Can Renewable Energy Replace Fossil Fuels, Meet Demand, & Power The World? (Moving Towards 100% Renewable Energy)

Can Renewable Energy Replace Fossil Fuels, Meet Demand, & Power The World? (Moving Towards 100% Renewable Energy)

We know that renewable energy is already being used in many places across the world.

But, can renewable energy replace fossil fuels, meet demand, and power the world?

Could we eventually see a world run 100% on renewable energy?

These are the questions we have to answer and summarise in this guide.


Summary – Can Renewable Energy Replace Fossil Fuels, Meet Demand, & Power The World?

  • Energy is required across many sectors in society
  • At the moment, renewable energy has made the biggest impact in electricity generation and consumption, with hydropower accounting for majority of the impact 
  • The transport, and heating and cooling sectors are still primarily run on fossil fuels (but in the future, there will likely be more progress made to electrify these sectors with renewable energy sources in the energy mix) 
  • Some major countries in the world like China and India still use fossil fuel heavy energy mixes, but China in particular is also the world leader in renewable energy investment
  • What we do know though, is that, as of 2018, there are at least 42 cities getting 100% of their electricity from renewable energy, with many more up around the 50% and 70% benchmarks
  • What we also know, is that, there are at least 12 countries getting 90%+ of their electricity from renewable energy
  • So, we know that it’s possible for cities, countries and regions to get majority of their electricity from renewable energy sources over fossil fuels
  • Some of these countries and cities have faced challenges and problems of varying sizes in their transition to increasing shares of renewable energy. The issues a country like Germany has faced in their transition have been well documented. Studying cities, States and countries that have already begun their transition to greater use of renewables and learning from them can help other places not make the same mistakes, and ensure a better transition with better planning and implementation
  • There are 100’s of studies and forecasts that have been published that explore the feasibility of 100% renewable energy and increasing shares of renewable energy for power worldwide, and for specific countries. Each of these studies list the benefits and challenges in transitioning to a higher share of renewable energy, and suggest different energy mixes for different regions and countries, but several summarise that there are less economic and technological barriers to increasing renewable energy share, and more political, social and cultural barriers
  • Pairing the examples of cities and countries already run on majority renewable energy with the positive studies and forecasts for increasing renewable energy in our electricity and overall energy mix worldwide, and it looks like a reality that renewables could majority or entirely take over from fossil fuels in the mid to long term future if social, cultural and political agenda leans that way
  • Solar, wind, and hydropower (to be able to store and supply energy when wind and solar aren’t producing) are suggested as the main renewable energy sources in some of the main studies and forecasts, but some also suggest energy mixes with geothermal, wave, tidal, bioenergy, and even natural gas or hydrogen
  • Overall, the factors and variables influencing the uptake of increased renewable energy share to replace fossil fuels is different in each region, town, city and country as a whole. Each one needs an individual assessment and short and long term strategy. The development and breakthroughs in new technology are a big variable too
  • The pros and cons of renewable energy have to be weighed against the pros and cons of fossil fuels in both the short and long term across social, environmental, economic and other areas. 
  • In slower transitions, it’s possible fossil fuels could compliment renewable energy in an energy mix until energy infrastructure and energy systems can fully support renewables
  • Nuclear is a forgotten energy source that fits somewhere in between fossil fuels and renewables, and could be utilised in some places. Some sources also indicate that coal fired CCS (carbon capture storage, or use) technology and some other forms of improved or hybrid fossil fuel technology could play a part in some energy mixes
  • Climate change/global warming and greenhouse gas emissions, air pollution from air contaminants (and the associated human health problems and mortality rates), an increase in the human global population (leading to increased demand for energy), growth of developing countries (leading to increased generation and consumption of energy), and the finite nature of fossil fuel resources are some of the biggest issues to consider that are related to the energy sector
  • When pursuing increased use of renewable energy sources, we might ask how effectively we are addressing each of the problems we are trying to solve (like reduced greenhouse gas emissions, peak oil, reduced air pollution), and what trade offs we are making by not pursuing the use of another energy source like fossil fuels. This can help keep an energy strategy and plan more objective as opposed to political or subjective
  • Although there are some that say that renewables are too costly and unreliable, there are others that point to the significant environmental and social costs of fossil fuels, as well as the current investment and subsidies fossil fuels have been afforded, and point out that renewables can only get better in the future with new technological breakthroughs (their potential might be a lot higher than fossil fuels). Others point out that some of the problems pointed out with renewables, apply to fossil fuels and nuclear too
  • Ultimately, a transition to 100% renewable energy systems worldwide will require a balancing of various social, economic, environmental, and other types of priorities and factors. It will involve possible breakthroughs in aspects like energy storage and back up dispatchable energy sources. And, while it’s clear there are problems like variability/intermittency of renewable energy, it’s also clear that it’s likely solutions to the current problems of renewable energy can be developed in the future. In any transition, a hybrid flexible energy system that composes of different types of energy (fossil fuels, nuclear, conventional renewables, and modern renewables) might be required as a bridging system 


Can Renewable Energy Replace Fossil Fuels?

Each city or country has it’s own energy mix i.e. the energy sources that provide overall energy or electricity for that city or country, and the proportions in which they provide that energy or electricity.

Some countries have an energy mix that is composed of mostly fossil fuels, whilst others have an electricity energy mix that is composed mostly of renewable energy sources.

An example of a country with majority fossil fuel energy sources is China (China is currently the world leader in coal consumption), while a country like Iceland gets 100% of it’s electricity from renewable energy sources.

So, yes, renewables can replace fossil fuels in a country or city’s energy mix in differing proportional amounts (could be anywhere from 0 to 100%).

What is important to note though is that energy is different to electricity. Electricity is a sector in itself, whilst energy stretches across various sectors – transport for example is a sector that is primarily powered by fossil fuels (although this will slowly change with more electric vehicles on the road in the future powered by renewable energy sources).

So, right now, renewable energy sources have penetrated into electricity production and consumption, but have not penetrated heavily into the transport and heating and cooling sectors – which are still both primarily fed by fossil fuels.


