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This document addresses the fundamentals of Residential Sustainable Energy. By focussing on Residential systems, we limit the size of systems considered. By focussing on Sustainable Energy sources, we limit the kind of technologies considered, eliminating the use of fossil fuels, and for now, eliminating connection to the traditional utilities of Gas and Electricity. Although the Electric Utility has begun to incorporate a small percentage of Sustainable Energy sources, it is in general, to date, primarily dependent on fossil fuels and toxic waste producing nuclear energy. Another consideration in not connecting to the Electric Utility is keeping at greater distance the 60Hz ELF (Extra-Low Frequency) EMF (Electro-Magnetic Field) pollution that comes with it. Residential energy needs fall primarily into these categories:
In an alternate or sustainable energy home, we typically look to use less energy than would be used in a home of traditional energy design. As we examine the big energy users in traditional home design, we find that the largest has to do with traditional HVAC (Heating, Ventilating, and Air Conditioning). As we study the economies of scale, it quickly becomes clear that it costs less to redesign the architecture of the building itself to become well insulated, reducing the need for heating and cooling, than it would cost to try to generate enough energy to heat or cool the traditional lossy building. This, then, moves most of the energetic design considerations having to do with HVAC needs into the realm of high R value insulation in the design of the building, and passive solar design for heat needs. These design considerations will not be addressed in depth in this document, instead being deferred to other sources. We will note however, that even the ultimate passive solar architectural home design which accommodates primary cooling needs through natural convective airflow through the structure, and accommodates primary heating needs through high insulation and passive solar heat gain through careful architectural design, may still have some use for electrically powered ventilation fans. We will also note that there may be occasions when we will have in our electrical system design, an excess of electricity beyond the active loads and recharging the batteries, which may be used to heat water or space.
In the traditional home, heat for cooking is typically utility provided and derived from either an electric source, or from a fossil fuel source (natural gas or propane gas). If the home is to not be connected to any energy utility, including the propane gas utility provided by a propane trucking company to a local tank, then our food cooking needs will have to be provided by some other source. While there are direct solar cooking tools, they only work on bright sunshine days and while the sun is up. What we are most likely left with is a woodstove... traditional since the days of yesteryear. This will provide space heat as well as stove and oven cooking heat. While the "wood" stove may be alternately fueled with any other combustible source from coal to cowchips, the bottom line is that cooking heat comes most easily from a source of flame. These days we need to be careful of city or county ordinances about wood stoves. I do not know of any which would prohibit the use of a woodstove for cooking, though there may be some that prevent designing a woodstove into new construction. Caveat Emptor.
One of the greatest insanities of traditional modern home design is evidenced in our no-brainer refrigeration installations. On a winter day, we first expend fossil fuels to heat the space from freezing to "room temperature", and then we use more fossil fuels to cool back down to near freezing a small part of that room known as the refrigerator. This gives us the convenience of having our foods handily available in the kitchen in an easily replaceable monolithic solution to refrigeration needs, "the refrigerator". It also traditionally intrudes upon our sacred space with the noise of a motor/compressor. And it is traditionally built with very little insulation, requiring a constant expenditure of energy. There has to be a better way. There is. A recent example is the "Sun Frost" refrigerator, available to run on 12VDC from a typical solar electric installation, built with more insulation around the box, and with the motor/compressor/condenser installed intelligently on the top of the box where the heat they produce can rise into the room rather than into the box we're trying to cool. It still leaves noise in our space.
In yesteryear, the only refrigeration available was the root cellar, conveniently kept cold just by being underground... not as cold as our refrigerators, and certainly not freezing cold except possibly in winter. It would make sense to install our sustainable energy refrigerator in the basement where its' outside is not exposed to room temperature. It also makes sense to put its' motor/compressor somewhere other than in our living space, and the condenser either in the living space in cold climates, or outside in hot climates. Ideally we'd use a bidirectional heat pump, but we're now talking total custom design and bigger bucks.
