There is unprecedented interest in renewable energy, as sources of sustainable energy, particularly solar and wind energy, which provide electricity with low. Renewable Energy and Electricity Sustainable Energy Renewable EnergyUpdated October 2. There is widespread popular support for using renewable energy, particularly solar and wind energy, which provide electricity without giving rise to any carbon dioxide emissions. Harnessing these for electricity depends on the cost and efficiency of the technology, which is constantly improving, thus reducing costs per peak kilowatt, and per k. Wh. Utilising electricity from solar and wind in a grid becomes problematical at high levels for complex but now well demonstrated reasons. Supply does not correspond with demand. Back up generating capacity is required due to the intermittent nature of solar and wind, but at high levels the economics of this are compromised. Policy settings to support renewables are generally required to confer priority in grid systems and also subsidise them, and some 5. Utilising solar and wind generated electricity in a stand alone system requires corresponding battery or other storage capacity. The possibility of large scale use of hydrogen in the future as a transport fuel increases the potential for both renewables and base load electricity supply. Technology to utilise the forces of nature for doing work to supply human needs is as old as the first sailing ship. But attention swung away from renewable sources as the industrial revolution progressed on the basis of the concentrated energy locked up in fossil fuels. This was compounded by the increasing use of reticulated electricity based on fossil fuels and the importance of portable high density energy sources for transport the era of oil. As electricity demand escalated, with supply depending largely on fossil fuels plus some hydro power and then nuclear energy, concerns arose about carbon dioxide emissions contributing to possible global warming. Wind power is the use of air flow through wind turbines to mechanically power generators for electric power. Wind power, as an alternative to burning fossil fuels, is. Power electronics. Wind converters Photovoltaic inverters Railway Traction Converters Frequency Converters Energy Storage, Facts, SSSC Electric Motors. Energy Sources. News and Research. Articles on everything from hydrogen powered cars and solar energy systems to nuclear reactors and fossil fuels. Renewable Energy Sources. Read the latest research on renewable sources of energy such as solar energy, wind power, nuclear energy, hydrogen fuel, ethanol. Investors. Waiting for legislation yet a recordbreaking year. Wind Energy. Poland 2014. The act on renewable sources of energy has for many years been awaited by. Attention again turned to the huge sources of energy surging around us in nature sun, wind, and seas in particular. There was never any doubt about the magnitude of these, the challenge was always in harnessing them so as to meet demand. Today we are well advanced in meeting that challenge, while also testing the practical limits of doing so. Wind turbines have developed greatly in recent decades, solar photovoltaic technology is much more efficient, and there are improved prospects of harnessing the energy in tides and waves. Solar thermal technologies in particular with some heat storage have great potential in sunny climates. With government encouragement to utilise wind and solar technologies, their costs have come down and are now in the same league per kilowatt hour as the increased costs of fossil fuel technologies, especially with likely carbon emission charges on electricity generation from them. However, the variability of wind and solar power does not correspond with most demand, and as substantial capacity has been built in several countries in response to government incentives, occasional massive output from these sources creates major problems in maintaining the reliability and economic viability of the whole system. In the following, the levelised cost of electricity LCOE is used to indicate the average cost per unit of electricity generated, allowing for the recovery of all costs over the lifetime of the plant. It includes capital, financing, operation and maintenance, fuel if any, and decommissioning. Another relevant metric is energy return on energy invested EROI. This is not quoted for particular projects, but is the subject of more general studies. EROI is the ratio of the energy delivered by a process to the energy used directly and indirectly in that process, and is part of lifecycle analysis LCA. An EROI of about 7 is considered break even economically for developed countries. The US average EROI across all generating technologies is about 4. The major published study on EROI, by Weissbach et al 2. Nuclear, hydro, coal, and natural gas power systems in this order are one order of magnitude more effective than photovoltaics and wind power. This raises questions about the sustainability of wind and solar PV which have not yet been addressed in national energy policies. A fuller account of EROI in electricity generation is in the information paper on Energy Return on Investment. The World Energy Outlook 2. WEO2. 01. 6 makes the points that wind and solar PV have five technical properties that make them distinct from more traditional forms of power generation. First, their maximum output fluctuates according to the real time availability of wind and sunlight. Second, such fluctuations can be predicted accurately only a few hours to days in advance. Third, they use devices known as power converters in order to connect to the grid this can be relevant in terms of how to ensure the stability of power systems. Fourth, they are more modular and can be deployed in a much more distributed fashion. Fifth, unlike fossil fuels, wind and sunlight cannot be transported, and while renewable energy resources are available in many areas, the best resources are frequently located at a distance from load centres thus, in some cases, increasing connection costs. According to WEO2. These measures include flexible power sources such as hydro and open cycle gas turbines, demand side measures, electricity storage, strong and smart transmission and distribution grids. The costs of all these, over and above the generation costs, are often referred to as system costs. Grid level system costs for variable renewables are large 1. MWh but depend on country, context and technology onshore wind lt offshore wind lt solar PV. See later section on System integration costs of intermittent renewable power generation. A further aspect of considering sources such as wind and solar in the context of grid supply is that their true capacity is discounted to allow for intermittency. In the UK this is by a factor of 0. PV, hence declared net capacity DNC is the figure used in national reporting   the nominal maximum capability of a generating set to supply electricity to consumers. It has a considerable effect on published load and capacity factors. This novel convention is not followed in this information paper. Demand for clean energy. There is a fundamental attractiveness about harnessing such forces in an age which is very conscious of the environmental effects of burning fossil fuels, and where sustainability is an ethical norm. So today the focus is on both adequacy of energy supply long term and also the environmental implications of particular sources. In that regard the near certainty of costs being imposed on carbon dioxide emissions in developed countries at least has profoundly changed the economic outlook of clean energy sources. A market determined carbon price will create incentives for energy sources that are cleaner than current fossil fuel sources without distinguishing among different technologies. This puts the onus on the generating utility to employ technologies which efficiently supply power to the consumer at a competitive price.  Wind, solar and nuclear are the main contenders. Sun, wind, waves, rivers, tides and the heat from radioactive decay in the earths mantle as well as biomass are all abundant and ongoing, hence the term renewables.