Can Renewable Energy Meet Demand?

Demand is the amount of energy or electricity required by all sectors and industries within a city or country.

Demand for energy might be classified in three categories – base load (the minimum amount of energy required to meet demand 24/7), intermediate and peak demand.

Some sources debate this, but traditionally, renewables have been a variable source of energy. Solar and wind for example provide a lot of energy when the sun shines and when winds are blowing, but that energy can drop significantly when the sun and wind drops off.

A few different approaches to address variability are:

  • Huge batteries to store solar and wind energy (as was done in South Australia). But, batteries tend to only be able to store enough energy for short term output (a few hours), and with currently technology, they are very costly the bigger they get and the more storage they have
  • Having fossil fuel or nuclear backups power plants that can ramp up quickly when solar and wind drops off
  • Having pumped hydro power with water storage (and energy storage) that can ramp up quickly when solar and wind drops off. Strategies for the future might involve using renewable solar and wind energy to power pumping water uphill to make pumped hydro completely or mostly clean energy

In Germany, variability and mismatching of the timing of energy supply and consumption, has caused a few issues such as overloading power grids, excess energy forcing utilities to have to pay customers to take excess power, and other issues.

Complimentary energy sources (in addition to wind and solar) can also help provide more power for peak energy demand periods as well.


Can Renewable Energy Power The Entire World?

This is perhaps too broad of a question.

Studies done on this question indicate they can, and that there are only political, social and cultural barriers, and not technological or economic.

Perhaps instead of asking if renewables can power the entire world, we look to ask if renewables can power individual towns, regions, cities and countries.

Every location has different factors and variables at play that will determine what the answer in the short, medium and long-term looks like to this question.

Also, developing countries are going to face starkly different factors and variables to developed countries.


Moving Towards 100% Renewable Energy …

100% renewable energy may be a goal for a city or country for electricity, or for all the major energy consuming sectors (such as transport, heating and cooling, commercial/industrial, agriculture etc.).

Some cities and countries already have a large amount of electricity sourced from renewable energy sources.

Other cities and countries have committed to certain targets to have a greater % of their electricity comes from renewables at different stages up until the year 2050.

It’s possible the transition (however slow or fast that might happen) to a greater majority of renewables in the energy mix may involve fossil fuels and nuclear as complimentary energy sources for different reasons.

Different sources point out the drawbacks of renewable energy, but, other sources point out that the drawbacks to renewable energy are nowhere near as destructive or harmful as fossil fuels in the mid to long term.

Greenhouse gas emissions and climate change, outdoor air pollution, resource depletion, and energy efficiency are some of the main issues that can be addressed in different ways by moving towards 100% RE (or majority renewable energy) in an energy or electricity supply.


Potential Challenges, Issues & Considerations With Moving Towards Increased Renewable Energy

Potential challenges, issues and considerations in moving towards renewable energy may include:


  • Solar and wind can be variable sources of energy i.e. they only provide energy when the sun is shining and the wind is blowing
  • Matching the timing of variable energy generation with consumption of this energy (energy needs to be consumed when it is produced unless it gets stored), and what to do in the event a power grid is overloaded 
  • Some sources think that the challenges are not technological or economics related, but rather political, institutional, cultural/social
  • Whether or not renewables can scale up fast enough by a certain year/target time, and whether fossil fuels and nuclear energy are required in the meantime
  • Adding turbines to existing hydropower dams (when using hydro power as a backup source for solar and wind) may not physically be possible. And, discharging hydro power in some ways described by some studies and reports on future expansion of renewable energy can put unacceptable impacts on aquatic ecosystems and downstream water users
  • Upgrading and changing existing power grids to accommodate renewable energy can be expensive
  • Large scale storage batteries for renewable energy (like solar and wind) can be expensive
  • Building new transmission power lines and interconnectors to accommodate renewables can be expensive and take a lot of time
  • A divided public and government on climate change as an issue (i.e. lack of awareness of what it is, and how important it may or may not be to address with renewable energy)
  • Lobbying by groups, such as fossil fuel groups, who have a vested interest in existing energy systems, to argue only against renewables (without presenting the benefits)
  • Solar and wind farms can be land intensive compared to nuclear and fossil fuels ( – i.e. more land is needed for the same amount of power
  • Renewables can have negative environmental and wildlife consequences e.g. wind farms can be in the way of migratory bird flight paths in some countries and regions (
  • Poorer countries and States might not be able to afford the sometimes more expensive upfront cost of renewables
  • Current technologies [in some US States] are intermittent, variable, and unpredictable as they depend on the weather and consequently have limited capacity factors. At the scale needed, storage is currently not a viable option as the technology is very expensive and still developing (
  • Supply and demand have to be equivalent in the power market at any given time [so, making a decision of what energy source to take offline when a new renewable energy source is added can be difficult]. Also, in the short-run and in emergency situations, the grid regulators have to shut off the connection to the grid from the renewable energy sources … and this makes it more difficult for investors to recover the costs of their systems, and it also raises transmission costs for everyone else (
  • Baseload power sources (coal, natural gas, and nuclear) require time to ramp up and down and thus are relatively less responsive to changes in demand … [and, this time taken to ramp up and down can be expensive] (
  • Over time, operating at lower scales [for energy sources that are decreased or reduced when renewables are added] raises costs for utilities (and later the ratepayers) as they now have to operate the power plants at scales that are inefficient (
  • Another issue with the large targets for renewable energy is that they create load uncertainty for nuclear power plant operators [and, as renewables become cheaper, it may lead to the shut down of nuclear plants as they may not be able to compete] (
  • [When renewables are supported by government portfolio standards instead of natural market demand, subsidies might be increased in value, and this increase might be passed onto electricity ratepayers if there is no cost control in place] (
  • [A shortage of strategic metals (nickel, cobalt, copper, lithium) could be a problem in the future for batteries and other renewable energy technology]
  • Barriers to electricity infrastructure like transmission lines could prevent an increase in grid capacity for renewables (
  •  … diluteness, proximity, and reliability can be three [barriers to renewable energy] (
  • [Power density and how much land wind and solar need compared to fossil fuels and nuclear can be an issue – wind and solar comparatively need a lot of land for the same power – especially the big wind and solar farms. Some domestic areas can install their own solar panels] (
  • [… areas where renewables are installed are usually nowhere near where energy is needed – transmission lines can be costly and slow to build … Texas has already spent billions of dollars on thousands of miles of transmission lines that transport electricity from wind and solar farms in West Texas to cities in East Texas.] (
  • [The last issue with wind and solar is reliability/dispatchability – dispatchable generators need to be able to ramp up and down to help match elec supply with demand (and wind and solar struggle because it isn’t always windy or sunny). To supplement this – large batteries are needed for energy storage, and they can be costly] (
  • [energy grids in fossil fuel dominated places are designed on the basis of large controllable generators … and, has little energy storage. Intermittent renewable energy present a problem in this instance. However, technological advancements are presenting solutions to intermittence, such as new hybrid solar panels that can harness energy from raindrops and therefore be effective during day and night] (
  • … geographical distribution and variability and uncertainty in output pose challenges to the US’ electricity system with renewables (
  • The case study from the CSIRO referenced below lists some of the technical challenges in moving towards 100% renewables such as flexibility of the energy grid in dealing with variable energy, dispatch ability of energy sources to complement renewables, need for energy storage, the need for frequency control and the provision of inertia, price signaling and communication between distributors and the wholesale electricity market, and deciding on base load from either fossil fuels, nuclear or other renewables
  • [Some of the challenges in increasing the penetration of renewables in all sectors are electricity transmission (the way electricity is transmitted, generated and sold) … The electricity system need to be flexible to deal with variable output, and market structures need to evolve to integrate renewable power properly] (
  • … political ideology and the capture of governments by powerful vested interests is a major barrier [to renewable energy growth] (
  • [market designs favor fossil fuels, market failure favors fossil fuels and fossil fuels want to cling to their traditional business models] (
  • Older power engineers are attached to the concepts of base load, intermediate and peak load power stations … and cannot envisage a system that contains a large fraction of variable RElec and where demand can be modified almost instantaneously (
  • [Intermittency and variability, overcapacity, grid stability, variable electricity prices, back up dispatchable power sources, and energy storage are some of the biggest challenges facing a transition to renewable energy] (
  • [Intermittency and variability of renewable energy means that power supply is lacking when there is less wind and sunshine, and there can be a surplus (overcapacity) supply of power when there is lots of sunshine and wind] (
  • [Overcapacity is when there is an over supply of renewable energy – usually caused by the variable/intermittent nature of wind and solar. Overcapacity can overload power grids, and can lead to variable electricity prices] (
  • [Grid stability can be impacted when there is an overcapacity of RE – examples of this are Poland and the Czech Republic’s power grids, which receive transmitted electricity from Germany’s power system] (
  • [Variable electricity prices can be a result of the introduction of renewable energy. RE can make the price of electricity more competitive. But, RE can also create problems with pricing of electricity when there is a surplus, due to variability. Power plants might actually have to pay commercial customers to take their electricity in times of surplus. This can create uncertainty and problems for all types of energy generation – as prices aren’t predictable and stable] (
  • [The variable nature of renewable energy means that back up energy sources, known as dispatchable energy sources, might be needed. These sources might need to be able to ramp up and down quickly to fill in energy gaps when renewable energy supply is down, and not overload the grid when renewable energy supply is up. Back up energy sources are usually coal or natural gas. Nuclear can also figure into this equation. Using natural gas or coal as backup energy sources can actually increase greenhouse gas emissions in the short term, as seen in Germany, and actually goes against short term carbon emission targets. Furthermore, if sufficient back up energy sources aren’t in place for some energy systems, this can lead to blackouts – as seen in South Australia] (
  • [Renewable energy use, along with how competitive natural gas and coal can be without carbon pricing, can mean the closure of nuclear plants – especially if not supported by the government] (
  • [Increasing installed capacity of solar and wind can have a negative impact on land use and the transformation of landscape in some countries – as solar and wind farms aren’t as land efficient as fossil fuel power plants] (
  • [Capital and upfront costs, siting and transmission, market entry, an unequal playing field for different energy sources and competitors, and reliability misconceptions can be some of the challenges for renewable energy technology in general, and when it comes to expansion and increased use] ( 


Other Considerations

  • The final energy mix a country or city uses i.e. how much of each renewable source, how much of each fossil fuel source, how much nuclear, and so on
  • Whether or not more debatable energy sources like nuclear, bioenergy, hybrid energy sources and hydrogen, and CSS fossil fuels are used in addition to modern renewables like solar, wind, hydro, geothermal and wave/tidal
  • Energy storage – whether batteries, or pumped hydro energy storage is used to store energy when variable energy sources like solar and wind are used. Other options are flexible natural gas power plants, or, adding turbines to more rapidly convert stored heat from solar thermal power plants into electricity.
  • The number of hours of energy storage available e.g. 2 hours, 12 hours, 24 hours, or more
  • The natural renewable resources each country has available e.g. Iceland’s renewable energy resources to draw from might be different to Australia (Australia is abundant in land, sun and win for example)
  • Level of financial investment in renewables (can vary from year to year, and with support from government mechanisms)
  • How much a government supports and commits to renewables, and the policies, subsidies and other incentives they introduce (subsidies on fossil fuel energy and renewable energy, subsidies for residential solar installation, carbon taxes etc.)
  • Certainty for businesses and investors in the market – they need to know (have some certainty) they can get a return and profit on investment over 20 or 30 years
  • How cheap each renewable source is to provide electricity
  • Whether or not renewable energy installations degrade grid reliability by undermining continuously operated “baseload” nuclear and coal power plants in countries like the US (
  • Whether baseload power is necessary to a well-functioning electric grid or not. Some say baseload (such as fossil fuels and nuclear power) isn’t necessary, but rather a flexible and dynamic power supply from both variable and energy storage renewables will suffice. An example of this is when California utility PG&E announced plans to shut down a nuclear plant as they said this baseload plant was ill suited to help manage the California power grid which has a diverse mix of energy sources and renewables  (
  • What happens to existing fossil fuel and nuclear equipment and infrastructure, and these industries as a while, when they are phased out – some future scenarios see them remodelling to supply hydrogen or synthetic gas (instead of real natural gas)
  • How fast (at what rate per year) fossil fuel is phased out
  • What happens to jobs in each industry with phase outs – are new jobs created, and are existing workers re-trained and re-skilled to work in new industries?
  • [Economically in the future, we will need large investments in grid storage, transmission to distribute power and to smooth out the issues of intermittency] (
  • [Politically, creation of the regulatory framework, setting standards and offering incentives to economies to make a significant shift in their energy usage to renewables will be required for increased use of renewables] (
  • Growth in renewable energy can be influenced by … strong lobby groups looking to support national industry … [and] National industry is in turn more likely to have grown where there are natural resources to support the early development of an industry (
  • Public interest and acceptance for particular types of renewable energy are driven by multiple factors, including support of local jobs and industry, visual impacts and public awareness of climate change (
  • [It’s possible there might be an] inadequate understanding of the engineering, scientific and quantitative modelling has found its way through to the political mainstream ( outlines some of the individual factors that might impact expansion of individual renewable energy sources globally into the future:


