January 2017

Special Focus: LNG, NGL and Alternative Feedstocks

Shift to gas: A contribution on the path to sustainability

The COP21 event left the world with new mandates to develop and implement low-emissions energy sources to power the global economy. To limit global warming, the world must increase the use of resources like natural gas, which offers a quick, relatively clean and inexpensive interim step in the global transition from high-emissions resources to renewable energy sources.

Koenig, E., Schneider Electric

The COP21 event left the world with new mandates to develop and implement low-emissions energy sources to power the global economy. To limit global warming, the world must increase the use of resources like natural gas, which offers a quick, relatively clean and inexpensive interim step in the global transition from high-emissions resources to renewable energy sources.

At present, fossil fuels represent approximately 80% of the primary source for power generation globally. Coal is plentiful in many countries; oil reserves are still abundant in many parts of the world; and new technology can provide more than 250 years of gas reserves. Nations are just scratching the surface of the potential for wind and solar power. The actual resources are not the problem. If a significant reduction in carbon dioxide (CO2) emissions is to be achieved, a new energy mix will be needed.

The opportunity for natural gas

Although coal, oil and natural gas are often viewed as one category under the broad label of fossil fuels, they are very different from an emissions perspective. Among the three, natural gas produces the least amount of CO2 emissions and particulates, when processed. Natural gas is also accessible to developing and emerging economies. On the other hand, of the fossil fuels that supply the majority of the world’s energy today, coal is by far the largest producer of emissions and adds many harmful pollutants and particulates to the air.

While the foothold of renewable energy programs and technologies is expanding, large volumes of clean energy cannot yet be produced at scale with these methods. One solution is an ambitious, transitional step to shift to gas over the next 10 yr–15 yr. Such an initiative will reduce global CO2 production by 25%, while complementing the efforts of growing renewable energy generation. If the prospect of carbon capture and storage (CCS) is factored in, CO2 levels could be reduced by an additional 35%.

CCS technology enables the capture of CO2 produced from fossil fuel combustion. It becomes relevant whenever large quantities of CO2 are produced (e.g., in a power generation plant). The infrastructure needed to support CCS operations is significant, and such an approach would be expensive to deploy at an industrial scale. However, the CO2 produced would be easy to liquefy and transport via pipelines that use the same existing and available natural gas pipeline technologies. The gathered CO2 can then be reinjected in a depleted gas reservoir, or in other such unused, vacant underground spaces.

While still early in its development, CCS technology for capturing and storing CO2 emissions could play an important role in the natural gas production lifecycle. Using CCS technology, a natural gas power plant would emit less than 5% of the CO2 of a new conventional coal power plant operating without CCS.

Why should natural gas be considered an interim step? Why not simply advocate a wholesale switch from coal to renewable energies? The intermittent nature of certain renewable energies, such as solar and wind (i.e., the lack of sun or wind equals the lack of energy produced), implies that natural gas has a significant role to play.

Solar plants and wind power generation need a permanent “backup” to compensate for built-in intermittencies. Although clean from a CO2 emissions perspective, nuclear plants have very long startup times, and hydropower sites are limited in number and not available in arid and semi-arid regions. Furthermore, battery technologies have not matured enough to accommodate more than short intermittency periods.

At present, much of this backup power is provided by high-CO2-emitting fossil fuel plants, with coal being the predominant feedstock. Natural gas, along with combined-cycle combustion turbines, will cost roughly one-third of conventional coal power, while generating the same capacities and producing a much smaller CO2 impact. Therefore, natural gas is emerging as a compelling solution to support renewable energy development and integration.

The case for natural gas

Fig. 1. Gas-fueled, combined-cycle combustion turbines cost roughly one-third of conventional coal power plants offering the same capacities, and generate much less CO2.

At COP21, 195 countries agreed to pursue measures to limit global warming to a rise of 1.5°C. The keys to the cause are reducing greenhouse gas (GHG) emissions and switching from coal to natural gas for power generation. Coal-generated power is the largest contributor of GHG emissions. Conversely, natural gas is the cleanest-burning fossil fuel, with the ability to reduce CO2 emissions by approximately 60% and nitrous oxide (N2O) emissions by 80%. It also produces almost no sulfur dioxide (SO2) or mercury (Fig. 1).

China, which consumes as much coal as the rest of the world combined, regularly battles poor air quality. In December 2015, Beijing issued its first-ever air pollution “red alert” when levels of deadly contaminants, directly attributable to the burning of coal, were recorded at 40 times the limit recommended by the World Health Organization (WHO). Coal’s noxious effects on air quality are well documented, contributing to high mortality rates, lung cancer, asthma and stunted lung development in children. China alone experiences 4,000 premature deaths per day as a result of poor air quality. By increasing its use of natural gas, the country can help reduce its pollution.

Natural gas is also the more sustainable alternative to coal, with gas-fueled power generation consuming 40%–60% less freshwater than coal-fueled power generation. The resource intensity of source fuels is important because, in addition to global warming and its associated negative impacts, the demand for water has increased as more agricultural land is needed to support growing populations.

While the urgent environmental benefits of the switch to gas are clear, the economics of gas vs. coal are equally compelling. Natural gas is both plentiful and affordable. In fact, estimates project that existing gas reserves are capable of meeting the world’s energy needs for the next 50 yr. The total available pool of natural gas supplies are projected to last more than 100 yr. This nexus of attributes—cheap, plentiful and environmentally beneficial—has driven a 2% compound annual growth rate for natural gas (almost twice that of coal), and has positioned natural gas as the primary fuel for power generation in the US by 2020.

