The endeavor to use 100% renewable energy for electricity, heating and cooling, and transport is motivated by global warming, pollution and other environmental issues, as well as economic and energy security concerns. Shifting the total global primary energy supply to renewable sources requires a transition of the energy system. In 2013 the Intergovernmental Panel on Climate Change said that there are few fundamental technological limits to integrating a portfolio of renewable energy technologies to meet most of total global energy demand. Renewable energy use has grown much faster than even advocates anticipated.
In 2014, renewable sources such as wind, geothermal, solar, biomass, and burnt waste provided 19% of the total energy consumed worldwide, with roughly half of that coming from traditional use of biomass. The most important sector is electricity with a renewable share of 22.8%, most of it coming from hydropower with a share of 16.6%, followed by wind with 3.1%. There are many places around the world with grids that are run almost exclusively on renewable energy. At the national level, at least 30 nations already have renewable energy contributing more than 20% of the energy supply.
Professors S. Pacala and Robert H. Socolow of Princeton University have developed a series of “Climate stabilization wedges” that can allow us to maintain our quality of life while avoiding catastrophic climate change, and "renewable energy sources," in aggregate, constitute the largest number of their "wedges."
Mark Z. Jacobson, professor of civil and environmental engineering at Stanford University and director of its Atmosphere and Energy program, says that producing all new energy with wind power, solar power, and hydropower by 2030 is feasible, and that existing energy supply arrangements could be replaced by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Jacobson says that energy costs today with a wind, solar, and water system should be similar to today's energy costs from other optimally cost-effective strategies. The main obstacle against this scenario is the lack of political will.
Similarly, in the United States, the independent National Research Council has noted that “sufficient domestic renewable resources exist to allow renewable electricity to play a significant role in future electricity generation and thus help confront issues related to climate change, energy security, and the escalation of energy costs … Renewable energy is an attractive option because renewable resources available in the United States, taken collectively, can supply significantly greater amounts of electricity than the total current or projected domestic demand."
The main barriers to the widespread implementation of large-scale renewable energy and low-carbon energy strategies are political rather than technological. According to the 2013 Post Carbon Pathways report, which reviewed many international studies, the key roadblocks are: climate change denial, the fossil fuels lobby, political inaction, unsustainable energy consumption, outdated energy infrastructure, and financial constraints.
Using 100% renewable energy was first suggested in a Science paper published in 1975 by Danish physicist Bent Sørensen, which was followed by several other proposals. In 1976 energy policy analyst Amory Lovins coined the term "soft energy path" to describe an alternative future where energy efficiency and appropriate renewable energy sources steadily replace a centralized energy system based on fossil and nuclear fuels.
In 1998 the first detailed analysis of scenarios with very high shares of renewables were published. These were followed by the first detailed 100% scenarios. In 2006 a PhD thesis was published by Czisch in which it was shown that in a 100% renewable scenario energy supply could match demand in every hour of the year in Europa and North Africa. In the same year Danish Energy professor Henrik Lund published a first paper in which he addresses the optimal combination of renewables, which was followed by several other papers on the transition to 100% renewable energy in Denmark. Since then Lund has been publishing several papers on 100% renewable energy. After 2009 publications began to rise steeply, covering 100% scenarios for countries in Europa, America, Australia and other parts of the world.
Even in the early 21st century it was extraordinary for scientists and decision-makers to consider the concept of 100 per cent renewable electricity. However, renewable energy progress has been so rapid that things have totally changed since then:
Solar photovoltaic modules have dropped about 75 per cent in price. Current scientific and technological advances in the laboratory suggest that they will soon be so cheap that the principal cost of going solar on residential and commercial buildings will be installation. On-shore wind power is spreading over all continents and is economically competitive with fossil and nuclear power in several regions. Concentrated solar thermal power (CST) with thermal storage has moved from the demonstration stage of maturity to the limited commercial stage and still has the potential for further cost reductions of about 50 per cent.
Renewable energy use has grown much faster than even advocates had anticipated. Wind turbines generate 39 percent of Danish electricity, and Denmark has many biogas digesters and waste-to-energy plants as well. Together, wind and biomass provide 44% of the electricity consumed by the country's six million inhabitants. In 2010, Portugal’s 10 million people produced more than half their electricity from indigenous renewable energy resources. Spain’s 40 million inhabitants meet one-third of their electrical needs from renewables.
Renewable energy has a history of strong public support. In America, for example, a 2013 Gallup survey showed that two in three Americans want the U.S. to increase domestic energy production using solar power (76%), wind power (71%), and natural gas (65%). Far fewer want more petroleum production (46%) and more nuclear power (37%). Least favored is coal, with about one in three Americans favouring it.
