Dali-micro windturbine

A group of small-scale wind turbines providing electricity to a community in Dali, Yunnan, China

Microgeneration is the small-scale generation of heat and electric power by individuals, small businesses and communities to meet their own needs, as alternatives or supplements to traditional centralized grid-connected power. Although this may be motivated by practical considerations, such as unreliable grid power or long distance from the electrical grid, the term is mainly used currently for environmentally conscious approaches that aspire to zero or low-carbon footprints or cost reduction. It differs from micropower in that it is principally concerned with fixed power plants rather than for use with mobile devices.

Technologies and set-up

Microgeneration technologies include small-scale wind turbines, micro hydro, solar PV systems, microbial fuel cells, ground source heat pumps, and micro combined heat and power installations.[1]

Power plant

In addition to the electricity production plant (e.g. wind turbine and solar panel), infrastructure for energy storage and power conversion and a hook-up to the regular electricity grid is usually needed and/or foreseen. Although a hookup to the regular electricity grid is not essential, it helps to decrease costs by allowing financial recompensation schemes. In the developing world however, the start-up cost for this equipment is generally too high, thus leaving no choice but to opt for alternative set-ups.[2]

Extra equipment needed besides the power plant


The whole of the equipment required to set up a working system and for an off-the-grid generation and/or a hook up to the electricity grid herefore is termed a balance of system[3] and is composed of the following parts with PV-systems:

Energy storage apparatus

A major issue with off-grid solar and wind systems is that the power is often needed when the sun is not shining or when the wind is calm, this is generally not required for purely grid-connected systems:

or other means of energy storage (e.g. hydrogen fuel cells, Flywheel energy storage, pumped-storage hydroelectricity, compressed air tanks, ...)[5]

For converting DC battery power into AC as required for many appliances, or for feeding excess power into a commercial power grid:

Safety equipment

Usually, in microgeneration for homes in the developing world, prefabricated house-wiring systems (as wiring harnesses or prefabricated distribution units) are used instead .[6] Simplified house-wiring boxes and cables, known as wiring harnesses, can simply be bought and mounted into the building without requiring much knowledge about the wiring itself. As such, even people without technical expertise are able to install them. In addition, they are also comparatively cheap and offer safety advantages.[7]

Wind turbine specific

Dali-micro windturbine

With wind turbines, hydroelectric plants, ... the extra equipment needed [8][9][10][11] is more or less the same as with PV-systems (depending on the type of wind turbine used,[12] yet also include:

  • a manual disconnect switch
  • foundation for the tower
  • grounding system
  • shutoff and/or dummy-load devices for use in high wind when power generated exceeds current needs and storage system capacity.
Vibro-wind power

A new wind energy technology is being developed that converts energy from wind energy vibrations to electricity. This energy, called Vibro-Wind technology, can use winds of less strength than normal wind turbines, and can be placed in almost any location.

A prototype consisted of a panel mounted with oscillators made out of pieces of foam. The conversion from mechanical to electrical energy is done using a piezoelectric transducer, a device made of a ceramic or polymer that emits electrons when stressed. The building of this prototype was led by Francis Moon, professor of mechanical and aerospace engineering at Cornell University. Moon's work in Vibro-Wind Technology was funded by the Atkinson Center for a Sustainable Future at Cornell.[13]

Possible set-ups

Several microgeneration set-ups are possible. These are:

  • Off-the-grid set-ups which include:
    • Off-the grid set-ups without energy storage (e.g., battery, ...)
    • Off-the grid set-ups with energy storage (e.g., battery, ...)
    • Battery charging stations [14]
  • Grid-connected set-ups which include:
    • Grid connected with backup to power critical loads
    • Grid-connected set-ups without financial recompensation scheme
    • Grid-connected set-ups with net metering
    • Grid connected set-ups with net purchase and sale [15]

All set-ups mentioned can work either on a single power plant or a combination of power plants (in which case it is called a hybrid power system). For safety, grid-connected set-ups must automatically switch off or enter an "anti-islanding mode" when there is a failure of the mains power supply. For more about this, see the article on the condition of islanding.


