Kauai Shows Solar + Storage is Starting to Become Cost Competitive With Fossil Fuels, Nuclear

It wasn’t too long ago that the cost of an average solar energy power plant was above 10 cents per kilowatt hour and the world was raving at the low prices for Middle East solar generation in the range of 6 cents per kilowatt hour. At that time, to the shock, awe, and dismay of many, solar began to become earnestly competitive with traditional power plants based on price of energy alone.

Base Wind + Solar Now Cheaper Than Fossil Fuels, Nuclear

But it’s amazing what a difference just two years can make. Now solar prices have fallen into a range of around 4-6 cents per kilowatt hour with the least expensive solar plants now hitting as low as 2-3 cents per kilowatt hour. These prices are now far less than diesel and nuclear based generation (in many cases 1/2 to 1/4 the price of these systems) and today even out-compete coal and gas fired generation.


(Research by Lazard now shows that wind and solar are less expensive than all forms of fossil fuel and nuclear based energy. Image source: Lazard and Clean Technica.)

For as you can see in the image above, the cost of new natural gas generation now ranges from 5 to 8 cents per kilowatt hour for the least expensive plants and the price for new coal generation ranges from 6 to 14 cents per kilowatt hour. Utility wind and solar, by comparison, now ranges from 3 to 6 cents per kilowatt hour in most cases.

These, far more competitive, prices for renewable energy based systems provide a very strong case for the base market competitiveness of renewables. One that supports a clear rational economic argument for rapid integration of renewable energy systems. A strong economic case that can now be made even when one doesn’t include the various harmful externalities coming from nuclear energy and fossil fuel based power or the related and continuously worsening climate crisis. Renewable energy detractors, therefore, can now no longer make an argument against clean energy sources based on price alone. As a result, the argument against more benevolent energy systems during recent months has tended to shift more and more to the issue of intermittency.

Facing Down Fears of Intermittency

As an example, in its most recent report on the cost of global energy, the typically pragmatic Lazard Consulting group recently noted:

Even though alternative energy is increasingly cost-competitive and storage technology holds great promise, alternative energy systems alone will not be capable of meeting the baseload generation needs of a developed economy for the foreseeable future. Therefore, the optimal solution for many regions of the world is to use complementary traditional and alternative energy resources in a diversified generation fleet.

It’s a statement that moves the consultancy group closer to reality. One that opens wide the door for a much needed rapid integration of clean energy supplies. But, as with the analysts who failed to predict the precipitous fall in solar prices and the related rapidly increased availability of renewable energy sources as a result, the Lazard report fails to understand the fundamental price and mass production supply dynamics now setting up. A dynamic that will likely transform the cost and availability of energy storage systems in a similar manner to those that acted to greatly reduce the price of solar energy systems during the period of 2011 through 2016. As a result, Lazard’s ‘not for the foreseeable future’ statement is likely to have a life expectancy of about 3-5 years.

Soft Limits

Wind and solar power generation systems do have the base limitation that they only produce energy when the wind is blowing or the sun is shining. Often, these energy sources have to be widely distributed and interconnected to cover a significant portion of demands coming from power grids (30 to 50 percent or more). And in the present understanding of energy supply economies, standby power or power storage systems have to be made available for the periods when majority renewable energy systems go off-line. All too often, this standby power generation comes from conventional sources like coal, gas, or nuclear.

That said, the underlying flexibility of renewable energy is starting to overcome the soft limit that is intermittency. And a recent report by the U.S. National Renewable Energy Laboratory found that as much as 80-90 percent of grid electricity demand could be met by widely distributed renewable energy sources such as wind and solar as soon as 2050 so long as an advanced grid and related energy storage systems are developed.

In order to meet the challenge of transitioning most or all electricity based energy supply to renewables — not only does the cost of renewable energy need to be competitive with fossil fuels, but the cost of intermittent renewable energy + the systems that store them must be similarly competitive. Fortunately for those of us concerned about the growing risks posed by the global climate crisis, it appears that we are now entering a period in which exactly this kind of cost competitiveness for integrated renewable + storage systems is starting to emerge.

