Also the re-use of the digested material has to be organized, a logistics issue that does not exist with solar or wind.
Storage of Energy
The storage of the biomass generated energy would be in form of liquid methane in super cooled containers that allow long term storage with little appreciable loss. The sotrage of solar and wind energy would be in a battery of some sort. The price per generated and stored kWh above was based on Lead Acid storage systems of industrial quality with a minimum battery life of 14 years.
Conclusion
Most regions, other than the cold extreme, lend themselves to harvesting of wind, sun and biomass renewable energy at a reasonable amortized cost. The amortization times are between 14 and 20 years depending on the technology, region and application specific circumstances. The systems can be designed to be fully automated and user friendly and provide lighting, heating and cooling under all seasonal weather conditions, but may have to be assisted by grid supplied energy or other fossil energy at times depending on the region.
Klaus Bollmann is a 30 year veteran in energy conservation, resource saving innovative products for a sustainable environment. Click the link If you are interested in ActiveLED high performance lighting and energy saving control products.
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