Off-the-grid or off-grid is a characteristic of buildings and a lifestyle designed in an independent manner without reliance on one or more public utilities. The term "off-the-grid" traditionally refers to not being connected to the electrical grid, but can also include other utilities like water, gas, and sewer systems, and can scale from residential homes to small communities. Off-the-grid living allows for buildings and people to be self-sufficient, which is advantageous in isolated locations where normal utilities cannot reach and is attractive to those who want to reduce environmental impact and cost of living. Generally, an off-grid building must be able to supply energy and potable water for itself, as well as manage food, waste and wastewater.
Energy Energy for electrical power and heating can be derived from burning hydrocarbons (e.g., diesel generators, propane heating), or generated on-site with renewable energy sources such as solar (particularly with photovoltaics), wind, or micro hydro. Additional forms of energy include biomass, commonly in the form of wood, waste, and alcohol fuels and geothermal energy, which uses differences in the underground temperature to regular indoor air environments in buildings. It is possible to simply eliminate energy shortage (e.g., via solar and wind tech such as in Old Order Amish - while used and sanctioned, not all agree) and Old Order Mennonite communities, and many Amish people still use steam engines.
Electrical power Grid-connected buildings receive electricity from power plants, which mainly use natural resources such as coal and natural gas as energy to convert into electrical power. 2017's breakdown of world energy sources shows that the globe, mainly dependent on grid power, uses a majority of non-renewables, while popular renewables such as solar PV and wind power are a small portion. When off the grid, such as in Africa where 55% people of do not have access to electricity, buildings and homes must take advantage of the renewable energy sources around them, because it is the most abundant and allows for self-sufficiency.
Solar photovoltaics
Solar photovoltaics (PV), which use energy from the sun, are one of the most popular energy solutions for off-grid buildings. PV arrays (solar panels) allow for energy from the sun to be converted into electrical energy. PV is dependent upon solar radiation and ambient temperature. Other components needed in a PV system include charge controllers, inverters, and rapid shutdown controls. These systems give off-grid sites the ability to generate energy without grid connection. Every quarter, Bloomberg New Energy Finance evaluates manufacturers on their actual projects over the previous quarter and publish a list of Tier 1 Solar Module (panel) Manufacturers.
Wind turbines Wind energy can be harnessed by wind turbines. Wind turbines components consist of blades that get pushed by wind, gearboxes, controllers, generators, brakes, and a tower. The amount of mechanical power captured from a wind turbine is a factor of the wind speed, air density, blade rotational area, and the aerodynamic power coefficient of the turbine.
Micro-hydro Where water is abundant, hydropower is a promising energy solution. Large scale hydropower involves a dam and reservoir, and small scale micro-hydro can use turbines in rivers with constant levels of water. The amount of mechanical power generated is a factor of the flow of the stream, turbine size, water density, and power coefficient, similar to wind turbines. The energy from waves and tides can also provide power to coastal areas.
Batteries When renewables produce energy that is not currently needed, the electrical energy is usually directed to charge a battery. This solves intermittency issues caused by the non-constant production of renewables and allows for variations in building loads. See here for an illustration of how to size an off-grid Solar PV and Battery system. Common batteries include the lead-acid battery and lithium-ion battery. There are portable batteries and non-portable batteries. These portable power stations are often used in remote areas, since they don't require installation and can be used in a variety of scenarios. The technology of these portable batteries has evolved much through the years. Most of the portable power stations use two types of lithium-ion batteries: nickel manganese cobalt and lithium iron phosphate batteries.
Hybrid energy systems In order to protect against intermittency issues and system failures, many off-grid communities create hybrid energy systems. These combine traditional renewables like solar PV, and wind, micro-hydro, batteries or even diesel generators. This can be cheaper and more effective than extending or maintaining grids to isolated communities.
Radioisotope thermoelectric generator Historically remote applications such as lighthouses, weather stations and the likes which draw a small but continuous amount of power were powered by radioisotope thermoelectric generators (RTGs) with the needed radioisotopes either extracted from spent nuclear fuel or produced in dedicated facilities. Both the Soviet Union and the United States employed numerous such devices on earth and almost every deep space probe reaching beyond the orbit of Mars (and even some in the inner solar system) has had an RTG to provide power where solar panels no longer deliver sufficient electricity per unit of mass.
