Clean Coal Technologies (CCT) – quo vadis?
By Alan M. Clegg Pr.Eng Pr.CPM PMP FSAIMM – Chairman, Shumba Energy Ltd and Spencer Eckstein – Director, Business Development, Ukwazi Mining Studies (Pty) Ltd
Socrates famously stated: “The secret of change is to focus all your energy not on fighting the old but on building the new.”
Any new Coal fired power plant (“CFPP”) projects constructed today will use Clean Coal Technologies (“CCT”) to enable permitting. Old power stations like the ones we have in South Africa that were predominantly built in the 1970’s do not have CCT, even newer ones built in the 2000’s namely the air-cooled Kusile and Medupi.
The issue of the ‘Just Energy Transition’ and how to implement it are likely to generate further debate and be a source of potential conflict between stakeholders, before becoming a reality in South Africa: not least because of the governance failures and corruption scandals surrounding their delivery on both sides of the aisle.
In contrast, other SADC countries such as Botswana are forging ahead with plans to deliver new CFPPs using CCT and based on their own significant thermal coal resources and economic growth requirements, which are driven the availability of cheap energy.
Globally, we have the COP27 Conference coming up in Sharm el-Sheikh, Egypt between 6-18 November 2022; and now following the Russian invasion of Ukraine, the exacerbated energy deficit in the developed, western economies has become a controversial energy delivery race. It has also highlighted the conflict between the ‘green lobby’ wanting to double down on the renewables proliferation strategy on the one hand and the established, reliable fossil fuelled energy lobby on the other. The European energy crisis has also refocused attention on nuclear energy, which has been temporarily declared, as a necessary evil and which has been allowed back into use, through sheer necessity.
So why is coal an issue?
Most mined thermal Coal was created 200 – 300 million years ago from plant material that decayed, and which formed underground due to heat and pressure. In South Africa, most of our coal forms part of a particular geological feature referred to as the Karoo supergroup and is mostly concentrated in Mpumalanga.
Coal derived-energy formed the basis of the industrial revolution (c1760-1820) and throughout the British Empire became the dominant global form of energy and which continues today.
Coal contains a variety of chemicals such as sulphur, nitrogen, moisture, and when burned in a power station produces carbon dioxide, sulphur dioxide, nitrous oxide, and ash.
When claims regarding coal emissions are made and causal connections are drawn between emissions and climate change, its important for these claims to be evaluated objectively based on the best available scientific evidence, and evaluated in a manner that differentiate between long term natural shifts in climate (e.g. earthquakes, volcanoes, shifts in the earth’s axis, etc.) and climate change due to human activity.
Burning coal to generate power does negatively impact the environment via emissions of CO2. It is also factual that when coal interacts with air, in some cases it produces spontaneous combustion. It is also true that when gaseous emissions that interacts with water in the atmosphere creates acid rain. Surface and ground water may also be adversely affected by their interaction with coal, when mined or when washed or used in a power station. Furthermore, there is always the potential human costs associated with mining via injuries or fatalities particularly in underground mining operations, and resulting impacts on local communities and stakeholders.
However, the adoption and increased use of mechanised mining and monitoring technologies in coal mining today has largely mitigated these risks as, mining companies increasingly adopting ‘Zero-Harm’ policies within their ESG (Environment, Social & Governance) profiles and practices.
The obvious question, then is. if coal is so harmful, why use it?
We use it because as an energy fuel source its readily available, cheap, and effective, particularly in creating baseload energy (energy that is always available within a 24-hour cycle and not dependent on environmental factors).
Interestingly, from a geopolitical perspective, it is not coal but oil that has shaped political conflicts and political alignments in Europe, the US, and the Middle East. It is the Petro-dollar that dominates the energy debate, while coal still prevails, generating c.60% of all global energy and c.83% of global electrical energy according to the International Energy Agency (“IEA”).
Critiques of renewables
The proponents of the use of renewables, claiming that via the use of different, complementary technologies, particularly battery deployment for energy storage and the use of different combinations of battery metal chemistries that the costs of renewable per kw/h is consistently declining relative to other power sources or types. The critics of renewables argue that they cannot provide baseload energy; that they are grossly inefficient and that they are more expensive across the value chain.
