There is a renewable energy debate about the constraints and opportunities associated with the use of renewable energy.
Renewable electricity production, from sources such as wind power and solar power, is sometimes criticized for being variable or intermittent. However, the International Energy Agency has stated that deployment of renewable technologies usually increases the diversity of electricity sources and, through local generation, contributes to the flexibility of the system and its resistance to central shocks.[1]
There have been "not in my back yard" (NIMBY) concerns relating to the visual and other impacts of some wind farms, with local residents sometimes fighting or blocking construction.[2] In the USA, the Massachusetts Cape Wind project was delayed for years partly because of aesthetic concerns. However, residents in other areas have been more positive and there are many examples of community wind farm developments. According to a town councilor, the overwhelming majority of locals believe that the Ardrossan Wind Farm in Scotland has enhanced the area.[3]
The market for renewable energy technologies has continued to grow. Climate change concerns, coupled with high oil prices, peak oil, and increasing government support, are driving increasing renewable energy legislation, incentives and commercialization.[4] New government spending, regulation and policies helped the industry weather the 2009 economic crisis better than many other sectors.[5]
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The Fukushima I nuclear accidents in Japan have brought new attention to how national energy systems are vulnerable to natural disasters, with climate change is already bringing more weather and climate extremes. These threats to our old energy systems provide a rationale for investing in renewable energy. Shifting to renewable energy "can help us to meet the dual goals of reducing greenhouse gas emissions, thereby limiting future extreme weather and climate impacts, and ensuring reliable, timely, and cost-efficient delivery of energy". Investing in renewable energy can have significant dividends for our energy security.[6]
There is no shortage of renewable energy and a "smart mix" of renewable energy sources can be used to reliably meet electricity demand:
Because the wind blows during stormy conditions when the sun does not shine and the sun often shines on calm days with little wind, combining wind and solar can go a long way toward meeting demand, especially when geothermal provides a steady base and hydroelectric can be called on to fill in the gaps.[7]
As Amory Lovins has said:
The variability of sun, wind and so on, turns out to be a non-problem if you do several sensible things. One is to diversify your renewables by technology, so that weather conditions bad for one kind are good for another. Second, you diversify by site so they're not all subject to the same weather pattern at the same time because they're in the same place. Third, you use standard weather forecasting techniques to forecast wind, sun and rain, and of course hydro operators do this right now. Fourth, you integrate all your resources — supply side and demand side..."[8]
The combination of diversifying variable renewables by type and location, forecasting their variation, and integrating them with despatchable renewables, flexible fueled generators, and demand response can create a power system that has the potential to meet our needs reliably. Integrating ever-higher levels of renewables is being successfully demonstrated in the real world:[9]
In 2009, eight American and three European authorities, writing in the leading electrical engineers' professional journal, didn't find "a credible and firm technical limit to the amount of wind energy that can be accommodated by electricity grids". In Fact, not one of more than 200 international studies, nor official studies for the eastern and western U.S. regions, nor the International Energy Agency, has found major costs or technical barriers to reliably integrating up to 30% variable renewable supplies into the grid, and in some studies much more.[9]
Renewable electricity supply in the 20-50+% range has already been implemented in several European systems, albeit in the context of a integrated European grid system:[9]
In 2010, four German states, totaling 10 million people, relied on wind power for 43-52% of their annual electricity needs. Denmark isn't far behind, supplying 22% of its power from wind in 2010 (26% in an average wind year). The Extremadura region of Spain is getting up to 25% of its electricity from solar, while the whole country meets 16% of its demand from wind. Just during 2005-2010, Portugal vaulted from 17% to 45% renewable electricity.[9]
Minnkota Power Cooperative, the leading U.S. wind utility in 2009, supplied 38% of its retail sales from the wind.[9]
Mark A. Delucchi and Mark Z. Jacobson report that there are at least seven ways to design and operate variable renewable energy systems so that they will reliably satisfy electricity demand:[10]
Jacobson and Delucchi argue that wind, water and solar power can be scaled up in cost-effective ways to meet our energy demands, freeing us from dependence on both fossil fuels and nuclear power. In 2009 they published “A Plan to Power 100 Percent of the Planet With Renewables” in Scientific American. The article addressed a number of issues, such as the worldwide spatial footprint of wind turbines, the availability of scarce materials needed for manufacture of new systems, the ability to produce reliable energy on demand and the average cost per kilowatt hour. A more detailed and updated technical analysis has been published as a two-part article in the journal Energy Policy.[11]