  • Market and policy framework developments (whether there are supportive government policies and market improvements)
  • Regulatory and financial challenges

Solar PV

  • Cost reductions of solar PV technology impact on technology competitiveness
  • Presence of feed in tariffs and deployment quotas

Solar CSP

  • Multilateral bank support
  • Cost reduction potential 
  • Technology risk
  • Access to financing
  • Project lead times
  • Market designs
  • Whether or not energy storage is valued 


  • Federal tax incentives
  • Presence of feed in tariffs
  • Grid integration challenges
  • Faster commissioning of transmission lines
  • Larger auction volumes (more auction activity and faster auction implementation)
  • Faster commissioning of planned projects


  • The development of large scale hydro
  • Concerns of social and environmental impact
  • Untapped resource potential
  • Attractive economics to improve electricity access affordably
  • Completing feasibility studies, securing finance, finishing civil works
  • Full commissioning of mega projects


  • Demand in developing countries and emerging economies
  • Abundant resource availability
  • Support of projects by government policy
  • Pre development risks, and securing financing for projects


  • Whether a renewable technology is in the large scale stage, or small-scale demonstration and pilot project stage (like marine renewable technology is) writes about some practical tips for moving towards 100% renewables:

  • Make sure the choices of consumers in green energy are privatised
  • Consider incentives or updating portfolios and adding a nuclear energy tier, to keep nuclear power in operation in the short term [as premature shutdowns and switching to natural gas may actually increase GHG emissions]
  • Keep investing in emerging energy technology
  • Keep updating existing energy policies
  • Find more ways to make CSS and direct capture technologies more economically feasible
  • Focus on energy efficiency in the future which can help increase capacity for renewables and provide ancillary services to the grid
  • In addition to the power sector, figure out how to decarbonize the transportation, manufacturing, and agriculture industries
  • Spread low carbon energy to developing economies


The environmental impacts of wind, solar and hydro energy are listed at


Additionally, we’ve written some guides which outline some of the other challenges in moving to renewables (generally, and for specific countries like China)


Benefits Of Using Increased Renewable Energy 

Potential benefits of moving to renewables over fossil fuels may include:

  • Addressing greenhouse gas emissions and climate change/global warming
  • Addressing outdoor air pollution, air quality, and the associated human health problems and mortality rate associated with it
  • Addressing future potential issues with scarcity of fossil fuel resources
  • Reduction of fossil fuel resources mining (and associated problems with mining)
  • Economic benefits like job creation, economic stimulus, additional income streams for individuals, and so on
  • Reduce costs and money spent addressing some of the other problems mentioned in this list
  • Addressing other environmental issues that happen directly or indirectly as a result of the above problems, like water pollution, land degradation, acid rain, ocean warming and acidification etc. 
  • Providing energy independence to countries who currently rely on importing fossil fuels from other countries
  • Renewable technology and equipment is only expected to get cheaper and better/more advanced in the future – leading to potentially only more favorable future outcomes
  • Renewable energy can compete with fossil fuels for cheaper wholesale electricity prices
  • Renewable energy can be brought to previously energy poor areas and address energy poverty (especially in places that are still using biofuels for indoor cooking and heating and suffer from indoor air pollution)
  • Save on other critical resources like water which is heavily used on fossil fuel plants for cooling (
  • Energy efficiency and and overall reduction in total energy use (by switching to renewables over fossil fuels)


You can read more about the potential benefits of using a greater share of renewables for energy and electricity in this guide:


Studies & Reports That Assess The Feasibility Of 100% Renewable Energy Scenarios Globally, & For Different Countries

There are various studies and reports that assess the feasibility of moving towards greater shares of renewable energy in the future, either globally, or in individual countries.

They may also list pathways of how we can get there, and what the energy mix would look like.

