Greener Energy Systems

Energy Production Technologies with Minimum Environmental Impact

Eric Jeffs

• Publisher: CRC Press
• Year: 2018
• ISBN:
  9781351832533
• Edition: 1
• Topic: Business
• Subtopic: Sostenibilità nel business
• Index: Business

Recent years have seen acceleration in the development of cleaner energy systems. In Europe and North America, many old coal-fired power plants will be shut down in the next few years and will likely be replaced by combined cycle plants with higher-efficiency gas turbines that can start up and load quickly. With the revival of nuclear energy, designers are creating smaller nuclear reactors of a simpler integrated design that could expand the application of clean, emission-free energy to industry. And a number of manufacturers now offer hybrid cars with an electric motor and a gasoline engine to charge the batteries on the move. This would seem to be the way forward in reducing transport emissions, until countries develop stronger electricity supply systems to cope with millions of electric cars being charged daily.

Greener Energy Systems: Energy Production Technologies with Minimum Environmental Impact tackles the question of how to generate enough electricity, efficiently and with minimum environmental impact, to meet future energy needs across the world. Supplemented with extensive figures and color photographs, this book:

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• Traces the development of electricity supply
• Explains energy production risks and how major accidents have influenced development
• Discusses the combined cycle, the preferred system for power capacity expansion in much of the world
• Looks at combined heat and power
• Addresses whether coal can continue to be a fuel for power generation
• Examines nuclear power generation
• Asks why shipping has not followed some of the world's navies into nuclear propulsion
• Considers how to electrify more transport systems
• Reviews the current state of renewable systems, particularly hydro and solar

The book defines the key elements of greener energy systems, noting that they must be highly efficient, with rapid start up and loading; produce minimum emissions; and use simpler technology. The author has more than forty years of experience as an international journalist reporting on power-generation technologies and energy policies around the world. He concludes that there is no place for coal and that combined cycle, hydro, solar, and biomass must complement nuclear energy, which must serve more applications than just generating electricity.

1
Present energy demand

Two extremely cold winters in Europe in successive years have done more to increase public cynicism about global warming. Yet there is now evidence of increased carbon dioxide in the atmosphere. Is it because of industrial and transport emissions, which technology has steadily reduced over the years, or rather because the world population has trebled to over six billion since the end of the Second World War, and could reach nine billion by 2050.

Against this background energy demand is bound to increase and it must be done in a way that does not impinge on the other needs of a growing population: the production of more food, potable water, and places to live. It must also be produced in a way which does not make an excessive impact on the environment.

We cannot reduce the population by war or disease but we can reduce energy consumption with new technology and produce it more efficiently. Given our existing technologies that effectively rules out coal as a suitable fuel, because as we have already seen with flue gas desulphurization, any add-on system to make the plant more environmentally acceptable will add to the auxiliary load so that less electricity will be produced, and more significantly push up the cost to the consumer. Provision of carbon capture and storage is a condition required of any new coal-fired plant. But the technology is in its infancy and for a given quantity of coal less electricity will be produced at a far greater cost.

Other technologies such as nuclear and combined cycle have developed on an opposite track. The developers of nuclear reactors seek to make them simpler to construct and therefore maintain their low cost of electricity production. Also smaller reactors are now being designed which can broaden the application of nuclear energy to shipping and combined heat and power for industry. Indeed one may ask, given the experience of small reactors of less than 100 MW output in nuclear submarines, aircraft carriers, and ice-breakers over the last fifty years, why these applications have not been tried before. One has only to point a finger at the Green movement to get the answer.

In fact Green Activists have until now had a field day. They came into being after the 1973 oil crisis and although their first concerns were about public health issues, such as lead in gasoline, they very quickly focused on American applications to build more nuclear power plants, particularly the fast breeder reactors which used a plutonium fuel cycle.

The American aim, as in the other industrial countries, was to take oil out of power generation. Forty years later, oil contributes less than 3% to the total electricity generated in the country and in that they have succeeded. Oil is mainly used as a reserve fuel for the gas-fired steam and combined cycle plants. But it was not until George W. Bush arrived in the White House in 2000 that the revival of nuclear power began in earnest.

