Microgeneration: Wikis


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Microgeneration is the generation of zero or low-carbon heat and power by individuals, small businesses and communities to meet their own needs.


Technologies and set-up

Microgeneration technologies include small scale wind turbines, hydroelectric plants, photovoltaic solar systems, ground source heat pumps, and Micro Combined Heat and Power (MicroCHP) installations.[1]


The power plant

In addition to the electricity production plant (eg wind turbine, 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

A complete PV-solar system

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:

  • a series of deep cycle, solar, stationary or sealed maintenance free batteries (the most common solution) [4]

or other means of energy storage (eg hydrogen fuel cells, Flywheel energy storage, Pumped-storage hydroelectric, 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:

  • an inverter or grid-interactive inverter. The whole is also sometimes referred to as "power conditioning equipment"

Safety equipment

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

Small scale (DIY) generation system

Wind turbine specific

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.

Possible set-ups

As mentioned before, 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 [13]
  • Grid-connected set-ups which include:

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).


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 (eg 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. .[15] 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% [16]

A recent summary of the various microgeneration technologies indicates that most are extremely expensive methods of carbon abatement with the exception of micro CHP [17]

Comparison of Microgeneration and 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.[18]

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.
sales-pitch exaggerations Focused on the "green-ness" of energy [19] Focused on the energy crisis Both produce electricity. Both are subject to misinformation.
Ability to meet needs
  • For wind and solar energy, the actual production is only a fraction of nameplate capacity.[20]
  • Fuel based systems are fully dispatchable
  • Some solar panels are simple to install and will provide green energy regardless of fluctuations in electricity markets, according to Jeremy Leggett.
  • 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.

Microgeneration as integrated part of domestic self-sufficient system

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), hydrogen or other extra electricity generation systems for self-sufficient transport, water harvesters, composting toilets or even complete greywater treatment systems. Domestic microgeneration technologies include: photovoltaic solar systems, small scale wind turbines, ground source heat pumps, micro combined heat and power installations, biodiesel and biogas.

5 Kilowatt Vertical Axis Wind Turbine by Green EcoSys & Electron Solar Energy

Installing Solar Photovoltaic systems decentralizes the generation of electricity and centralizes the pooling of surplus energy. While they have to be purchased, solar shingles and panels are both available. Initial startup costs more, but saves in the long run. Solar PV panels can run any number of electric appliances including fans, water pumps, food dryers, signs, refrigerators, fencing and even entertainment electronics. [21]

Passive solar 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. [22]

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. You can acquire designs through the National Center for Appropriate Technology or design your own. [23]

Wind turbines can be purchased for a wide range of prices. It takes a little more technical knowledge to assemble one yourself but plans are available Mother Earth News.

Ground source heat pumps utilize stable ground temperatures to maintain heat in the pumps. Typically ground source heat pumps have a high initial cost and can’t be created by the average homeowner. While efficient, they are still hooked to non-renewable energy systems. Try combining ground heat with photovoltaics or wind generators. [21]

Biodiesel, an alternative diesel made from used vegetable or cooking oil from restaurants, is a limited fuel source, but utilizes a waste product. You can transform any diesel vehicle to run on biofuels, as long as they are brewed properly. If you already own a diesel vehicle, this change is simple, requiring only a recipe for biofuel and a restaurant willing to give up their waste oil. Domestic heat can also run on biofuels, though it takes more effort in revamping the infrastructure of your heating system. [24]

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. [21]

Government policy

There is considerable resistance to microgeneration from many governments, local authorities and energy companies. Current incentives discourage energy suppliers and grid operators from bringing energy generation to the point of demand.

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

A number of countries, including the United Kingdom, Germany, Israel[25] and USA have laws allowing microgenerated electricity to be sold into the national grid.

United States

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.