We’ve listed and summarised them below: (renewable energy globally, and in a range of individual countries)

  • According to a review of the 181 peer-reviewed papers on 100% renewable energy which were published until 2018, “[the] great majority of all publications highlights the technical feasibility and economic viability of 100% Renewable Energy systems
  • Mark Z Jacobsen 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’
  • 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
  • The barriers to large scale renewable energy are: climate change denial, the fossil fuels lobby, political inaction, unsustainable energy consumption, outdated energy infrastructure, and financial constraints
  • [Overall, when considering 100% renewable energy scenarios] 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
  • In countries with high variation in energy demand by season (for example the UK uses far more gas for heating in the winter than it uses electricity) but lacking hydropower electrical interconnectors to countries with lots of hydropower (e.g. UK – Norway) will probably be insufficient and development of a hydrogen economy will likely be needed: this is being trialled in the UK and 8 TWh of inter-seasonal hydrogen energy storage has been proposed.
  • In Australia, as well as storing renewable energy as hydrogen, it is also proposed to be exported in the form of ammonia. (renewable energy globally):

  • A new Jacobson paper outlined that …
  • 139 countries can be broken down to 20 regions and the most appropriate energy storage resolution individually suited to those regions can be implemented.
  • … [first though] stability of the grid [needs to be found out] every 30 seconds in 5 years, in each region
  • 100% renewables has risk and demands a significant amount of efforts (renewable energy in the US):

  • … the U.S. can generate most of its electricity from renewable energy by 2050
  • … an 80 percent renewables future is feasible with currently available technologies, including wind turbines, solar photovoltaics, concentrating solar power, biopower, geothermal, and hydropower
  • … [a high renewable scenario can] meet electricity demand across the country every hour of every day, year-round.
  • Variable resources such as wind and solar power can provide up to about half of U.S. electricity, with the remaining 30 percent from other renewable sources.
  • [there are] multiple pathways to reach this goal
  • [to reach this goal] the right long term clean energy policies are needed, the electricity grid needs to be improved, there needs to be more advanced grid planning, there needs to be prices on carbon emissions, and there needs to be increases in funding for research and development of renewables (renewable energy in the US):

  • A Renewable Electricity Futures Study (RE Futures) concludes that ‘renewable electricity generation… in combination with a more flexible electric system, is more than adequate to supply 80% of total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the country’
  • [This can happen via a] portfolio of supply- and demand-side options, including flexible conventional generation, grid storage, new transmission, more responsive loads, and changes in power system operations
  • The abundance and diversity of U.S. renewable energy resources can support multiple combinations of renewable technologies
  • [some benefits would be decreased GHG emissions and decreased water use]

– (renewable energy in Australia):

  • [the CSIRO says] there is no apparent technical impediment to reaching 100 per cent renewables for the [Aus] national electricity grid
  • … introducing renewables at a share of 10, 20 or 30 per cent is fairly trivial on the basis that the existing generation capacity has a lot of flexibility to deal with the variability
  • … existing back-up and redundancy for the current coal-dominated grid [is] already in place
  • … peaking gas, using the dispatchability of coal and the interconnection between states allow renewables to contribute to the system. That has generally been the approach in most states
  • [in South Australia, and in renewable modelling, problems can begin to occur at around 40% renewable energy share. To deal with this, you either have to add energy storage, or a dispatchable form of energy that can support renewables. Dispatchable energy could be other renewables like solar thermal or geothermal, or another form of dispatchable energy]
  • [for 100% renewable penetration into the electricity system … we might need] very, very high battery deployment to achieve that … and also technologies like biogas, which is dispatchable, and dispatchable biomass. This take care of energy balancing on a half-hour basis. There are also other issues around the need for frequency control and so forth, where you need additional technologies that provide inertia. That could include things like synchronous condensers and more advanced inverters for the battery technologies, and so forth.]
  • [it should be noted that deploying high renewable energy penetration solutions and having them work in reality can be different to simulation and modelling]
  • [price signalling and communication between technologies down at the distribution end of the market and up into the wholesale market … could be useful in the future]
  • [base load is not essential with fossil fuels if you have an energy mix of wind and solar PV, and pumped hydro storage] (renewable energy in the US)

  • [when running every major energy sector on renewable energy] across all 50 states, [there was a] 39 percent reduction in total end-use power demand by the year 2050
  • About 6 percentage points of that is gained through efficiency improvements to infrastructure, but the bulk is the result of replacing current sources and uses of combustion energy with electricity
  • … clear plan[s] [have been laid out] for each state to make an 80% transition to renewable energy by 2030, and reach 100% by 2050
  • Some States will have a much more achievable plan than others
  • Initial costs will be high, but would eventually average out to roughly the current cost of fossil fuel infrastructure (renewable energy for the world):

  • The world can limit global warming to 1.5℃ and move to 100% renewable energy [by 2050] … without relying on technological fixes such as carbon capture and storage …
  • the gas industry can be a transition fuel … without its infrastructure becoming obsolete once natural gas is phased out
  • [there can be a] conversion of the gas industry to synthetic fuels and hydrogen over the coming decades … Natural gas will be increasingly replaced by hydrogen and/or renewable methane produced by solar power and wind turbines. While most scenarios rely on batteries and pumped hydro as main storage technologies, these renewable forms of gas can also play a significant role in the energy mix.
  • [there can be an increase in the] amount of economic output per unit of energy use
  • [there’s a relatively slow phase out of natural gas in this scenario]
  • [different types of jobs in the energy sector are impacted differently with the above scenario] (renewable energy for each State of America):

  • … a 50-state roadmap has been developed for transforming the United States from dependence on fossil fuels to 100 percent renewable energy by 2050
  • [it is designed to] maximize the renewable resource potential of each of the 50 states (renewable energy in the US)

  • This study considered only wind and solar
  • Wind, solar, and storage could meet 90–100% of America’s electricity needs [based on 36 years of hourly weather data, and the US’ electrical demand and variation over this time]
  • Wind and solar are variable – they fluctuate in space and time with their supply of energy
  • Fluctuation of these energy sources can complement each other though – solar power generation is highest in the summer and lowest in the winter. Wind power is greatest in the spring and fall. Wind turbines work at night when solar panels are dormant 
  • There were two future scenarios the authors of this study focussed on … 
  • 1. … with 100% power capacity and no mechanism to store energy, a wind-heavy portfolio is best (about 75% wind, 25% solar) and using large aggregate regions is optimal. It is possible to supply about 75-80% of US electrical needs.
  • 2. If the system were designed with excess capacity (the 150% case), the US could meet about 90% of its needs with wind and solar power.
  • … both systems could generate too much power for use. In this event, excess energy could be stored in several ways, for example in batteries or by pumping water into elevated tanks and then letting the water fall at night and turn a turbine.
  • When the above study was modified to allow up to 12 hours of US energy storage … They then found that the 100% capacity system fared even better (about 90% of the country’s energy) and the optimal balance was now more solar (approximately 70% solar and 30% wind). For the over-capacity system, the authors found that virtually all the country’s power needs could be met with wind, solar, and storage.
  • Furthermore, people are learning to use energy more wisely, either by using more efficient products or purchasing electricity during off-peak hours. These behavioral changes can also help us reach a 100% clean energy target. (renewable energy in Australia, and the US)

