TL;DR: The energy supply sector is responsible for over a third of global greenhouse gas emissions. To achieve net zero emissions by 2050, we need to focus on (1) boosting energy efficiency, (2) rapidly switching to clean energy sources, and (3) investing in supportive technologies.

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Energy supply is the largest contributor to global emissions

The energy supply sector is the single largest contributor to global greenhouse gas emissions. It includes electricity generation (extraction and processing) as well as energy transportation, storage, and distribution. In 2010, energy supply was responsible for 35% of total human-caused greenhouse gas emissions. 

While we’ve made great technological advances, global emissions from energy supply are still rising, driven by rising demand for energy and continued reliance on coal and fossil fuels (C2ES 2018, UNIPCC 2018). To draw down emissions from the energy supply, we need to (1) boost energy efficiency, (2) rapidly switch to clean energy sources, and (3) invest in supporting technologies.

Decarbonizing our energy supply is critical - and fast, cost-effective, and scalable

Any plan to achieve net zero emissions by 2050 and keep global warming below the critical 1.5°C threshold requires us to decarbonize our energy supply. Most models project that we will need to phase out use of fossil fuels from about 70%, where they are now, to less than 20% by 2050, eliminating them entirely by 2100 (UNIPCC 2018). 

The good news is that our solutions are mature enough to deploy rapidly, at scale, and at competitive prices. This transition can happen much faster than other solutions that require changes to industry, buildings, and transportation. 

1. Boosting energy efficiency

According to the International Energy Agency, energy efficiency is the single largest potential source of global emissions reduction. It could reduce global electricity demand by over 20% and is one of the least expensive ways to decarbonize at scale (WRI 2019). 

There are many steps that businesses can take to boost energy efficiency, including building retrofitting, building automation systems, green and cool roofs, vehicle and aviation efficiency, and more (C2ES 2018, Drawdown Solutions).

People can also help increase energy efficiency with newer lighting and appliance technologies, effective insulation, better building heating and cooling, high-efficiency heat pumps, and reducing idle energy consumption, among other steps. 

2. Rapidly switching to clean energy sources

Eliminate coal (without relying heavily on natural gas)

Coal generation is the single largest contributor to greenhouse gas emissions in the United States (WRI 2019). Yet low-carbon energy sources are economically viable, environmentally beneficial, and healthier and safer for all life on earth. 

In the United States, natural gas has displaced some emissions from coal-fired power plants in recent years. Natural gas plants do emit approximately half the carbon dioxide of a typical coal plant, but methane leakage in the process eats into emissions savings (US DOE 2010). Furthermore, natural gas is also displacing lower-carbon sources of electricity, preventing more effective approaches to energy decarbonization. 

It is not enough to phase out coal; while natural gas may be a near-term bandaid, in the medium run, we need to make the leap to low-carbon energy (Benson and Majumdar, 2016).

Scale up low-carbon energy sources

Low-carbon energy sources are defined as renewables (e.g. solar, bioenergy, geothermal, hydropower, ocean energy, and wind energy) and nuclear. Solar and wind have become especially viable in recent years, with the price of solar having dropped 85% in the last 10 years and the cost of wind power having dropped by 50% (WRI 2019).

Nuclear energy is another effective, low-emissions energy source. However, its share in global energy generation has declined in the last 30 years due to perceived health and safety risks. Decarbonizing the grid in the long term will likely require greater use of nuclear energy. Recent technological advances have reduced costs and improved safety. Many countries are successfully investing in new, improved nuclear strategies, including France, Sweden, UK, South Korea, and China (WRI 2019). Effective carbon pricing policy could help renew interest and investment in nuclear energy.

3. Invest in supporting technologies‍

Improve grid storage and flexibility

Renewable energy sources like solar and wind are produced intermittently. As we ramp up renewables, we need better grid storage and flexibility to ensure energy is available when we need it (C2ES 2018). 

On the storage side, hydro storage (in which energy is stored by being pumped from a lower reservoir to a higher one) is the most common approach, with 94% of installed capacity. Lithium-ion batteries have also become popular, dropping in price by 7x from 2010 to 2019. However, additional research and investment is needed to scale, decrease capital costs, and increase long-duration storage. The market for batteries is expected to grow by 13x from 2018 to 2024 (CSIS 2020).

On grid flexibility, technology (e.g. smart thermostats, smart grid technology) and behavior change (e.g. incentivizing energy use outside of peak times) can play significant roles. Developing more flexible and intelligent grid systems can help avoid new capital costs and make effective use of existing energy supply. 

Invest in Carbon Dioxide Capture and Storage (CCS) to phase out dirty fuels

The solutions above are necessary but insufficient to achieve our 2050 net zero targets. CCS uses machines to pull carbon from the air and sequester it in the ground or other materials, and can supplement efforts to draw down emissions from dirty sources.

However, current approaches are expensive and energy intensive. To make CCS viable, we need increased investment in zero-carbon electricity to power this technology, effective storage and transport, and mitigating potential health and safety risks. Furthermore, well-defined policy regulations and economic incentives will be important for scaling up future deployment. (UN IPCC 2018).