Total ash management

Fly ash from coal-fired power plants need not be a costly waste product requiring disposal. Thomas Duve of Evonik Power Minerals explains how total ash management providers can offer power utilities a convenient and profitable alternative.

Whilst public concern about global warming grows and CO₂ emissions produced during power generation increasingly become the focus of debate, the insatiable worldwide appetite for electricity is only accelerating. Consumer demand in developed nations alone, coupled with issues around security of supply, mean that coal-fired generation has a guaranteed role in the energy mix for the foreseeable future. Increasing industrial capacity and personal wealth in developing nations such as China and India, coupled with huge coal reserves and well-developed construction programmes, have already seen massive growth within the coal-fired sector. Going by newspaper headlines and campaigners’ rhetoric, one might think that the power generation business is blind to the environmental issues we all face, but it does not take too much digging to find that huge and fairly fundamental changes are already taking place.

Whilst Europe is, for the first time in a quarter of a century, building new coal-fired power stations, we have also seen massive investment in sustainable technologies, such as wind and wave, and the development of biomass and clean-coal technologies. Materials such as fly ash are now seen within the industry as a resource to be utilised, rather than as a waste to be discarded. Many companies once associated solely with fossil fuel power generation have diversified, whilst others have shifted their emphasis entirely.

Evolving business

One example of this changing emphasis is apparent at Evonik Industries, the German-based international chemicals, energy and real estate group which has sprung, reborn and in many ways reinvented, from its predecessor, RAG Beteiligungs-AG. The company was renamed following a strategic realignment which saw it shed its coal-mining operations to focus on products and services which help lower the consumption of natural resources and reduce CO₂ emissions.

One of the Evonik companies currently leading this new approach is Evonik Power Minerals, which has taken over from its previous incarnation of STEAG PowerMinerals to become one of Europe’s leading recyclers of coal-fired power station by-products. Now well-established in the UK, Evonik Power Minerals offers total ash management – that is, the removal, transport and storage of ash from power stations, the processing and quality control of the by-products, and the supply of dependable, high quality products to the construction industry.

“Only around half of the 5.7Mta of fly ash in the UK is recycled,
with the remainder going to landfill.”

Evonik Power Minerals’ launch in the UK in 2006 followed the identification of a huge opportunity. Coal-fired power stations account for 32.9 per cent of Britain’s electricity production and the UK Government’s recent Energy Review confirmed that coal-fired power is likely to remain a significant part of the country’s energy mix for many years to come. At the same time, only around half of the 5.7Mta of fly ash produced in the UK is recycled, with the remainder going to landfill. This is in stark contrast to Germany and other parts of Europe where over 95 per cent of fly ash is now recycled. Evonik Power Minerals was convinced that, with its proven ability to meet the needs of both power station producers and construction industry consumers of fly ash, it could make real inroads into that so-far-unutilised 50 per cent. Added to this is the fact that dumping fly ash at landfill can often prove unpopular with local communities and thanks to the European Landfill Directive is becoming an increasingly expensive option. What makes it even less appealing is that doing so wastes an increasingly valuable resource.

Evonik currently recycles more than 5Mta of power station residues in Germany and has a great deal of experience in terms of both working with fly ash producers and in satisfying the needs of customers in the construction sector. The opportunity to do business in the UK had obvious attractions for Evonik Power Minerals, but the expansion of the country’s total ash management capacity also offered advantages for power producers.

Total ash management

Total ash management offers a simple and reliable solution to the issue of ash produced by coal-fired power stations. Providers have many customers, not just in one country, and they base their work on networks of sources and demands. This guarantees their customers regularity of supply and consistent quality. It also ensures their suppliers that their ash will be removed.

While a single power station can, of course, if it chooses, sell fly ash directly to customers, outages and variations in the quality of the ash can make it difficult to retain such customers. Once gone, they are very difficult to get back, especially if they have found another supplier or an alternative product. Customers need to know that they will get what they require when they need it and individual power stations cannot guarantee that, unlike total ash management providers.

Additionally, lost customers don’t just represent lost income for individually-trading power stations. They are also left with the problem of what to do with the ash they subsequently produce.