Renewable power technologies reduce dependence on foreign sources of fuel and therefore increase energy security. They decentralise electricity supply so that an accidental or intentional outage affects a smaller amount of capacity than an outage at a larger power station.[12] They improve the reliability of power generation by producing power close to the end-user, and minimise the need to produce, transport and store hazardous fuels. Unlike generators relying on uranium and recycled plutonium, renewable energy is naturally replenished and not subject to the volatility of global fuel markets.[12]
Both solar and wind have been criticized from an aesthetic point of view.[13] However, methods and opportunities exist to deploy these renewable technologies efficiently and unobtrusively: fixed solar collectors can double as noise barriers along highways, and extensive roadway, parking lot, and roof-top area is currently available; amorphous photovoltaic cells can also be used to tint windows and produce energy.[14] Advocates of renewable energy also argue that current infrastructure is less aesthetically pleasing than alternatives, but sited further from the view of most critics.[15]
Renewable power technologies have significant environmental benefits since their use tends to avoid air pollution and the dangers and risks of extracting coal or uranium. They generate electricity without releasing significant quantities of CO2 and other greenhouse gases that contribute to climate change.[12]
One environmental issue, particularly with biomass and biofuels, is the large amount of land required to harvest energy, which otherwise could be used for other purposes or left as undeveloped land.[16] However, it should be pointed out that these fuels may reduce the need for harvesting non-renewable energy sources, such as vast strip-mined areas and slag mountains for coal, safety zones around nuclear plants, and hundreds of square miles being strip-mined for oil sands. These responses, however, do not account for the extremely high biodiversity and endemism of land used for ethanol crops, particularly sugar cane.
In the U.S., crops grown for biofuels are the most land- and water-intensive of the renewable energy sources. In 2005, about 12% of the nation’s corn crop (covering 11 million acres (45,000 km²) of farmland) was used to produce four billion gallons of ethanol—which equates to about 2% of annual U.S. gasoline consumption. For biofuels to make a much larger contribution to the energy economy, the industry will have to accelerate the development of new feedstocks, agricultural practices, and technologies that are more land and water efficient.
The efficiency of biofuels production has increased significantly[17] and there are new methods to boost biofuel production,[18] although using bioelectricity, by burning the biomass to produce electricity for an electric car, increases the distance that a car can go from a hectare (about 2.5 acres) of crops by 81%, from 30,000 km to 54,000 km per year.[19] However, covering that same hectare with photovoltaics (in relatively sunless Germany or England) allows the electric car to go 3,250,000 km/year, over 100 times as far as from biofuel.[20]
The major advantage of hydroelectric systems is the elimination of the cost of fuel. Other advantages include longer life than fuel-fired generation, low operating costs, and the provision of facilities for water sports. Operation of pumped-storage plants improves the daily load factor of the generation system. Overall, hydroelectric power can be far less expensive than electricity generated from fossil fuels or nuclear energy, and areas with abundant hydroelectric power attract industry.
However, there are several disadvantages of hydroelectricity systems. These include: dislocation of people living where the reservoirs are planned, release of significant amounts of carbon dioxide at construction and flooding of the reservoir, disruption of aquatic ecosystems and birdlife, adverse impacts on the river environment, potential risks of sabotage and terrorism, and in rare cases catastrophic failure of the dam wall.
Large hydroelectric power is considered to be a renewable energy by a large number of sources, however, many groups have lobbied for it to be excluded from renewable electricity standards, any initiative to promote the use of renewable energies, and sometimes the definition of renewable itself.[21][22] Some organizations, including US federal agencies, will specifically refer to "non-hydro renewable energy".[23]
Hydroelectric power is now more difficult to site in developed nations because most major sites within these nations are either already being exploited or may be unavailable for other reasons such as environmental considerations.
In the last twenty years international organizations like International Rivers, Hydropower Reform Coalition, World Commission on Dams, UNEP, World Conservation Union (IUCN), and the World Bank considered changing politics on large dams, as awareness about dams and hydro-energy generation environmental disadvantages grew, especially among affected populations. Hydro-energy and large dams may not be considered "clean" nor "renewable" sources of electricity because of their serious social and environmental impacts.[24][25][26][27][28]
Mark Diesendorf, formerly Professor of Environmental Science at the University of Technology, Sydney and a principal research scientist with CSIRO has summarised some of the benefits of onshore wind farms as follows.[29]
A wind farm, when installed on agricultural land, has one of the lowest environmental impacts of all energy sources:
- It occupies less land area per kilowatt-hour (kWh) of electricity generated than any other energy conversion system, apart from rooftop solar energy, and is compatible with grazing and crops.
