Examples of Renewable Resources

Vijayalaxmi Kinhal
Contributor: Beth Asaff
Renewable energy

Renewable resources can be seen daily around the world. Putting an emphasis on renewable and sustainable resources, for energy as well as other material goods, can make a big environmental impact by creating a smaller environmental footprint.

What Makes a Resource Renewable?

A renewable resource is defined as a natural resource that renews itself at a rate that is faster, or equal to the rate of consumption, according to Oregon State University. Renewable resources differ from resources that once depleted never return, such as fossil fuels. The use and cultivation of renewable resources helps to minimize the impact humanity has on the Earth while supporting a growing population, notes Investopedia.

  • Recycling renewable resources: Sometimes renewable resources and recycling can go hand-in-hand. Paper and trees for example, can be a renewable resource when enough time is given for trees to reseed and replenish harvested forests.
  • Equality of renewables: All renewable resources are not equal as Scitable by Nature Education emphasises. Each resource is renewed at different time scales. So examples of renewable resources can be broken down into three categories: sustainable or inexhaustible, naturally renewable resources, and renewable commodities.

Sustainable Resources

Sustainable resources are those that are perpetually available or seem infinite. These resources are inexhaustible and can be used indefinitely.

Sun and Solar Energy

The sun, which is expected to exist for another six billion years, compared to human lifespan seems to last forever. This makes solar energy a reliable source.

Air Energy

The Earth is the only planet known that has an atmosphere made of air that makes life possible observes Space.com. The important and major components are nitrogen, oxygen, carbon dioxide and hydrogen. However, air pollution is developing into a threat.

Tidal Energy

As the National Oceanic and Atmospheric Administration (NOAA) puts it, "Tides are one of the most reliable phenomena in the world." They are caused by gravity that the sun and moon exert on the oceans, and inertia that keeps the water moving. Continental shorelines are major factor influencing direction and tide strength. Tidal energy is a major alternative source.

Geothermal Power

This energy uses the near constant heat available at deeper levels in the soil for heating and cooling buildings be it homes, institutions or greenhouses. Geothermal energy is available everywhere on land.

Renewable Resources

Renewable resources are those that naturally replenish themselves at a sustainable rate, when not polluted or degraded by human activities, in which case they have long renewable times.

Water

Trees and Stream In Forest

Ground water and open water sources like rivers and streams are dependent on a functional and vegetated watershed to recharge, and are necessary for drinking, growing crops and many manufacture processes. Moreover as National Geographic reports, deforestation is decreasing rainfall and the water cycle is being disrupted. These sources are also being contaminated by pollution which can impact environmental and human health. It is necessary to conserve water and use it efficiently to prevent its shortage.

Hydroelectricity

Hoover Dam

Hydroelectricity is usually produced with dams, and rivers can go dry due to deforestation reducing hydropower, unless forests in the catchment area are protected.

Soil

Soil provides the substrata to live and grow crops. It can be degraded, polluted and lose fertility and productivity, making soil conservation important.

Renewable Commodities

Renewable commodities are those items that are depleted, but careful harvesting, planting and recycling can make commodities renewable that might otherwise be lost.

Trees and Crops

Trees require more years to grow and mature than annual and biennial crops, which means the latter's renewability is higher. Given good weather and water supply it is possible to harvest three or more crops in a year, according to Food Agriculture Organization.

  • Grains In Market
    Annual food crops produce most of the food - cereals, pulses, oilseeds, vegetables and many fruits.
  • Fibres are derived from cotton, flax, and hemp, and jute.
  • Pastures and fodder crops are the main source of feed for animals which give milk, meat and leather.
  • Perennial trees produce many fruits, oil, and materials like rubber.
  • Timber and pulp are obtained by cutting down forests and trees, which is currently happening at unsustainable rates. World Wildlife Fund (WWF) fears "(u)nsustainable logging by some businesses in the paper industry degrades forests, accelerates climate change and leads to wildlife loss." Forty percent of wood is used for making paper and paperboard alone. WWF urges producing 70% of paper by 2020 from recycled sources to protect forests.

Natural Fertilizers

There are many renewable sources which were used before the advent of unrenewable chemical fertilizers in farming. Organic farming and gardens rely on them. They include manure and compost from farm and animal waste, fish- and blood-meal from factory wastes, bird and bat guano, marine kelp and mulch according to SFGate.

Bioenergy

This popular alternative source of energy includes waste biomass, bioenergy crops like wheat switch grass, poplar, and miscanthus, and from methane production from landfills or animal waste. Biogas and bioethanol can also be derived from biomass and energy crops.

