The Audubon Center of the North Woods, on Grindstone Lake near Sandstone

Sandstone, Minnesota

As of the census of 2000, there were 1,549 people, 580 households, and 359 families residing in the city. The population density was 292.5 people per square mile . There were 634 housing units at an average density of 119.7 per square mile...

, Minnesota

Minnesota

Minnesota is a U.S. state located in the Midwestern United States. The twelfth largest state of the U.S., it is the twenty-first most populous, with 5.3 million residents. Minnesota was carved out of the eastern half of the Minnesota Territory and admitted to the Union as the thirty-second state...

, is a non-profit

Non-profit organization

Nonprofit organization is neither a legal nor technical definition but generally refers to an organization that uses surplus revenues to achieve its goals, rather than distributing them as profit or dividends...

 residential environmental

Environmentalism

Environmentalism is a broad philosophy, ideology and social movement regarding concerns for environmental conservation and improvement of the health of the environment, particularly as the measure for this health seeks to incorporate the concerns of non-human elements...

 learning center, wildlife

Wildlife

Wildlife includes all non-domesticated plants, animals and other organisms. Domesticating wild plant and animal species for human benefit has occurred many times all over the planet, and has a major impact on the environment, both positive and negative....

 rehabilitation facility, and conference/retreat facility.

Located about 5 miles (8 km) west of Sandstone, the Audubon Center provides environmental education

Education

Education in its broadest, general sense is the means through which the aims and habits of a group of people lives on from one generation to the next. Generally, it occurs through any experience that has a formative effect on the way one thinks, feels, or acts...

 about the various renewable energy

Renewable energy

Renewable energy is energy which comes from natural resources such as sunlight, wind, rain, tides, and geothermal heat, which are renewable . About 16% of global final energy consumption comes from renewables, with 10% coming from traditional biomass, which is mainly used for heating, and 3.4% from...

 systems that it uses, including geothermal heating

Geothermal heating

Geothermal heating is the direct use of geothermal energy for heating applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a total of 270 PJ of geothermal heating in 2004...

 and cooling (ground source heat pumps), wind generators

Wind turbine

A wind turbine is a device that converts kinetic energy from the wind into mechanical energy. If the mechanical energy is used to produce electricity, the device may be called a wind generator or wind charger. If the mechanical energy is used to drive machinery, such as for grinding grain or...

, biodiesel

Biodiesel

Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....

-powered vehicles which run on used vegetable oil, and grid-connected solar arrays

Photovoltaic module

A solar panel is a packaged, connected assembly of solar cells, also known as photovoltaic cells...

. The 535 acres (2.2 km²) sanctuary includes over 7 miles (11.3 km) of hiking

Hiking

Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...

 and cross-country ski

Cross-country skiing

Cross-country skiing is a winter sport in which participants propel themselves across snow-covered terrain using skis and poles...

 trails through a variety of habitats, such as old-growth red and white pines, hardwood forests, restored wetland

Wetland

A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

s and prairie

Prairie

Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...

s.