The late sixties and early seventies were the middle years of the cold war. Relatively fresh in the public mind was the standoff between the United States and the Soviet Union over a plan to station ballistic missiles in Cuba. Green anti-nuclear views fell on fertile ground because many people, particularly on the political left, were of the opinion that we had only narrowly avoided nuclear war.

There are several Green parties in Europe, in some cases holding the balance of power as a minority group in a coalition government. Indeed when they actually got into power in Germany in 1997, they immediately wanted to shut down all the nuclear power stations which then supplied 33% of the country’s electricity.

Besides raising public fears about nuclear energy, they have also attacked genetically modified (GM) crops as a source of “Frankenstein food,” which would be unsafe to eat, and which would kill off biodiversity. In Europe, trial plantings of GM crops have been trashed by Green Activists in the fields where they were growing. Yet farmers in Africa and India have happily planted and harvested GM crops in the knowledge that they are of better quality with less pest damage, and therefore give them a higher income.

Anybody who has visited the United States in the last five years will probably have unknowingly eaten something which has been prepared from a genetically modified plant, or the meat of a cloned animal, and lived to tell the tale. But not in Europe, where GM crops and cloned animals are subjects for study and not for human consumption. When a cloned animal is killed the carcass must be burned. Yet in the autumn of 2010 there was a huge outcry because meat from a cloned animal had inadvertently got into the UK food chain.

The Green influence in European Governments has been profound. Protests against capital projects have seriously delayed, if not cancelled, their implementation. Their contribution to energy policy has been based on opposition to nuclear energy and the advocacy of renewable energy systems, except traditional Hydro Power, which they vehemently oppose.

The result has been the creation of the wind power industry which might never have happened without them, and their influence on governments particularly in Europe, who have created energy policies which specify a percentage of renewables, principally wind power, to be included in the plant mix.

Combined cycle goes for higher gas turbine performance and higher efficiency. As an electricity producer only, efficiency has risen to 60 %, as compared with 45% for a large coal-fired supercritical steam plant. But the big gas turbine applications have been to industrial combined heat and power schemes which started in the United States with the Public Utility Regulatory Policies Act (PURPA) of 1979, and was directed specifically to industrial power generation.

Privatization of the British electricity supply system in 1990 and subsequent deregulation of electricity supply in other countries saw combined heat and power expand around the world. Deregulation also gave the impetus to deployment of renewable energy systems: first a plethora of wind farms, which was followed by the development of photovoltaic semiconductors which have found application in solar energy schemes for offices and some homes; and feed water heaters for some combined cycles.

Other renewables are hydro power but not the large hydro plants of today but rather redevelopment of the small hydro sites from 80 to 100 years ago which were built for a specific job wherever suitable water supply was found. Many were abandoned as large thermal power plants were built to deal with a growing electricity demand after the Second World War. Such hydro schemes would have then been almost 50 years old with outputs between 100 kW and 10 MW.

Biomass is the other renewable which is judged to be green because burning it simply releases the carbon dioxide absorbed in its growth. But it doesn’t mean cutting down trees to fuel a wood-fired power station. There are some tree species which are fast growing and can be pollarded; selected branches are cut and, in typically three years, new growth can be harvested again. Then there is cropping for biomass with specialist crops such as miscanthus (elephant grass) which is planted as rhyzomes that sprout every year, and can be harvested annually in spring using a combine harvester.

The one biomass success story which has been running for over forty years is in Brazil, the world’s leading sugar producer, which in the early 1970s was an oil importer. The government after the first oil crisis authorised the planting of more sugar which could be distilled to make alcohol as a fuel to blend with gasoline. By the end of that decade cars throughout Brazil were running on a gasoline/alcohol mixture containing about 5% alcohol.

