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
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.
Extra equipment needed besides the power plant
The whole of the equipment required to set up a working system and for a off-the-grid generation and/or a hook up to the electricity grid herefore is termed a balance-of-system and is composed of 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 (eg hydrogen fuel cells, Flywheel energy storage, Pumped-storage hydroelectric, compressed air tanks, ...)
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"
Usually, in microgeneration for homes in the developing world, a prefabricated house-wiring systems (as wiring harnesses or prefabricated distribution units) is used instead . 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.
Wind turbine specific
With wind turbines, hydroelectric plants, ... the extra equipment needed is more or less the same as with PV-systems (depending on the type of wind turbine used , 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.
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 (eg battery, ...)
- Off-the grid set-ups with energy storage (eg battery, ...)
- Battery charging stations
- 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 to electricity per month. . 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%
Comparison of Microgeneration and Large-Scale generation
|| large-scale generation
| 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).
Is often not used in centralized electric power plants. It is used in some privately-owned industrial combined heat and power (CHP) installations.||
| Transmission losses
|| Proximity to end user typically closer resulting in 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
|| Focused on the energy crisis
|| Both produce electricity. Both are subject to misinformation. Buyer beware. |
| Ability to meet needs
- For wind and solar energy, the actual production is only a fraction of maximum rated capacity.
- 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
|| Favors mass production, and systems are less expensive when produced in quantity
|| Favors larger systems, and systems are less expensive when production capacity is higher
|| Both have advantages and disadvantages. Overall efficiency is highest when a mix of both is used. |
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
Often, microgeneration is an integrated part of a self-sufficient
house. This approach has been popularised by TV series such as It's not easy being green
. Often, it is complemented with other technologies as solar thermal collectors
, domestic food production
systems (as permaculture
, ...), hydrogen
or extra electricity generation systems for self-sufficient transport, water harvesters
and composting toilets
or even complete greywater treatment
systems. By combining all these technologies, home owners can operate their house autonomously, i.e. without the need of any communal/city services.
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 and USA have laws allowing microgenerated electricity to be sold into the national grid.
The United States is just that -- a union of 50 entities that sometimes have their own energy policy, which may or may not always agree with Federal policy. Hence energy law 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 -- 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 be applicable. In other areas, such rebates may differ or may not be available.
The UK Government published its Microgeneration Strategy in March 2006, although it was seen as a disappointment by many commentators. 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 Labour 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
Microgeneration has been popularised by several movies, TV-shows, magazines, ...
Movies as The Mosquito Coast
, The Time Machine
, Beverly Hills Family Robinson
have done a great deal in raising interest to the general public. More specialised magazines as OtherPower
and Home Power
magazine finally are giving more practical advice/guidance. Finally websites as Instructables
, Practical Action
, ... are again increasing popularity by proposing DIY-solutions which can decrease the cost of microgeneration even further.
External links on the systems' self-suffiency parts