Another alternative on a smaller scale is the Peletier Effect refrigerator, which uses DC electricity directly to transport heat, and possibly also a fan to blow cooling air across the hot side of the Peletier heat pump. Koolatron of Canada is one brand for such refrigerators.
We can revert entirely to hand operated pumps, or even buckets lowered into the well, but most likely we will try to produce the traditional hot and cold running water. Here we'll address how to get running water, the next section deals with heating part of it. First we'll address collecting water from its source. This can become very site specific, but in general, our non-utility water source is going to come from some combination of:
In the case of running water available at the surface we will most likely need to pump it uphill to a storage tank. The first reason is that home building sites are rarely located down-hill from the creekbed unless you like flash floods washing through your living room. The second is, that by pumping not only up out of the creekbed but to a storage tank located above the home, we solve the problem of providing water pressure to the tap in the home at the same time, with only one pumping operation. If we don't have a storage tank above the house, then once we've pumped water out of the creek to the storage tank, we have the same situation as a Shallow Well, we have a simple Cistern storage tank. In either case, the easiest technology for pumping running water uphill is the Ram Pump. These use the flow of water collected from a small dam in the stream to pump most of that flow uphill. In Colorado, water rights restrictions have to do with usage of water (removing it from the flow of the stream). There should be no restrictions to building a small dam, which does not reduce the overall flow of water past the dam, merely creating a water-fall through our water pump.
It is possible that if we don't build a water tower, and we site on reasonably level ground, that our water storage may be an underground cistern, or the source may be simply a shallow well. In either case, we primarily need to create through pumping, water pressure to the tap. In a sustainable energy system, this is easily provided by a DC powered pump running off our household batteries.
In the case of a deep well, we need a fairly powerful pump to raise the water up out of the well. In some installations this may be the only pump, and the well itself is the only "storage" of water. If we have no other water storage, then we need to pump on demand, which implies a fairly big powerful pump/motor running from our house batteries on demand. Alternatively we split the job and have a water storage tank. In this latter case, we may utilize either the traditional jack-pump driven by a windmill as was the case on so many homestead farms of yesteryear, or driven by a modern electric motor powered from solar or wind electric generators, or we may utilize a deep well pump/motor driven from either dedicated solar electric collectors or our house batteries. This is also an excellent use for "surplus" electricity which will be discussed further in association with the electronic system which regulates battery charging. If we've chosen to pump to storage from the deep well, and the storage is not located above the house, then we also need a pressure pump to pump on demand from storage to the house.
If we do not have a water storage tank located above the house to provide flowing water pressure on demand, then we need a pressure pump activated on demand to provide the water flow from storage to our taps. This is typically handled by a DC powered pump operating from our house batteries.
Domestic Hot Water heating is best provided by a combination of heat sources. Any existing woodstove may have installed in it some plumbing so that heat from the fire heats the water, which is circulated back to the storage tank. Excess electric power (once the batteries are fully charged) may be dumped into a resistive heating element in the water storage tank (similar to traditional electric water heaters) or may be used for irregular loads such as water or space heating, or water pumping from source to storage. Two options in DHW design depend on the feasibility of putting the hot water storage tanks above the hot water solar collectors. If the tanks are mounted higher than the collectors, than natural convection will circulate the fluid between the collectors and the storage tanks. Otherwise, it is necessary to utilize a circulation pump, which in this case would be powered from our house batteries.
Primary heat may be provided by solar thermal collectors, often roof mounted. Note that nice conductive copper collectors and copper pipe mounted on the roof and leading down into the house will serve quite nicely as a lightning rod, inviting lightning to visit your home. See the section on lightning elimination. Collectors come in three primary configurations:
The actual water to be consumed in the house flows through the solar collector. Depending on the condition of the water, its' hardness, etc. this may be ok or may produce accelerated aging of the collector by leaving deposits on the inside wall of the plumbing, reducing the effectiveness of the collector.