Depending on the set-up chosen (financial recompensation scheme, power plant, extra equipment), prices may vary. According to Practical Action, microgeneration at home which uses the latest in cost saving-technology (wiring harnesses, ready boards, cheap DIY-power plants, e.g. DIY wind turbines) the household expenditure can be extremely low-cost. In fact, Practical Action mentions that many households in farming communities in the developing world spend less than $1 for electricity per month. .[16] However, if matters are handled less economically (using more commercial systems/approaches), costs will be dramatically higher. In most cases however, financial advantage will still be done using microgeneration on renewable power plants; often in the range of 50-90% [17] as local production has no electricity transportation losses on long distance power lines or energy losses from the Joule effect in transformers where in general 8-15% of the energy is lost.[18]

In the UK, the government offers both grants and feedback payments to help businesses, communities and private homes to install these technologies. Businesses can write the full cost of installation off against taxable profits whilst homeowners receive a flat rate grant or payments per kW h of electricity generated and paid back into the national grid. Community organisations can also receive up to £200,000 in grant funding.[19]

In the UK, the Microgeneration Certification Scheme provides approval for Microgeneration Installers and Products which is a mandatory requirement of funding schemes such as the Feed in Tariffs and Renewable Heat Incentive.

Grid parity

Grid parity (or socket parity) occurs when an alternative energy source can generate electricity at a levelized cost (LCoE) that is less than or equal to the price of purchasing power from the electricity grid. Reaching grid parity is considered to be the point at which an energy source becomes a contender for widespread development without subsidies or government support. It is widely believed that a wholesale shift in generation to these forms of energy will take place when they reach grid parity.

Grid parity has been reached in some locations with on-shore wind power around 2000, and with solar power it was achieved for the first time in Spain in 2013.[20][21][22]

Comparison with large-scale generation

microgeneration large-scale generation Notes
Other names Distributed generation Centralized generation
Waste Heat by-product

Can be used for heating purposes, thus greatly increasing efficiency and offsetting energy total costs. This method is known as micro combined heat and power (microCHP).

It is used in some privately owned industrial combined heat and power (CHP) installations. It's also use in large-scale applications where it's called district heating and uses the heat that is normally exhausted by inefficient powerplants.[23]

Transmission losses Proximity to end user typically closer resulting in potentially fewer losses. A significant proportion of electrical power is lost during transmission (approximately 8% in the United Kingdom according to BBC Radio 4 Today programme in March 2006).
Changes to Grid reduces the transmission load, and thus reduces the need for grid upgrades increases the power transmitted, and thus increases the need for grid upgrades
Grid failure event Electricity may still be available to local area in many circumstances Electricity may be not available due to grid
Consumer choices May choose to purchase any legal system May choose to purchase offerings of the power company
Reliability and Maintenance requirements photovoltaics, Stirling engines, and certain other systems, are usually extremely reliable, and can generate electric power continuously for many thousands of hours with little or no maintenance. However, unreliable systems will incur additional maintenance labor and costs. Managed by power company. Grid reliability varies with location.
Ability to meet needs
  • For wind and solar energy, the actual production is only a fraction of nameplate capacity.[24]
  • Fuel based systems are fully dispatchable
  • Solar panels are simple and reliable, they can provide a little electricity at a reasonable cost.
  • Commentators claim that householders who buy their electricity with green energy tariffs can reduce their carbon usage further than with microgeneration and at a lower cost.
Economy of scale Necessitates mass production of generators which will create an associated environmental impact. Systems are less expensive when produced in quantity. More economical given the larger scale of the generators.

Microgeneration can dynamically balance the supply and demand for electric power, by producing more power during periods of high demand and high grid prices, and less power during periods of low demand and low grid prices. This "hybridized grid" allows both microgeneration systems and large power plants to operate with greater energy efficiency and cost effectiveness than either could alone.

Domestic self-sufficiency

Micro WindMill

Horizontal Axis Micro-Windmill in Lahore, 1000Watt Rated Output

Microgeneration can be integrated as part of a self-sufficient house and is typically complemented with other technologies such as domestic food production systems (permaculture and agroecosystem), rainwater harvesting, composting toilets or even complete greywater treatment systems. Domestic microgeneration technologies include: photovoltaic solar systems, small-scale wind turbines, micro combined heat and power installations, biodiesel and biogas.

Quietrevolution Bristol 3513051949

A small Quietrevolution QR5 Gorlov type vertical axis wind turbine in Bristol, England. Measuring 3 m in diameter and 5 m high, it has a nameplate rating of 6.5 kW to the grid.

Private generation decentralizes the generation of electricity and may also centralize the pooling of surplus energy. While they have to be purchased, solar shingles and panels are both available. Capital cost is high, but saves in the long run. With appropriate power conversion, solar PV panels can run the same electric appliances as electricity from other sources.[25]

Passive solar water heating is another effective method of utilizing solar power. The simplest method is the solar (or a black plastic) bag. Set between 1 and 5 gallons out in the sun and allow to heat. Perfect for a quick warm shower.[26]

The ‘breadbox’ heater can be constructed easily with recycled materials and basic building experience. Consisting of a single or array of black tanks mounted inside a sturdy box insulated on the bottom and sides. The lid, either horizontal or angled to catch the most sun, should be well sealed and of a transparent glazing material (glass, fiberglass, or high temp resistant molded plastic). Cold water enters the tank near the bottom, heats and rises to the top where it is piped back into the home.[26]

Ground source heat pumps exploit stable ground temperatures by benefiting from the thermal energy storage capacity of the ground. Typically ground source heat pumps have a high initial cost and are difficult to install by the average homeowner. They use electric motors to transfer heat from the ground with a high level of efficiency. The electricity may come from renewable sources or from external non-renewable sources.