How do we mitigate impacts from coal powered energy generation?
Locally and globally the focus remains on net zero carbon emissions and to restrict global warming by 1.5 degrees Celsius (or more) and to move away from coal as a source of energy.
The main way in which the mineral and energy sector can contribute to mitigation efforts is to reduce CO2 emissions from coal powered plants and to reduce all harmful emissions, reduce the use of coal and other hydrocarbons to follow new energy pathways for society.
However, the war in Ukraine and the energy crisis in Europe has inevitably re-opened the debates around clean coal technologies (CCT) and the current global reinvestment in coal operations. It is the perfect storm to leverage and introduce CCT.
There are many elements to CCT, but appropriately combined within a CFPP design they are focussed on two main results:
- reducing total emissions (reduced carbon dioxide, sulphur dioxide, and nitrous oxide emissions, via carbon capture and/or carbon storage typically proposed for underground during or after combustion); and
- focusing on higher combustion efficiencies for delivery of lower overall emissions.
The suite of CCTs available include:
- Coal beneficiation ‘washing’ which reduces emissions of ash and sulphur dioxide when the coal is burned.
- Electrostatic precipitators and fabric filters can remove significant amounts of the fly ash from the flue gases reducing emissions to within regulated levels.
- Wet Flue gas desulphurisation captures the output of sulphur dioxide to the atmosphere to within legal limits, potentially allowing for generation of secondary industrial production of Sulphuric acid or gypsum, but the quantum depends on the level of sulphur in the coal.
- Low-NOx burners allow coal-fired plants to reduce nitrogen oxide emissions by up to 40%. Coupled with re-burning techniques NOx can be reduced 70% and selective catalytic reduction can clean up 90% of NOx emissions.
- Other technologies such as integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) ensure the coal burns more efficiently with lower emissions.
- Ultra-clean coal (UCC) injection to boilers from new processing technologies which reduce ash and sulphur, and which use pelletised washed coal fines produced using energy efficient cold agglomeration processes.
- Gasification, including underground coal gasification (UCG) in situ, uses steam and oxygen to turn the coal into carbon monoxide and hydrogen.
- Coal-to-Liquids (CTL) technologies for production of clean burning liquid fuels and useful petrochemical by-products called Aromatics, e.g., DBT (Dibenzyl-toluene) or BT (Benzyl-toluene) useful as LOHC (Liquid Organic Hydrogen Carrier) media for grid scale energy storage complementary for renewable energy generation.
The technology options all come at different and increasing costs due to availability of metals and mineral components, variances in their respective EROI (Energy Return on Investment) and efficiencies and the level of market adoption for renewables has been variable, primarily driven by subsidies in some countries.
The mineral-energy complex may be shifting and evolving but given the ongoing proliferation and construction delivery of commissioned CFPPs, in particular in China (120Gw in 2021/22), India (40Gw in 2021/2022) and South-east Asia (90Gw in 2021/22); and noting that a CFPP has a life of at least 40 to 50 years, then coal is likely to remain as the primary base-load energy source globally for at least to beyond 2070. According to the IEA forecasts predicting Coal will move from 60% to 40%, Liquid Fuels from 14% to 5%, LNG from 10% to 20%, Nuclear from 10% to 20%, and Renewables from 6% to 15% of global energy generation.
In conclusion then, and as Socrates said, we must focus on building the new. The reality is that coal is likely to prevail as the dominant base-load electrical power provider for the foreseeable future; and therefore, we have an obligation to pursue the adoption of CCTs for all new CFPPs, and as far as possible to retrofit certain technology elements of CCT in older power plant to improve existing CFPP emissions performance.
First things first, while “circular” and “green” are often used interchangeably, it is important to distinguish between them. The UN…Read More
Ukwazi’s head of mining in the Northern Cape, Jaco Mans, has first-hand experience of conducting studies for companies who wish…Read More