For us to escape the worst ravages of global climate change, time is of the essence. What is meaningful is not grand declarations of reaching net zero emissions by 2040 or 2050 or 2060.

What really counts is what happens in the next decade, to make substantial progress in reducing carbon-dioxide equivalent emissions as quickly as possible as we experience the ever-worsening consequences of climate instability. This means in addition to cutting carbon dioxide, slashing methane from natural gas fracking, deep water drilling and from agriculture, cutting nitrous oxides from fossil fuel combustion, and chlorofluorocarbons (CFCs) escaping from refrigerators, air conditioners and aerosol sprays.

The good news is that solar is a readily available tool to use right now at scale. Every solar panel that displaces greenhouse gas emissions counts in the global effort to cut greenhouse gas emissions by embracing sustainable technologies and practices in energy, agriculture, industry, forestry and aquaculture.

Unfortunately, this is a widely shared by far from universal sentiment. Solar energy skeptics include not just the usual climate change denier suspects. There are three common objections to solar and renewables that need to be faced head-on.

First, solar and wind are intermittent. What happens with solar at night, on cloudy days, in mid-winter when the sun is low in the sky or when the wind doesn’t blow?

Second, adequate and affordable energy storage is allegedly an impossible problem for renewables. In addition, using rare earth metals like lithium and cobalt will physically limit storage capacity and will become an inescapable environmental catastrophe.

Third, solar takes up huge amounts of land that will require turning an impossible percentage of land into solar farms.

The good news is that the concerns about intermittent renewables and storage have clear technical solutions. Meanwhile, often-voiced tales of a country covered by solar panels are simply and wildly false.

Renewable solutions: intermittency

The challenge of intermittent renewables is very similar to the challenges faced in the design of the existing power grid. The development of the grid began in the 1920s. It became clear that for each of the 3,000 separate town electric systems to build generation to meet peak loads that occur one hour a year was incredibly wasteful. Instead, regional or national power grids were developed with a series of large power plants, powered by fossil fuels and hydro, connected by high voltage transmission lines to provide power to all when needed, including sufficient amounts of backup power to meet peak loads plus dedicated power plants available to help maintain grid voltage and frequency on an ongoing basis.

The larger the grid, the more uniform and predictable the loads and needs of the system. The same is true for renewables. There is now, for example, reliable data on global sun and wind daily hourly output. The Journal Nature Communications Oct. 2021 article Geophysical constraints on the reliability of solar and wind power worldwide uses 39 years of hourly solar and wind data (1980–2018) to analyze the ability of solar and wind resources to meet electricity demand in 42 countries, varying the mix of renewable generation as well as energy storage capacity.

Further, the latest analysis in Nature, January 2022, finds solar energy alone can “lead to full power availability all year round” with continental scale interconnections with 13-hour time differences, for example, Asia and North America. As the sun sets at 6 PM in California, it’s 10 AM in Beijing. This means a connection between an Asia super-grid across the Bering Straight, 52 miles wide with an average depth of only 160 feet, to Alaska and the North American super-grid could be entirely solar powered. Zero fuel costs. Zero emissions. On a less-than-continental scale, a mixture of wind, solar, hydro, geothermal, and tidal combined with storage can do the job for 100% renewables.

Large-scale regional networking of renewables combined with energy storage that will include the batteries of millions of electric vehicles plugged into the grid, and peak load combustion turbines fueled by green hydrogen produced by renewable powered electrolyzers provide the basis for a reliable 100% renewable grid. In California for example, energy storage is already replacing large-scale natural gas peaking plants on the path to 100 percent renewables.