Biodiesel is an alternative fuel that can power diesel engines and can be used for domestic heating. Numerous forms of biomass, including soybeans, peanuts, and algae (which has the highest yield), can be used to make biodiesel. Recycled vegetable oil (from restaurants) can also be converted into biodiesel.

Biogas is another alternative fuel, created from the waste product of animals. Though less practical for most homes, a farm environment provides a perfect place to implement the process. By mixing the waste and water in a tank with space left for air, methane produces naturally in the airspace. This methane can be piped out and burned, and used for a cookfire.

The biogaspro digester provides an easily installed digester suitable for small farms or even large homes. Groups of homes can possible group together to use a digester [27]

Government policy

Policymakers were accustomed to an energy system based on big, centralised projects like nuclear or gas-fired power stations. A change of mindsets and incentives are bringing microgeneration into the mainstream. Planning regulations may also require streamlining to facilitate the retrofitting of microgenerating facilities onto homes and buildings.

The United States has inconsistent energy generation policies across its 50 states. State energy policies and laws may vary significantly with location. Some states have imposed requirements on utilities that a certain percentage of total power generation be from renewable sources. For this purpose, renewable sources include wind, hydroelectric, and solar power whether from large or microgeneration projects. Further, in some areas transferrable "renewable source energy" credits are needed by power companies to meet these mandates. As a result, in some portions of the United States, power companies will pay a portion of the cost of renewable source microgeneration projects in their service areas. These rebates are in addition to any Federal or State renewable-energy income-tax credits that may be applicable. In other areas, such rebates may differ or may not be available.

In popular culture

Several movies and TV shows such as The Mosquito Coast, Jericho, The Time Machine and Beverly Hills Family Robinson have done a great deal in raising interest in microgeneration among the general public. Websites such as Instructables and Practical Action propose DIY solutions that can lower the cost of microgeneration, thus increasing its popularity. Specialised magazines such as OtherPower and Home Power also provide practical advice and guidance.[28]

See also


  1. "On-site renewable energy - Renewable Energy - Reusable Energy - The Merton Rule - Pros Cons Renewable Energy Options - Microgeneration - Green Energy Solutions - Ground Source Heat Pumps - Green Energy Options". 
  2. Practical Action - Energy for rural communities
  3. "Office of Energy Efficiency & Renewable Energy - Department of Energy". 
  4. Practical Action - Energy for rural communities (includes short description batteries)
  5. "Welcome to The Sietch - Projects Make Your Own Hydrogen". 
  6. Mentioning of prefabricated house-wiring and its systems
  7. Benefits of wiring harnasses
  8. "Office of Energy Efficiency & Renewable Energy - Department of Energy". 
  9. "Shop Gaiam for yoga, fitness, meditation, active sitting, and wellness products". 
  10. Extra equipment needed with wind turbines (EnergyAlternatives)
  11. "Chispito Information - VelaCreations". 
  12. Schematic showing certain components as controllers built into the wind turbine itself
  13. Ju, Anne (25 May 2010). "Students harness vibrations from wind for electricity". Cornell Chronicle. Retrieved 20 July 2011. 
  14. Battery charging stations explained
  15. "Office of Energy Efficiency & Renewable Energy - Department of Energy". 
  16. Households reducing their energy ependitures to $1 a month using renewable microgeneration
  17. "Office of Energy Efficiency & Renewable Energy - Department of Energy". 
  18. "How big are Power line losses? - Schneider Electric Blog". 25 March 2013. 
  19. UK Grant Funding information
  20. Kelly-Detwiler, Peter. "Solar Grid Parity Comes to Spain". 
  21. "Spain Achieves Grid Parity for Solar Power -". 
  23. Milieu Centraal, 29 April 2009 -- Stadsverwarming en blokverwarming
  24. "Green Building magazine has moved to". 
  25. Fritsch, Al, and Paul Gallimore. Healing Appalachia: Sustainable Living Through Appropriate Technology. Lexington, KY. The UP of Kentucky, 2007.
  26. 26.0 26.1 "How to Build a Passive Solar Water Heater". 
  27. "Renewable Energy Solutions - Living Lightly". 
  28. OtherPower and Home Power as popular diy microgeneration magazines

External links

Systems' self-sufficiency parts

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