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Arenewable resource (also known as aflow resource[note 1][1]) is anatural resource which will replenish to replace the portiondepleted by usage and consumption, either through natural reproduction or other recurring processes in a finite amount of time in a human time scale. When the recovery rate of resources is unlikely to ever exceed a human time scale, these are calledperpetual resources.[1] Renewable resources are a part of Earth's natural environment and the largest components of itsecosphere. A positivelife-cycle assessment is a key indicator of a resource'ssustainability.
Definitions of renewable resources may also include agricultural production, as inagricultural products and to an extentwater resources.[2] In 1962,Paul Alfred Weiss defined renewable resources as: "The total range of living organisms providing man with life, fibres, etc...".[3] Another type of renewable resources isrenewable energy resources. Common sources of renewable energy include solar, geothermal and wind power, which are all categorized as renewable resources. Fresh water is an example of a renewable resource.
Water can be considered arenewable material when carefully controlled usage and temperature, treatment, and release are followed. If not, it would become a non-renewable resource at that location. For example, asgroundwater is usually removed from anaquifer at a rate much greater than its very slow natural recharge, it is a considered non-renewable resource. Removal of water from the pore spaces in aquifers may cause permanent compaction (subsidence) that cannot be renewed. 97.5% of the water on the Earth is salt water, and 3% isfresh water; slightly over two thirds of this is frozen inglaciers andpolarice caps.[4] The remaining unfrozen freshwater is found mainly as groundwater, with only a small fraction (0.008%) present above ground or in the air.[5]
Water pollution is one of the main concerns regarding water resources. It is estimated that 22% of worldwide water is used in industry.[6] Major industrial users include hydroelectric dams,thermoelectric power plants (which use water for cooling),ore andoil refineries (which use water in chemical processes) and manufacturing plants (which use water as a solvent), it is also used for dumping garbage.
Desalination of seawater is considered a renewable source of water, although reducing its dependence on fossil fuel energy is needed for it to be fully renewable.[7]
Food is any substance consumed to provide nutritional support for the body.[8] Most food has its origin in renewable resources. Food is obtained directly from plants and animals.
Hunting may not be the first source of meat in the modernised world, but it is still an important and essential source for many rural and remote groups. It is also the sole source of feeding for wild carnivores.[9]
The phrasesustainable agriculture was coined by Australian agricultural scientistGordon McClymont.[10] It has been defined as "an integrated system of plant and animal production practices having a site-specific application that will last over the long term".[11] Expansion of agricultural land reducesbiodiversity and contributes todeforestation. TheFood and Agriculture Organization of the United Nations estimates that in coming decades, cropland will continue to be lost to industrial and urban development, along with reclamation of wetlands, and conversion of forest to cultivation, resulting in theloss of biodiversity and increasedsoil erosion.[12]
Althoughair andsunlight are available everywhere onEarth,crops also depend onsoilnutrients and the availability ofwater.Monoculture is a method of growing only one crop at a time in a given field, which can damage land and cause it to become either unusable or suffer from reducedyields. Monoculture can also cause the build-up ofpathogens and pests that target one specific species. TheGreat Irish Famine (1845–1849) is a well-known example of the dangers of monoculture.
Crop rotation andlong-term crop rotations confer the replenishment of nitrogen through the use ofgreen manure in sequence with cereals and other crops, and can improvesoil structure andfertility by alternating deep-rooted and shallow-rooted plants. Other methods to combat lost soil nutrients are returning to natural cycles that annually flood cultivated lands (returning lost nutrients indefinitely) such as theFlooding of the Nile, the long-term use ofbiochar, and use of crop and livestocklandraces that are adapted to less than ideal conditions such as pests, drought, or lack of nutrients.
Agricultural practices are one of the single greatest contributor to the global increase insoil erosion rates.[13] It is estimated that "more than a thousand million tonnes of southern Africa's soil are eroded every year. Experts predict that crop yields will be halved within thirty to fifty years if erosion continues at present rates."[14] TheDust Bowl phenomenon in the 1930s was caused by severedrought combined with farming methods that did not include crop rotation, fallow fields,cover crops, soil terracing and wind-breaking trees to preventwind erosion.[15]
Thetillage of agricultural lands is one of the primary contributing factors to erosion, due to mechanised agricultural equipment that allows for deep plowing, which severely increases the amount of soil that is available for transport bywater erosion.[16][17]The phenomenon calledpeak soil describes how large-scale factory farming techniques are affecting humanity's ability to grow food in the future.[18] Without efforts to improvesoil management practices, the availability ofarable soil may become increasingly problematic.[19][unreliable source?]
