Off Grid/Grid Down Power Systems: Part II
By: Tom Chatham
For a prolonged situation where you may need to produce your own fuel, a wood gas unit may be the best answer. With one of these units you can turn ordinary wood into flammable gas that your generator motor and even your car can run on.
One way to get around the need for a generator is to use your vehicles charging system as a power source. You can mount a few deep cycle batteries in your vehicles trunk and connect them to your charging system using a battery isolator to keep your vehicle battery separate from the battery pack. Every time you drive your vehicle you will be charging up the battery pack. When you have a power failure, you can simply connect your power inverter to your battery pack and supply your home with limited power with no noise and no exposure of your power system to others.
This is one way to avoid some of the problems with a generator that sits for prolonged periods of time and may not work when you need it. If you utilize this type of system, you will still need extra gas for running your car every day to keep your batteries charged up. This type of system is not as efficient fuel wise as a small motor but may be a viable option for someone in the city An advantage of this system is the ability to use a wood gas generator to power your vehicle for prolonged periods when fuel is not available otherwise. You can have a transportation system and a generating system all in one powered by renewable fuel. This type of setup would work well with an old pickup truck.
If you have a flowing stream on your property you may be able to use a hydroelectric system for power. Depending on the flow rate and head pressure, even a micro hydropower system producing 100 watts continuously can produce a great deal of usable power. The benefit of using hydropower is that the water flows day and night and is not dependant on the changing wind. The only problems you may encounter are drought cutting off the flow of water and freezing weather in your location that may stop the flow of water. These are problems you must evaluate before you decide to go this route.
One newer type of power source that has not taken off yet but I think will in the coming years is the thermoelectric generator. This is a unit that converts heat directly into power that you can use or store in a battery. Small units are now available that you can sit on top of your wood stove and connect directly to a 12v battery to charge it. You can even buy the thermoelectric modules individually and assemble your own higher output generator.
For someone living off the grid I think this is a perfect fit for solar, hydro and wind systems. The thermoelectric generator can provide the extra power you need to supplement solar and wind without a lot of generating equipment. You will be producing power by using your wood stove as you would any way. When fully developed and marketed these systems will drastically change the way we use power.
One of the problems with off grid power is having continuous power. A generator is not efficient for producing continuous power for individual homes so a method of storing power for use on demand is needed. The most readily available source is a battery pack. The use of several connected batteries can provide for your power needs. Lead acid batteries are the most common in use today and are efficient storage devices. Deep cycle batteries are the preferred type because they are designed with heavier plates that can handle repeated discharge cycles. Even so, it is not a good idea to discharge them below 50% and discharge below 20% can actually damage them and reduce their service life. These batteries need to be kept fully charged when setting to maintain service life but will still have to be replaced about every 5 or 6 years. This should be taken into account when designing the size of the system you will need. These types of batteries can be stored for many years in a dry state for future use and can be filled and charged when needed to replace older batteries.
A second type of battery that is good for off grid use is the nickel-iron battery. This type of battery was designed by Thomas Edison and has some features that make it superior to lead acid batteries. A nickel-iron battery has a service life of over 50 years and some have been in use for 100 years. They require a change of electrolyte every 10 to 20 years which makes the battery a long term solution for someone that stores extra electrolyte. Another good aspect of these batteries is that they are very durable and can withstand overcharging and will not be damaged by complete discharge or setting in a discharged state for long periods. The negative aspects of this type of battery are that they must be topped off often with distilled water that boils off during charging and they are not as efficient as lead acid batteries.
Another way to store power is by having a large volume of water stored in a high area that can be allowed to flow down hill to a second storage vessel and power a hydroelectric generator. Some large utilities have used storage devices in the past like this. The excess power being produced by power generators was used to pump water into the higher storage vessel and was used to produce hydro power when they needed extra power. For a homestead that produces a lot of excess power with a generator using homemade fuel, this might be a way to store this extra power for later use. For someone with a small stream they wish to use for power, they might want to store some of this water in a pond or behind a dam to increase the amount of power they can produce.
For those that rely on a battery pack, a power inverter to convert the 12v DC into 120v AC will be necessary. Keep in mind that your inverter will need to be larger than the amount of power you intend to use. For items such as refrigerators, the compressors will draw about twice the rated power when they start. This means you may need to use an inverter with a surge capacity of 1,500 or 2,000 watts for units that run on 500 or 1,000 watts. This is one reason you need to evaluate the appliances you intend to use to allow for the proper size of battery pack and inverter size.
For someone that is planning on long term self sufficiency, one of the problems they will have to address is the need for replacement parts for their equipment. With a motor and generator, you have a number of parts that will wear out or burn out over time. By simplifying your system you will reduce the need for parts and the number of possible breakdowns over time.
One way to simplify your system and make it more durable is to use a steam engine for power. A steam engine has a minimum of moving parts and can utilize wood or coal as a power source. A well built steam engine and boiler can last many years and allow for homemade parts if necessary. This will require tools and knowledge but is more feasible long term than making parts for gas or diesel engines. For gas and diesel engines the best option would be the storage of several engine rebuild kits.
A steam engine used to power an automotive type alternator would be the simplest generating system. An alternator only has a few parts that will wear out over time and can be repaired by an individual. The bearings, brushes and voltage regulator can be stocked in depth and provide many years of replacement parts. The type of long term system used will depend on many factors and the abilities of the operator.
One interesting note on steam engines is that many gasoline engines are capable of being converted into steam engines. Gasoline engines are actually just a converted steam engine. Some internal changes are needed but are well within the capabilities of a do-it-yourselfer.
One thing that must be taken into account for long term use of generators and motors is the lubricant needs of these items. It may be possible to store many years of fuel and spare parts but without a sufficient supply of oil and lubricants these items would soon become unusable.
The ultimate off grid power system
A small solar array, a small wind turbine, a thermoelectric generator and a set of nickel iron batteries can provide you with decades of power for a small off grid home. A power inverter is necessary if you intend to power any 120v AC appliances but if you stick to 12v DC appliances you can avoid the need for an inverter. The less equipment you need, the fewer weak links you will have in your system. A solar array for sunny days, a wind turbine for windy days and a thermoelectric generator powered by a wood stove can keep your batteries sufficiently charged. The nickel-iron batteries can last literally a century and only need the electrolyte changed every 10 to 20 years. Thermoelectric modules will last up to 200,000 hours of use. This system is not cheap but is very durable.
There are many types of systems you can set up depending on your resources. The best system for you is one you research and plan and determine will work best for your situation. Every situation and everyone’s needs are different so these things must be taken into account before you sped a lot of money on components. With the many options available to you, you should be able to design a system that is cost effective and dependable for you. In the coming years it is inevitable that energy prices will climb substantially rendering electrical power out of the reach of many people. The use of electricity is not necessary but will provide you with a better standard of living and more capabilities. Now is the time for you to evaluate the way you acquire and use power to avoid problems in the future that may leave you in want of basic needs.