The fluid which flows through the solar collector also flows through a heat exchanger, moving the heat from the collector to the hot water storage tank, without cross contamination between the hot water used in the house and the fluid circulating between the collector and storage tank. Because of this separation, the collector is not prematurely aged by mineral deposits usually found in home water.
In this case the circulating fluid is water, though it may be treated with chemical such as anti-freeze, corrosion inhibitors, etc.
In this case the circulating fluid is a chloro-flouro-carbon compound, similar to what is used in our refrigerators and air-conditioners. Yes, were it to be released into the atmosphere, it would help destroy the ozone layer. Don't release it. Simple. The only system of this design I've seen on the market is intended to be self-circulating through mounting the storage tanks above the collectors.
Aside from daytime solar lighting, the lighting needs of a residence may best be provided for by compact fluorescent lights using high-frequency inverter ballasts operating from DC power. Other options include quartz-hallogen or regular incandescent bulbs. The RV and Marine markets have many products suitable for this application.
If the traditional telephone utility is utilized to provide communications service, no power is required. Answering service may be provided by the telephone company, or a traditional answering machine may be operated with a DC adapter in place of the traditional AC adapter. Alternatively, cellular service my provide the house's telephone communications without wires from a telephone pole, though this option will be more expensive ($0.25/minute night, $0.45/minute day), and again, powered by DC. Communications needs may also be served by DC powered radio transceivers.
Entertainment needs of typical home variety may be provided by DC powered FM/AM receivers, cassette recorders, CD players, VCRs, television receivers or video monitors, etc. At this point we may wish to note that Televisions with Color CathodeRayTubes are often a major source of ELF EMF pollution in the home environment, which may be eliminated through the use of newer LCD based flat display panels.
Modern laptop type computers are easily powered by DC adapters, as are their accessory peripherals such as printers, modems, etc.
Equipment such as dishwashers, clothes washers, vacuum cleaners, food processors, microwave ovens, toaster ovens, etc. share common characteristics from the perspective of providing them with electric power:
Those which produce heat would be unwieldy in 12VDC versions as their current draw would be so high as to require heavy-duty wiring. Microwave ovens are bad news for food anyway. Those which operate primarily as a motor driven device may be rebuilt with DC motors, or in some cases found in 12VDC versions. I have seen available: blenders, vacuum cleaners.
As for those items which are not easily found in 12VDC versions, or not easily converted to 12VDC operation by motor replacement, they can either be done without, or can be powered from an inverter which turns the 12VDC into 120VAC 60Hz electric power traditionally available from wall plugs in "normal" housing. Note that the RV and Marine markets are the best sources for alternative appliances which run on 12VDC. In fact, if you don't care about the 60Hz AC power Electro-Magnetic Fields in your house, you can simply wire the whole house like a traditional house and run the whole thing from a heavy-duty inverter operated from your DC storage batteries.
One form of energy "storage" is called "utility interactive", whereby the electric "consumer" also becomes a producer. Whatever energy collection devices you have are hooked-up to a "utility interactive synchronous inverter" which produces 240 / 120VAC 60HZ. Any energy generated is applied to the utility line, causing your utility meter to "run backwards" as you sell energy to the utility company. Depending upon the specific utility or specific state regulations, it is entirely possible and likely probable that the utility may want a separate meter for the energy you generate and sell to it, and another for the energy you consume from it, thereby allowing a differential rate structure, usually implying that they pay you less for your electricity than they charge you for theirs. With judicious choice of generator sizing you can still turn a net profit. One advantage of this system is that you become part of a solution to pollution which is greater than your own home... not only are you not consuming resources via the utility, but you are helping your neighbors consume clean energy instead of fossil or nuclear fuels. These utility interactive synchronous inverters are available in the commercial marketplace, and from solar and wind power equipment manufacturers.
The synchronous inverter and control system are responsible for ensuring that the AC power they generate and apply to the utility line is synchronous with the 60Hz signal already present, and especially they must ensure that they do not apply power to the utility line when the utility line is not applying power to it. This is necessary so that a branch circuit of the utility's power distribution network, when turned off by them, is actually "off". Were our synchronous inverter and controller to blithely continue to generate power into the line, some utility worker is likely to meet his death by electrocution, thinking he'd turned off a segment of power distribution wiring to work on it.