By plugging a gap created by problems at one power station with fly ash produced at another, total ash management satisfies the customer’s demand. When ash production resumes at the original source, the ash is once again taken away by the total ash management provider, and with it, a potentially huge headache for the utility.

An additional advantage is that total ash management providers such as Evonik Power Minerals have research and development departments which are constantly looking into new and better ways to recycle fly ash, and creating improved ‘recipes’ for concrete mixes.

This adds huge value for the customer in a way that power stations simply can’t compete with. The main reason for this is one of specialisation. After all, the core business of power stations is, self-evidently, the generation of power. For specialists like Evonik Power Minerals, total ash management is the core business and they can focus on managing the ash on behalf of power stations not only more effectively, but also cheaper than they can themselves.

Logistics

This is especially the case when the costs to power stations of total ash management are compared with those of landfill. New landfill sites are now incredibly expensive and likely to become more so, even before environmental considerations are included in the calculations.

Let’s use Evonik as an example of how a total ash management provider works. It fully accepts and manages all of the logistical issues involved, such as removing all the ash from a site, on a regular basis, ensuring dependability of supply to the construction industry. However, for such an arrangement to be a success, the quality of the ash needs to be of a marketable standard. There also has to be sufficient silo capacity and the ash needs to be offered at a competitive price. The distance to the relevant market regions is also an important factor because of the imperative to keep costs low and deliver a competitively priced product to the customer.

An illustration of how this might impact in the UK is that power stations in the South East of England, where a lot of construction work is taking place, are in a stronger position than in the North East, where a lot of fly ash is produced. A similar situation can be seen in Germany where there is a large amount of fly ash produced in the North Rhine-Westphalia region, which is not covered by local demand. The value per tonne of fly ash is not high enough to justify high transport costs, so logistics is an issue and Evonik tends to seek local customers.

However, the company sometimes transports ash over significant distances, to get it away from production “hot spots”. This helps to keep the market stable and to ensure security of supply for power stations, as well as allowing it to deliver large quantities where and when it is required. For example, in Europe, at various times, Evonik has moved fly ash from the Czech Republic and Poland to Germany, or from Germany to Switzerland.

Once fly ash has been removed from a power station, its quality determines the next stage of the management process.

Fly ash can be suitable for high value applications like concrete manufacturing, block-making, paving slabs and pre-cast concrete, straight from its source. If that is the case, total ash management providers can deliver it direct to their customers. If it is of slightly lower quality, refinement (or ‘beneficiation’) may be needed before it is used for these purposes. Throughout Europe, fly ash for use in concrete must meet the EN450-N quality standard and, uniquely, the UK market can demand that it meets the finer EN450-S standard.

If beneficiation is not possible, the ash will be used in road construction, ground levelling, grouting and stabilisation.

Other mineral by-products

Total ash management is not, however, just concerned with fly ash. Furnace bottom ash (FBA) is also utilised, although in a different manner. Because it is not a powder and is wet, it is easier to handle, does not have to be transported in sealed environments and can be stored outdoors. In addition, there are much smaller quantities of FBA being produced, as it accounts for only around 10-20 per cent of the total ash produced through coal combustion. There is a long tradition of recycling FBA and nearly 100 per cent of total production is now utilised, mainly as a lightweight aggregate.

The third area of Evonik Power Minerals’ recycling work is the product of action already undertaken by the coal-fired energy sector to reduce its environmental impact. Flue gas desulphurisation (FGD) gypsum is a well-known alternative to mined gypsum, helps reduce the impact of mining and offers a high quality raw material for plasterboards and other plaster products.

The lion’s share of the company’s total ash management work, remains focused on fly ash. The vast quantities produced mean that landfill is a genuine concern and, while Evonik is a profit-making business, it also has a commitment to using its knowledge and experience to address some of the environmental issues that face us all today.

The environment

Probably the most high-profile environmental issue today, is that of CO₂ emissions. The United Kingdom Quality Ash Association (UKQAA) has produced estimates for the reduction of carbon emissions when using fly ash in construction materials, instead of naturally-occurring materials such as aggregate or Portland cement. When the full range of factors – such as extraction, processing and transportation of natural materials and the technical benefits of fly ash products – are taken into account, the UK’s calculated annual reduction in CO₂ emissions is 600,000t. As only half of the fly ash currently produced in the country is used, this figure could, in principle, be doubled.

