Cofiring high ratios of biomass with coal

As the world’s largest consumer of coal and leading CO2 emitter, China’s role in the international effort to combat climate change can hardly be overstated. The challenges China faces to control emission and pollution levels while meeting the country’s increasing energy demand are enormous. Over the years, China has made considerable efforts to reduce CO2 emissions and control pollution levels, and notable progress has been made through the implementation of ambitious programmes aimed at improving energy efficiency across a number of industrial sectors and a rapid scale up of renewable energy. This study reviews China’s policy and regulatory initiatives, in particular those aimed at improving energy efficiency and reducing emissions, HELE (high efficiency low emissions) upgrades, diversify the energy mix, as well as the progress to date in reaching a series of ambitious goals. China’s rapid expansion of non-fossil energy which affects the structural change of the power sector and coal use in electricity generation, and therefore, CO2 emissions from coal-fired power generation are also discussed.

China has provided strong financing and policy support for the R&D of HELE technologies. China now possesses a range of HELE technologies that are applicable to new and/or retrofitting of the existing coal-fired power plants and they are described in the webinar. Finally, the peak of coal consumption and CO2 emissions from power generation from coal, in light of China’s economic and policy trends affecting the structure of the economy and the coal consumption, are assessed.

Global energy demand is rising, while water is becoming a scarcer commodity in many parts of the world due to over-exploitation, droughts, heat waves, and other factors. Meeting the growing demand will place
increasing stress on limited fresh water resources. The power generation industry is typically the largest industrial user of fresh water in a country. Consequently, the vulnerability of the power generation
industry to constraints in water availability can be expected to increase. Hence non-fresh water sources will become increasingly important. This report examines the availability and use of potential non-fresh water sources in China, India, South Africa and the USA. These are the four top thermal coal consuming countries in the world. The alternative sources are municipal waste water, brackish and sea water, mine
water, produced water from oil and gas wells (including coalbed methane wells), and water extracted from deep saline aquifers during CO2 storage. In certain cases, and with suitable design of the on-site
water treatment plant, a coal-fired power plant could become a supplier of both energy and fresh water, instead of a water consumer.

Countries are setting ever higher goals for producing power from clean, renewable energies and some are actively turning their backs on fossil fuels. However, many of these regions are discovering the real challenges of trying to produce baseload power for public consumption from renewable sources which are, at best, intermittent, and, at worse, unpredictable and unreliable. Until large scale energy storage is available and affordable, baseload power from coal, gas, and/or nuclear will remain necessary in many regions for several more years. Obviously this baseload power is required when renewable output is low (when the sun doesn't shine and the wind doesn't blow). However, it is also still required to make up the balance of power in a diverse energy mix. Under the new energy policy regimes in many regions, renewable sources have priority into the grid and sit in the guaranteed dispatch mix in the base region which coal used to occupy. Coal has now been nudged into the dispatchable area of the mix, being asked to ramp up or down or even to idle or run beyond normal capacity, sometimes at short notice, to produce the balance of power required to maintain grid output. And whilst coal plants can run relatively flexibly, this does not come without cost. Most older coal-fired units were designed to run at steady output. Asking these plants to cycle and ramp puts stresses on the plant which can result in added cost, less efficient production, increased wear and tear and, in some cases, damage causing enforced outages for repair and/or upgrade. This webinar, looks at the stresses placed on coal-fired plants as they are asked to help levelise and counterbalance the intermittency of renewable sources, concentrating on the risks and costs. Case studies and examples of issues being encountered in the USA, the UK and Germany are included.

It is a concern that emissions from coal combustion may pollute the air. A lot of effort has been made to
regulate, control and prevent the pollutants emitted from coal-fired power plants. The coal industry is
facing increasingly stringent emission regulations, for the release of SO2, NOx, toxic volatile organic
compounds, heavy metals, and particulate matter (PM). PM can contain any or all of the aforementioned
chemical species or their compounds, plus water and biogenic organic species. PM2.5, as fine PM, can be
inhaled into human respiratory systems and travel deep into the lungs causing health problems. PM2.5 is
also considered to be a major cause of smog in cities and elsewhere. This webinar describes the
international and selected countries’ national air quality and PM emission standards for stationary
sources that are relevant to coal-fired power plants. Emission standards for SO2 and NOx are included
since they are precursors of secondary fine PM. International and national measurement standards are
summarised. Recent developments in PM emission control technologies are reviewed.