REN21 says renewable energy already plays a significant role and there are many policy targets which aim to increase this:
At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond, and some 120 countries have various policy targets for longer-term shares of renewable energy, including a binding 20% by 2020 target for the European Union. Some countries have much higher long-term policy targets of up to 100% renewables. Outside Europe, a diverse group of 20 or more other countries target renewable energy shares in the 2020–2030 time frame that range from 10% to 50%.
Nuclear power involves substantial accident risks (e.g., Fukushima nuclear disaster, Chernobyl disaster) and the unsolved problem of safe long-term high-level radioactive waste management, and carbon capture and storage has rather limited safe storage potentials. These constraints have also led to an interest in 100% renewable energy. A well established body of academic literature has been written over the past decade, evaluating scenarios for 100% renewable energy for various geographical areas. In recent years, more detailed analyses have emerged from government and industry sources. The incentive to use 100% renewable energy is created by global warming and ecological as well as economic concerns, post peak oil.
The first country to propose 100% renewable energy was Iceland, in 1998. Proposals have been made for Japan in 2003, and for Australia in 2011. Albania, Iceland, and Paraguay obtain essentially all of their electricity from renewable sources (Albania and Paraguay 100% from hydroelectricity, Iceland 72% hydro and 28% geothermal). Norway obtains nearly all of its electricity from renewable sources (97 percent from hydropower). Iceland proposed using hydrogen for transportation and its fishing fleet. Australia proposed biofuel for those elements of transportation not easily converted to electricity. The road map for the United States, commitment by Denmark, and Vision 2050 for Europe set a 2050 timeline for converting to 100% renewable energy, later reduced to 2040 in 2011. Zero Carbon Britain 2030 proposes eliminating carbon emissions in Britain by 2030 by transitioning to renewable energy. In 2015, Hawaii enacted a law that the Renewable Portfolio Standard shall be 100 percent by 2045. This is often confused with renewable energy. If electricity produced on the grid is 65 GWh from fossil fuel and 35 GWh from renewable energy and rooftop off grid solar produces 80 GWh of renewable energy then the total renewable energy is 115 GWh and the total electricity on the grid is 100 GWh. Then the RPS is 115 percent.
It is estimated that the world will spend an extra $8 trillion over the next 25 years to prolong the use of non-renewable resources, a cost that would be eliminated by transitioning instead to 100% renewable energy. Research that has been published in Energy Policy suggests that converting the entire world to 100% renewable energy by 2030 is both possible and affordable, but requires political support. It would require building many more wind turbines and solar power systems but wouldn't utilize bioenergy. Other changes involve use of electric cars and the development of enhanced transmission grids and storage.
The Fourth Revolution: Energy is a German documentary film released in 2010. It shows the vision of a global society, which lives in a world where the energy is produced 100% with renewable energies, showing a complete reconstruction of the economy, to reach this goal. In 2011, Hermann Scheer wrote the book The Energy Imperative: 100 Percent Renewable Now, published by Routledge.
Reinventing Fire is a book by Amory Lovins released in October 2011. By combining reduced energy use with energy efficiency gains, Lovins says that there will be a $5 trillion saving and a faster-growing economy. This can all be done with the profitable commercialization of existing energy-saving technologies, through market forces, led by business. Bill Clinton says the book is a "wise, detailed and comprehensive blueprint". The first paragraph of the preface says:
Imagine fuel without fear. No climate change. No oil spills, dead coal miners, dirty air, devastated lands, lost wildlife. No energy poverty. No oil-fed wars, tyrannies, or terrorists. Nothing to run out. Nothing to cut off. Nothing to worry about. Just energy abundance, benign and affordable, for all, for ever.
The Intergovernmental Panel on Climate Change has said that there are few fundamental technological limits to integrating a portfolio of renewable energy technologies to meet most of total global energy demand. In a 2011 review of 164 recent scenarios of future renewable energy growth, the report noted that the majority expected renewable sources to supply more than 17% of total energy by 2030, and 27% by 2050; the highest forecast projected 43% supplied by renewables by 2030 and 77% by 2050.
In 2011, the International Energy Agency has said that solar energy technologies, in its many forms, can make considerable contributions to solving some of the most urgent problems the world now faces:
The development of affordable, inexhaustible and clean solar energy technologies will have huge longer-term benefits. It will increase countries’ energy security through reliance on an indigenous, inexhaustible and mostly import-independent resource, enhance sustainability, reduce pollution, lower the costs of mitigating climate change, and keep fossil fuel prices lower than otherwise. These advantages are global. Hence the additional costs of the incentives for early deployment should be considered learning investments; they must be wisely spent and need to be widely shared.