Extrapolating the UKQAA’s calculations and applying them to the world production of fly ash without making adjustments for any regional variation may not be entirely scientific, but may give a broad indication of the global potential for reducing carbon emissions. By this measure, a reduction in CO₂ emissions of 90Mt could be made if the world’s entire fly ash output (some 480Mta) was recycled, thereby replacing naturally-occurring equivalents.

In addition to the issue of CO₂ emissions, using fly ash reduces the need for the extraction and processing of virgin aggregate or Portland cement, as well as reducing the environmental impact caused in their production and avoiding the depletion of natural resources.

Of particular relevance to the producers of coal fly ash is the issue of landfill. Not only is landfill, particularly in developed countries, an increasingly expensive activity, but it is increasingly hard to find suitable sites. In addition, local communities are becoming more vocal in their opposition to landfill, especially when there is a perceived conflict with alternative uses for the sites, such as leisure.
Historically, fly ash was seen as a waste product and landfilling reflects that attitude. Now, however, the prevailing view is that fly ash is a resource: a by-product of the power industry which has value because of its properties and uses

Recycling fly ash also reduces the production of clinker, the name given to the intermittent state of Portland cement after its constituent components leave the kiln . Portland cement, by the nature of its chemistry and manufacture, has a relatively high CO₂ emission of around 960kg/t. When fly ash is used in concrete, environmental savings can equate to between approximately 20-30 per cent reductions in overall CO₂, depending on the percentage ash content.

Given the increasing concerns regarding climate change, the need to cut CO₂ emissions should be acknowledged everywhere, perhaps especially within the power and construction sectors. It is little wonder then that Evonik is pleased to be working side-by-side with cement companies to reduce clinker production. There appears to be a genuine will within the cement industry to reduce their CO₂ emissions and that commitment deserves acknowledgement.

The market for fly ash

With coal-fired power back on the agenda in the UK, albeit on a smaller scale than in the past, and plants such as Kingsnorth and Tilbury expected to go ahead, fly ash production is set to increase.
The market for fly ash products is a strong one. Fly ash concrete is tough, durable, workable and can be pumped over longer distances, making it ideal for a range of modern construction projects, such as dams, offshore platforms, industrial developments and schemes like the Thames Gateway, a city the size of Leeds which is planned for the South East of England.

Whilst the modern use of coal fly ash has developed rapidly over the last 30 years, the use of fly ash in concrete dates back well over 2000 years, when volcanic ash was used in ancient Mexico and by the Romans. One example is to be found in the Italian town of Pozzouli, which gives its name to the “pozzolanic” property of fly ash. This describes a siliceous or siliceous/aluminous material that, when mixed with lime and water, forms a cementitious compound. A number of pozzolanic materials exist, but fly ash is the world’s best-known and most commonly used – not least because huge, and growing, quantities are being produced.

It has been estimated that approximately 1Mt of fly ash goes into high value applications in the UK each year. If all the available fly ash was used, this figure could rise to 3Mt, but a realistically achievable target is likely to be nearer the 2Mt mark.

Fly ash can be used in the construction of roads and as a replacement
for cement in the production of concrete.

Some very significant construction projects in the UK are using, or are likely to use fly ash. The current widening of the M1 motorway involves using fly ash for bedding and the Olympic Delivery Authority is talking to cement suppliers who are likely to use fly ash products. An ideal use for fly ash concrete, however, would be in the construction of Britain’s flood defences which, as recent experience has shown us, are much needed. It is to be hoped that the construction industry seriously considers this option, because particular blends of fly ash concrete are ideally suited to the challenges of a marine environment, as its use in the Brighton Marina demonstrates.

Whilst the market is strong, one cloud on the horizon is the much-heralded global economic downturn. To date, however, the uncertainty this prospect offers has not resulted in significant changes to Evonik Power Minerals’ view of the future and the company has yet to see the stock market’s volatility impact on the fly ash market.