Methods to combat erosion includeno-till farming, using akeyline design, growingwind breaks to hold the soil, and widespread use ofcompost.Fertilizers andpesticides can also have an effect of soil erosion,[20] which can contribute tosoil salinity and prevent other species from growing.Phosphate is a primary component in the chemical fertiliser applied most commonly in modern agricultural production. However, scientists estimate that rock phosphate reserves will be depleted in 50–100 years and thatPeak Phosphate will occur in about 2030.[21]
Industrial processing andlogistics also have an effect on agriculture's sustainability. The way and locations crops aresold requires energy for transportation, as well as the energy cost for materials,labour, andtransport. Food sold at a local location, such afarmers' market, have reduced energy overheads.
Air is a renewable resource. Allliving organisms needoxygen,nitrogen (directly or indirectly),carbon (directly or indirectly) and many other gases in smallquantities for theirsurvival.
An important renewable resource iswood provided by means offorestry, which has been used for construction, housing and firewood since ancient times.[22][23][24] Plants provide the main sources for renewable resources, the main distinction is betweenenergy crops andnon-food crops. A large variety oflubricants, industrially used vegetable oils, textiles and fibre made e.g. ofcotton,copra orhemp,paper derived fromwood,rags orgrasses,bioplastic are based on plant renewable resources. A large variety of chemical based products likelatex,ethanol,resin,sugar andstarch can be provided with plant renewables. Animal based renewables includefur,leather, technicalfat and lubricants and further derived products, as e.g.animal glue,tendons,casings or in historical timesambra andbaleen provided bywhaling.
With regard to pharmacy ingredients and legal and illegal drugs, plants are important sources, however e.g. venom of snakes, frogs and insects has been a valuable renewable source of pharmacological ingredients. Before GMO production set in,insulin and importanthormones were based on animal sources.Feathers, an important byproduct of poultry farming for food, is still being used as filler and as base forkeratin in general. Same applies for thechitin produced in farmingCrustaceans which may be used as base ofchitosan. The most important part of the human body used for non-medical purposes ishuman hair as forartificial hair integrations, which is being traded worldwide.
Historically, renewable resources like firewood,latex,guano,charcoal,wood ash, plant colors asindigo, and whale products have been crucial for human needs but failed to supply demand in the beginning of the industrial era.[25] Early modern times faced large problems with overuse of renewable resources as indeforestation,overgrazing oroverfishing.[25]
In addition to fresh meat and milk, which as food items are not the topic of this section,livestock farmers and artisans used further animal ingredients astendons, horn, bones, bladders. Complex technical constructions as thecomposite bow were based on combination of animal and plant based materials. The current distribution conflict between biofuel and food production is being described asFood vs. fuel. Conflicts between food needs and usage, as supposed byfief obligations were in so far common in historical times as well.[26] However, a significant percentage of (middle European) farmers yields went intolivestock, which provides as well organic fertiliser.[27] Oxen and horses were important for transportation purposes, drove engines as e.g. intreadmills.
Other regions solved the transportation problem withterracing,urban and garden agriculture.[25] Further conflicts as between forestry and herding, or (sheep) herders and cattle farmers led to various solutions. Some confined wool production and sheep to large state and nobility domains or outsourced to professional shepherds with larger wandering herds.[28]
TheBritish Agricultural Revolution was mainly based on a new system ofcrop rotation, the four-field rotation.British agriculturistCharles Townshend recognised the invention in DutchWaasland and popularised it in the 18th century UK,George Washington Carver in the USA. The system usedwheat,turnips andbarley and introduced as wellclover. Clover is able to fix nitrogen from air, a practically non exhaustive renewable resource, into fertilizing compounds to the soil and allowed to increase yields by large. Farmers opened up a fodder crop and grazing crop. Thuslivestock could to be bred year-round and winterculling was avoided. The amount of manure rose and allowed more crops but to refrain fromwood pasture.[25]
Early modern times and the 19th century saw the previous resource base partially replaced respectively supplemented by large scale chemical synthesis and by the use of fossil and mineral resources respectively.[29] Besides the still central role of wood, there is a sort of renaissance of renewable products based on modern agriculture, genetic research and extraction technology. Besides fears about an upcomingglobal shortage of fossil fuels, local shortages due to boycotts, war and blockades or just transportation problems in remote regions have contributed to different methods of replacing or substituting fossil resources based on renewables.