  • … simulated up to six years using real data on sun and wind and electricity demand, and in [a] peer-reviewed paper [have] shown [Australia] could have operated the national electricity market if [it had] installed enough [infrastructure] entirely on renewable energy with the same reliability as the same existing system
  • [there’s not technical challenges in this transition, but political challenges … for example, some politicians might have too close of a relationship with fossil fuel industries, or, a government may simply not show enough commitment to renewables and this can cause uncertainty for investors]
  • [the renewable energy setup would include wind, solar PV, high voltage transmission lines, pumped hydro and energy storage batteries]
  • [the US has more than enough resources to run entirely on renewables as well]
  • [challenges for a transition to renewables are mostly political, institutional, cultural] (renewable energy globally, and in the US):

  • [Mark Jacobsen, a Stanford University engineer, says the world can be run on solar, wind and hydro energy by mid century]
  • Critics of Jacobsen’s journal publication debate it citing invalid modeling tools, modeling errors, and “implausible and inadequately supported assumptions
  • Jacobsen’s evaluation of a renewable future does not include fossil fuels with CSS technology, or nuclear reactors
  • [Critics say that a new generation of nuclear reactors are required because renewables] cannot scale up fast enough
  • [Jacobson’s model for the US] replaces fossil fuels for heating and transportation with hydrogen and electricity generated by renewables]
  • Jacobsen’s model for the US implies a [15-fold expansion in hydropower generating capacity] as he uses hydro power for a backup to wind and solar.
  • Critics point out that Jacobsen’s approach of adding turbines to existing hydropower dams is not physically possible
  • Critics point out discharging hydro power from dams in some ways described can put unacceptable impacts on aquatic ecosystems and downstream water users
  • Critics point out that invalidating Jacobsen’s hydropower approach means blackouts and a breakdown of the system
  • But, Jacobsen says his hydropower upgrade proposals have technical and economic viability, and ‘reflect a cost that policymakers pursuing his road map would need to consider’
  • All clean energy proposals will always have trade offs compared to existing fossil fuel set-ups
  • Jacobson also has alternative sources of backup power, such as adding turbines to more rapidly convert stored heat from solar thermal power plants into electricity
  • Battery storage is yet another option, but is deemed unnecessarily costly
  • [other studies apart from Jacobsen’s have relied mostly on flexible natural gas power plants rather than dams or batteries to handle residual power demand]
  • Some say renewables may degrade the US’ power grid reliability
  • Some say base load power is necessary to a well-functioning electric grid – whilst other say flexibility is required, not base load power plants


There Might Be A Critical Point Where Energy Share Of Renewables Creates Major Challenges, Changes Or Support To Be Implemented For An Energy System Or Electricity System

There may be a critical point where a certain % of renewable energy share of electricity supply creates major challenges for energy grid operators and designers, or creates the need for changes, upgrades or support to be implemented.

Some say this % is as low as 20%, at which point there are ‘challenges for electricity grids in both managing intermittency and stabilising the system’s frequency’ (

Other sources say that ‘a share of more than 60 per cent can be absorbed without the need for storage’ or ‘… we could probably add that introducing renewables at a share of 10, 20 or 30 per cent is fairly trivial on the basis that the existing generation capacity has a lot of flexibility to deal with the variability’ (

Regardless of what the number is and what changes have to take place – what matters is that energy and electricity planners know their own city, State and national energy systems well, and know how to support new, increased or changing energy sources being implemented into a grid or system.


Residential Renewable Energy Set-Up, & Energy Efficiency Improvement – Changing The Energy Sector

Countries like Australia for the first time are starting to consider the impact of residential/household renewable energy power setups, and advances in energy efficiency on the main energy grid:

  • … the rise of rooftop solar and household batteries, as well as improvements to energy efficiency [is transforming the energy sector]. AEMO says these advances will continue to flatten grid demand and reduce demand for baseload generation – particularly during daylight hours.

What this means is that there has to be more planning around what the forecasted future electricity demand of the population might be, how much power might be supplied by residents themselves, and how much needs to be supplied by the main electricity grid. The grid and commercial/utility infrastructure needs to be planned around this, instead of just utility side generation like it always has been in the past.

Furthermore, energy planners have to consider how energy efficiency improvements to the whole energy sector will impact both the supplier and consumer sides.


Further Resources On A Future With Increased Use Of Renewable Energy 

Below are some resources that contain different information relevant to a future with increased use of renewable energy. We’ve summarised (paraphrased) each:

  • Renewable Energy Portfolio Standards require the utilities to generate or procure a minimal percentage of energy in their portfolios from renewables energy
  • [favorable technical potentials in a State can lead to more of a particular renewable energy being established]

  • … policies, such as renewable energy subsidies and mandates and extra taxes on fossil fuels [can be economically devastating]

  • each region or State in a country has current energy demands, and these energy demands might change over time 
  • energy use [might be divided] into four sectors: residential, commercial, industrial and transportation

  • As of 2019, however, [renewable energy] needs to grow six times faster to limit global warming to 2 °C (3.6 °F)
  • [After the power sector, the transport and heating and cooling sectors could be next to be electrified by renewable energy sources]

