Microgeneration

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 Setup

Microgeneration technologies include small-scale wind turbines, hydroelectric plants, photovoltaic solar systems, ground-source heat pumps, and micro combined heat and power (MicroCHP) installations.

The power plant

In addition to the electricity production plant (e.g., wind turbines and solar panels), infrastructure for energy storage and power conversion and a hookup to the regular electricity grid is usually needed or foreseen (or both). 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 setups.

Extra equipment needed besides the power plant

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. The following 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)
• other means of energy storage (e.g., hydrogen fuel cells, Flywheel energy storage, Pumped-storage hydroelectric, and compressed air tanks)
• a charge controller for charging the batteries or other energy storage

For converting DC battery power into AC (as required for many appliances) or feeding excess power into a commercial power grid, an inverter or grid-interactive inverter is required. The whole is also sometimes referred to as "power-conditioning equipment."

Safety equipment

Safety equipment is composed of  groundings, transfer switches or safety disconnects, and surge protectors. 

In the developing world,  prefabricated house-wiring systems (such as wiring harnesses or prefabricated distribution units) are instead used for microgeneration in homes. Simplified house-wiring boxes, known as wiring harnesses, can be simply bought and drilled in the wall without requiring much knowledge of the wiring.  So even villagers are able to install them. In addition, they are comparatively cheap and safe.

Battery meters (for charging rate and voltage), and meters for power consumption and electricity provision to the regular power grid can also be installed. 

Wind turbine specific

With wind turbines, the extra equipment needed is more or less the same as with PV systems (depending on the type of wind turbine used).  The extra equipment needed may also include the following:

• manual disconnect switch
• foundation for the tower
• grounding system
• shutoff or dummy-load device (or both) for use in high wind when power generated exceeds current needs and storage system capacity

Possible setups

As mentioned before, several microgeneration setups are possible. These are:

• Off-the-grid setups, which include:
  • Off-the grid setups without energy storage (e.g., batteries)
  • Off-the grid set-ups with energy storage (e.g., batteries)
  • Battery-charging stations

• Grid-connected setups, which include:
  • Grid-connected setups without a financial recompensation scheme
  • Grid-connected setups with net metering
  • Grid-connected setups with net purchase and sale

All setups mentioned can work either on a single power plant or a combination of power plants. In the latter case, it is called a hybrid power system.

Costs

Depending on the setup chosen (financial recompensation scheme, power plant, or extra equipment), prices may vary. According to Practical Action, household costs can be extremely low, given that  microgeneration at home uses the latest in cost-saving technology (e.g., wiring harnesses, ready boards, and cheap do-it-yourself [DIY] power plants such as wind turbines). In fact, Practical Action mentions that many households in farming communities in the developing world spend less than $1 on electricity per month. However, if matters are handled less economically (using more commercial systems and approaches), costs will be dramatically higher. In most cases, however, financial savings of 50-90%  will still be gained using microgeneration from renewable power plants.

Comparison of Microgeneration and Large-Scale Generation

Microgeneration can dynamically balance the supply and demand for electric power. It does this 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 an Integrated Part of a Domestically Self-Sufficient System

Often, microgeneration is an integrated part of a self-sufficient house. This approach has been popularized by TV series such as It's Not Easy Being Green. Often, it is complemented with other technologies such as solar thermal collectors, domestic food production systems (e.g., permaculture and agro-ecosystem), hydrogen, or extra electricity generation systems for self-sufficient transport. Other systems include water harvesters, composting toilets, or even complete greywater treatment systems. By combining all of these technologies, homeowners can operate their houses autonomously (i.e., without the need of any communal or city services).

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.

Policymakers are used to an energy system based on big, centralized projects such as nuclear or gas-fired power stations. 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 other buildings.

A number of countries, including the United Kingdom, Germany, and the U.S. have laws allowing microgenerated electricity to be sold into the national grid.

United States

The United States is just that -- a union of 50 entities with their own energy policies that may or may not always agree with federal policy. Hence, energy law may vary significantly with location.

Some states have required utilities to generate a certain percentage of their total power from renewable sources such as wind, hydroelectric, and solar power. In some areas, power companies need transferrable "renewable source energy" credits to meet these mandates.

As a result, in some areas of the United States, power companies will pay a portion of the cost of renewable source microgeneration projects in their service areas -- in some cases even if the project is off-grid! These rebates are in addition to any federal or state renewable energy income tax credits that may apply. In other areas, such rebates may differ or may not be available.

United Kingdom

The U.K. government published its Microgeneration Strategy in March 2006, although many commentators saw it as a disappointment. In contrast, the Climate Change and Sustainable Energy Act 2006 has been viewed as a positive step. 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 Labor Science Minister, Malcolm Wicks.

In the December 2006 Pre-Budget Report, 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.

Microgeneration in Popular Culture

Several movies, TV shows, and magazines have popularized microgeneration. Movies such as The Mosquito Coast, Jericho, The Time Machine, and Beverly Hills Family Robinson have done a great deal in raising interest in the general public. More specialized magazines such as OtherPower and Home Power finally are giving more practical advice and guidance.  Finally, web sites such as Instructables and Practical Action are increasing in popularity by proposing DIY solutions that can further decrease the cost of microgeneration.

External Links

• Microgeneration.com - Provides basic information on setting up microgeneration at home
• USDA EERE's off-grid generation page
• Instructables' article on how to set up an autonomous home in a cheap way
• Information on precise domestic power consumption calculations to create partial or completely off-grid systems
• Practical action's information on setting up microgeneration at home
• Earthship Biotincture's information and practical (low-cost) modules on setting up microgeneration systems in practice
• VillageEarth AT SourceBook: Contains information on microgeneration systems and setups
• BlueEnergy - Provides general schematic of parts required for self-sufficient energy generation system, and also provides info on DIY equipment (wind turbine in setups)
• PESwiki Home Generation: contains information on microgeneration and the setup of self-sufficient homes