In times of increasing importance of wind power in the world’s energy mix, this study focuses on a better understanding of the influences of large-scale climate variability on wind power resource over Europe. The impact of the North Atlantic Oscillation (NAO), the Arctic Oscillation (AO), the El Niño Southern Oscillation (ENSO) and the Atlantic Multidecadal Oscillation (AMO) are investigated in terms of their correlation with wind power density (WPD) at 80 m hub height. These WPDs are calculated based on the MERRA Reanalysis data set covering 31 years of measurements. Not surprisingly, AO and NAO are highly correlated with the time series of WPD. This correlation can also be found in the first principal component of a Principal Component Analysis (PCA) of WPD over Europe explaining 14% of the overall variation. Further, cross-correlation analyses indicates the strongest associated variations are achieved with AO/NAO leading WPD by at most one day. Furthermore, the impact of high and low phases of the respective oscillations has been assessed to provide a more comprehensive illustration. The fraction of WPD for high and low AO/NAO increases considerably for northern Europe, whereas the opposite pattern can be observed for southern Europe. Similar results are obtained by calculating the energy output of three hypothetical wind turbines for every grid point over Europe. Thus, we identified a high interconnection potential between wind farms in order to reduce intermittency, one of the primary challenges in wind power generation. In addition, we observe significant correlations between WPD and AMO.

What will large-scale global bioenergy production look like? We investigate this question by developing a detailed representation of bioenergy in a global economy-wide model. We develop a scenario with a global carbon dioxide price, applied to all anthropogenic emissions except those from land-use change, that rises from $15 per metric ton in 2015 to $59 in 2050. This creates market conditions favorable to biomass energy, resulting in global non-traditional bioenergy production of ~150 exajoules (EJ) in 2050. By comparison, in 2010 global energy production was primarily from coal (139 EJ), oil (175 EJ) and gas (108 EJ). With this policy, 2050 emissions are 16% less in our Base Policy case than our Reference case, although extending the scope of the carbon price to include emissions from land-use change would reduce 2050 emissions by 57% relative to the same baseline. Our results from various policy scenarios show that lignocellulosic (LC) ethanol may become the major form of bioenergy, if its production costs fall by amounts predicted in a recent survey and ethanol blending constraints disappear by 2030; however, if its costs remain higher than expected or the ethanol blend wall continues to bind, bioelectricity and bioheat may prevail. Higher LC ethanol costs may also result in expanded production of first-generation biofuels (ethanol from sugarcane and corn) so that they remain in the fuel mix through 2050. Deforestation occurs if emissions from landuse change are not priced, although the availability of biomass residues and improvements in crop yields and conversion efficiencies mitigate pressure on land markets. As regions are linked via international agricultural markets, irrespective of the location of bioenergy production, natural forest decreases are largest in regions with the lowest political constraints to deforestation. The combination of carbon price and bioenergy production increases food prices by 2.6%–4.7%, with bioenergy accounting for 1.3%–2.6%.

Be Cautious about Bioenergy, but Don't Rule It Out

Research commentary by Niven Winchester in response to the World Resources Institute report on biofuels and bioenergy.

A report published by the World Resources Institute (WRI) in January has reignited the old debate over biofuels and other forms of bioenergy, casting doubt on their climate benefits and effects on food availability. With recent low oil prices, and the EPA set to announce updated biofuel standards in the spring, the stakes for considering what role bioenergy will play in a sustainable future are higher than ever.

While the WRI report’s authors outline valid reasons to be cautious about bioenergy, the report contains misleading statements about the role of bioenergy in abating emissions.

The report claims that bioenergy made from fuel crops does not reduce direct carbon emissions because, say, diverting maize from food to ethanol does not result in additional absorption of carbon. While this is true, focusing on direct emissions is short-sighted because it doesn’t take into account the bigger picture of where energy comes from. Regardless of whether maize is used for food or fuel, emissions absorbed will end back into the atmosphere, mainly through respiration in the former and combustion in the latter. However, if maize is used for ethanol, it displaces oil and reduces carbon emissions.

If direct emissions were used to evaluate solar power, this technology would also be judged not to reduce carbon emissions, as no emissions are either stored or released when sunlight is converted to electricity. This is not to say that the carbon benefits from bioenergy are equal to the emissions from the fossil energy that it displaces. Growing bioenergy crops requires energy to plant, harvest and process, and may result in deforestation. Emissions from these activities reduce the carbon benefits of bioenergy, but there is still the potential for it to reduce emissions.