- It generates the energy used in its construction in just 3 months of operation, yet its operational lifetime is 20-25 years.
- Greenhouse gas emissions and air pollution produced by its construction are very tiny and declining. There are no emissions or pollution produced by its operation.
- In substituting for base-load (mostly coal power) [...] wind power produces a net decrease in greenhouse gas emissions and air pollution, and a net increase in biodiversity.
- Modern wind turbines are almost silent and rotate so slowly (in terms of revolutions per minute) that they are rarely a hazard to birds.
Studies of birds and offshore wind farms in Europe have found that there are very few bird collisions.[30] Several offshore wind sites in Europe have been in areas heavily used by seabirds. Improvements in wind turbine design, including a much slower rate of rotation of the blades and a smooth tower base instead of perchable lattice towers, have helped reduce bird mortality at wind farms around the world. However older smaller wind turbines may be hazardous to flying birds.[31] Birds are severely impacted by fossil fuel energy; examples include birds dying from exposure to oil spills, habitat loss from acid rain and mountaintop removal coal mining, and mercury poisoning.[32]
Many wind power companies work with local communities to reduce environmental and other concerns associated with particular wind farms.[36][37][38][39] In other cases there is direct community ownership of wind farm projects. Appropriate government consultation, planning and approval procedures also help to minimize environmental risks.[40][41][42] Some people may still object to wind farms but, according to The Australia Institute, their concerns should be weighed against the need to address the threats posed by climate change and the opinions of the broader community.[43] Surveys of public attitudes across Europe and in many other countries show strong public support for wind power.[40][44][45]
In Germany, for example, hundreds of thousands of people have invested in citizens' wind farms across the country and thousands of small and medium sized enterprises are running successful businesses in a new sector that in 2008 employed 90,000 people and generated 8 percent of Germany's electricity.[46] Wind power has gained very high social acceptance in Germany.[47]
In America, wind projects are reported to boost local tax bases, helping to pay for schools, roads and hospitals. Wind projects also revitalize the economy of rural communities by providing steady income to farmers and other landowners.[33]
The Intrepid Wind Farm, in Iowa, is an example of one wind farm where the environmental impact of the project has been minimized through consultation and co-operation:
"Making sure the wind farm made as gentle an environmental impact as possible was an important consideration. Therefore, when MidAmerican first began planning the Intrepid site, they worked closely with a number of state and national environmental groups. Using input from such diverse groups as the Iowa Department of Natural Resources, the Nature Conservancy, Iowa State University, the U.S. Fish and Wildlife Service, the Iowa Natural Heritage Foundation, and the Iowa Chapter of the Sierra Club, MidAmerican created a statewide map of areas in the proposed region that contained specific bird populations or habitats. Those areas were then avoided as site planning got underway in earnest. In order to minimize the wind farm's environmental impact even further, MidAmerican also worked in conjunction with the Army Corp of Engineers, to secure all necessary permits related to any potential risk to wetlands in the area. Regular inspections are also conducted to make certain that the wind farm is causing no adverse environmental impact to the region."[48]
Other examples include:
Even though a source of renewable energy may last for billions of years, renewable energy infrastructure, like hydroelectric dams, will not last forever, and must be removed and replaced at some point. Events like the shifting of riverbeds, or changing weather patterns could potentially alter or even halt the function of hydroelectric dams, lowering the amount of time they are available to generate electricity. Hydropower dams is also affected by silting which may or may not be cost effective to remove.
Some have claimed that geothermal being a renewable energy source depends on the rate of extraction being slow enough such that depletion does not occur. If depletion does occur, the temperature can regenerate if given a long period of non-use.[73][74]
The government of Iceland states: "It should be stressed that the geothermal resource is not strictly renewable in the same sense as the hydro resource." It estimates that Iceland's geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW.[75] Radioactive elements in the Earth's crust continuously decay, replenishing the heat. The International Energy Agency classifies geothermal power as renewable.[76]
All biomass needs to go through some of these steps: it needs to be grown, collected, dried, fermented and burned. All of these steps require resources and an infrastructure.
