Small Energy Sources Everywhere

Photovoltaic 'tree' in Austria
Solar photovoltaic 'tree' in Styria, Austria

Parts/Contexts:

Local energy sources that are too small to connect to large-scale systems.

Keywords:

renewable energy sources, wind power, wind turbines, solar power, solar cells, solar heating, hyrdopower, micro-hydro, geothermal power, geothermal heat pump, energy recovery and recycling

Predecessor Patterns

. . . Using Local Energy Sources can reduce a region's reliance on foreign sources, but using them for large-scale centralized energy systems isn't the only solution. Using many small decentralized energy sources that are also local, even better renewable, can help further achieve energy independence.

Problem Summary

While increasing, the use of small decentralized local energy sources to independently power individual buildings, products and equipment still has untapped potential.

Analysis

Economies of Scale

In principle this pattern is all about scaling energy sources to fit energy uses. The terms large and small, centralized and decentralized are relative. For example, unless wind farms are connected to a national electrical supergrid they are relatively decentralized. But a wind farm is larger than a single wind turbine, and they are still connected as a relatively big centralized system compared to an individual building. This pattern addresses the potentials and benefits of the extreme end: small decentralized energy sources for small decentralized energy uses.

The world's major non-renewable energy sources, oil, coal, natural gas and nuclear, generally aren't suited as small local energy sources. While in some ways they have great economies of scale, they all require considerable processing and refinement to make the raw materials into usable energy forms. Few people have coal mines in their back yards where they can pick a shovel full of coal to power their coal burning furnaces. You don't fill up your car's gas tank with crude oil, and you don't power a nuclear plant with raw uranium ore.

Processing these non-renewable energy sources requires a large industrial infrastructure, which economically requires large volumes of raw materials, which requires transporting those materials to large centralized processing facilities. After processing them in centralized facilities, getting the refined energy sources to where they are needed requires large, integrated distribution systems.

In contrast, one or more of the world's major renewable energy resources, biomass, hydropower, solar, wind and geothermal, are in some form available almost everywhere, and small sources of these can be used locally with a minimum of processing and equipment, much less a large centralized industrial complex to refine the energy itself.

Pumping water for livestock
Using wind and solar power to pump water for livestock

Small local renewable energy sources could be tied into large-scale centralized energy systems, but for various reasons, whether environmental, technical or economic, this isn't always feasible. First, small energy sources might be too far from large distribution systems to make their transport or transmission economically viable. Second, even if they could be easily connected to a large distribution system, accommodating many small sources into the system presents other problems, for example, regulating the intermittent output of solar and wind power for fluctuating load demands in the electrical grid. Rather than tying them into a large energy infrastructure, small local energy sources are better suited to direct local use as decentralized stand-alone systems, scaled to power small communities, buildings, vehicles and devices.

Even where using a small local energy source in a large centralized system is feasible, many small decentralized uses of that source can collectively produce a lot of energy, even rivaling the total amount produced by centralized systems. For example, instead of a large-scale electric power plant based on big solar photovoltaic panels, smaller solar panels on individual buildings, and solar cells on a multitude of devices, could collectively produce a tremendous amount of electric power.

Using small energy sources everywhere has other advantages. Since the distribution system for local energy sources is smaller it takes less energy, materials and money to get the energy where it's needed. While waiting for a large centralized facility for a given energy source to come on line, the contribution of small decentralized energy sources would be relatively immediate, ramping up over time to equal or exceed the capacity of that one facility. Small electrical energy sources, even intermittent ones like wind and solar, can be networked in small decentralized local "smart grids" that gradually interconnect to make regional and national smart grids.

Small Biomass Sources

A lot of energy can come from local biomass sources that might otherwise be discarded and wasted. A common use of small biomass power is burning wood from trees that have been cut down or trimmed in fireplaces and Franklin stoves. Where forests are harvested and wood products are manufactured, wood chips are another local source. Where wood is pulped, such as in the production of paper, pulping liquor or "black liquor" can be burned in recovery boilers. Other forms of local biomass energy include organic municipal solid wastes (notably paper), organic manufacturing wastes, scrap wood materials from construction and demolition, and biogas from agricultural wastes and landfills.

