Yes, We Can! A Path to 100% Renewables

Imagine a world powered by clean, renewable energy.

The air is clear, even in urban centers.

Streams, rivers, lakes, and oceans are no longer fouled by oil spills, coal mine waste, or other fossil pollutants.

Ecosystems are healthy and valued for the multiple services they provide.

Local economies are vibrant because energy dollars circulate locally.

Sound like a utopian pipe dream? Think again.

I retired from a 31-year career as a solar scientist in 2007. After more than three decades in solar, the most expedient strategies I know for slowing climate change are to increase energy efficiency and to accelerate the transition to clean, renewable energy sources.

I focus on solar photovoltaics (PV) here because PV systems produce cost-effective electricity at every level — from households to utility-scale power plants. In my view, PV is especially important to this effort because its “fuel” is free and nonpolluting, the technology is mature, it is quick to install, and it is modular and scalable. Most solar thermal and wind turbine technologies meet these criteria too. All renewables can be used for more than making electricity, but electrical energy is an important backbone of our economy so is the focus here.


Climate change is largely a result of fossil fuel combustion gas emissions, as well as methane leaks from a variety of sources. These “greenhouse gases” trap heat and increase the earth’s average temperature.

Evidence abounds that climate change has reached significant proportions, is proceeding unabated, and is in fact accelerating, with potentially dire consequences for humanity and the ecosystems on which we depend. A rapid phase out of greenhouse gas emissions can still avoid serious, long-term societal disruptions. Switching quickly from fossil fuels to renewables will accomplish the phase out.


During my years in solar, I identified four challenges we would have to overcome in the United States to make the transition to 100% renewable energy (RE).

  1. Cost

The first challenge was that the available replacements for fossil fuels were too expensive. I feared it would take far longer to improve the economics of solar through research and development — if it was even possible — than for climate change to devastate the world’s economy and ecology.

When I started in solar energy, the holy grail for PV was to reduce the market price of silicon PV cells from the 1976 value of $76 per watt to the magic goal of $0.50 per watt. A chart from Bloomberg News shows the price passed the $0.50 threshold in about 2013 and is now close to a remarkable $0.30 per watt!

Of course, more than just the price of solar cells has to come down. The U.S. Department of Energy’s SunShot Initiative now estimates that dropping the price of a PV system to $1 per peak watt, “would make solar without additional subsidies competitive with the wholesale rate of electricity, nearly everywhere in the U.S.” It’s not just solar PV that has experienced a dramatic fall in prices. Utility-scale solar thermal electric and wind turbines have similarly dropped in price, making it economical to generate power from these renewable technologies.

But how do current solar costs compare with utility-provided electricity from fossil-fuel plants?

Grid parity” is the point at which a source of energy — RE in this case — generates electricity at a cost less than or equal to the price of buying power from the electric grid. According to Greentech Media, PV has reached this status in 22 U.S. states, and will reach it in another 20 by 2020.

The bottom line is that electricity from PV, wind, and solar thermal sources is no longer too expensive.

2. Source Variability and 3. Storage

I’m combining these two challenges because they’re closely linked.

The second challenge is that the most promising renewable energy technologies, PV, solar thermal electric, and wind farms are variable energy sources. Sure, they are clean and the “fuel” is free, but what do we do at night or when it’s cloudy?

Storage is the apparently obvious solution, but my third challenge was that energy storage technology was developing very slowly and storage options were too expensive to be practical. The good news is that affordable battery storage is now on the market and sales are increasing.

Elon Musk’s Tesla Motors sells a battery it calls the “7-kilowatt-hour Daily Powerwall” at a wholesale market price of $3,000 to installers.

These devices are called POWERWALLs because they are designed to mount smartly on an interior or exterior wall of a typical single-family residence. Tesla is building a large, solar-powered factory in Nevada to manufacture these batteries as well as larger capacity POWERPACK batteries, appropriate for gigawatt, grid-connected applications.

It’s not just Tesla that’s aggressively pushing for improved energy storage. The U.S. Department of Energy has been funding research and development to improve batteries for PV applications and to explore a variety of other ways to store energy.