Established CO2 capture technologies such as absorption with amine solvents are associated with significant energetic and economic penalties, reducing power plant efficiency by around 10% points and increasing the cost of electricity production by up to 80%. Dedicated research programmes worldwide have pursued the development of a wide range of innovative, alternative technologies for CO2 capture, largely by addressing the fundamental gas separation step at the heart of post-combustion, pre-combustion or oxyfuel combustion processes. Novel solvents with lower energy requirements than conventional amines, using phase change systems, ionic liquids, enzyme-activation, or non-aqueous solvents, are promising approaches for post-combustion capture. Alternatively, techniques used in other commercial gas separations, including solid sorbents, membranes, and cryogenic separation, have also been developed for carbon capture through extensive materials research and process optimisation. Whilst challenging for post-combustion capture applications, these techniques may be of particular benefit to pre-combustion capture systems where much higher partial pressures of CO2 are available, and integration of the CO2 capture step and water gas shift reaction can be achieved using sorbents or membranes. In oxyfuel combustion, membranes are also an option for efficient oxygen production, but pressurised combustion systems have demonstrated the most potential for efficiency improvements, potentially in combination with novel power cycles which are better-suited to exploiting the altered combustion conditions. Finally, chemical looping combustion is a unique approach to carbon capture which can achieve dramatic energy savings through its inherent avoidance of any gas separation step, and is undergoing significant scale up. This webinar will review these developments in novel capture technologies and highlight the most promising strategies for achieving major cost reductions.

The lignite power industry produces low cost electricity but the associated pollutant emissions are higher than from other fossil fuels. Tighter environmental legislation requires older facilities to either upgrade or face closure. Plants designed to operate until 2040 already possess the latest effluent treatment systems while older facilities seek lower cost solutions. The rising contribution of renewable energy sources obliges plants to operate more flexibly, responding to variable demands.
This webinar reviews suitable technologies for the retrofitting of lignite PC power plants to lower emissions while raising plant performance. Drying and pre-treatment of the lignite fuel is explored as one route to improved heat rate. Adaptations based upon the existing plant technology include: combustor modification and boiler re-engineering, advanced instruments and controls, anti-fouling systems and steam turbine upgrades. Alternatives to mainstream effluent treatments are discussed, including hybrid and multi-component technologies to lower emission of NOx, SOx, particulates and mercury. Flexible plant options reviewed include energy storage, indirect firing and natural gas integrated co-generation. Latest developments on the introduction of CCUS techniques applied to lignite plants are discussed together with other means to lower plant carbon footprint.

The webinar presents the recent regulatory trends, practices and developments in major coal producing and consuming countries, which are affecting and may influence future demand for coal and coal-fired power generation. As legislative requirements become more demanding and environmental pressures increase, especially with regard to greenhouse gas emissions (GHGs) and climate change, investment in coal fired power-generating facilities is declining rapidly in most developed countries and to a lesser extent in some developing regions of the world, except Asia where forecasts indicate that demand will increase for some time to come. The report explores the implications of further curbs on GHG emissions from coal-fired plants in the most recent and forthcoming national regulations and international agreements. Policy, legislation and pollution reduction strategies are presented as well as future projections of coal utilisation in major coal consuming economies, including those where forecasts indicate that coal will remain a major player in power generation for the estimable future, such as China and India.

Greece’s financial crisis continues to have a major impact on all facets of the country’s economy. In 2015, the financial crisis continued unabated. When significant economic recovery does occur, the energy sector will have a major role to play. The country has a high energy import dependency, which is expensive ‒ reportedly, about ~US$ 20 billion/year. The overall diversification of the energy mix is rather limited. Greece’s main indigenous energy resource is poor quality lignite, used to generate a significant proportion of the country’s electricity. The state-owned energy company Public Power Corporation S.A. (PPC) is the largest lignite producer. More than 93% of Greece’s energy is provided by fossil fuels, (EU average is 75%). In 2014, a new government was elected and energy policy changed direction as earlier plans to privatise parts of the energy sector were curtailed. However, conditions demanded recently by EU and IMF creditors, mean that privatisation schemes may be back on the table. This is likely to encompass natural gas and electricity supply. There has been a renewed focus on the potential of the country’s lignite resources. In order to minimise the cost of imported energy and improve security of energy supply, the present government intends to increase their use, primarily for electricity generation. The webinar examines the situation prevailing in the Greek energy sector, and how this might change in the future. Existing and proposed clean coal-based activities are discussed. However, major uncertainties (in terms of scope and timescale) remain over many aspects of energy production ‒ the nature of, and rate of economic recovery will undoubtedly have major impacts.

The output and efficiency of a coal-fired power station unit fitted with CO2 capture equipment will be significantly lower than that of a similar plant without capture because some of the energy produced by burning the fuel will be needed to operate the added systems. Incorporating an aqueous amine-based CO2 scrubbing system in a simple arrangement could decrease the efficiency by as much as 30% of value. However, work at various research institutes and universities shows that the decrease in performance could be reduced by improved heat integration and other techniques. The webinar reviews these studies.

Coal contracts can be typically split into two broad categories, spot contracts (single shipments) and term contracts (multiple shipments). Term contracts can span any period, but in China in 2014, the National Development and Reform Commission announced a desire for coal buyers to negotiate long-term contracts with suppliers. Security of supply of fuel and limiting exposure to shorter-term volatility in prices and fuel supplies are clearly a strategic aim of some Asian economies. Such approaches to coal procurement is used across the world to varying degrees depending on the particular circumstances of the power generators and the markets in which they operate. This webinar provides an overview of a recent publication by the IEA CCC regarding coal procurement and contractual needs, and describes some of the aspects associated with the long-term nature of some coal contracts. It provides an introduction to some of the fundamentals of coal contracts and buying to those unfamiliar with fuel procurement, as well as a review of some regions which have been active in long term coal procurement in recent years.