Biomass however has political and economic problems. A growing world population puts many demands on land use, and not only for agriculture. Every hectare used to grow biomass fuel is one less on which to grow food crops. So the more biomass crops are grown the less food crops and so the price of basic food stuffs increases. Biomass power plants alone are small, and are mainly using scrap wood from paper mills and sawmills. But some old coal-fired power stations are regularly burning biomass as up to 10% of their fuel input.

There are a number of issues behind energy production in the future. Where can we find it, and in what environment, and what are the risks attached to developing it?

First, how much electricity do we need? About 6000 kWh/year is roughly the average individual consumption in Europe. The typical electricity use in European homes is with a refrigerator and freezer to store food; a washing machine and tumbler drier to clean and dry clothes; other small electrical appliances such as a vacuum cleaner, electric iron; several radios, and television sets, and one or more computers.

Cooking, if not by gas would be with an electric cooker; and in any case there might also now be a microwave cooker. Water heating is generally from the same gas or oil-fired boiler that supplies space heating but there will be an immersion heater in the tank to heat water during the summer months.

Since we are entering an 11-year cyclic period of greater solar activity we may experience a hitherto benign climate change. But perhaps more important is the future price of oil. If it becomes too expensive will people switch more to diesel or electric cars, which in one case are more fuel-efficient and in the other have much lower fuel costs? If they do, then the Greens Activists are waiting for them.

In the UK some local authorities are looking at charging more for diesel cars in permanently paid long-term car parks, because of the particulate matter in the exhaust. This might have been true fifty years ago when it was common to see diesel trucks climbing a hill with great clouds of black smoke issuing from the exhaust. The huge public protest at the time resulted in threats to take such vehicles off the road, which very quickly led to improvements in the design and maintenance of diesel engines.

The other energy saving protest was that fluorescent lights were less bright that the traditional incandescent bulbs, which are no longer in production. A 20 W fluorescent lamp can produce as much light as a 100 W incandescent bulb, and the only way to get a bulb now is from a shop that has not completely cleared its old stock; if such can be found.

So there are two energy saving measures which have been a matter of personal choice, and one of which, at least, is now permanent and offers to produce a considerable saving in electricity demand. But still some of the greatest energy loss is from office buildings, and homes. Single glazing and no loft insulation in older houses is one of the reasons why. For new houses, current building standards require them to be heavily insulated in the wall cavities and roof space, and also to have double-glazed windows.

All these measures can be back fitted in existing houses, some more easily than others, as many people have already done. The double-glazing units are supplied as prefabricated modules to be fitted in UPVC high strength plastic frames which require no painting. Roof insulation is available in 400 mm wide by 10 m long rolls which fit in between the rafters. As more new houses and converted older houses account for a greater proportion of the housing stock the demand for heat is likely to reduce.

Few houses have been built with electric heating, but many old houses with coal fires in selected rooms have converted to electric heating. Forty years ago as the first nuclear power stations came into operation, to counter their poor load-following capability, night storage heating was introduced.

The householder, in each room, had to install heaters consisting of a ceramic block of high thermal capacity in a casing forming a duct around it. The blocks are heated during a defined period at night when electricity is charged at a special low price per kWh. The householder can control the rate of charge and of discharge, for each heater.

The room is effectively heated by convection; the heater is designed so that it stands about 10 cm off the floor, which allows cold air to flow in at the bottom which is heated as it passes over the core and out through a grille at the top.

In the UK the charging period is seven hours from midnight to 07.00 a.m. GMT, all year round. During this period the price per kWh of electricity is one third of the price at other times. People with this tariff also heat water and use programmable appliances such as a washing machine or a dishwasher, to take advantage of the lower rates. The modern machines have a single cold water feed which they heat to the required temperature for the program.

The Greens give an impression that much of the present day lifestyle will have to be given up to counter global warming and avoid having to build more nuclear power stations. But the fanatics are beginning to fall out among themselves, some of them realise the importance of electricity in running society and the value of nuclear plants as having no emissions in operation.

In any case, in spite of its removal from a large part of electricity production, oil is still the only fuel available for transport on roads and in the air. We must therefore move energy consumption to other fuels than oil, and in the home to electricity. To drastically reduce energy consumption would not be good for public health even if it meant we had to walk more often.