If that were not enough, great strides have been made in designing and testing high voltage direct current (HVDC) long-distance power lines, making possible very efficient transport of electrical power over large distances (greatly reducing the line losses from electrical heating and other effects). In 2013, the world maximum DC voltage for long distance transport was ±800kV. An order was placed in July 2016 for the world’s first ±1,100 kV ultra-high-voltage direct current (UHVDC) transmission link in China. Thus, it is becoming increasingly possible to move solar power from areas where the sun is shining to areas where it is not, due to cloud cover and nighttime.

To complement such breakthroughs, the U.S. Department of Energy is conducting research and demonstration projects in “Renewable Energy Integration.” The purpose is to “incorporate renewable energy, distributed generation, energy storage, thermally activated technologies, and demand response into the electric distribution and transmission systems to better manage the variability of source supply and end-user demand over large regions.” In 2014, the Electric Power Research Institute (EPRI) published its vision for such a grid and in 2015 Lawrence Livermore National Laboratory described its new software for what it called a “dynamic simulation of a large-scale integrated electric-transmission and distribution-grid.”

Combining these new technologies in a great new smart grid will make possible the elimination of my second and third challenges.

4. Societal Resistance

The fourth challenge may seem the most intractable. Political, corporate, and institutional resistance has been an issue since I became involved with solar energy forty years ago. Political polarization, corporate shortsightedness, and institutional inertia have made very difficult the swift progress necessary to mitigate climate change.

Fortunately, the Citizens Climate Lobby (CCL) has developed what I think is the best strategy for overcoming various resistances to the switch from fossil fuels to energy efficiency and renewable energy, throughout our society. Their remarkably straightforward approach can be described in these two simple points.

· Empower thousands to millions of citizens to connect with and influence their members of Congress in a completely non-partisan manner

· Purpose: Pass appropriate legislation to require and implement a Carbon Fee and Dividend program, designed to bridge any partisan divides

The carbon fee collects a steadily rising tax on fossil fuels as they are brought into the U.S. economy. The fees will be made to increase on a carefully programmed schedule, to enable corporations to plan for fee impacts. One hundred percent of the funds collected from these fees (less modest administrative costs) will be given back to each household monthly, through existing agencies of the government, only a very small portion of their operations for this program to be paid for out of fee collections.

Firms seeking to escape higher energy costs will be discouraged from relocating to non-compliant nations (“leakage”), as their products will be subject to import fees if the exporting countries do not impose similar carbon fees of their own.

CCL is mobilizing citizen chapters in House political districts around the country and hopes to have legislation enabling this “carbon fee and dividend” program passed by Congress in 2017. This program (or any other that accomplishes the same goal) will eliminate my last inhibitor to 100% clean, renewable energy. This is why I have concluded that we can, indeed, switch completely from fossil fuels to renewables.


The United States has overcome difficult challenges before. Remember that we are the country that put a man on the moon.

The current challenge, however, is more difficult, and — although we have the technology, tools, and skills to prevail — it remains to be seen whether we have the collective will.

To stop runaway climate change, we need to focus on one goal — replacing fossil fuels with renewables now. There are no ultimate technological or economic barriers to reaching this goal, but it will require an extraordinary level of participation, commitment, and cooperation amongst all sectors of U.S. society. The CCL approach is a stunningly straightforward way to do the important political part of it.

My former fears that cost, resource variability, and immature storage technologies would impede the switch from fossil fuels to renewables have been replaced with the conviction that such a switch is already well underway, including all components of it, primarily motivated by existing market forces, and is technically possible and necessary. The only problem is that it’s not fast enough. In spite of current progress, we are losing ground in the climate war each year. We need to accelerate the process. That’s what the CCL program is designed to do.

I am also convinced we could make major progress in about the same timeframe that it took the U.S. to go to the moon. To meet this challenge, we’ll need to develop the requisite collaborative skills and political will, without delay.

The path is clear. Let’s do it!

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Dr. Ross McCluney holds B.A., M.S., and Ph.D. degrees in physics, worked at NASA’s Goddard Space Flight Center for three years as an optical oceanographer and then as a principal research scientist at the University of Central Florida’s Florida Solar Energy Center for over 30 years. He has been an active environmentalist since before the first Earth Day Teach-in of 1970 and helped organize the University of Miami’s observance of that first Earth Day. He has taught classes in algebra, radiometry and photometry, and environmental ethics; written books and chapters in books by others; and made presentations to a variety of audiences on energy and environmental topics.