Addressing the energy trilemma in mining operations with natural gas and renewable power

21st April 2022

Addressing the energy trilemma in mining operations with natural gas and renewable power

The world today is faced with the energy trilemma of achieving the right balance between reliability, sustainability and affordability for electricity generation, delivery and consumption. Energy Intensive users such as those in the mining and minerals industry, are particularly under a lot of pressure from governments, investors, and society to reduce emissions even as demand for these minerals grows.  In February this year, the International Council of Mining and Metals released its 2022 to 2024 strategy and action plan which clearly outlines the commitment of its members to achieve net-zero Scope 1 and Scope 2 greenhouse-gas (GHG) emissions by 2050 or sooner with clear pathways of how they are going to achieve that. 

According to Mckinsey, mining is currently responsible for 4% to 7% of GHG emissions globally. Scope 1 and Scope 2 carbon dioxide emissions from the sector (those incurred through mining operations and power consumption, respectively) amount to 1%, and fugitive-methane emissions from coal mining are estimated at 3% to 6%. A significant share of global emissions—28%—would be considered Scope 3 (indirect) emissions, including the combustion of coal.

It is also important to note that many of these minerals are mined in Africa, which has its own energy deficits. It therefore becomes very important that the mining industry is very deliberate around how it meets these energy needs, how it decarbonises and how it positions itself to the export market. 

General Electric (GE) believes that gas-to-power, in combination with renewable energy plays an important role in the decarbonisation efforts in the mining and minerals industry, particularly in Africa, where, historically, heavy fuel oil (HFO) and diesel have dominated the power generation landscape.

“The complementary strength of natural gas and renewables plays a critical role in delivering low carbon and reliable power generation for mining operations,” GE Gas Power sales executive Oluwatoyin Abegunde tells Mining Weekly.

She points out that there have been many significant discoveries of natural gas resources across the African continent in countries like Mozambique, Nigeria, Ghana, Senegal, South Africa and Namibia, which will be critical to support power generation to drive Africa’s industrialisation ambitions. 

“There are also decarbonisation benefits to switching from coal and high carbon liquid fuels to a combination of natural gas and renewables. Switching from coal-based power generation to natural gas-based power generation reduces carbon emissions by about 60%, while switching from diesel to natural gas reduces these emissions by about 40%. “

“It is also important to note that switching to a combination of gas plus renewables actually reduces these emissions further, by about 78%. Thus, replacing diesel with complementary fuels such as gas and renewables is the fastest and most viable path to reducing carbon emissions in Africa,” Abegunde notes. 

Renewable energy can offer close to zero carbon footprint. However, the challenge is that while renewable energy as a standalone, and together with batteries, can reduce up to 100% of the carbon, it is only available between 35% to 50% of the time owing to the inherent seasonal and daily variability of wind and solar energy.  

Gas plants can compensate for long gaps in renewable production in ways that today’s battery storage technology may not. Batteries can be used for short-term (typically <8 hours) storage of renewable energy, while gas is economical for longer duration peaking needs. Further, gas power plants are flexible, with the ability to start quickly, ramp power up or down, and turndown to very low output levels, so they provide affordable, dispatchable power that can fill the supply/demand gap as and when needed.

The global energy system is transforming at a scale and pace never experienced before. Integrating intermittent renewables into the existing grid requires flexible and resilient technologies, able to ramp up or down rapidly and dynamically adjust to real-time grid signals.

Gas Plus Renewables

In order to supply electricity to the grid for critical industrial applications as well as to support Africa’s industrialisation goals, there needs to be clear priority around the deployment and implementation of gas plus renewables to deliver flexible, affordable power whenever it is needed. 

“Gas and renewables are complementary to each other. This, therefore, makes them a powerful combination to address climate change challenges at the speed and scale that Africa and the world requires. 

“As sub-Saharan Africa balances the need for more access to power, along with the push towards cleaner energy sources, the accelerated and strategic deployment of renewables and gas power together can deliver these sustainable reductions in emissions quickly,” says Abegunde.

There is also a growing demand for mined products that are used in the energy transition to be low carbon, and with the World Bank reporting that production of minerals such as aluminium, copper, graphite, lithium and cobalt is likely to increase by nearly 500% by 2050, it is imperative that the power generation industry achieves that objective. 

GE’s thermal hybrid solutions offer a reliable, cost effective and sustainable pathway for reducing carbon emissions for industry players in the mining and metals, plastic, paper and pulp, and chemicals industries, among others. 

The benefits of this hybrid solution using gas power generation include high-capacity factors at lower capital expenditure compared to battery storage utilisation, lower levelized cost of electricity compared to pure thermal operation, lower variable costs, reduced renewable energy curtailment, and significantly decreased GHG emissions compared to coal, diesel and HFO power generation.

In addition, the mining industry is keenly focused on sustainability goals. That means, in part, lowering reliance on carbon-heavy fuels like coal, diesel and HFO. Mining energy solutions that integrate natural gas and renewable energy solutions can help meet important sustainability goals as well as achieve reliable performance at a lower the cost of electricity.

Remote Gas Supply

Although much of Africa has limited gas supply infrastructure, the continent can take advantage of virtual gas pipeline solutions like small-scale liquified natural gas (LNG) and compressed natural gas (CNG) that can be explored where gas pipelines do not exist. 

Abegunde acknowledges that supplying gas to remote mining sites where there is no gas pipeline is a challenge. However, this can be mitigated by using several virtual pipeline options for gas supply through trucking of small-scale LNG or CNG. 

She points out, however, that each customer would need to be evaluated based on their proximity to the gas supply as well as the road network and route for trucking. 

“A road network for trucking CNG is feasible within distances of up to a 200 km radius from the gas supply, while natural gas trucks are feasible up to about 2 000 km radius from the supply points,” says Abegunde. 

Trucking of fuel to mining sites is not a new concept. Many remotely located mines truck liquid fuel such as diesel and HFO across many kilometres and are quite familiar with these trucking logistics. 

Additionally, Abegunde notes that GE’s gas turbine technology is highly fuel-flexible, able to operate on a wide variety of gaseous and liquid fuels. Over the last decade, GE experts have performed over 20 000 hours of combustion testing to validate its technology as well as develop new technologies and expanded fuel capabilities. 

Gaseous fuels include natural gas, LNG, flare gases, lean methane, refinery gases, as well as ethane, propane, and other higher molecular weight hydrocarbons, i.e., natural gas liquids (NGLs) and liquid petroleum gas. Liquid fuels include diesel (also known as light distillate or diesel fuel oil), biodiesel, condensates, crude oils, and heavy/residual fuel oils. This fuel flexibility capability could play an increasing role in a future low- or zero-carbon energy ecosystem.

GE gas turbines are also hydrogen ready, having more experience running on hydrogen and related fuels than any other OEM with over 100 gas turbines operating in the field around the world today. GE has combustion technologies that can operate on a wide range of hydrogen concentrations up to ~100% (by volume). 

GE gas turbines are well positioned to support a zero carbon future, not leaving customers with stranded assets, powering thermal hybrids plants on a combination of hydrogen and renewables when the volumes and pricing of hydrogen become feasible and associated infrastructure to support transportation and storage are available.

“GE works with its customers to evaluate their specific needs and evaluates all the different fuel sources that can be feasible for their site. Then, based on the fuel flexibility of our gas turbines, we provide the perfect solution that provides sustainable, reliable and cost-effective power generation for their operation,” she explains.

GE’s mining energy solutions include power plant generators, as well as aeroderivative and heavy-duty gas turbines, many of which feature the flexibility to burn a wide range of fuels and enable similar synchronisation with renewable power.