Will Renewables Replace Fossil Fuels?

September 28, 2015

NOTE: Images in this archived article have been removed.

Image RemovedRenewable energy development has taken off in the United States over the past decade.  Solar, wind, and other renewable technologies are projected to continue to grow rapidly. But renewables still have a long way to go to replace oil, coal, and natural gas as primary sources of energy.  What will it take to reach that threshold and what obstacles and limits do we need to understand as we transition to a truly sustainable energy economy?

We’ll examine these and other key questions regarding the outlook for renewable energy and what it means for America’s future.


Key Questions:

Cost: What are the important factors driving the total cost of different renewable technologies—e.g. equipment vs. soft costs? How far will costs continue to decline? Will costs be affordable enough to deploy at very large scale?

Density/Scale: Renewables are generally diffuse and distributed energy sources, how does that aid or hinder their prospects to become a primary source of energy?

Energy Quality/Substitutability: Renewable energy is most commonly used to make electricity, how does that affect its substitutability for uses that are currently non-electric—i.e. thermal heating and transportation?

Storage: How important is storage to the future of renewable energy? Are the oft-cited issues about storage overstated?


Bullets below summarize remarks by featured guests; they are not definitive statements by The Energy Xchange. In the spirit of discourse, this information may be revised through continued discussion.

  • Transitioning America’s energy system to run on mostly or entirely renewable wind, water, and solar energy is technically and economically feasible (based on projected costs), according to research led by Mark Jacobson of Stanford University and Mark Delucchi of the University of California, Davis. Their study simulated six years under varying weather conditions with no gaps in energy supply. The primary barriers are social and political–as well as perceptual, most of the public does not understand where their energy comes from or what a transition would look like.
  • Electrification of all sectors—including heating, cooling, industrial processes, and transportation—would be implicit to an all-renewable economy. The efficiency advantages of electric power alone would reduce total U.S. energy use by approximately 30 percent. Modest end-use efficiency improvements would potentially reduce energy use by an additional five to 25 percent.
  • For example, a plan for New York state would include 50 percent wind energy (mostly offshore) and 43 percent solar (mostly from large photovoltaic plants) with remainder from water (hydro and tidal power). The plan would require less than 1 percent of New York’s total land area, mostly for solar PV plants.
  • The projected cost per unit energy would be comparable to present-day fossil fuels—on the order of 13 cents per kilowatt-hour, but total expenses for consumers would be lower because of lower energy use. In many cases, renewables are already the least expensive form of electricity–.e.g. 3.7 cents per kwh for wind in Iowa and South Dakota.
  • An estimated $15 trillion in capital investments—approximately $12 trillion in generation plus $3 trillion in storage—would be required to effect the transition for the United States—for the world, an estimate $100 trillion (for comparison, current global investment in the energy sector is between $1.5 and $2 trillion per year). But investments would offset costs or pay for themselves over time–high capital costs but zero fuel cost.
  • Conversion to renewable energy would also eliminate external costs associated with air pollution and climate change— estimated at approximately $5000 per person—costs which thus far have been de facto subsidies to fossil energy.
  • Solar and wind had been developing slowly but have taken off since about 2008, in part because of high-volume production in China. However, to approach 100 percent renewable energy by 2050, the rate of deployment would need to accelerate by an order of magnitude (factor of ten).
  • The key challenge is that most renewables are diffuse, low-density energy resources which require systems for concentration and storage. However, most storage would not depend on electric storage such as batteries. Most peak loads are associated with heating and cooling which could employ sensible heat storage that basically uses excess energy to heat water or make ice. Seasonal heat storage in soil and use of existing hydropower facilities for pumped water storage would also be important. Most of these storage options are low-cost.
  • The longer we wait to make a transition, the more difficult and costly it is likely to be. It will take both money and ENERGY—nature does offer a financing package for energy, we will need the energy upfront. If we wait too long, energy may be the very resource we find in shortest supply.

Other Key Points

  • Batteries and electric storage using hydrogen would be most important for transportation. Batteries are more efficient, but hydrogen storage may have cost and scale advantages that will expand its role.
  • Vermont has set a statewide goal of 90 percent renewable energy by 2050 for all sectors including transportation, which would require an estimated $30-50 billion in capital investments. Vermont, as a small state with relatively strong political support, is a test case of what is possible
  • Key things that are needed to accelerate deployment of renewables:

Reduce unnecessary delays that drive up costs—“time is money.” Approximately 50 percent of costs for solar, for example, are “soft” costs—installation, permitting, etc. It should not take 6 months to permit something that takes a day to install. For example, Vermont is the only state to implement online registration instead of a permit application process for residential rooftop solar.

Need to get ready for “two ways streets” on the grid to embrace distributed energy.

Demand control—storage is less critical if peak loads can be shaved and shaped.

Fossil fuels should be used for backup not base load when renewables are on line

A major change in thinking—among grid operators and many others. A lot of decisions are still being made based on assumptions about a fossil fuel future.

  • Transportation will be especially challenging because of high POWER demands (not just energy, but energy per unit time) and because of extreme dependence on liquid fossil fuels. Solutions will vary depending on application–freight, passenger, urban, long-haul etc.
  • Electric vehicles have multiple advantages—in terms of energy efficiency, safety, maintenance, air pollution etc. and there is theoretically more than enough available material resources—steel, lithium, rare earth metals etc. But going down the “consumption road” will make the whole endeavor harder—not to mention the embedded costs and energy of maintaining our road system, which may also be economically unsustainable. We need innovation to drive down both the energy and economic costs of moving people and freight.
  • If we want the future to be as comfortable as today, we collectively as a society need to choose a direction, otherwise, we’ll continue to flounder and suffer the negative effects. “Don’t pick winners and losers” has become a red herringwe need to pick some winners.
  • The Solutions Project is bringing together a wide variety of people that might not otherwise collaborate to work through the opportunities and challenges for achieving a 100 percent renewable energy future.

Mark Jacobson

Mark Jacobson is a Professor at Stanford. He has written several books and co-authored over one hundred research articles. His career has focused on better understanding the problems of air pollution and global warming and on developing large-scale renewable energy solutions to them. He has developed three-dimensional atmosphere-biosphere-ocean computer models to simulate air pollution, weather, climate, and renewable energy. He has also developed roadmaps to transition states and entire countries to 100% Wind Water and Solar (WWS), along with computer models to examine electric grid stability.

Tags: Renewable Energy, renewable energy transition