Five Major Renewable Energy Sources

In 2015 at the Paris Agreement initiated by the United Nations Framework Convention on Climate Change, 197 nations agreed to work towards limiting temperature rise to below 1.5 degrees Celsius. The U.S. is also a signatory as listed at the United Nations (UN). The U.S. submission to the UN aims to reduce "its greenhouse gas emissions by 26% -28% below its 2005 level in 2025 and to make best efforts to reduce its emissions by 28%." The International Renewable Energy Agency (IRENA) says it is possible to get 36% of energy from renewables by 2030 to help achieve necessary reduction in emissions.

There are also many other benefits to the environment and society in using renewable energy. The U.S. or the world can take advantage of any of the following sources, points out National Renewable Energy Laboratory (NREL). Renewables accounted for 15% of energy produced in U.S. by 2016, according to U.S. Energy Information Administration FAQ (EIA).

1. Wind Power

Wind turbines at sea

Power is generated from wind by converting its energy into electricity, explains NREL's wind basics page. The EIA FAQ figures show that in 2016, 5.6% of energy produced in U.S. originated from wind power. The use of wind turbines is expected to increase in the future, both on land and in the ocean, propelled by new designs claims Popular Mechanics. The two main types of wind power generation are explained by Centurion Energy:

  • Vertical Axis - This type of turbine operates with its main rotator shaft arranged vertically. A vertical axis turbine works well for areas with variable wind speeds.
  • Horizontal Axis - This turbine type has a rotating shaft mounted horizontally on a vertical tower or pole. This turbine works well in flat, large areas such as a field or ocean.

2. Hydropower

Power harnessed from water accounts for 6.5% of energy generation in U.S., according to the EIA FAQ. The U.S. Department of Energy (DOE) explains that this dynamic source of energy can be produced in multiple ways:

  • Impoundment or dam hydropower: This uses dams to store large quantities of water, that are released when electricity is needed to work the turbines to generate electricity for many weeks and months. There are 2,400 dams in the U.S. producing hydroelectricity.
  • Pumped-storage hydropower: Here water is stored in lower and upper reservoir. During times of surplus energy the water is pumped up, and released down to the lower reservoir through turbines for electricity production in times of demand
  • Run- of-river or diversion hydropower: This type of power is extracted from the natural flow of rivers.
  • Tidal or offshore hydropower: This type of power is generated by the tides of oceans and seas, according to International Hydropower Association.

3. Geothermal Energy

The near constant earth temperatures can be used for energy generation that is nearly emission free for heating and cooling by using geothermal heat pumps (GHPs). The US has been a world leader in geothermal energy production a 2017 Renewable Energy World report states. It contributed 0.4% of the energy needs of the US in 2016 according to EIA FAQ.

Geothermal energy works through either closed or open loop systems. You'll find plenty of advantages to geothermal energy, but there are also bad things about the pumps, depending on the system selected. In U.S., of 1.4 million GHPs 90% are closed loop and only 10% are open loop systems in 2015, according to a report from the Proceedings World Geothermal Congress (p. 6).

4. Solar Energy

The U.S. produced 0.9% of its energy from solar in 2016 according to EIA FAQ. Bloomberg points out this was also the year that solar power generation nearly doubled (95%) in US. The DOE explains "There are two main types of solar energy technologies-photovoltaic (PV) and concentrating solar power (CSP)."

  • Photovoltaics funnel the sun through a specific medium like copper or silicon to harness the energy from solar radiation. It is the type that is used on roof-tops for residents and buildings.
  • Concentrating solar power is used in large scale power generation using mirrors to help connect the sun's rays to receivers in order to produce heat and electricity.

Passive solar systems reduce the amount of energy traditionally needed to power a location, such as a building or house.

5. Biomass and Biofuels

Biomass produced 1.5% of energy in 2016 for the U.S. according to the EIA FAQ. Biomass can be used for bio-energy and to produce biofuels according to Renewable Energy World.

  • Biomass fuel facility
    Bio-energy is the heat derived from directly burning wood. The sources are residues from crops, forests, primary and secondary mills, and waste, according to the NREL's Biomass Maps page. This has been used for centuries for cooking and heating the house points out Renewable Energy World.
  • Biofuels can be liquid biofuels or and biogas. Bioenergy crops like switch grass and others, agricultural crops and waste materials can be converted to liquid biofuels. While landfill wastes produce methane that is tapped, biogas can be produced from human sewage and animal wastes, explains the EIA's Biomass Explained page.

Energy from biomass in the U.S. comes "43% from wood and wood-derived biomass, 46% from biofuels (mainly ethanol), and about 11% from municipal waste," according to the EIA's Biomass Explained page.

The Shift Toward Sustainable and Renewable Goods

Renewable resources are crucial to the continued survival of life on Earth. While renewable commodities have been cultivated for centuries, use of resources like power from oceans, and solar power is new. Increased use of these resources can improve the quality of life on Earth.

Examples of Renewable Resources