Off-the-grid

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[4] 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,[5] 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 (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.[6] 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 energy can be harnessed by wind turbines. Wind turbines components consist of blades that get pushed by wind, gearboxes, controllers, generators, breaks, and a tower.[7] 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.[8]

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.[9][10] 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 be provide power to coastal areas.[11]

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. Common batteries include the lead-acid battery and lithium-ion battery.[12]

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.[13]

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 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.

Nearby streams, ponds, rivers, and lakes are easy access points for fresh water. Oceans can also be considered with proper desalination.

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.[20] Systems for bringing underground water to buildings include wind and solar driven pumps or hand pumps.[21] 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.[22]

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.[23] Rain water is typically funneled from the roof of a building to water tanks where the water is stored until needed.

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.[24]

Atmospheric water generators have a large potential for off-the-grid water generation.[25]

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.

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.[26]

In order to disinfect water, such as chlorine, chlorine dioxide, and ozone are introduced which kill microorganisms.[27]

A UV system uses bulbs that emit ultraviolet light into filtered water to kill all types of viruses, bacteria, and protozoa.[28]

A less typical approach, this involves applying a current to water that has a small salt solution added to disinfect biological contaminants.[29] Combined with filtration, this is a means to provide safe drinking water.

Some groundwater may have high salinity levels[30] 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.

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.[31]

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.[32] 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 greywater, which can then be reused as a non-potable water source.

If an off-grid home is not connected to a sewer system, a wastewater system must also be included. On-site wastewater management is usually done through storage and leaching. This involves storing greywater and blackwater in a septic tank or aeration tank to be treated, which is connected to a leaching field that slowly allows the water to percolate out into the ground. While more and expensive waste water treatment options are also available, this is a common reliable means to dispose of waste water without polluting the environment.

Canada has about 175 aboriginal and northern off-grid communities, defined as "a community that is neither connected to the North American electrical grid nor to the piped natural gas network; it is permanent or long-term (5 years or more), and the settlements have at least 10 permanent buildings."[33] Aboriginal Affairs and Northern Development Canada lists the following environmental concerns for these off-grid communities:

• Burning large amounts of diesel produces substantial greenhouse gas emissions. This contributes to climate change which negatively affects communities.
• Fuel must be transported long distances by airplane, truck or barge, leading to a greater risk of fuel spills.
• The transportation of fuel by trucks on winter roads impacts the environment negatively through high greenhouse gas emissions from the vehicles.
• Fuel spills may take place while the fuel is being transported and stored, posing environmental risks.
• Fuel tank leaks contaminate soil and groundwater.
• Generators can be noisy and disruptive, especially in quiet, remote communities.
• Emissions from diesel generators could contribute to health problems in community members.[33]

The environmental impacts of the systems used in off-grid buildings must also be considered due to embodied energy, embodied carbon, choice and source of materials, which can contribute to world issues such as climate change, air, water, and soil pollution, resource depletion and more.[34]

The concept of a sustainable off-grid community must take into consideration the basic needs of all who live in the community. To become truly self-sufficient, the community would need to provide all of its own electrical power, food, shelter and water. Using renewable energy, an on-site water source, sustainable agriculture and vertical farming techniques is paramount in taking a community off the grid. A recent concept design by Eric Wichman shows a multi-family community, which combines all of these technologies into one self-sufficient neighborhood. To grow the community you simply add neighborhoods using the same model as the first. A self-sustained community reduces its impact on the environment by controlling its waste and carbon footprint.

In situations where grid parity has been reached, it becomes cheaper to generate one's own electricity rather than purchasing it from the grid. This depends on equipment costs, the availability of renewable energy sources, and the cost of a grid connection. For example, in certain remote areas a grid connection would be prohibitively expensive, resulting in grid parity being reached immediately.

It is often done to residential buildings only occasionally occupied, such as vacation cabins, to avoid high initial costs of traditional utility connections. Other people choose to live in houses where the cost of outside utilities is prohibitive, or such a distance away as to be impractical. In his book How to live off-grid Nick Rosen lists seven reasons for going off-grid. The top two are saving money, and reducing the carbon footprint. Others include survivalists, preparing for the collapse of the oil economy and bringing life back to the countryside.[35]

Reliable centralized electricity systems have provided supply constancy which has bolstered societies and their economies.[36] Electricity provides opportunities for improved productivity, learning, and hygienic end-uses in the home, such as cooking without the use of polluting biomass fuel sources, yet as of 2016, 20 percent of people world wide lived without it.[37] Bridging the gap from the current under-provision of grid electricity to universal access has been projected to require US$17 trillion and 30 years even on a rigorous timetable.[38] Researchers have argued that a lack of centralized energy infrastructure can result in low resilience to damage to productivity and property from changing climates and severe weather.[38][39] In addition, the advantages of central power generation and distribution are receding in the face of climatic degradation due to fossil fuel powered generation, vulnerabilities to extreme weather events and electronic manipulation, and increasingly complex design and regulatory processes.[36]

Decentralized, off-grid energy systems can constitute a sustainable interim alternative to extending national grids to rural customers.[39] Those using limited off-grid power as a stepping stool to eventual grid access can accumulate energy efficient knowledge, behavior, and products that confer added resiliency while grid networks increase in reliability[39] and carbon neutrality. However, providing off-grid electricity to rural users without also including training and education about its use and applications can result in under-utilization.[38][40] To counteract this possibility, off-grid systems should reflect the cultural structures, values, and mores of host communities.[37][41]

Off-grid electrical systems can power individual residences or a community linked in a shared arrangement known as a micro-grid. In addition, they may be powered by renewable energy sources or by conventional fossil fuels. In Kenya, Mpeketoni township began a community-based, diesel-powered micro-grid project (the Mpeketoni Electricity Project [MEP]) in 1994 with an outlay of approximately US$40,000, and eventually grew to serve 105 residences and 116 commercial, educational, government, and healthcare buildings.[42] The MEP demonstrated unanticipated supply and demand effects when artisans using tools powered by MEP electricity increased their productivity enough to cause depreciation of their wares, necessitating lowering of their prices; however, higher volumes of sales eventually offset these losses.[42] MEP electricity facilitated cold storage of agricultural products, in addition to well pumping, which allowed students who previously spent several hours per day fetching water to spend that time studying in the evening by electric light.[42] Electricity provided by the MEP also expanded teaching hours and sanitation at local schools through electric lighting and pumped water.[42] The MEP off-grid project had numerous direct and indirect benefits for community members, and because the MEP emphasized promotion of the uses for electricity and the community had the ability to pay nominal rates for its use, the project achieved 94 percent cost recovery in its first ten years of operation.[42]