Renewable Energy in Power Systems

David Infield, Leon Freris

• Editorial: Wiley
• Año: 2019
• ISBN:
  9781118788561
• Edición: 2
• Categoría: Tecnología e ingeniería
• Categoría: Recursos energéticos

An up to date account of renewable sources of electricity generation and their integration into power systems

With the growth in installed capacity of renewable energy (RE) generation, many countries such as the UK are relying on higher levels of RE generation to meet targets for reduced greenhouse gas emissions. In the face of this, the integration issue is now of increasing concern, in particular to system operators.

This updated text describes the individual renewable technologies and their power generation characteristics alongside an expanded introduction to power systems and the challenges posed by high levels of penetrations from such technologies, together with an account of technologies and changes to system operation that can ease RE integration.

Features of this edition:

• Covers power conditioning, the characteristics of RE generators, with emphasis on their time varying nature, and the use of power electronics in interfacing RE sources to grids
• Outlines up to date RE integration issues such as power flow in networks supplied from a combination of conventional and renewable energy sources
• Updatedcoverage ofthe economics of power generation and the role of markets in delivering investment in sustainable solutions
• Considers the challenge of maintaining power balance in a system with increasing RE input, including recent moves toward power system frequency support from RE sources
• Offers an insightful perspective on the shape of future power systems including offshore networks and demand side management
• Includes worked examples that enhance this edition's suitability as a textbook for introductory courses in RE systems technology

Firmly established as an essential reference, theSecond Edition of Renewable Energy in Power Systems will prove a real asset to engineers and others involved in both the traditional power and fast growing renewables sector. This text should also be of particular benefit to students of electrical power engineering and will additionally appeal to non-specialists through the inclusion of background material covering the basics of electricity generation.

1
Energy and Electricity

1.1 The World Energy Scene

1.1.1 History

Energy has played a key role in the development of society. In the pre-industrial world, this energy was provided mostly by man and animal power and from the burning of wood for heating, cooking and smelting of metals. Coal, through the then new technology of steam engines, mechanised production, improved transportation and powered the industrial revolution. The inter-war years saw the rise of oil exploration and use. Access to this critical fuel became a key issue during the Second World War. Post-war industrial expansion and prosperity was increasingly driven by oil, as was the massive growth in private car use. More recently, a new phase of economic growth has been underpinned by natural gas; most recently much of this derived by fracking. Nuclear power makes a contribution to electricity generation. However, transport still depends almost entirely on oil.

A substantial proportion of coal and gas production, and all nuclear power, is used to generate electricity, which has been widely available now for over a century. Electricity is a premium form of energy due to its flexibility and ease of distribution and use. Demand worldwide continues to grow driven by increased industrial activity and the widening of access to electricity from consumers in the developing world.

1.1.2 World Energy Consumption

The present global yearly primary energy¹ consumption is in round figures about 550 EJ² This is equivalent to about 1.5 × 10¹⁷ Wh or 150 000 TWh. Dividing this figure by the number of hours in the year gives 17 TW or 17 000 GW as the average rate of world primary power consumption. The pie chart in Figure 1.1 shows the percentage contribution to world primary energy from the different energy sources according to data taken from the International Energy Agency (IEA) Key World Energy Statistics, 2016 [1].

Figure 1.1 Percentage contribution to world primary energy in 2014 (²peat and oil shale included with coal,³ other includes the remaining renewable energy sources, wind, solar, geothermal and tidal).

Figure 1.2 Recent growth in world primary energy supply by fuel in Mtoe (²peat and oil shale included with coal,³ other includes the remaining renewable energy sources, wind, solar, geothermal and tidal).

World energy supply continues to increase steadily as can be seen in Figure 1.2 (also taken from the IEA Statistics 2016), with most of this being accounted for by an increase in fossil fuels, particularly coal and gas. The rapid development of the economies of India and China is contributing significantly to this growth, despite currently much lower per capita energy consumption in these countries than in Europe and North America.

1.1.3 Finite Resources

It is extremely difficult to determine precise figures on the ultimate availability of fossil fuels. According to the major oil and gas companies, significant new resources of oil are still being developed or remain to be discovered. A safe assessment is that there is enough oil from traditional sources to cover the present demand for at least 30 years. The latest figures for global gas reserves indicate that these are approximately 50% higher than for oil, at some 60 years of current demand. And gas is far less explored than oil so there is probably more to be found. There are, however, unconventional hydrocarbon resources – such as heavy oil and bitumen, oil shale, shale gas and coal bed methane – whose total global reserves have been assessed very roughly to be three times the size of conventional oil and gas resources. These are more expensive to extract but are now being exploited as the price of fossil fuels increases due to the steady depletion of the more easily accessible reserves. Most notable has been the recent increase in shale gas extraction in the USA derived through the process known as fracking. Fortunately for fossil-fuel dependent economies, coal reserves are considered to be many times those of oil and gas and could last for hundreds of years. The down-side of coal is its high carbon content, a topic to be discussed later.

Much debate is currently focused on when the so called, peak oil and gas might occur. This is when the oil and gas extraction rate starts to fall, and occurs well before resources run out. It is important because it signals that demand will most likely not be fully met with prices rising significantly as a consequence. Certainly, the UK's North Sea reserves of oil and gas are fast declining with peak extraction having already occurred in 2003. Given the enormous investment in extraction and supply infrastructure, and the profits to be made, it would be surprising if those with vested interests did not work hard to maintain confidence in these sources.

Fuel for nuclear fission is not unlimited and several decades ago this prompted interest in the fast breeder reactor that, in effect, extends the life of the fuel. However, the political dangers inherent in the fast breeder cycle, with its production of weapons grade plutonium, has limited its development to a few prototype reactors that had major operational problems and are now decommissioned. The lifetime of uranium reserves for conventional fission at current usage has been estimated by some as around 50 years but such calculations are very dependent on assumptions. If an extremely high ore price is tolerable, then very low grades of uranium ore can be considered as possible reserves. The DTI cites OECD/NEA ‘Red Book’ figures to claim that based on 2004 generation levels, known uranium reserves (at $130/kg) will last for around 85 years (see References [2, 3]).

1.1.4 Energy Security and Disparity of Use

Energy security is a major concern worldwide. A large part of the world's oil is located in the Middle East and other politically unstable countries. The conflict between ‘Western’ and ‘Islamic’ cultures is at present exacerbating the anxiety over reliability of energy supply. Russia is a major producer of gas but recent events in Ukraine have made European countries aware how dependent they are on this single source. Until 2010, the USA was the world's largest consumer of energy (at which point it was overtaken by China following years of significant economic growth there); it remains dependent on imported oil and gas, although much less now than in ...