The report also claims that bioenergy analyses double-count land by assuming that biomass for other purposes, like food and lumber, continue to be met when land is used for bioenergy. In fact, studies that consider the economy-wide effects of bioenergy cultivation explicitly represent resource constraints, so land used for bioenergy cannot be used for other purposes. In these studies, as in the real world, increased demand for land to grow bioenergy crops will increase land prices.

The effects of the higher land prices propagate throughout the economy in several ways. Land may be used more intensively by, for example, developing new cultivars. On the other side of the equation, demand for food can be reduced through greater use of refrigeration and packaging to reduce food waste.

That is, incentives for bioenergy can drive efficiency improvements in crop production and use that allow food and fuel demands to be met using limited resources. These efficiency improvements come at a cost, but so do other carbon abatement options.

Bioenergy is not a “silver bullet” against climate change, has been over-hyped in some circles, and governments should guard against negative impacts on water and biodiversity. At the same time, bioenergy should not be erroneously excluded from our toolkit for fighting climate change, because we will need all the tools available to us.

Niven Winchester is an environmental energy economist at the Joint Program on the Science and Policy of Global Change. He is a coauthor of the recent report "The Contributions of Biomass to Emissions Mitigation under a Global Climate Policy."

China’s recently-adopted targets for developing renewable electricity—wind, solar, and biomass—would require expansion on an unprecedented scale in China and relative to existing global installations. An important question is how far this deployment will go toward achieving China’s low carbon development goals, which include a carbon intensity reduction target of 40–45% relative to 2005 and a non-fossil primary energy target of 15% by 2020. During the period from 2010 to 2020, we find that current renewable electricity targets result in significant additional renewable energy installation and a reduction in cumulative CO2 emissions of 1.2% relative to a no policy baseline. After 2020, the role of renewables is sensitive to both economic growth and technology cost assumptions. Importantly, we find that CO2 emissions reductions due to increased renewables are offset in each year by emissions increases in non-covered sectors through 2050. By increasing reliance on renewable energy sources in the electricity sector, fossil fuel demand in the power sector falls, resulting in lower fossil fuel prices, which in turn leads to greater demand for these fuels in unconstrained sectors. We consider sensitivity to renewable electricity cost after 2020 and find that if cost falls due to policy or other reasons, renewable electricity share increases and results in slightly higher economic growth through 2050. However, regardless of the cost assumption, projected CO2 emissions reductions are very modest under a policy that only targets the supply side in the electricity sector. A policy approach that covers all sectors and allows flexibility to reduce CO2 at lowest cost—such as an emissions trading system—will prevent this emissions leakage and ensure targeted reductions in CO2 emissions are achieved over the long term.

Solar electricity generation is one of very few low-carbon energy technologies with the potential to grow to very large scale. As a consequence, massive expansion of global solar generating capacity to multi-terawatt scale is very likely an essential component of a workable strategy to mitigate climate change risk. Recent years have seen rapid growth in installed solar generating capacity, great improvements in technology, price, and performance, and the development of creative business models that have spurred investment in residential solar systems. Nonetheless, further advances are needed to enable a dramatic increase in the solar contribution at socially acceptable costs. Achieving this role for solar energy will ultimately require that solar technologies become cost-competitive with fossil generation, appropriately penalized for carbon dioxide (CO₂) emissions, with — most likely — substantially reduced subsidies.

This study examines the current state of U.S. solar electricity generation, the several technological approaches that have been and could be followed to convert sunlight to electricity, and the market and policy environments the solar industry has faced. Our objective is to assess solar energy’s current and potential competitive position and to identify changes in U.S. government policies that could more efficiently and effectively support the industry’s robust, long-term growth.

We focus in particular on three preeminent challenges for solar generation: reducing the cost of installed solar capacity, ensuring the availability of technologies that can support expansion to very large scale at low cost, and easing the integration of solar generation into existing electric systems. Progress on these fronts will contribute to greenhouse-gas reduction efforts, not only in the United States but also in other nations with developed electric systems. It will also help bring light and power to the more than one billion people worldwide who now live without access to electricity.