In an application without the availability of energy on demand from the electric utility, we must depend on energy storage. Less common forms of energy storage are compressed air tanks, and pumped water storage. In these systems, the mechanically stored energy is used to generate electricity on demand by operating a turbine which drives a generator. More commonly, electric energy is stored directly in a storage battery. Given that we will be collecting energy into the storage system from sustainable sources of variable and undependable regularity, we basically design the overall system to operate such that the household needs can be provided for from the batteries only, for a typical period of from 3 to 7 days. Battery longevity is also facilitated by designing for a longer period of autonomy than is typically used even during poor energy collection periods. Batteries function more efficiently and last longer in a temperature moderated environment. They don't like a freezing cold environment. In Colorado, with normal freezing weather conditions during winter snow season, we want our batteries mounted inside an insulated room. Batteries, when being charged, produce a certain amount of gas. This gas may carry small amounts of corrosive liquid, but even more important to beware of, is that that gas is the perfect proportion of hydrogen and oxygen to produce an explosion should the vapor accumulate. Therefore, battery rooms need to be ventilated. There are catalytic battery caps available which facilitate the recombination without explosion of that hydrogen and oxygen back into the water they came from (highly recommended), thereby reducing danger of explosion, and reducing potential battery maintenance of adding distilled water to the cells. Major battery technologies are:
Power to be distributed to the house may be either the DC from the batteries directly, or it may be routed through a DC-to-DC converter to change its DC voltage, or it may be passed through an inverter to produce the traditional 60Hz AC 120/240Volts common in most North American homes. This latter option is the easiest from several aspects, including user familiarity and appliance availability. It also perpetuates the ELF EMF pollution problems which have adverse affects on life forms indigenous to this planet.
Based on the magnitude of the system voltage, the size of wiring required to distribute a given quantity of power will be smaller, as will be the losses in the wire itself. Loss is limited simply by increasing wire size. Given a 120VDC system, we would use the same wire as normally used in a house wired for AC power. In days of yesteryear, this was actually not uncommon. Many rural systems, and many early electrical systems utilized DC power. Many older tools and appliances were built with "Universal" motors which worked equally happily on either 120VDC or 120VAC. Some of these may still be available. Many newer generation appliances and tools are built with motors which operate on AC only. Most "electronics" equipment have transformer inputs which require AC power. Some switching power supplies as might be found in some computer designs or some professional equipment for audio/video use may be capable of operating on 120VDC power. Caution in this regard is necessary, as 120VDC power applied to an item designed for only 120VAC power will produce an acrid smelling smoke as the unit melts down.
One of the main advantages of utilizing higher system voltages is the lessening in the size, bulk, cost and hassle of wiring the home, as smaller wire may be used. The most weighty factor in choosing system voltage will be the actual loads used. Obvious choices for system voltage, and the reasons for their advantages and disadvantages are:
The telecommunications industry has DC-to-DC converters available to change between these DC standards, allowing the choice of different voltages for different purposes, and the possible wiring of the home with multiple standards of power availability even though it is only stored in the form of one standard. Note that high-power inverters to provide 120VAC 60Hz for utility equipment in the home, a quite practical alternative for intermittent use of otherwise hard to find appliances for different standards, minimizing the exposure to ELF EMF, are an attractive option. These work more efficiently from, and in the case of the higher power models, work only from, higher battery voltages. Ultimately, a careful analysis of expected load usage is necessary to choose the most efficient and cheapest combination of equipment to power the loads. The absolutely simplest no-brainer approach is to wire everything for 12VDC and suffer any concomitant loss of appliances not available for that power, and add one or more inverters to produce 120VAC 60Hz power as deemed necessary.