  • Outlines reasons why some countries aren’t using renewables
  • Every country has different natural renewable resources and potential available – for example, Iceland gets it’s electricity from hydro power and geothermal sources. Australia, on the other hand, is a country rich in large scale solar and wind potential because of the amount of land it has (so much so, that there is potential to export solar energy to Asia in the future). Texas has one of the biggest capacities for wind in the US
  • How much a government commits to renewables can determine their uptake in a State or country
  • Hydropower has traditionally been cheapest way to source renewable electricity, but solar and wind are starting to outpace and become cheaper than hydro economically
  • Solar panels can either be installed on buildings and feed energy into a battery, or they can be set up in solar farms and feed directly into the grid
  • Government incentive in Germany encouraged much more solar installation than in a country like Australia
  • Batteries to store wind and solar energy can be expensive if you need one for more than a day’s worth of energy (South Australia recently installed one as an example) – they are good for short term bursts of power, like for example an energy peak demand period which might last 2 or 3 hours
  • Solar and wind can be variable sources of energy i.e. energy is produced more when there is wind and sunlight, but less when there isn’t
  • Two of the main sources of hydro energy are hydroelectric plants, and pumped storage hydro energy
  • Pumped storage hydro energy is a cheaper way of storing renewable energy than using batteries
  • Pumped storage hydro energy could be used as a backup to solar and wind energy (seeing as though solar and wind are variable)
  • It’s possible South Australia could have prevented their last blackout if they had pumped hydro storage energy to compliment their current renewable energy sources
  • Successful use of hydro can maintain electricity during times of drought

  • Outlines the potential that pumped storage hydro energy has for the future to provide enough stored energy to power the world
  • Thousands of new pumped storage hydro energy sites have been found worldwide via an algorithm
  • These sites still have to pass on-site inspections and tests (there’s several factors that need to be checked off for a site to be suitable), but if only 1% of them pass final assessment, they will have adequate storage capacity for the world
  • The big positive that pumped storage hydro energy offers is that it can store energy. Solar and wind energy don’t have this ability
  • In the future, we might see pumped storage hydro energy sites that use wind and solar energy to pump water up to the top water reservoir – providing almost a completely clean form of energy 


  • apart from the electricity sector, there are the heat and transport sectors which could become renewable powered. Right now, transport, through the use of petrol and diesel-fuelled cars; and for heating, through the use of oil and natural gas boilers in buildings [are fossil fuel powered]
  • [we could switch to bio fuel or electric and hybrid cars]
  • [we could switch to district heating or electrification of heat]
  • [Although each country has different renewable energy resources … this difference is thought to be smaller than those relating to fossil fuel reserves]
  • [It’s expected as renewables become cheaper, subsidies will drop away – which is good, and brings the market back into play for pricing, as opposed to regulation controlling pricing]
  • [One of the biggest challenges in the future with renewables is matching timing of energy supply with demand]
  • Digitalisation, energy storage and demand response are the keys to helping future energy systems maintain balance
  • The generation of energy for heat, electricity and transport is interconnected through storage, monitored through smart meters, and changed through voluntary shifting of demand



  • [Several types of renewable energy can provide baseload power such as] … geothermal energy is available at all times, concentrated solar thermal energy has storage capability, and wind energy can be stored in compressed air
  • It will be over a decade before we can produce sufficient intermittent renewable energy to require high levels of storage, and there are several promising energy storage technologies



  • [The fact that carbon isn’t priced in some countries allows coal to beat out nuclear and other energy sources]
  • [Some people say that renewables aren’t reliable enough to provide baseload energy because of their intermittency, whilst others say renewables can provide a flexible and dispatchable grid, and can be designed for reliability, security and affordability]
  • … several of the [renewable energy] simulation studies achieve reliability with zero or negligible base-load capacity
  • … for a reliable generating system [it is unnecessary for renewable power stations to be dispatchable
  • [Increased demand for energy in the future doesn’t take into account the increased] energy efficiency renewables can provide … [or the facts that] a unit of electricity from wind and solar uses three times less energy to produce than fossil fuels, and EVs half as much as internal combustion engines
  • The capacity factors of different energy sources matter in calculations and models
  • [100% renewable electricity supply system are possible even if] RElec is limited to technologies that are commercially available now. Regions with insufficient local RE resources will in future be able to import RE via transmission line and/or tanker carrying renewable fuels