A large number of sophisticated models have come to the same conclusion that a 100% renewable grid can provide reliable energy 24/7/365 at lower costs than fossil fuels and nukes. High-fuel-cost fossil fuels and nukes simply cannot compete against zero-fuel-cost renewables. For example, is the 2022 CleanTechnica “A 100 Percent Renewable Electricity Calculator For The United States”. This spreadsheet tool allows you to run your own simulations based on four decades of real hourly solar and wind data and adjust the amount of solar, wind, and storage to optimize the costs of a 100% renewable energy grid. CleanTechnica’s tool then “calculates the percentage of demand that is covered by solar and wind power, amount of curtailment [excess generation], the required backup capacity, and the amount of power-to-gas (synthetic, carbon-neutral gas made from hydrogen and direct-air-capture carbon dioxide)” needed for a 100% renewable grid and the cost per kilowatt hour.

A global renewable energy system that is emerging is additive. It combines primary generation from solar, wind, geothermal, hydro, tidal, and biomass with further renewably driven non-polluting tools.

These include green hydrogen produced by renewable power electrolyzers that split water into hydrogen and oxygen, energy storage, micro-grids and smart distribution networks, and high-voltage DC transmission. The hydrogen becomes a tool to power combustion turbines to meet peak power demands and to replace natural gas in existing pipelines.

Renewable energy solutions: storage

Energy storage is quite diverse. It’s much more than responding to peak loads and demands for a few hours. Storage must respond to long-term and seasonal demands. Storage can help balance grid voltage and frequency. There is always a dynamic balance between generation, storage and improved efficiency and between distributed storage and system storage. The future renewable grid will be a combination of town and city-scale micro-grids with their own generation and storage resources providing some, but not all, of their energy and storage needs. The micro-grid feeder(s) will separate from the larger grid if voltage and frequency are outside of operational norms and serve some, but not all, of the micro-grid, needs using its generation and storage resources.

Grid system storage hubs can take advantage of high-voltage transmission lines from decommissioned fossil fuel plants. It can combine not just conventional batteries of various chemistries, but also flow batteries which can provide automatic generation control (AGC) services to maintain grid voltage and frequency, supercapacitors that can provide very quick response to fluctuations, flywheels, and high-temperature long-term storage, for example, large sandboxes, or below the surface rock and water storage to provide district heating and cooling.

A new generation of flow batteries such as the Form Energy Iron-Air flow batteries will slash fixed storage costs. A 760 million dollar West Virginia factory in Weirton will open in 2024 to produce a battery based on reversible rusting. Discharging, the battery uses oxygen from the air and converts iron metal to rust. Charging, an electrical current converts the rust back to iron and the battery releases oxygen.

The Form Energy projected future energy capacity cost per kilowatt is $25 compared to over $80 to $100 a kilowatt for current lithium batteries. The iron-air system is designed for 100-hour storage output. Latest Carnegie Mellon chemical and cost analysis concludes: “Recent studies on the long duration energy storage systems capable of addressing intermittency in renewable energy generation should have a system cost ≤ US$20/kWh ...The iron-air system shows considerable promise in this context with the material costs of about US$4/kWh and total system cost of US $25/kWh with room for improvements in terms of engineering the hardware and gas delivery systems to further drive costs down.” A fundamental new era in storage technology is dawning.

We have not yet fully understood the enormous capabilities of distributed storage resources, in particular, from large numbers of electric vehicles providing available stored power to the grid. New York City residents, for example, own 2 million automobiles. When fully charged, current EV batteries on average can supply 66 kWh of electric power. This represents a maximum potential of 132,000-megawatt hours (mWh).

Assume just 10% of autos are not on the road, fully charged and connected to the grid and capable of providing 50% or 33kwh each to the grid. This means 6,600 mWh available for grid changing. This is about equal to the total New York City 2020 daily electric demand from February to April. This represents a fundamental shift not just in storage, but in supply with renewables providing the charging power.

EVs operate with much higher efficiency than the internal combustion engine, with the equivalent cost equal to $1.00 a gallon of fossil fuels. Not yet fully monetized, the value of EV storage to the grid will represent substantial income flows to EV owners, further reducing net operating costs far below $1.00 per gallon equivalent.