The most standard of DC power connectors is the ubiquitous cigarette-lighter-plug: large, unwieldy, and unreliable because of its tendency to easily pull out of the socket. Yet it is impossible to accidentally plug it into any other socket than one providing 12VDC. It is important that whatever power we choose to have available around the home have associated with it a standard plug and socket scheme which protects us from injury, and protects equipment from the damage that would be incurred by providing it with incompatible power. It is therefore recommended that any cigarette-lighter-socket be wired for 12VDC only. If we have other voltages available, they belong available through a different kind of connector. Likewise, the traditional wall sockets should not be wired for anything other than 120VAC 60Hz power. If we choose a non-12VDC DC standard, we need to standardize on an unusual plug and socket for its distribution. In the 12VDC realm, there are two other standard plug and socket configurations than the cigarette-lighter abomination. These, therefore should likewise not be used for DC voltages other than 12VDC. From the professional audio / video world, we have 4-pin XLR connectors used to connect 12VDC waist-carried battery belts to things like video cameras, video lights, etc. The standard of wiring for this 4-pin XLR connector is Pin 1 = Ground/Neutral/Return and Pin 4 = B+ (nominal 12VDC), with Pins 2 and 3 unused. Another advantage of the XLR connectors are that they latch into place and will not pull out. As long as we've mentioned grounding, be it noted that it is common practice to ground the negative pole of DC systems, in homes as well as in boats, cars, RVs, etc.
From the radio amateur world, we have a standard 2-pin Molex connector. The Molex 1545 connector is distributed by Radio Shack as their part number 274-222. Positive is the Pointed Pole. Negative is the Square Pole. I do not know if this is available in a panel-mount version or only as an in-line connector. Panel mount connectors mounted in the wall are likely to be what we desire in our residence, which narrows the choice down to the traditional cigarette lighter socket, and the XLR 4-pin connector. Again, the XLR connector has the advantage of latching into place. If this is adopted as our residential standard, it is easy enough to make a few adapter cords to keep around the home, which plug into the XLR4 connector in the wall, and have a cigarette lighter socket at the other end of the cord for powering gypsy equipment while visiting the residence.
Wikipedia now provides an excellent reference regarding DC power connectors.
Small scale hydroelectric plants are extremely feasible, if and only if, you have a reasonable flow of water available from a local creek, which you can dam. Year round water flow would certainly justify the investment, while creeks which run dry during summer may be more questionable financially. In combination with solar-electric collectors you may still fare well, as dry creek time is most likely high sun time for the photovoltaic panels. Once you have a piped water stream directed into a turbine, it will happily spin an electric generator 24 hours per day.
The wind is the most variable of energy sources. In combination with solar-electric collectors you may still fare well, as low wind time is most likely high sun time for the photovoltaic panels. There may be still overcast days it's true, but most often either the sun is shining or the wind is blowing or both. Windmills are just generators hooked up to a propeller, all mounted on a reasonably tall pole. Things like tall poles may serve to attract lightning... an intense source of much electric power, so much so that you're more likely to burn things to the ground by collecting lightning, than you are to get your batteries charged by it. Key design factors in windmills have to do with minimum wind speed... most sites have reasonable amounts of low speed wind... how fast does the wind have to be blowing to start the windmill though? And cleverly enough, an efficient windmill design that starts easily in slow winds, will also tend to effectively and efficiently want to blow over the whole tower it's mounted on in a hurricane. Any reasonable windmill design will accommodate high winds without overspeeding and having the propeller fly apart through some system of braking... the designs for which vary widely. Most windmills are rated for a maximum of 120mph winds. If your building site experiences greater extremes, you're going to lose, or have destroyed, your precious, expensive, life-line of electric power. Windmills can be mounted on tilt-over towers, being manually lowered to the ground in case of impending hurricane winds. Depending on tower guying and windmill size, this can take 3 or 4 people, so you don't want to do this often.