United Kingdom

The UK Government published its Microgeneration Strategy[26] in March 2006, although it was seen as a disappointment by many commentators.[27] In contrast, the Climate Change and Sustainable Energy Act 2006 has been viewed as a positive step.[28] To replace earlier schemes, the Department of Trade and Industry (DTI) launched the Low Carbon Buildings Programme in April 2006, which provides grants to individuals, communities and businesses wishing to invest in microgenerating technologies.

Prominent British Politicians who have announced they are fitting microgenerating facilities to their homes include the Conservative party leader, David Cameron, and the Labour Science Minister, Malcolm Wicks.

In the December 2006 Pre-Budget Report[29] the Government announced that the sale of surplus electricity from installations designed for personal use, would not be subject to Income Tax. Legislation to this effect is to be included in the Finance Bill 2007.

In June 2009 Better Generation[30], the popular green energy site, launched the Power Predictor[31] which the easiest way for UK residents to find out if their site is suitable for microgeneration.

Microgeneration in popular culture

Microgeneration has been popularised by several movies, TV-shows, and magazines. Movies such as The Mosquito Coast, Jericho, The Time Machine, and Beverly Hills Family Robinson have done a great deal in raising interest to the general public. More specialised magazines such as OtherPower and Home Power give more practical advice and guidance.[32] Websites such as Instructables and Practical Action are increasing the popularity of microgeneration by proposing DIY-solutions which can decrease the cost of microgeneration.

See also


  1. ^ Microgeneration technology options
  2. ^ Practical Action - Energy for rural communities
  3. ^ Equipment required for off-grid-operation
  4. ^ Practical Action - Energy for rural communities (includes short description batteries)
  5. ^ Hydrogen fuel cells for domestic energy generation
  6. ^ Mentioning of prefabricated house-wiring and its systems
  7. ^ Benefits of wiring harnasses
  8. ^ Balance-of-system for wind turbines
  9. ^ Extra equipment needed with wind turbines (Gaiam)
  10. ^ Extra equipment needed with wind turbines (EnergyAlternatives)
  11. ^ System layout + schematic of diy wind turbine
  12. ^ Schematic showing certain components as controllers built into the wind turbine itself
  13. ^ Battery charging stations explained
  14. ^ Net purchase and sale explained
  15. ^ Households reducing their energy ependitures to $1 a month using renewable microgeneration
  16. ^ EERE mentioning 50-90% financial advantage using microgeneration
  17. ^ "What is microgeneration?" Jeremy Harrisson, paper given at the Claverton Energy Conference, Bath 24th Oct 2008
  18. ^ Milieu Centraal, 29 april 2009 -- Stadsverwarming en blokverwarming
  19. ^ Low wattage thinking, New Scientist, 30 September 2006, page 24 -- preview of part of article
  20. ^ Green building magazine - the No.1 sustainable building magazine
  21. ^ a b c Fritsch, Al, and Paul Gallimore. Healing Appalachia: Sustainable Living Through Appropriate Technology. Lexington, KY. The UP of Kentucky, 2007.
  22. ^ http://www.motherearthnews.com/Green-Homes/2007-10-01/Build-Your-Own-Solar-Water-Heater.aspx
  23. ^ http://www.motherearthnews.com/Green-Homes/2007-10-01/Build-Your-Own-Solar-Water-Heater.aspx
  24. ^ http://www.motherearthnews.com/Green-Transportation/2006-02-01/Biodiesel.asp
  25. ^ [1]State of Israel Public Utilities Authority Decision #216 (Hebrew)
  26. ^ UK Department of Trade and Industry Microgeneration Strategy
  27. ^ Home power plan 'disappointment' BBC News report on the UK Department of Trade and Industry Microgeneration Strategy
  28. ^ Sustainable energy groups welcome parliamentary initiative to reduce climate change emissions, article by micropower on the Climate Change and Sustainable Energy Act 2006
  29. ^ [2] Pre-Budget Report 2006, Section 7.31.
  30. ^ [3]
  31. ^ [4]
  32. ^ OtherPower and Home Power as popular diy microgeneration magazines

External links

External links on the systems' self-suffiency parts

UK related


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