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Access to clean, affordable and reliable energy has been a cornerstone of the world's increasing prosperity and economic growth since the beginning of the industrial revolution. Our use of energy in the twenty–first century must also be sustainable. Solar and water–based energy generation, and engineering of microbes to produce biofuels are a few examples of the alternatives. This Perspective puts these opportunities into a larger context by relating them to a number of aspects in the transportation and electricity generation sectors. It also provides a snapshot of the current energy landscape and discusses several research and development opportunities and pathways that could lead to a prosperous, sustainable and secure energy future for the world.

The energy-efficiency drive at the information factories that serve us Facebook, Google and Bitcoin. The energy-efficiency drive at the information factories that serve us Facebook, Google and Bitcoin.

Fossil fuels—coal, oil and gas—supply most of the world’s energy and also form the basis of many products essential for everyday life. Their use is the largest contributor to the carbon dioxide emissions that drive global climate change, prompting joint efforts to find renewable alternatives that might enable a carbon-neutral society by as early as 2050. There are clear paths for renewable electricity to replace fossil-fuel-based energy, but the transport fuels and chemicals produced in oil refineries will still be needed. We can attempt to close the carbon cycle associated with their use by electrifying refinery processes and by changing the raw materials that go into a refinery from fossils fuels to carbon dioxide for making hydrocarbon fuels and to agricultural and municipal waste for making chemicals and polymers. We argue that, with sufficient long-term commitment and support, the science and technology for such a completely fossil-free refinery, delivering the products required after 2050 (less fuels, more chemicals), could be developed. This future refinery will require substantially larger areas and greater mineral resources than is the case at present and critically depends on the capacity to generate large amounts of renewable energy for hydrogen production and carbon dioxide capture. Efforts to find renewable alternatives to fossil fuels that might enable a carbon-neutral society by 2050 are described, as well as outlining a possible roadmap towards a refinery of the future and evaluating its requirements.

Christiana Figueres and colleagues set out a six-point plan for turning the tide of the world’s carbon dioxide by 2020.

New synthesis shows what a wasted decade means for the climate pact made in Paris. New synthesis shows what a wasted decade means for the climate pact made in Paris.

A comparative assessment of six alternative cropping systems over 20 years shows that, once well established, successional herbaceous vegetation grown on marginal lands has a direct greenhouse gas emissions mitigation capacity that rivals that of purpose-grown crops. Biofuel production at the margins Productive agricultural land that could otherwise be used to produce much-needed food crops is being diverted towards grain-based ethanol production in both Europe and the United States, partly in response to government legislation. An alternative is to grow cellulosic crops on so-called marginal lands. An evaluation of the potential of marginal lands in the Midwestern United States to produce biofuel while mitigating direct greenhouse gas emissions now finds that they have the capacity to produce a significant amount of biofuel energy without the initial carbon debt and indirect land-use costs associated with food-based biofuels. Legislation on biofuels production in the USA 1 and Europe 2 , 3 is directing food crops towards the production of grain-based ethanol 2 , 3 , which can have detrimental consequences for soil carbon sequestration 4 , nitrous oxide emissions 5 , nitrate pollution 6 , biodiversity 7 and human health 8 . An alternative is to grow lignocellulosic (cellulosic) crops on ‘marginal’ lands 9 . Cellulosic feedstocks can have positive environmental outcomes 10 , 11 and could make up a substantial proportion of future energy portfolios 12 , 13 . However, the availability of marginal lands for cellulosic feedstock production, and the resulting greenhouse gas (GHG) emissions, remains uncertain. Here we evaluate the potential for marginal lands in ten Midwestern US states to produce sizeable amounts of biomass and concurrently mitigate GHG emissions. In a comparative assessment of six alternative cropping systems over 20 years, we found that successional herbaceous vegetation, once well established, has a direct GHG emissions mitigation capacity that rivals that of purpose-grown crops (−851 ± 46 grams of CO 2 equivalent emissions per square metre per year (gCO 2 e m −2  yr −1 )). If fertilized, these communities have the capacity to produce about 63 ± 5 gigajoules of ethanol energy per hectare per year. By contrast, an adjacent, no-till corn–soybean–wheat rotation produces on average 41 ± 1 gigajoules of biofuel energy per hectare per year and has a net direct mitigation capacity of −397 ± 32 gCO 2 e m −2  yr −1 ; a continuous corn rotation would probably produce about 62 ± 7 gigajoules of biofuel energy per hectare per year, with 13% less mitigation. We also perform quantitative modelling of successional vegetation on marginal lands in the region at a resolution of 0.4 hectares, constrained by the requirement that each modelled location be within 80 kilometres of a potential biorefinery. Our results suggest that such vegetation could produce about 21 gigalitres of ethanol per year from around 11 million hectares, or approximately 25 per cent of the 2022 target for cellulosic biofuel mandated by the US Energy Independence and Security Act of 2007, with no initial carbon debt nor the indirect land-use costs associated with food-based biofuels. Other regional-scale aspects of biofuel sustainability 2 , such as water quality 11 , 14 and biodiversity 15 , await future study.