Some studies contend that ethanol is "energy negative", meaning that it takes more energy to produce than is contained in the final product.[77] However, a large number of recent studies, including a 2006 article[78] in the journal Science offer the opinion that fuels like ethanol are energy positive. Furthermore, fossil fuels also require significant energy inputs which have seldom been accounted for in the past.
Additionally, ethanol is not the only product created during production, and the energy content of the by-products must also be considered. Corn is typically 66% starch and the remaining 33% is not fermented. This unfermented component is called distillers grain, which is high in fats and proteins, and makes good animal feed.[79] In Brazil, where sugar cane is used, the yield is higher, and conversion to ethanol is somewhat more energy efficient than corn. Recent developments with cellulosic ethanol production may improve yields even further.[80]
According to the International Energy Agency, new biofuels technologies being developed today, notably cellulosic ethanol, could allow biofuels to play a much bigger role in the future than previously thought.[81] Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants. Crop residues (such as corn stalks, wheat straw and rice straw), wood waste, and municipal solid waste are potential sources of cellulosic biomass. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be sustainably produced in many regions of the United States.[82]
The ethanol and biodiesel production industries also create jobs in plant construction, operations, and maintenance, mostly in rural communities. According to the Renewable Fuels Association, the ethanol industry created almost 154,000 U.S. jobs in 2005 alone, boosting household income by $5.7 billion. It also contributed about $3.5 billion in tax revenues at the local, state, and federal levels.[17]
The U.S. electric power industry now relies on large, central power stations, including coal, natural gas, nuclear, and hydropower plants that together generate more than 95% of the nation’s electricity. Over the next few decades uses of renewable energy could help to diversify the nation’s bulk power supply. Already, appropriate renewable resources (which excludes large hydropower) produce 12% of northern California’s electricity.[17]
Although most of today’s electricity comes from large, central-station power plants, new technologies offer a range of options for generating electricity nearer to where it is needed, saving on the cost of transmitting and distributing power and improving the overall efficiency and reliability of the system.[17]
Improving energy efficiency represents the most immediate and often the most cost-effective way to reduce oil dependence, improve energy security, and reduce the health and environmental impact of the energy system. By reducing the total energy requirements of the economy, improved energy efficiency could make increased reliance on renewable energy sources more practical and affordable.[17]
Nuclear power continues to be considered as an alternative to fossil-fuel power sources (see Low carbon power generation), and in 1956, when the first peak oil paper was presented, nuclear energy was presented as the replacement for fossil fuels.[83] However, the prospect of increased nuclear power deployment was seriously undermined in the United States as a result of the Three Mile Island accident, and in the rest of the world after the Chernobyl disaster. This trend has been slowly reversing, and several new nuclear reactors are scheduled for construction,[84] however, there is again increasing resistance in light of the 2011 Japanese nuclear accidents.
Physicist Bernard Cohen proposed in 1983 that uranium dissolved in seawater, when used in fast neutron reactors, is effectively inexhaustible and constantly replenished by rivers, and could therefore be considered a renewable source of energy.[85][86] However, this idea is not universally accepted, and issues such as peak uranium and uranium depletion are ongoing debates.
An assessment of the full environmental, social and political impacts of both renewable electricity and nuclear power technologies by Benjamin K. Sovacool concluded that:
"... renewable electricity technologies present policy makers with a superior alternative for minimising the risk of fuel interruptions and shortages, helping improve the fragile transmission network and reducing environmental harm. These smaller and more environmentally friendly generators cost less to construct, produce power in smaller increments and need not rely on continuous government subsidies. They generate little to no waste, have less greenhouse gas emissions per unit of electricity produced and do not contribute significantly to the risk of accidents. In contrast, the costs for nuclear plant construction, fuel, reprocessing, storage, decommissioning and further research are significant. Even modern nuclear reactors run the risk of accidents and failures, shortages of high quality uranium ore may be imminent and the thermoelectric fuel cycle of nuclear plants consumes and sometimes degrades vast quantities of water. Greenhouse gas emissions associated with the nuclear lifecycle are notable and reactors and waste storage sites invariably damage and degrade the natural environment".[87]
Legislative and scientific definitions of renewable energy, used when determining energy projects eligible for subsidies or tax breaks, usually exclude nuclear power.