The use of certain basically renewable products as inTCMendangers various species. Just the black market inrhinoceros horn reduced the world's rhino population by more than 90 percent over the past 40 years.[30][31]
The success of the German chemical industry till World War I was based on the replacement of colonial products. The predecessors ofIG Farben dominated the world market forsynthetic dyes at the beginning of the 20th century[32][33] and had an important role in artificialpharmaceuticals,photographic film,agricultural chemicals andelectrochemicals.[29]
However the formerPlant breeding research institutes took a different approach. After the loss of theGerman colonial empire, important players in the field asErwin Baur andKonrad Meyer switched to using local crops as base for economicautarky.[34][35] Meyer as a key agricultural scientist and spatial planner of the Nazi era managed and leadDeutsche Forschungsgemeinschaft resources and focused about a third of the complete research grants in Nazi Germany on agricultural and genetic research and especially on resources needed in case of a further German war effort.[34] A wide array of agrarian research institutes still existing today and having importance in the field was founded or enlarged in the time.
There were some major failures as trying to e.g. growfrost resistant olive species, but some success in the case ofhemp,flax,rapeseed, which are still of current importance.[34] During World War 2, German scientists tried to use RussianTaraxacum (dandelion) species to manufacturenatural rubber.[34] Rubber dandelions are still of interest, as scientists in the Fraunhofer Institute for Molecular Biology and Applied Ecology (IME) announced 2013 to have developed a cultivar that is suitable for commercial production of natural rubber.[36]
Several legal and economic means have been used to enhance the market share of renewables. The UK usesNon-Fossil Fuel Obligations (NFFO), a collection oforders requiring the electricitydistribution network operators inEngland andWales to purchase electricity from thenuclear power andrenewable energy sectors. Similar mechanisms operate inScotland (the Scottish Renewable Orders under the Scottish Renewables Obligation) andNorthern Ireland (the Northern Ireland Non-Fossil Fuel Obligation). In the US,Renewable Energy Certificates (RECs), use a similar approach. GermanEnergiewende is using feed-in tariffs. An unexpected outcome of the subsidies was the quick increase of pellet byfiring in conventional fossil fuel plants (compareTilbury power stations) and cement works, making wood respectively biomass accounting for about half of Europe's renewable-energy consumption.[24]
Biorenewable chemicals are chemicals created by biological organisms that provide feedstocks for the chemical industry.[37] Biorenewable chemicals can provide solar-energy-powered substitutes for the petroleum-based carbon feedstocks that currently supply the chemical industry. The tremendous diversity of enzymes in biological organisms, and the potential forsynthetic biology to alter these enzymes to create yet new chemical functionalities, can drive the chemical industry. A major platform for creation of new chemicals is thepolyketide biosynthetic pathway, which generates chemicals containing repeatedalkyl chain units with potential for a wide variety offunctional groups at the different carbon atoms.[37][38][39]Polyurethane research is ongoing that specifically uses renewable resources.[40]
Bioplastics are a form ofplastics derived from renewablebiomass sources, such asvegetable fats and oils,lignin,corn starch,peastarch[41] ormicrobiota.[42] The most common form of bioplastic isthermoplastic starch. Other forms includeCellulose bioplastics, biopolyester,Polylactic acid, and bio-derivedpolyethylene.
The production and use of bioplastics is generally regarded as a moresustainable activity when compared to plastic production from petroleum (petroplastic); however, manufacturing of bioplastic materials is often still reliant upon petroleum as an energy and materials source. Because of the fragmentation in the market and ambiguous definitions it is difficult to describe the total market size for bioplastics, but the global production capacity is estimated at 327,000 tonnes.[43] In contrast, global consumption of all flexible packaging is estimated at 12.3 million tonnes.[44]
Bioasphalt is anasphalt alternative made from non-petroleum based renewable resources. Manufacturing sources of bioasphalt includesugar,molasses andrice,corn andpotatostarches, and vegetable oil based waste. Asphalt made with vegetable oil based binders was patented by Colas SA in France in 2004.[45][46]
Renewable energy refers to the provision of energy via renewable resources which are naturally replenished as fast as they are being used. Examples aresunlight,wind,biomass,rain,tides,waves andgeothermal heat.[47] Renewable energy may replace conventional fuels in four distinct markets, namelyelectricity generation,hot water/space heating,motor fuels, andrural (off-grid) energy services.[48] Manufacturing of renewable energy devices usesnon-renewable resources such as mined metals andland surface.
Biomass is referring tobiological material from living, or recently living organisms, most often referring to plants or plant-derived materials.