We should not disregard the enormous opportunity for millions of EV car batteries to provide a robust ability for EVs to transmit power when needed by the grid or feed power to your home. EV batteries will charge during low-demand evenings and nights and feed power to the grid during peak mornings and afternoons. Underway is the aggregation of EVs into Virtual Power Plants (VPP) by Swell Energy Inc. to respond to utility needs. Similarly, home storage units used for both operational security and lower cost of peak power are being aggregated. Market forces are now driving storage aggregation and monetization of storage as an income stream and not a cost.

Renewable energy solutions: square miles of solar panels

The total amount of squared miles of solar panels in the aggregate, plus storage, to power all U.S. energy needs are about much less than 1% of the total area. This amounts to about 100 square miles of panels alone, about 10% of the area of Rhode Island our smallest state. This does not mean that this much land is designated for solar use only.

Rooftops, walls and windows can be solar sites. Solar awnings over lots awning, along or above highways, and dual-use agricultural solar above pasture and crops can be the sites for all the solar and all the energy we will need. It’s also important to recognize that more area is dedicated, beyond panels alone, to roads for service, access, setbacks, interconnection, and small areas for energy storage, in total still a fraction of one percent of the total area.

U.S. land area is 3.8 million square miles. There are about 3,100 square miles of solar suitable roofs. This is estimated to potentially provide 40% of total U.S. energy. There are about 925 square miles of parking lots. There are 895 billion acres of farmland; that’s 1.4. million square miles, that can supply much or all of our solar energy needs through dual-use AG solar above pasture and cropland or as solar fences with dual-sided panels.

Total U.S. electric energy sales in 2021 were 3.8 trillion kilowatt hours. 27% of generation capacity was renewables, including hydro. What does it mean to generate 1 trillion kilowatt hours with solar?

A few years ago, a typical fixed solar system solar capacity was 10 watts a square foot or 100,000 square feet for a megawatt of solar capacity on a large roof. But there have been continual improvements in solar output efficiency for commercial solar panels from 18% a few years ago to 22% today, a net 22% efficiency improvement. Further, commercial and utility panels are now both dual-sided to capture reflected sunlight off reflective material below panels, plus single or dual-axis trackers improving solar production by 35% or more. Thus, current panel production has increased by 50%. This increases new solar capacity production to 15 watts a square foot.

The average U.S. solar capacity output factor is 2,146,000 kilowatt hours of solar energy a year per megawatt of solar, a 24% capacity factor. At 15 watts a square foot, installing a megawatt means 66,666 square feet per megawatt or 1.53 acres of roof, parking lot, and solar awning. Add a necessary area for acess and support increases net areas to 2 acres a megawatt. Ground mounts are now 3.5 to 4 acres a megawatt.

A trillion kilowatt hours requires 466,000 megawatts of solar or 932,000 acres of roofs, parking lots, and solar awnings amounts to 1456 square miles. This decidedly does not call for one giant desert-based system. The 1456 square miles should be distributed among the states and among the towns and cities establishing the basis for decentralized renewables and micro-grids as the foundation for 100 % renewable energy systems. The rapid pursuit of a trillion kilowatt hours of solar production is the essential and readily available path for rapid greenhouse gas reduction in the next decade.

Solar, not a fusion future is within reach

With great fanfare, the success of laser fusion to reach net positive energy output for a few seconds was proclaimed as the harbinger of endless energy to come with commercialization beginning after an uncertain number of decades. That’s great but does little or nothing to address clear and present climate danger. As I write, in late December 2022, a bomb cyclone is plunging much of the U.S. into frigid blizzard conditions as Arctic warming has weakened the polar vortex allowing frigid Arctic air to pour southward.

Fusion machine dreams are nice. But solar is already the fusion energy product available from the sun every day and can easily provide all our energy needs and will be combined with wind, water, and geothermal energy to meet our zero greenhouse gas emission reduction goals.

The essential issues we face are much more political than technical. For the U.S., the Inflation Reduction Act (IRA) has established the basis for rapid solar development. Now’s the time for taking acton as if our lives and futures will depend on solar. That’s the unvarnished truth.


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