With sources of renewable energy spreading fast, all sectors can do more to decarbonize the world, argue Christiana Figueres and colleagues. With sources of renewable energy spreading fast, all sectors can do more to decarbonize the world, argue Christiana Figueres and colleagues.

This study aims to examine the impact of renewable and non-renewable energy consumption on the agriculture, industry, services, and overall economic activities (GDP) across a panel of G20 nations. The study makes use of annual data from 1980 to 2012 on 17 countries of the G20. To achieve the study objectives, we apply several robust panel econometric models which account for cross-sectional dependence and heterogeneity in the analysis. The empirical findings confirm the significant long-run equilibrium relationship among the variables. The long-run elasticities indicate that both renewable and non-renewable energy consumptions have significant positive effect on the economic activities across the sectors and also on the overall economic output. These results also imply that the impact is more from renewable energy on economic activities than that of non-renewable energy. Given that, our results offer significant policy implications. We suggest that the policy makers should aim to initiate effective policies to turn domestic and foreign investments into renewable energy projects. This eventually ensures low carbon emissions and sustainable economic development across the G20 nations.

This article aims to investigate the relationship among renewable energy consumption, carbon dioxide (CO 2 ) emissions, and GDP using panel data for 24 Asian countries between 1990 and 2012. Panel cross-sectional dependence tests and unit root test, which considers cross-sectional dependence across countries, are used to ensure that the empirical results are correct. Using the panel cointegration model, the vector error correction model, and the Granger causality test, this paper finds that a long-run equilibrium exists among renewable energy consumption, carbon emission, and GDP. CO 2 emissions have a positive effect on renewable energy consumption in the Philippines, Pakistan, China, Iraq, Yemen, and Saudi Arabia. A 1% increase in GDP will increase renewable energy by 0.64%. Renewable energy is significantly determined by GDP in India, Sri Lanka, the Philippines, Thailand, Turkey, Malaysia, Jordan, United Arab Emirates, Saudi Arabia, and Mongolia. A unidirectional causality runs from GDP to CO 2 emissions, and two bidirectional causal relationships were found between CO 2 emissions and renewable energy consumption and between renewable energy consumption and GDP. The findings can assist governments in curbing pollution from air pollutants, execute energy conservation policy, and reduce unnecessary wastage of energy.

The planning of the energy transition from fossil fuels to renewables requires estimates for how much electricity wind turbines can generate from the prevailing atmospheric conditions. Here, we estimate monthly ideal wind energy generation from datasets of wind speeds, air density and installed wind turbines in Germany and compare these to reported actual yields. Both yields were used in a statistical model to identify and quantify factors that reduced actual compared to ideal yields. The installed capacity within the region had no significant influence. Turbine age and park size resulted in significant yield reductions. Predicted yields increased from 9.1 TWh/a in 2000 to 58.9 TWh/a in 2014 resulting from an increase in installed capacity from 5.7 GW to 37.6 GW, which agrees very well with reported estimates for Germany. The age effect, which includes turbine aging and possibly other external effects, lowered yields from 3.6 to 6.7% from 2000 to 2014. The effect of park size decreased annual yields by 1.9% throughout this period. However, actual monthly yields represent on average only 73.7% of the ideal yields, with unknown causes. We conclude that the combination of ideal yields predicted from wind conditions with observed yields is suitable to derive realistic estimates of wind energy generation as well as realistic resource potentials.