The refrigeration of foodstuffs has been a major factor in the improvement of health over the years. Until sixty years ago most women walked to nearby shops almost every day to buy food for their family. Once ownership of refrigerators became widespread it was possible to store food, particularly meat, milk and vegetables in conditions which protected them from changes in temperature that might have made them sour or otherwise unfit to eat.

As daily food shopping reduced, and car ownership became more widespread, the big grocery companies built supermarkets which include the traditional trades of greengrocer and butcher and have expanded into clothing and electrical goods. Other facilities included are Automatic Teller Machines so the customers can withdraw money, and filling stations attached to the car parks where often gasoline is cheaper than outside at the regular filling stations. A round trip of about 10 to 20 km to the supermarket once a week is now normal for most families.

A large supermarket has several aisles of freezer cabinets for particularly meat, both fresh and manufactured meat products, packed in standard quantities, and frozen vegetables and all to be sold, if not eaten, before a certain date printed on the packet. The whole shop would be air-conditioned to remove the heat from the refrigerators and freezers and provide a comfortable environment for people to walk around and make their purchases. So each supermarket represents a large electricity load 24 hours a day.

In many countries oil has been taken out of the power generation market except for use as a back-up fuel for combined cycles and other gas-fired power plant. This has been relatively easy to do, and similarly the electrification of some railways has lowered the demand for diesel fuel for locomotives. There are still many long distance routes which are not electrified, particularly in the United States and Canada, and the United Kingdom. Diesel power would be retained for marshalling yards and at docksides and on small branch lines where it would be uneconomic and impractical to string overhead conductor wires.

High speed trains are now commonplace across Europe and some services, notably Eurostar through the Channel Tunnel, have taken some business from the airlines. There have been some high-speed trains introduced in the Far East, notably in Korea, but in Japan the Shinkansen system predates all the others. The Shinkansen was built to provide a higher speed service across Japan to all four main islands because the original railway network was built on a metre gauge. Shinkansen is therefore a standard gauge system as are all the European high-speed services.

This summary of present energy use is met with the present electricity generation system. But a much larger switch to electricity in transport and space heating in rural areas would require a large program of power station construction and grid connexions.

Given that to build a power plant first involves legal issues of deciding where to build it and obtaining a construction permit; and assuming that all consents have been obtained for construction and connexion to the grid, a 500 MW combined cycle block could be up and running in about 30 months. In any event more combined cycles will be needed because with their flexible operation and rapid starting capability they are important as back-up for renewables such as wind and solar which have variable outputs.

A 1200 MW nuclear plant with the currently available new reactor designs could also be up and running in five years. Again reactor design has produced standardized units from all the leading manufacturers in North America, Europe, Russia and the Far East, and all of which are designed for a service life of sixty years.

Not only must more generating capacity be built, and also to replace old plants, but intelligent grids must be deployed. An intelligent grid is one which can look where the greatest energy demand is occurring and bring on under-utilised plant to meet the load whenever it is required.

The intermittent nature of wind power created the demand for the intelligent grid and a widespread conversion to electric cars will also need it. Say half the houses in a street of 100 each had one electric car which they charged every night that could be around 1500 kWh taken over seven hours. But the use of the cars will vary and the amount drawn every night might vary considerably from day to day.

How fast will it all happen? In Europe at least the ambition is to have reduced greenhouse gas emissions by 80% up to 2050. But current projections of population growth suggest that food production must increase by 70% over the same period. Surely this rules out biomass energy on a large scale and other renewables which may interfere with farm land (on-shore wind) or fishing (off shore wind and tidal stream systems).

This must mean a significant switch over to electric or hybrid cars and electric heating powered by nuclear plant, which generate electricity without emitting one gram of greenhouse gas. It cannot be achieved totally with renewable systems, although, particularly, photovoltaic cells can be an important accessory for an electric car to extend its range, and as a source of electricity supply to a large office building, and there are many opportunities for these applications around the world.

This is possible because of the conditions attached to energy production. Much m...