The Decarbonization of the Global Energy System

Climate change has dominated the news over the past 15 months. First, nearly 200 nations signed a historic accord in Paris during the COP21 climate talks in December 2015. The signatories to the accord, including the United States, the countries of the European Union, China and India, agreed to do their part to cut carbon emissions, and the Paris agreement entered into force months ahead of schedule. 

With their commitments to the Paris agreement, participating nations seek to limit global temperature rise to 2 degrees Celsius above pre-industrial temperatures. If temperatures rise over that limit, scientists say global warming will accelerate to catastrophic levels. Even worse, it will no longer be possible to reverse these temperature shifts. 

But climate change has also become something of a political football, at least in the United States. For the new presidential administration, early moves seem to focus on easing fossil fuel extraction restrictions. And fossil fuels like oil and coal increase carbon emissions.

It is possible, though, to see the push toward decarbonization as a global movement despite the temporary ascendancy inherent in multiple political parties. Around the world, adoption of decarbonization methods and research into optimal deployment is widespread.

Decarbonization is possible…

One encouraging sign can be found in a recent report by the International Renewable Energy Agency (IRENA). The agency estimates carbon dioxide (CO2) emissions related to energy can be cut back 70 percent by 2050 with a net-positive economic outlook. A complete phase-out is possible by 2060. 

These emissions reductions will keep the world on track to achieve the 2-degree target  -- without any damage to the global economy, the agency concluded.

But accomplishing this will require increased development and use of renewable energy sources in the G20 countries and worldwide.

… But how best to achieve it?

Countries across the world are debating how best to achieve the necessary carbon emissions reductions. The Global CCS Institute cites four methods.

1. Improved energy efficiency: Energy efficiency includes cutting back on emissions in vehicles and improving the energy efficiency in buildings, both in their heating, ventilation and air conditioning (HVAC) systems and in their design. Smart urban design, as well as the recycling and repurposing of materials, are also central to improving energy efficiency.

2. Low-carbon electricity: Development of low-carbon electricity requires reducing dependence upon fossil fuels like oil and coal and increasing use of renewable energy sources like solar, hydro and wind. Solar captures energy from the sun, hydro from water and wind from wind turbines. None of the renewable sources emit carbon, so they do not contribute to carbon emissions.

3. Electrification and fuel switching: Fossil fuels are used for more than electricity. They are also widely utilized in areas like transportation, industry and building. These sectors must also transition to renewable energy sources or fossil fuels that use less carbon.

4. Non-energy emissions: Best-practice farming and reforestation can both reduce carbon emissions. Reforestation and vegetation, in particular, can be used in decarbonization and sustainability practices because trees and vegetation breathe in carbon dioxide and breathe out oxygen.

Renewables and fossil fuels: Working together

At one point, renewable energy and fossil fuels seemed to be in different camps. One of the most intriguing new energy methods, however, is to combine renewable energy sources with fossil fuels such as natural gas derived from shale.

Although renewable sources such as solar and wind are emission-free, they also have drawbacks. Their power supply is intermittent. Renewable power also currently requires connecting to existing power grids, which can be complicated.

Some observers believe rising production of shale gas in the U.S. has resulted in natural gas becoming potentially highly important in decarbonization. Natural gas has greater efficiency than other fossil fuels in supplying electricity.

Should carbon capture technologies become less expensive, natural gas could be used along with renewable energy sources. The renewables would provide clean energy, and natural gas would counterbalance their comparative unreliability with good energy reliability and strong grid interface.

The decarbonization of the global energy system is very achievable by the mid-21st century if attempts to rein in carbon emissions continue. A great deal will depend on replacing fossil fuel energy with renewable energy like solar and wind power. Innovative new methods to combine the strong points of fossil fuels with the strong points of renewable power are in the works and promise to aid in the effort.

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