Solar + Battery Storage Becoming Cost Competitive

Last year, the Hawaiian Island of Kauai purchased a ground-breaking solar + battery storage system from Tesla and Solar City. The system paired solar panels with Tesla power packs to provide 17 megawatts of solar energy and 10 megawatts of battery storage in order to replace about 10 percent of the island’s expensive diesel electricity generation.


(Tropical Kauai aims to be powered by the sun. In doing so, it’s starting to shift away from dirty and expensive energy derived from coal and diesel generating plants. Image source:

On Kuaui, diesel generation costs about 22 cents per kilowatt hour. Expensive fuel and equally expensive heavy machinery must be shipped from far-flung locations to the remote island. And this adds to the overall cost of fossil fuel generation. During 2016, Solar City and Tesla significantly out-competed the price of diesel generation by offering its solar + storage generating system for 13.9 cents per kilowatt hour — a cost that was comparable to the more expensive versions of nuclear, coal, and gas fired generation plants the world over.

Fast forward to early 2017 and another solar + storage provider was being contracted to add still more renewable based electrical power to Kauai’s grid. AES Distributed Energy is now contracted to build 28 megawatts of solar photovoltaic panels mated to 20 megawatts of battery based storage. The price? About half that of diesel-fired power generation at 11 cents per kilowatt hour.

This is about 20 percent less than the Solar City + Tesla offering just one year later. A system that hits a price comparable to mid-range coal and nuclear generation systems. And, more to the point, AES’s solar panels + battery packs will enable Kuaui to produce 50 percent of its electricity through renewable, non-carbon-emitting sources.

Renewables + Storage to Beat Fossil Fuels in Near Future

Compared to the cost of renewable energy, the price of batteries is still comparitively expensive — effectively doubling the price of base solar. However, widespread adoption of battery-based electrical vehicles is helping to both rapidly drive down the cost of batteries and to provide a large global after-market supply of batteries useful for storing energy. By 2017, it’s likely that about 50 gigawatts worth of energy storage will be sold on the world market in the form of electrical vehicle batteries. By the early 2020s, this number could easily grow to 150 gigawatts of storage produced by the world’s clean energy suppliers every year.


(Global lithium ion battery production is expected to hit more than 120 GW and possibly as high as 140 GW by 2020. This production spike is coming on the back of newly planned battery plants in China, the U.S., and Europe. Presently, the largest plant currently operating is LG Chem’s China facility which was completed in 2016. Tesla’s Gigafactory is already producing batteries and is expected to ramp up to 35-50 GW worth of annual production by 2018-2019. Volkswagen has recently announced its own large battery plant to rival Tesla’s Gigafactory [not included in chart above]. FoxConn, BYD, and Boston Power round out the large projects now planned or underway. Image source: The Lithium-Ion Megafactories Are Coming.)

As electrical vehicles are driven, the batteries they use lose some of their charge. However, by the time the life of the electrical vehicle is over, the batteries still retain enough juice to be used after-market as energy storage systems. Meanwhile, the same factories that produce batteries for electrical vehicles can co-produce batteries for grid and residential based energy storage systems. This mass production capacity and second use co-production and multipurpose versatility will help to drive down the cost of batteries while making energy storage systems more widely available.

Though mass produced batteries represent one avenue for rapidly reducing the cost of energy storage systems mated to renewables, other forms of energy storage including pumped hydro, molten salt thermal storage, flywheels, and compressed air storage also provide price-competitive options for extending the effectiveness of low-cost variable power sources like wind and solar. And with the price of solar + storage options falling into the 11 cent per kilowatt hour range, it appears likely that these varied mated systems have the potential to largely out-compete fossil fuels and nuclear based on price alone well within the foreseeable future and possibly as soon as the next 3-5 years.


The World’s Cheapest Solar Energy in January 2015 Was 6 Cents Per Kilowatt Hour

Levelized Cost of Energy Analysis

Cost of Solar and Wind Beats Coal, Nuclear and Natural Gas

The National Renewable Energy Laboratory

Kauai Solar Peaker Shows How Fast Solar + Storage Costs are Falling

The Lithium-Ion Megafactories Are Coming

AES Distributed Energy

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