Powering the world: Renewables are still far behind coal and natural gas

The United States and the world need to continually improve electrical energy mixes with respect to economic and environmental factors. Key sources of U.S. and world energy include natural gas, coal, nuclear power, hydropower and renewables (such as wind and solar).

Despite much debate on which are the right and wrong power sources, the reality is nearly two-thirds of the global electricity currently come from fossil fuels. The climate-harming emissions of these sources vary and their abundance in parts of the world — both must be considered in the energy debate.

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This also means renewable energy sources still make up a small portion of power generation. Their capability to produce consistent power must also be considered. 

In the U.S., we rely most heavily on natural gas and coal as power sources, American electric power sources include:

  • Natural gas: 32 percent
  • Coal: 30 percent
  • Nuclear power: 20 percent
  • Hydropower: 7.5 percent
  • Wind: 6.3 percent
  • Solar: 1.3 percent
  • Other fuels: 2.9 percent

Similarly, world electrical power is produced by:

  • Coal: 41 percent
  • Natural gas: 22 percent
  • Hydropower: 16 percent
  • Nuclear: 11 percent
  • Wind: 6 percent
  • Solar: 1 percent
  • Other fuels 3 percent

Let’s now work through the pros and cons of each electrical energy source, with focuses on the U.S. and the world.

Coal

Coal is not our cleanest fuel, but it is the least expensive and most abundant. It will be critical to develop use of advanced coal technologies like the ultra-supercritical pulverized coal process, which is already in commercial use. That would reduce power-plant emissions from coal and promise even greater reductions in the years ahead.

For countries like China and India whose economies are based on coal, advanced coal technologies could become the energy of choice for many. And don’t count out coal in the United States or Europe, given forecasts that coal will continue to play a major role through about 2040.

Keep in mind also that Germany, which increased its use of coal following the Fukushima nuclear accident in Japan, is building some of the most advanced coal plants in the world. 

A pragmatic energy strategy, one that reflects global energy trends and weighs economic and environmental health should be the path forward. While we may be ramping down our use of coal, others are notChina, the world's largest carbon emitter, is now using more coal than the rest of the world combined.

However, an important issue is the fact that coal from China, India, U.S. and Europe are increasing to add to world carbon emissions. So, coal energy must continually be improved, while adding cleaner fuels such as natural gas and nuclear power.

Natural Gas

Utilities have increased the use of gas in place of coal. Importantly, natural gas produces just half the carbon dioxide when burned to generate electricity. Consequently, coal plants are being converted to use cleaner natural gas. 

While there is room for debate about various climate plans, it is clear that the cornerstone of American energy policy and climate action is the fracking revolution. 

Fortunately, through surging gas production from vast shale formations, the U.S. has become the largest natural gas producer in the world. Gas, now cheap and abundant, is driving a U.S manufacturing renaissance, reducing energy bills and allowing a transition away from coal.

The problem may be an eventual lack of robust competition. It begs the question: What will be the cost of natural gas when it is our only major source of electric power?

Nuclear Power

As for nuclear power, it is our only large emissions-free energy source. But building new large nuclear plants can take too long, so existing plants need to stay on-line as long as feasible.

In addition, on the horizon is a new generation of small modular reactors that can be built in less time and at a fraction of today’s cost.  

Hydropower

While not discussed much these days, use of water power to produce electrical power is substantial and is free of carbon emissions. Hydropower produces about 7.5 percent of U.S. electricity and 16 percent of the global electricity.

Interestingly, hydropower is still our largest renewable energy source.

Renewables

But what about more popular renewables such as wind and solar? These can be helpful, but currently provide only about 8 percent of our electricity and work only when the wind is blowing or the sun is shining.

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Thus, wind and solar only provide energy about 30 percent of the time. For comparison, nuclear plants are “on line” some 90 percent of the time, with coal and gas in the 60 to 70 percent range. 

As a result, backup power from natural gas, nuclear or coal are needed to ensure a steady stream of electricity when wind or solar is used. And don’t forget that costly taxpayer subsidies are needed for most renewables.

The bottom line is that the most important aspect of the six major producers of electricity is: All of them are important and robust competition between producers is critical.

J. Winston Porter, Ph.D., is a national energy and environmental consultant, based in Atlanta. He previously worked as an assistant administrator of the U.S. EPA.