Sustainable harvesting and use of renewable resources (i.e., maintaining a positive renewal rate) can reduceair pollution,soil contamination,habitat destruction andland degradation.[49] Biomass energy is derived from six distinct energy sources: garbage, wood, plants, waste,landfill gases, andalcohol fuels. Historically, humans have harnessed biomass-derived energy since the advent of burning wood to make fire, and wood remains the largest biomass energy source today.[50][51]
However, low tech use of biomass, which still amounts for more than 10% of world energy needs may induceindoor air pollution in developing nations[52] and results in between 1.5 million and 2 million deaths in 2000.[53]
The biomass used for electricity generation varies by region.[54] Forest by-products, such as wood residues, are common in theUnited States.[54] Agricultural waste is common inMauritius (sugar cane residue) andSoutheast Asia (rice husks).[54] Animal husbandry residues, such as poultry litter, are common in theUK.[54] The biomass power generating industry in the United States, which consists of approximately 11,000MW of summer operating capacity actively supplying power to the grid, produces about 1.4 percent of the U.S. electricity supply.[55]
A biofuel is a type offuel whose energy is derived from biologicalcarbon fixation. Biofuels include fuels derived frombiomass conversion, as well assolid biomass,liquid fuels and variousbiogases.[56]
Bioethanol is analcohol made byfermentation, mostly fromcarbohydrates produced insugar orstarch crops such ascorn,sugarcane orswitchgrass.
Biodiesel is made fromvegetable oils andanimal fats. Biodiesel is produced from oils or fats usingtransesterification and is the most common biofuel in Europe.
Biogas ismethane produced by the process ofanaerobic digestion oforganic material byanaerobes.,[57] etc. is also a renewable source of energy.
Biogas typically refers to a mixture ofgases produced by the breakdown oforganic matter in the absence ofoxygen. Biogas is produced byanaerobic digestion with anaerobic bacteria orfermentation of biodegradable materials such asmanure,sewage,municipal waste,green waste,plant material, and crops.[58] It is primarilymethane (CH
4) andcarbon dioxide (CO2) and may have small amounts ofhydrogen sulphide (H
2S), moisture andsiloxanes.
Natural fibres are a class of hair-like materials that are continuous filaments or are in discrete elongated pieces, similar to pieces ofthread. They can be used as a component ofcomposite materials. They can also bematted into sheets to make products such aspaper orfelt. Fibres are of two types: natural fibre which consists of animal and plant fibres, and man made fibre which consists of synthetic fibres and regenerated fibres.
Renewable resources are endangered by non-regulated industrial developments and growth.[59] They must be carefully managed to avoid exceeding the natural world's capacity to replenish them.[60] A life cycle assessment provides a systematic means of evaluating renewability. This is a matter of sustainability in the natural environment.[61]
National Geographic has described ocean over fishing as "simply the taking of wildlife from the sea at rates too high for fished species to replace themselves."[62]
Tuna meat is driving overfishing as to endanger some species like the bluefin tuna. The European Community and other organisations are trying to regulate fishery as to protect species and to prevent their extinctions.[63] TheUnited Nations Convention on the Law of the Sea treaty deals with aspects of overfishing in articles 61, 62, and 65.[64]
Examples of overfishing exist in areas such as theNorth Sea ofEurope, theGrand Banks ofNorth America and theEast China Sea of Asia.[65]
The decline ofpenguin population is caused in part by overfishing, caused by human competition over the same renewable resources[66]
Besides their role as a resource for fuel and building material, trees protect the environment by absorbing carbon dioxide and by creating oxygen.[67] The destruction of rain forests is one of the critical causes ofclimate change. Deforestation causes carbon dioxide to linger in the atmosphere. As carbon dioxide accrues, it produces a layer in the atmosphere that traps radiation from the sun. The radiation converts to heat which causesglobal warming, which is better known as thegreenhouse effect.[68]
Deforestation also affects thewater cycle. It reduces the content of water in the soil and groundwater as well as atmospheric moisture.[69] Deforestation reduces soil cohesion, so thaterosion, flooding andlandslides ensue.[70][71]
Rain forests house many species and organisms providing people with food and other commodities. In this way biofuels may well be unsustainable if their production contributes to deforestation.[72]
Some renewable resources, species and organisms are facing a very high risk of extinction caused by growing human population and over-consumption. It has been estimated that over 40% of all living species on Earth are at risk of going extinct.[73] Many nations have laws to protect hunted species and to restrict the practice of hunting. Other conservation methods include restricting land development or creating preserves. TheIUCN Red List of Threatened Species is the best-known worldwide conservation status listing and ranking system.[74] Internationally, 199 countries have signed an accord agreeing to createBiodiversity Action Plans to protect endangered and other threatened species.
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