Global fly ash production

The UK market is not the only one to offer potential opportunities for fly ash recycling. As developing nations such as China and India see demand for electricity spiral, the expansion of coal-fired generation has led to an increase in fly ash production.

In 2000, 100Mt of fly ash were produced in China. By 2002 a figure of 150Mt was being quoted by the China Fly Ash Utilisation Technology Centre in Shanghai. Even though utilisation of fly ash had grown from just 10 per cent in 1980 to 66 per cent in 2002, the remaining 50Mt of unused fly ash represents a huge resource for the global construction industry.

Elsewhere in the world, India produces over 100Mt of fly ash and utilises about 26 per cent, Russia produces around 50Mt and utilises about 15 per cent, and the US produced 127.8Mt and utilised around 35.4 per cent in 2002.

It is clear that, globally, there is a significant gap between the amount of fly ash produced and the amount that is recycled. This might not be an issue if it were not for the lost opportunities of using superior quality building materials and helping to decrease environmental impact.

Looking forward

The global picture for fly ash utilisation appears very positive. The market is currently strong and getting stronger and with China effectively building one new coal-fired power station a week, fly ash production is soaring. One of the major challenges is to ensure that output is used to benefit the power industry, the construction industry and, crucially, the environment.

For many commodities, global pricing dictates the success or failure of a market but, for fly ash, pricing structures are more complex. Because it is used largely as a replacement constituent in cement, its price reflects that of naturally extracted materials at a local level and can therefore vary greatly from one region to another.

This has not, however, slowed progress in developing countries and credit should be given to cement producers like Holcim, Lafarge and Cemex for playing an important part in developing a strong and sustainable market for the use of recycled materials in countries like India and China. They are pioneering the recycling of fly ash at a local level and they genuinely want to reduce their overall carbon footprint.

In Europe, a somewhat different, but no less interesting picture is emerging. The construction sector is coming under increasing pressure to use recycled materials, including fly ash, in its work, And that pressure takes different forms, depending on which country you look at.

For example, in Germany the authorities are introducing regulations requiring the use of recycled materials. In the UK, the pressure comes from within the industry. BRE, the well-regarded sustainable development organisation which focuses on the built environment, awards ‘Ecopoints’ for products or processes which cover a range of environmental impacts and this system is attracting increasing interest and credibility, throughout Britain.

Throughout Europe there are numerous other systems with shared aims. What they all have in common is a significant influence on the ways in which fly ash and other materials are viewed and used by the construction industry.

These issues, combined with the re-emergence of the coal-fired energy sector, signal greater opportunities for all involved with fly ash and particularly for the practice of total ash management.

For Evonik Power Minerals, the future promises organic growth and the aim of widespread recognition within the UK as a reliable partner for both the power and construction industries.

In addition to its total ash management services, Evonik is actively considering the building and management of several biomass power stations in the UK. These will be an important addition to its business activity and one which will, again, build on our extensive experience in Europe, our commitment to developing sustainable solutions and our belief in resources, rather than waste.

Evonik Power Minerals is one of the few suppliers of Waste Incineration Directive-compliant (WID-compliant) wood boilers. These are designed to burn treated woods, such as painted or varnished furniture, doors and window frames, without emitting any environmentally-harmful substances. Existing biomass power stations in the UK do not meet the terms of the WID and rely on exemptions to continue operating. In terms of trialling biomass in the UK, those plants have done pioneering work and the exemptions have been valuable, but Evonik is keen to introduce its cleaner, greener technology as soon as it can. Despite this development, total ash management will remain the company’s core business.

Evonik Power Minerals intends to build up its networks of supply and demand in the UK and connect them with its existing networks in Europe. Evonik is also aiming to be the first choice for any power station considering the recycling of their fly ash and can offer them a total ash management service capable of providing the benefits, both financial and environmental, that they are seeking. If the coal-fired power industry is to make the most of its resources and is committed to minimising its impact on the environment, total ash management really is the way forward.

Thomas Duve is the chief executive of Evonik Power Minerals Ltd. If you require more information about total ash management, the author can be contacted at tel. +44 (0) 20 8334 8073 or email: thomas.duve@evonik.com
www.evonik.com/powerminerals-uk