An increasing reliance on natural gas for power generation does come with risk. While natural gas is by far the cleanest-burning fossil fuel, its extraction, processing and transport can leak methane, a more potent greenhouse gas than CO2. However, this risk is manageable. Reducing natural gas leakage to 1% or less of total production is an achievable and cost-effective benchmark. Solutions include an aggressive regimen of retrofits throughout the drilling, production and transmission infrastructure, as well as the development of gas capture technologies that can reroute leaks back through the normal gas processing loop—all of which are achievable measures.1

Renewables as a complement to natural gas

The climate accord that resulted from COP21 is a clear signal that an era of zero-emissions, clean-energy solutions is coming. Investors and established business interests, including fossil fuel producers, are now pledging an end to “business as usual” and taking the necessary steps to embrace a sustainable future.

Nevertheless, the actions required to enable such a transition present challenges. Renewables account for approximately 10% of the world’s power generation, with most of that percentage coming from hydroelectric sources. How and when will 100% of renewable power generation be achievable? Two immediate problems face the adoption of renewable solutions: scale and maturity.

The size of earth’s population poses a challenge for the production of existing renewables. For example, consider a 500-MW power generation plant that runs on gas and is large enough to power a city of 250,000 people. Such a plant requires a few acres of land, a small incoming gas pipeline to supply the fuel and a power line to export the power. Compare that to a similarly sized power generation asset fueled by renewables. The same power generation capability with solar panels would require 500 km2 (200 mi2) of solar farms. If available land is a constraint, consider how many rooftops would be required, as well as the complexity of the implementation and integration. Additionally, existing building structures may not permit the installation of solar panels.

On the other hand, the generation footprint for wind would require approximately 200 wind turbines (or possibly 100 of the largest offshore versions), spread over tens of kilometers of prime coastline and/or habitable or workable land. If hydropower were involved, most of the major rivers and locations for hydroelectric projects would have already been tapped. Dams are also large-scale projects and can be disruptive; they may require massive displacements of native populations (human, animal and fauna alike).

The issue of scalability is also an extension of the second constraint that is slowing the mass implementation and adoption of renewables—technological maturity. Renewable technologies (i.e., wind and solar) have come very far in a short period of time. However, they are not yet efficient nor cost-effective enough to meet growing global energy demand on their own.

At present, renewables provide intermittent power and require backup when the sun does not shine or the wind does not blow. The need for backup can be partly reduced by demand-side management, which is the modification of consumer demand for energy through various methods, such as financial incentives and behavioral changes through education.

These scenarios show why the idea of a “bridge” fuel that can provide a lower-emissions, more environmentally friendly alternative to coal is so appealing. Natural gas is ideally suited for this purpose. It also can leverage the existing power generation and distribution infrastructure relatively quickly and inexpensively. Displacing coal with natural gas can “buy time” while technologies driving renewables and energy storage continue to improve.

According to the “450 scenario” proposed by the International Energy Agency (IEA), global use of coal and oil began to decline in 2015. By 2040, natural gas will become the most consumed fossil fuel. However, the IEA’s “new policies” scenario in its World Energy Outlook is more conservative, forecasting limited growth for oil and coal and sustained growth for natural gas.

Many other scenarios are possible, with the most desirable being sustained growth of renewables and gas, accompanied by a rapid decline in coal use. In this ideal scenario, these changes would go hand in hand with the widespread acceptance and proliferation of standardized benchmark energy-efficiency measures.

The move toward natural gas

The most tangible benefit of switching from coal to natural gas—improved air quality as a result of lower emissions and better use of resources—makes a compelling argument for rapidly reducing the use of coal. However, additional technological and regulatory innovations stand to amplify the CO2 emissions reduction benefits that will result from a transition from coal to gas.

Plans for a global carbon trading mechanism did not materialize from the COP21 talks. However, business leaders around the world have increasingly called upon governments to set a price on carbon so that they can build it into their cost of operations, creating greater certainty for planning purposes. A price on carbon would further tilt the economic balance toward natural gas over coal, since businesses and the fossil fuel industry itself would be required to pay more to emit GHGs.

Along with providing cleaner power for industry and residential properties, natural gas has other advantages over coal. Gas is being steadily adopted for use in captive fleets—such as postal service vehicles and municipal buses—that improve emissions in the transportation sector. While electric cars, which are growing in popularity, are essentially emissions free, if the electricity that powers them is sourced from coal-fired power generation, how efficient can they really be?

Perhaps the biggest argument against the global adoption of natural gas over coal is its perceived impact on jobs. While millions are employed in the coal industry, especially in the developing world, the innovations needed to make the transition from coal to natural gas to renewables should spur robust job creation. These jobs would not be restricted to the technology/innovation sector, but would include the building and retrofitting of plants and pipelines, as well as their ongoing service and maintenance.

The shift from coal to natural gas stands in contrast to the development of renewable energy generation, green transportation and energy-efficiency measures for buildings and industries. Both are necessary and complementary steps for curbing the impact of climate change driven by carbon emissions.

Technology is one of the answers for addressing this issue. From generation to transmission, and from delivery to consumption, all steps in the cycle can be rendered highly efficient. Traditional, entrenched habits can be overcome if the new approaches make life simpler. Relatively inexpensive technologies make energy consumption easier to manage and will enable the shift to a cleaner energy future. HP

LITERATURE CITED

  1. Obeiter, M. and Weber, C., “Reducing methane emissions from natural gas development: Strategies for state-level policymakers,” World Resources Institute, July 2015.

The Author

Related Articles

From the Archive

Comments