In 2011, the refereed journal Energy Policy published two articles by Mark Z. Jacobson, a professor of engineering at Stanford University, and research scientist Mark A. Delucchi, about changing our energy supply mix and "Providing all global energy with wind, water, and solar power". The articles analyze the feasibility of providing worldwide energy for electric power, transportation, and heating/cooling from wind, water, and sunlight (WWS), which are safe clean options. In Part I, Jacobson and Delucchi discuss WWS energy system characteristics, aspects of energy demand, WWS resource availability, WWS devices needed, and material requirements. They estimate that 3,800,000 5 MW wind turbines, 5350 100 MW geothermal power plants, and 270 new 1300 MW hydroelectric power plants will be required. In terms of solar power, an additional 49,000 300 MW concentrating solar plants, 40,000 300 MW solar photovoltaic power plants, and 1.7 billion 3 kW rooftop photovoltaic systems will also be needed. Such an extensive WWS infrastructure could decrease world power demand by 30%. In Part II, Jacobson and Delucchi address variability of supply, system economics, and energy policy initiatives associated with a WWS system. The authors advocate producing all new energy with WWS by 2030 and replacing existing energy supply arrangements by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Energy costs with a WWS system should be similar to today's energy costs.
In general, Jacobson has said wind, water and solar technologies can provide 100 per cent of the world's energy, eliminating all fossil fuels. He advocates a "smart mix" of renewable energy sources 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.
A 2012 study by the University of Delaware for a 72 GW system considered 28 billion combinations of renewable energy and storage and found the most cost-effective, for the PJM Interconnection, would use 17 GW of solar, 68 GW of offshore wind, and 115 GW of onshore wind, although at times as much as three times the demand would be provided. 0.1% of the time would require generation from other sources.
In March 2012, Denmark's parliament agreed on a comprehensive new set promotional programs for energy efficiency and renewable energy that will lead to the country getting 100 percent of electricity, heat and fuels from renewables by 2050. IRENEC is an annual conference on 100% renewable energy started in 2011 by Eurosolar Turkey. The 2013 conference was in Istanbul.
More recently, Jacobson and his colleagues have developed detailed proposals for switching to 100% renewable energy produced by wind, water and sunlight, for New York, California and Washington states, by 2050. As of 2014, a more expansive new plan for the 50 states has been drawn up, which includes an online interactive map showing the renewable resource potential of each of the 50 states. The 50-state plan is part of The Solutions Project, an independent outreach effort led by Jacobson, actor Mark Ruffalo, and film director Josh Fox.
As of 2014, many detailed assessments show that the energy service needs of a world enjoying radically higher levels of wellbeing, can be economically met entirely through the diverse currently available technological and organisational innovations around wind, solar, biomass, biofuel, hydro, ocean and geothermal energy. Debate over detailed plans remain, but transformations in global energy services based entirely around renewable energy are in principle technically practicable, economically feasible, socially viable, and so realisable. This prospect underpins the ambitious commitment by Germany, one of the world's most successful industrial economies, to undertake a major energy transition, Energiewende.
In 2015 a study was published in Energy and Environmental Science that describes a pathway to 100% renewable energy in the United States by 2050 without using biomass. Implementation of this roadmap is regarded as both environmentally and economically feasible and reasonable, as by 2050 it would save about $600 Billion Dollars health costs a year due to reduced air pollution and $3.3 Trillion global warming costs. This would translate in yearly cost savings per head of around $8300 compared to a business as usual pathway. According to that study, barriers that could hamper implementation are neither technical nor economic but social and political, as most people didn't know that benefits from such a transformation far exceeded the costs.
The following places meet 90% or more of their average yearly electricity demand with renewable energy:
Some other places have high percentages, for example the electricity sector in Denmark, as of 2014, is 40% wind power, with plans in place to reach 85%. The electricity sector in Canada and the electricity sector in New Zealand have even higher percentages, 65% and 75% respectively, and Austria is approaching 70%. As of 2015, the electricity sector in Germany sometimes meets almost 100% of the electricity demand with PV and wind power, and renewable electricity is over 25%. Albania has 94.8% of installed capacity as hydroelectric, 5.2% diesel generator; but Albania imports 39% of its electricity. In 2016, Portugal achieved 100% renewable electricity for four days between 7 May and 11 May, partly because efficient energy use had reduced electricity demand. France and Sweden have low carbon intensity, since they predominately use a mixture of nuclear power and hydroelectricity.