Solar Photovoltaic collectors typically have a lifespan of over 30 years with no maintenance. They are not cheap when you look at initial purchase price, so remember you're buying a lifetime supply of electricity all at once, and that they're actually therefore quite a bargain. They may be mounted on the side of a building, or they are often roof mounted. They may also be mounted on tracking equipment which keeps them pointed at the sun for higher efficiency, the tracker in turn mounted on a pole stuck in the ground. Some tracking systems are designed to cooperate with roof-mounting. Note that nice conductive solar panels and copper wire mounted on the roof and leading down into the house will serve quite nicely as a lightning rod, inviting lightning to visit your home. See the section on lightning elimination. Note that most solar panel mounting systems are only rated to withstand 120mph winds. If your building site experiences greater extremes, you're going to lose, or have destroyed, your precious, expensive, life-line of electric power.
In situations where the feasible combination of sustainable energy sources is too intermittent, it is common to use a motor generator set for backup. This is an engine, typically diesel for long reliable life, running an electric generator to charge the batteries or run heavy loads directly as needed. These are available in fully automated versions that start and stop automatically as directed by the electrical system controller, when alternative energy sources are not producing. Depending on the site, alternative fuels may be propane or natural gas.
In the days of yesteryear, we had lightning rods. Their purpose was to attract lightning, away from what it might otherwise hit and damage. In modern times we have a more effective approach, that of lightning elimination. The difference between these two philosophies is significant. As in California, where they prefer many small daily earthquakes dissipating tectonic movement to "the big one", we can likewise prefer many ions wafting up to the clouds from an ionic radiator to dissipate the clouds' electrostatic charge slowly and gradually, to the sudden and sometimes catastrophic release of a huge electric arc. Boulder, Colorado's Lightning Elimination Consultants sells some nifty stainless steel radiators that look like a cross between a porcupine and a dandelion, perfect to put at the top of a windmill pole, or at the cornices of a building. The other half of the lightning elimination equation is called grounding, connecting that ionic radiator to the earth, electrically, very effectively. I don't know if LEC uses them or not, but the absolute best ground rods available are the Lyncole XIT ground rods. In the Rocky Mountains, a mountain home doesn't have to have solar collectors on the roof or a windmill on a tall tower to be in need of lightning protection.
If the electrical system must meet Underwriters Laboratories approval or certification, the simplest solution is to utilize a controller manufactured by Ananda Power Technologies, Nevada City, CA. They manufacture complete boxes already UL approved, and are currently (February, 1994) the only UL approved solution. This is a recent concept, and may not be necessary. Many solar or wind plus solar electric systems are in existence, and meet local building codes, and for that matter may actually meet UL parameters even though they have not been approved by Underwriters Labs. Even installing the APT UL-approved power center is not the slightest guarantee that the overall system is safe. Even meeting all local building codes may not guarantee a safe electrical system. The overall combination of site, weather, equipment, installation, wiring, design, etc. in an alternative / sustainable energy installation must be considered carefully, and all details considered by the architect / designer. This is not like the more standard electrical wiring inside a traditional house, nor will an electric utility company solve all problems right up to your electrical meter and breaker box.
The place where the whole electrical system comes together is in the smallest and simplest system a charge controller. There may be more options and functions in a larger or more complex system, but it will still focus on its charge controller. There are many methods of optimally charging the batteries. A useful option is a "Low Voltage Disconnect" to protect the batteries from being overly discharged and damaged in case you try to use more juice than they can healthily give you. It is also beneficial to use a charge controller whose design entails, or whose options include, that when the batteries become charged, any excess electrical power is "diverted" to an auxiliary load. This load may be a heating element immersed in water, to change the excess electricity into heat for your DHW needs, or it may be a well pump to refill your water storage tank.2 Site specific concerns drive the overall design here. There are also circuit breakers for each power source, and for each load or group of loads, similar to the breaker boxes in traditional homes, automobiles, RVs or boats.
The following diagrams illustrate possible options, not all of which would be used in any given system.
For electricity collected by the sustainable energy collectors, I recommend that it be utilized in the following priority order:
For periods of poor sustainable electric generation, I recommend that utility power be called upon for assistance in two independent cases:
Let us look at these considerations from the opposite perspective:
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