In many areas of the US there are four potential sources of renewable energy suitable for rural communities. These are: a) electricity from wind turbines, b) solar energy as both electricity from photovoltaic cells (PV) and from passive solar heat, c) geothermal energy, and d) burnable oil from various types of crops. Animal power is an additional minor source, such as using oxen to run a mill or even a generator for specific applications.

Of these four, burnable oil from crops is the least desirable as a primary source, since it requires the use of land which could otherwise be used for crops for consumption or clothing, or for grazing land for animals. It could be undertaken in later stages as a suitable long-term replacement for lighting from electricity, but we won't cover that subject now. Castor oil is considered by many to be the best source.

Wind energy requires that sufficient steady wind be available in a community's location. Solar photovoltaic energy has also proven to be a reliable long-term source. The initial costs are cheaper than wind, especially if we install it ourselves. (We do not recommend building do-it-yourself solar panels.) Passive solar energy for space and hot water heating is very economical and should most definitely be used, in conjunction with other energy sources. However, both wind and solar are intermittent, and designs must take this into account. Last, there are two types of geothermal energy; one is available everywhere and is economical, and the other is only available in certain areas and is very economical for heating.

Wind

Wind power is harnessed by the use of wind turbines.  Wind turbines can only be operated in areas with Wind Class 2 or higher, and commercial power generation requires at least Wind Class 3. Wind measurements are usually taken at a height of 150 feet. Commercial turbines are 150 feet high, and a height of at least 50 feet is best for small home turbines. Most of the southern US is in Wind Class 1, which is pretty much useless for producing electricity from wind turbines (see US wind map). 

Combined with the construction of highly energy efficient homes, the use of wind turbines is practical and cost effective. A medium-sized energy efficient home can be designed that uses 400 kilowatt hours of electricity per month, and a single small wind turbine that produces this amount of electricity can be purchased and installed for well under $10,000. The amount of energy produced will be dependent upon the Wind Class in the area, and in Wind Class 1 the cost per watt is simply too high. Solar photovoltaic systems are nearly always cheaper per watt produced.

Within a community, economies of scale can be obtained by purchasing larger wind turbines. The industry continues to grow, with new designs coming on the market regularly, and competition is very slowly driving down the prices.

There are hundreds of commercial wind turbines being built in West Texas every year, in areas with Wind Class 3. Texas has recently surpassed California as the largest producer of wind power. However, the Eastern portion of the state is all in Wind Class 1. 

Most rural areas in Texas have electricity provided by electric cooperatives, and savings gained by purchasing electricity at group rates are passed back to the coop members. We may be grid-connected in the beginning, but over the long term we intend to be off the grid.

Solar and wind power are both intermittent. However, even in an area with good wind energy, one downside to wind turbines is that they don't produce more energy when it is needed. Far less energy is needed at night when everyone is asleep. 

Solar

Solar energy is available in two basic forms, photovoltaic (PV or solar panels) and passive solar heating. In our above sample of an energy efficient home, a comparable and complete professional PV installation would cost around $15,000. This is the reason why solar power is not used much, even in southern states.

However, a huge amount of this cost is the professional installation. Solar panels can now be purchased in bulk for $1.00 per watt, and sometimes as low as $.80 per watt. If we install ourselves it is far cheaper than wind turbines, even including the inverter and other equipment. 

Peak electricity demand is highest on hot sunny days in the summer. This is exactly the time that PV produces the most electricity. Wind turbines do not produce more power during the day, so to use wind alone the system has to be over-sized to accommodate the daytime need, which means at night excess power is generated. This is not a problem if we are grid-connected but otherwise the electricity is wasted without a grid connection and net metering.

Many rural electric coops now charge a high flat monthly rate for net metering, which defeats the purpose of having a grid connection. 

Passive solar heating is the most economical use of solar energy.  Passive solar energy can be used directly for space heating. Building design should take advantage of passive solar energy by positioning skylights or windows so that the light falls on brick or rock areas with high thermal mass inside the home, but only during the winter months.

Water can also be heated by direct solar energy. This can be used for hot water, which in turn can also be used for space heating by the use of a radiator within each room, or by pipes under the floors.

Geothermal

There are three primary types of geothermal energy, although there is a fourth resource which is sometimes called geothermal.  Of the three primary types, only one - hydrothermal - is available without large power plant installations. Geothermal energy is completely dependent upon location, and most locations have none available.

Geothermal energy is used in two ways, direct and indirect.

The fourth type is quite common because it is available for use everywhere. The mechanism for extraction is known by different names. The most common name is a Ground Source Heat Pump, or GSHP. The soil temperature three feet underground is quite stable all year; for example in central Texas it is around 75 degrees. By contrast, the air temperature throughout the year varies from 25-100 degrees. Cooling from 100 degrees (the outside air temperature in summer) down to a comfortable 70 takes a lot more energy than cooling down from only 75 degrees (the soil temperature in summer.) The same is true for heating up from 30 degrees in the winter versus using 75 degree soil temperature as a starting point.

A GSHP has underground coils with a circulating liquid which is brought into the home. It can either be used directly, via continuing the piping inside the home, or indirectly, by providing that temperature to a heat exchange unit that has a separate set of pipes inside the home. GSHPs are usually installed in a way that also lets them produce hot water. Installation in existing homes in the city is more expensive because the coils have to be installed vertically into the soil due to small lot sizes, but where there is sufficient land around the house they are installed horizontally, which is cheaper. There is considerable interest in geothermal energy, and a number of resources are available.

The only true geothermal source of energy suitable for non-commercial use is hydrothermal energy, which is even more economical for heat than a GSHP system.  Texas has several “hot spots” or areas where there is hot water underground, from 90-150 degrees. This water can be pumped to the surface and run through radiators or other coils, and then returned to the ground (called a closed-loop system). After installation the only cost is the electricity for the water pump. This is the most long-term economic option of all heating methods - where it is available. Due to the higher temperatures of the water this method does not require a heat pump. In the town of Marlin, Texas, the Chamber of Commerce as well as a county hospital have used such hydrothermal energy for over 100 years. Marlin was formerly famous for its hot springs that supplied a number of bathhouses, and in the center of town there is a fountain with running hot water. Hydrothermal water is typically found at a minimum of 3000 feet below the surface, so it does not affect surface temperature.

Using these two energy sources is called “direct” when the water is pumped directly through the radiators or other pipes in the building, and called “indirect” when it is done through a heat exchanger, which uses a separate set of pipes inside the building.

The availability of all these energy sources varies by location. Wind is restricted to certain areas as described above; solar is available throughout most of the country and especially in the south; stable ground temperature is available everywhere; and hydrothermal is available only in a few areas.

An article describes that Renewable Resources could provide 99 percent of US Electricity Generation by 2020.

All these energy criteria were considered in the location research for the forming Texas community.

Another natural source of energy is the use of animals, particularly oxen.  They can be yoked to grain grinders, water pumps, sawmills, and even generators and similar devices. Of course they are also the best for tilling the land, hauling logs, and many other purposes.

Humans can also provide indirect energy by pedaling equipment that produces mechanical or electromagnetic energy. Here is an example of an electric generator, and here some mechanical generators and a video. 

Next - (Providing Necessities) Animal Husbandry