Global energy demand is rising primarily as a result of population and economic growth in the emerging economies. Meeting this growing demand places increasing stress on limited fresh water resources as electricity production uses large amounts of water. This has repercussions for other water consumers in the agricultural, industrial and domestic sectors. Climate change could exacerbate the situation. This webinar examines the availability of fresh water for power generation, in particular for coal-fired power plants. It shows where the water stressed areas are in the world today and the demand for power. Global water and energy demand are discussed, and the water requirements of different power generation technologies. Some technologies that use less water, for example, dry-cooled power plants, operate at a lower efficiency. Finally, water availability and management in China and the USA, with reference to their energy production and policies are compared.

Most pulverised coal combustion (PCC) plants employ single-reheat cycles. However, double-reheat cycles can significantly improve the electrical efficiency of PCC plants. Surprisingly, no double-reheat units have been commissioned since the 1990s. However, with rising primary energy costs, more stringent emission limits and advances in thermal power engineering, double-reheat cycles are being considered to minimise the cost of electricity, reduce emissions and prolong valuable coal supplies, especially in China. This webinar reviews, analyses and assesses the application and development prospects of coal-fired double-reheat units.

Recent developments in process waste recycling and biomass utilisation have driven the use of these so-called ‘low value fuels’ for energy generation on a stand-alone basis, and in combination with coal. One particular technology stands out as being particularly well suited to utilising these low value fuels, circulating fluidised bed combustion (CFBC). The upcoming webinar sets out examples of the range of low value fuels, their reserves and properties, with particular emphasis on coal-derived materials, the issues for CFB plant in utilising these fuels and selected examples of manufacturer and operator experience with purpose built, or modified CFB plant.

Dr Steve Mills presents his recent researxh

Dr Lesley Sloss presents her latest research

Coal power plant control systems have progressively evolved to meet the growing demand for efficient and flexible power generation whilst maintaining low emissions. In particular, optimisation of the combustion process has required increased use of online monitoring technologies and the replacement of standard control loops with more advanced algorithms
capable of handling multivariable systems. Improved stoichiometric control can be achieved with
coal and air flow sensors or imaging and spectral analysis of the flame itself, whilst in-situ laser absorption spectroscopy provides a means of mapping CO and O2 distribution in hot regions of the furnace. Modern plant control systems are able to draw on a range of computational
techniques to determine the appropriate control response, including artificial intelligence which
mimics the actions of expert operators and complex empirical models built from operational data.
New sensor technologies are also being researched to further improve control and to withstand the high temperature and corrosive environments of advanced coal plant and gasifiers. Increased use of optical technologies is of particular interest, with sensors based on optical fibres able to perform low noise, highly sensitive, and distributed measurements at high temperatures.
Microelectronic fabrication techniques and newly developed high temperature materials are also being combined to develop miniaturised devices which provide a robust and low cost solution for in-situ monitoring of gases and other parameters. These new sensors can be integrated with wireless communication technology and self-powering systems to facilitate the deployment of distributed sensor networks and monitoring of inaccessible locations. Using principles of self-organisation to optimise their output, such networks may play a growing role in future control systems.

Microalgal removal of CO2 from flue gas
Various methods have been developed to remove CO2 from the flue gas of coal-fired power plants. Biological post-combustion capture is one of these. Microalgae may be used for bio-fixation of CO2 because of their capacity for photosynthesis and rapid growth. The ability of microalgae to withstand the high concentrations of CO2 in flue gas, as well as the potentially toxic accompanying SOx and NOx has been researched. Microalgal strains that are particularly suitable for this application have been isolated. Most of the research on algal bio-fixation has been concerned with carbon fixation strategies, photobioreactor designs, conversion technology from microalgal biomass to bioenergy, and economic evaluations of microalgal energy. This webinar considers current progress in algal technology and product utilisation, together with an analysis of the advantages and challenges of the technologies. It opens with a brief introduction to the theory of algal bio-fixation and factors that influence its efficiency especially in terms of flue gas characteristics, and then discusses culturing, processing technologies and the applications of bio-fixation by-products. Current algae-based CO2 capture demonstration projects at coal-fired power stations around the world are described.

Competition between coal and natural gas for power generation has been observed to occur in North America and Europe in recent years, where the costs of the two fuels have played a key role in determining the relative competitiveness. It is perceived that such a competition could also happen in Asian countries. More importantly, as these countries are expanding their generation capacity to meet growing electricity demand, a key question is raised of whether coal or gas power plants should be built with priority. This webinar is based on a recent report published by IEA CCC, where the authors investigate nine Asian countries to seek to understand the mechanisms that drive the competition between coal and gas for power generation.