  • [Even though a country or city might have an average % of it’s electricity provided by renewable energy sources, on some days that are very sunny and breezy, that % can significantly increase. For example, Germany had an average at the end of 2017 of around 36%, but on very sunny and breezy days, that number can jump up as high as 86%. On those days, coal plants and nuclear plants may either not be in use, or severely reduced in use.]
  • [Intermittency and variability, overcapacity, grid stability, volatile electricity prices, back up dispatchable power sources, and available energy storage are some of the problems that face increased use of renewable energy]
  • [Intermittence and variability is the nature of how consistent the energy supply is from renewables i.e. whether the sun and wind are consistent and how consistent the resulting energy supply is to the grid]
  • [Overcapacity is when a power grid gets flooded with surplus/excess energy – usually caused by very sunny and highly windy conditions]
  • [Grid stability is a grid’s ability to deal with excess power being pushed through it, and the result of that extra power i.e. are there blackouts and shutdowns, or is there a non destructive way that excess energy is dealt with and used such as filtering off to the power grids of other States and countries who need it]
  • [Volatile energy prices can be a result of overcapacity – when there is too much electricity – it pushes prices down … sometimes in the negative. Volatile prices not only reduce profits, but increase uncertainty for investors and energy suppliers]
  • [Backup energy sources that are dispatchable are needed when renewable energy is highly variable and there is inadequate forms of energy storage in place. These dispatchable energy sources like coal and natural gas need to be able to ramp up and down quickly when more power is needed, or when power needs to be reduced quickly]
  • [Energy storage can be important in a renewable energy system. If there is stored energy, then this energy can be used in the event that there is lower renewable energy being supplied due to poor wind and sun conditions]
  • [Some regulations, like those in Germany, require renewable energy to be used first in the grid, so fossil fuel energy is pushed out of the grid and used by neighboring countries when there is an excess of renewable energy. Countries like Poland and Czech Republic have suffered overloaded power grids as a result of variable energy from Germany]
  • [Germany energy suppliers have also experienced volatile electricity prices, which have sometimes gone in the negative, as a result of overcapacity and variability. This means power plants have to pay commercial customers to take their electricity]
  • [Volatile electricity prices] can be somewhat addressed by replacing the feed-in tariff subsidy with a market-responsive auction system based on pre-set RES capacity growth caps
  • [In Germany, because of a lack of Government support for nuclear, natural gas and coal power are usually the back up sources of power for variable renewable energy sources. This has led to a short term increase in greenhouse gas emissions]
  • [Because of intermittency, even in a given year when solar and wind installed capacity increases, poor wind and sun conditions can lead to an overall drop in solar and wind energy generation]
  • [Intermittency and overcapacity, without adequate back up energy sources, or without proper energy storage, can lead to blackouts]
  • [South Australia is an example of a place that has experienced blackouts as a result of renewable energy and a lack of adequate energy back up … although they have now got a giant energy storage battery installed]
  • [California is an example of a State that has experienced issues with intermittency and overcapacity of renewable energy]
  • [Some estimates of what Germany would need to do to go 100% renewable, is build a hugely expansive solar and wind system compared to what they have now, and also invest in a significant energy storage system compared to what they have now … so there are costs to expansion]. This could cause a host of problems related to overcapacity, energy spot prices and carbon-intensive back-up power when RES output falls, not to mention the landscape impact of wind turbine installation on this scale and the resistance this might cause. [Also, in this scenario] … If the back up power sources are replacing expensive gas fuel by cheap lignite – then GHGs will increase 
  • [Increased production by intermittent renewable energy sources may not be the way to go as there would also be huge tradeoffs on land use and how landscape is transformed with solar and wind farms that take up far more land than fossil fuel power plants. Wind converters and transmission lines also take up a lot of land. For these reasons and others …] countries might look at other forms of CO2 free energy production
  • [Ultimately, a transition to renewables isn’t going to be without challenges] … It requires balancing environmental efficiency, energy security and harmonious electricity markets is a complex task that will take many decades to solve
  • [An approach that falls somewhere between supporting existing energy systems and new renewable energy systems might be required]
  • Nuclear power could play an important role in providing low-carbon baseload or back-up power, although its suitability for dispatchable capacity is limited by how slowly nuclear plants can ramp up or down on demand when compared to gas turbines. Public and political appetite for significant nuclear fleet expansion is also low in many countries, with Germany proving particularly nuclear-averse.
  • [A strategy that provides solutions and components in moving towards increased use of renewables might involve] back-up dispatchable power, demand response and energy efficiency measures, distributed generation, data-driven smart technologies, grid-level energy storage and more integrated networks. The EU, through its harmonised policy environment, has an opportunity to take the lead on common energy markets and interconnected grids, although technical, political and financial obstacles to this are currently formidable
  • … If you want to use fluctuating renewable power, you have to upgrade the grids across Europe
  • Given the extended timespan of the challenge [of moving towards 100% renewables], breakthrough power sources such as fusion energy – which could provide emissions-free baseload power in virtually unlimited amounts – could emerge as well. Large-scale energy storage is still in the early stages of development with several competing technologies; the efficiency of dispatchable storage will be a concern moving forward, but breakthroughs in this area could also have a decisive effect on the feasibility of greater RES predominance.
  • While it’s undeniable that RES intermittency and overcapacity are significant problems for the energy systems of today, a host of options can be developed to create solutions for the energy systems of tomorrow. But until fully clean energy systems become technologically and economically feasible, some level of hybridism will be needed to offset the variability of intermittent renewables



  • [some of the barriers and challenges for renewable energy technology are …]
  • [Capital Costs – such as the upfront of building solar and wind farms compared to fossil fuel plants. Higher costs can lead to less investment by investors in some places. Over time though, costs can average out, and renewables seem to be getting cheaper and more affordable over time too. It’s also worth noting that new coal and natural gas plants that have to meet environmental regulations are becoming increasingly expensive as they have to have certain systems and devices fitted to decrease emissions and pollution]
  • [Decentralization, Siting and Transmission – fossil fuels are centralized generally to one spot, where as renewables like solar and wind can be decentralized i.e. spread out providing energy from many locations … solar for example can come from utility solar farms, or from distributed solar panels on buildings and in residential locations. Siting renewable energy that is decentralized can present issues with] negotiations, contracts, permits, and community relations, all of which can increase costs and delay or kill projects … [Transmission can also be an issue as power lines, interconnectors, power grids, and other infrastructure are required or need to be upgraded in order to get energy] from where it is to where it needs to be. [Areas that have the best renewable energy expansion potential for large solar and wind farms might be located far away from where the power is actually needed, which might be in cities for example … and it might be very difficult and expensive to build new infrastructure to service this expansion]
  • [Market Entry – fossil fuels are well established and developed industries with] existing infrastructure, expertise, and policy. [Renewable energy sources are less established and developed, and it can be harder for renewable sources in general, and individual renewable competitors to take a foot hold] Increased government investment in clean energy—in the form of subsidies, loan assistance, and research and development—would help
  • [Unequal Playing Field – fossil fuels might have political support, as well as subsidies, tax breaks and other incentives and loop holes available that renewables don’t have. It’s also possible investment and support for fossil fuels in the past could have went to renewables or energy efficiency instead. Fossil fuels, unless forced to have new environmentally friendly systems that minimize emissions and pollution, don’t pay the full environmental and social cost of their operation] Emission fees or caps on total pollution, potentially with tradable emission permits, are examples of ways we could use to help remove this barrier
  • [Reliability Misconceptions – such as pointing out that RE is variable and needs the support of other energy sources to meet base load requirements. But, renewables can be more predictable] when spread across a large enough geographic area—and paired with complementary generation sources. Modern grid technologies like advanced batteries, real-time pricing, and smart appliances can also help solar and wind be essential elements of a well-performing grid. Tests performed in California … a place with high renewable energy use … shows real-world validation for the idea that solar and wind can actually enhance grid reliability. Many utilities, though, still don’t consider the full value of wind, solar, and other renewable sources. Energy planners often consider narrow cost parameters, and miss the big-picture, long-term opportunities that renewables offer. [So, there needs to be more awareness around this and a willingness to go beyond these misconceptions]






































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