Direct current buildings
Electricity produced by photovoltaics is direct current and is stored in batteries as direct current and DC buildings would eliminate the need for conversions from AC to DC. One third of electricity in the home is used as DC for electronics, LED lights, and other appliances already. The market for DC home appliances is maturing, which is necessary to have a 100% DC powered home. The electrical panel, circuit breakers, and fuses would need to be replaced with DC compatible components if retrofitting an AC house to DC. For net metering, to sell back to the grid, an inverter would still be needed, and also to use the grid-as-a-backup, if still using a grid-tied electrical system. DC electricity doesn't transmit over power lines efficiently over long distances, but if it is generated and stored in batteries on site, it is more efficient by 10-20 percent to keep it as DC and run appliances that way without inverting.
Temperature control
Types of solar-energy passive off-grid cooling systems could be used for cooling houses and/or refrigeration – including some that do not require electrical components and are allowing for chemically stored on-demand energy. Such may be useful for climate change mitigation and adaptation.
Communications
Meshnets such as B.A.T.M.A.N. could be used to sustain or establish communications without conventional infrastructure. Moreover, off-grid communications technologies could be used for environmental, security and agricultural monitoring as well as for emergency communications and coordination – such as for work assignation.
Healthcare
According to the CDC off-the-grid and rural lifestyles face significantly more health challenges than those living in urban life, and even face significantly higher chances of death compared to their urban counterparts due to challenges accessing proper care. Off-grid technologies can also be used to improve healthcare systems, allowing for more reliable energy sources for health care facilities, power everything from lights to essential life-saving equipment. Drones have been used for off-grid healthcare, especially in the most remote regions of the world. With communications enabled, they deliver test samples, medicine, vaccines, food, water, and anti-venoms.
Waste management
Small-scale waste management techniques in Western Europe, often for specific or standardized waste, were reported to mostly use one of two main strategies: aerobic (with plants) and anaerobic treatment (with biogas production).
Water and sanitation
Water is a crucial consideration in the off-grid environment, which must be collected, used, and disposed of efficiently to make use of the environment. There are many ways to supply water for indoor domestic use, which vary based on local access and preference.
Sources
Local water bodies Nearby streams, ponds, rivers, and lakes are easy access points for fresh water. Oceans can also be considered with proper desalination.
Wells and springs
This traditional method involves digging down to where water is present and abundant underground, usually to the water table or to an aquifer, and bringing it up for use, or collecting at springs where underground water comes to the surface. Systems for bringing underground water to buildings include wind and solar driven pumps or hand pumps. Well water should be tested on a regular basis and when changes in the water's taste, odor, or appearance occur to ensure its quality.
Rain catchments This system relies on the weather to provide water. Catchment systems are designed based on the water demand of the users and local rainfall characteristics. Rain water is typically funneled from the roof of a building to water tanks where the water is stored until needed.
Foreign supplies Another, less self-sufficient method involves bringing large amounts of clean water to the site where it is stored. This system relies on access to clean drinking water elsewhere and transportation to the off-grid site.
Devices Atmospheric water generators have a large potential for off-the-grid water generation.
Treatment Wherever the water does come from, it must be safe to drink and use indoors. For various issues with water quality, different water treatment strategies are available.
Filtration
A physical barrier allows water to pass through and blocks impurities in the water and, if the filter is fine enough, can filter out biological contaminants.
Chemical treatment In order to disinfect water, such as chlorine, chlorine dioxide, and ozone are introduced which kill microorganisms.
Ultraviolet light (UV) A UV system uses bulbs that emit ultraviolet light into filtered water to kill all types of viruses, bacteria, and protozoa.
Electrochemically activated solutions A less typical approach, this involves applying a current to water that has a small salt solution added to disinfect biological contaminants. Combined with filtration, this is a means to provide safe drinking water.
Desalination Some groundwater may have high salinity levels and can be non-potable, which is fixed through distillation. Coastal communities may benefit by getting water from the ocean through the use of desalination plants that remove salt.
Water softening The presence of certain minerals in water creates hard water which can clog pipes over time, interfere with soap and detergents, and can leave scum on glasses and dishes. Water softening systems introduce sodium and potassium ions which make the hard minerals precipitate.
Usage and sanitation For off-grid buildings, efficient use of water is needed to prevent water supplies from running out. While this is ultimately habit-dependent, measures involve low-flow fixtures for faucets, shower heads, and toilets which decreases the flow rate of faucets or the volume of water per flush to reduce total water used. Water can be eliminated in toilets through the uses of a composting toilet. Automatic leak detectors and tap closures can reduce amounts of wasted water. Greywater recycling can further save on water by reusing water from faucets, showers, dishwashers, and clothes washers. This is done through storing and treating the grey water, which can then be reused as a non-potable water source.