Small Hydropower

The oldest form of hydropower uses water motion to turn a water wheel, which turns a shaft to provide mechanical power. Today large sources of hydropower entail running rivers of water through huge dams to turn big generators in hyrdoelectric plants. Large hydroelectric dams aren't practicable where a fast moving stream is too small, or the land around a large river is too low. At these hydropower sources many small current generators could produce a lot of electricity with "micro-hydro" and damless hydroelectric technology.

Small Solar Sources

In urban areas where there is no open space for a large photovoltaic power station, putting photovoltaic panels on lots of rooftops and over parking lots could be equivalent to, or even bigger than, an humongous solar farm out it the desert. Solar photovoltaic cells are increasingly being used to power devices, from satellites to products such as wrist watches, calculators, garden lights, street lights, and battery chargers. We can imagine innovative uses of photovoltaic cells, such as arrays on top of hybrid-electric buses and trucks to help charge the batteries and increase range.

In addition to directly producing electricity, another form of small decentralized solar power is utilizing heat from the sun. Some big solar plants use mirrors to focus its heat to produce steam to drive electric generators. A more common use of solar energy is to use it directly for small space and water heating, whether actively with solar thermal collectors, or implementing passive solar building designs.

Small Wind Sources

The oldest forms of wind power include sail boats and wind mills. Today the biggest form of wind power employs big turbines in wind farms to produce electricity. Small wind turbines can be used to generate electricity off-grid for individual buildings and to power equipment. When not directly supplying electricity these typically are used to charge batteries. Where wind speeds are relatively low a big wind turbine might not work well, but a whole bunch of little ones could collectively add up to a lot of power.

Small Geothermal Sources

Large geothermal energy facilities poke deep into the earth's crust to tap heat to produce steam to turn generators to produce electricity. But a form of local geothermal power can be used to heat and cool individual buildings everywhere. The old fashioned root cellar took advantage of underground temperatures, which are quite constant throughout the year below the frost line, roughly the average annual temperature above ground. Simply putting a building's foundation below the frost line helps flatten out temperature extremes, reducing energy demands for heating and cooling throughout the year. Geothermal heat pumps which circulate air through channels or water through tubing deep underground can both heat and cool buildings. A variation of geothermal heat pumps uses cool water deep in wells, ponds or lakes to cool buildings. Where the ground is unusually warm, such as near hot springs and steam vents, the energy can be directly used to heat buildings.

Other Small Energy Sources

There are many other existing and potential ways to use small energy sources to collectively off-load large centralized systems. A whole category of examples capture energy that would otherwise be wasted through energy recovery and recycling. These examples include recovering waste heat in manufacturing for space heating and electricity, cogeneration systems that produce both electricity and heat, and regenerative braking systems in electric and hybrid-electric vehicles that charge the batteries.

Solution Summary

Therefore:

Use small local energy sources as decentralized stand-alone systems, scaled to directly power small communities, buildings, vehicles and devices.

Successor Patterns

Use small locally available energy sources for temperature control, such as Passive Solar Heating and Cooling and Geothermal Heating and Cooling . Use small locally available energy sources for electric power, such as Micro-hydropower where there are small rivers and streams, Small Wind Turbines where it is fairly windy, and Small Solar Photovoltaics to power small communities, individual buildings, vehicles and devices wherever the sun shines. Solar Carports everywhere can help power adjacent buildings and recharge plug-in electric vehicles while sheltering them from the sun and weather. Use small sources of energy that might otherwise be wasted with Energy Recovery and Recycling such as waste heat recovery, cogeneration systems that produce both electricity and heat, and regenerative braking systems to slow and stop electric and hybrid-electric vehicles. Use Small Mechanical Power Sources like windmills and water wheels to raise water from wells, turn crankshafts, etc. . . .


References/Sources

  1. Distributed generation at Wikipedia.
  2. Small Wind Systems at the State Energy Conservation Office of Texas.
  3. Photovoltaics at Wikipedia.
  4. Small hydro at Wikipedia.
  5. Energy recycling at Wikipedia.

Author/Date

Gary Swift, 14 November 2008.
09 February, 2009. Added link to Solar Carports.
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