Although electricity is currently a big fraction of primary energy; it is to be expected that with renewable energy deployment primary energy use will go down sharply as electricity use increases, as it is likely to be combined with some degree of further electrification. For example, electric cars achieve much better miles per gallon equivalent than fossil fuel cars, and another example is renewable heat such as in the case of Denmark which is proposing to move to greater use of heat pumps for heating buildings which provide multiple kilowatts of heat per kilowatt of electricity.
The most significant barriers to the widespread implementation of large-scale renewable energy and low carbon energy strategies, at the pace required to prevent runaway climate change, are primarily political and not technological. According to the 2013 Post Carbon Pathways report, which reviewed many international studies, the key roadblocks are:Climate change denial
Efforts to impede renewable energy by the fossil fuel industry
Unsustainable consumption of energy and resources
Path dependencies and outdated infrastructure
Financial and governance constraints
NASA Climate scientist James Hansen discusses the problem with rapid phase out of fossil fuels and said that while it is conceivable in places such as New Zealand and Norway, "suggesting that renewables will let us phase rapidly off fossil fuels in the United States, China, India, or the world as a whole is almost the equivalent of believing in the Easter Bunny and Tooth Fairy." In 2013, Smil analyzed proposals to depend on wind and solar-generated electricity including the proposals of Jacobson and colleagues, and writing in an issue of Spectrum prepared by the Institute of Electrical and Electronics Engineers, he identified numerous points of concern, such as cost, intermittent power supply, growing NIMBYism, and a lack of infrastructure as negative factors and said that "History and a consideration of the technical requirements show that the problem is much greater than these advocates have supposed." Smil and Hansen are concerned about the variable output of solar and wind power, but American physicist Amory Lovins has said that the electricity grid can cope, just as it routinely backs up nonworking coal-fired and nuclear plants with working ones.
In 1999 American academic Dr. Gregory Unruh published a dissertation identifying the systemic barriers to the adoption and diffusion of renewable energy technologies. This theoretical framework was called Carbon Lock-in and pointed to the creation of self-reinforcing feedbacks that arise through the co-evolution of large technological systems, like electricity and transportation networks, with the social and political institutions that support and benefit from system growth. Once established, these techno-institutional complexes become "locked-in" and resist efforts to transform them towards more environmentally sustainable systems based on renewable sources.
Lester R. Brown founder and president of the Earth Policy Institute, a nonprofit research organization based in Washington, D.C., says a rapid transition to 100% renewable energy is both possible and necessary. Brown compares with the U.S. entry into World War II and the subsequent rapid mobilization and transformation of the US industry and economy. A quick transition to 100% renewable energy and saving of our civilization is proposed by Brown to follow an approach with similar urgency.
The International Energy Agency says that there has been too much attention on issue of the variability of renewable electricity production. The issue of intermittent supply applies to popular renewable technologies, mainly wind power and solar photovoltaics, and its significance depends on a range of factors which include the market penetration of the renewables concerned, the balance of plant and the wider connectivity of the system, as well as the demand side flexibility. Variability will rarely be a barrier to increased renewable energy deployment when dispatchable generation such as hydroelectricity or solar thermal storage is also available. But at high levels of market penetration it requires careful analysis and management, and additional costs may be required for back-up or system modification. Renewable electricity supply in the 20-50+% penetration range has already been implemented in several European systems, albeit in the context of an integrated European grid system:
In 2011, the Intergovernmental Panel on Climate Change, the world's leading climate researchers selected by the United Nations, said "as infrastructure and energy systems develop, in spite of the complexities, there are few, if any, fundamental technological limits to integrating a portfolio of renewable energy technologies to meet a majority share of total energy demand in locations where suitable renewable resources exist or can be supplied". IPCC scenarios "generally indicate that growth in renewable energy will be widespread around the world". The IPCC said that if governments were supportive, and the full complement of renewable energy technologies were deployed, renewable energy supply could account for almost 80% of the world's energy use within forty years. Rajendra Pachauri, chairman of the IPCC, said the necessary investment in renewables would cost only about 1% of global GDP annually. This approach could contain greenhouse gas levels to less than 450 parts per million, the safe level beyond which climate change becomes catastrophic and irreversible.
In November 2014 the Intergovernmental Panel on Climate Change came out with their fifth report, saying that in the absence of any one technology (such as bioenergy, carbon dioxide capture and storage, nuclear, wind and solar), climate change mitigation costs can increase substantially depending on which technology is absent. For example, it may cost 40% more to reduce carbon emissions without carbon dioxide capture. (Table 3.2)
Google spent $30 million on their RE<C project to develop renewable energy and stave off catastrophic climate change. The project was cancelled after concluding that a best-case scenario for rapid advances in renewable energy could only result in emissions 55 percent below the fossil fuel projections for 2050.