Solar power plant in Crimea, Ukraine. Photo by Zachary Shahan | CleanTechnica.

Renewable Choices: Global Clean Technology Transition

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By David Andresen, PI Energy

Fossil fuels provide about 80% of total primary energy consumed globally, and this figure has not substantially changed over the past 30 years. PI Energy was founded to develop a next-generation solar PV technology, to be cost competitive and globally scalable, in order to create a pragmatic path to mitigate climate change and shift to clean technology.  

There are many potential sources of renewable energy, including wind, solar, geothermal, wave, tidal, hydroelectric, biomass and more, each with technologies at different stages of commercial maturity and development. Which type of renewable energy has the potential to provide the bulk of clean energy in the coming decades?

Sometimes too many options make a decision difficult1. A transition to clean energy is by definition a complex problem, a task that has never been accomplished before. With so many choices, how do we choose the right technology to lead a clean energy transition? Not all renewable energy sources work well everywhere or all the time, with some technologies being practical in just a few locations (e.g., tidal energy in Scotland2 ), while other sources may work well in many parts of the world.

In recent years, new findings in climate science3 point to greenhouse gas increases as amplifying extreme weather events around the world. While renewable energy and clean technology have made some progress, during 1999–2019, global consumption of fossil fuels has actually grown by more than 32%, and over the past two decades, fossil fuels still provide about 80% of total primary energy. We are still very much in the age of fossil fuels.

Image courtesy Pacific Integrated Energy, Inc.

In October 2021, heavy rainfall in Shanxi caused widespread flooding of many coal mines in China, which resulted in coal shortages, which caused a stall in solar panel4 manufacturing, resulting in a global price surge5. This ironic link between fossil fuels and current renewable energy underlines the fact that coal, and its fossil cousins (gas and oil), are still relatively cheap, and that renewable energy has yet to become far more sustainable and cost-competitive in order to really expand globally. All energy sources, including current renewables, have carbon footprints which need to be minimized. Energy choices linger for decades, so that poor choices can be expensive and may actually eliminate our ability to adequately respond to climate change.  

In the high stakes challenge of selecting a renewable energy and clean technology priority, what might be the criteria to select the best clean energy choices to realistically mitigate climate change? This question is at the core of the climate crisis, a rational selection must be pragmatic, and would likely include the following requirements for a successful and global clean energy transition, where current and in-development technologies should be considered if they have the potential for:

  1. Near-zero GHG emissions
  2. Regionally available around the world
  3. High energy potential and power density to practically meet most demand
  4. Made from earth-abundant nontoxic elements for global scalability
  5. Low-cost, including manufacture and installation for globally scalability

These goal-driven criteria should identify the types of renewable energy that may be prioritized, but it does not mean that the resulting choice will be the best for all people everywhere. We are also going to assume that energy storage, whether large batteries, hydrogen, or other scalable solutions are getting solved, so that variability in power generation is less of an issue. Let’s apply the criteria list across different forms of renewable energy.

Initial list of candidate renewable energy categories:  

1. Near-zero GHG. The source of energy must have the potential to have a very low carbon net footprint. Biomass and biofuels involve combustion and frequently have significant fossil fuel inputs. Solar thermal power plants often require lots of water to drive turbines in arid locations (high carbon footprint). Large hydro dams can have significant impacts, including carbon footprints, but micro hydro has potential to be far cleaner. 

2. Regionally available around the world. While hydro, geothermal, wave, and tides can be good sources of energy, they are most often geographically restricted. To avoid huge costs of transporting energy across large distances, sources of energy need to potentially supply most regions around the world.  

  1. High energy potential and power density are necessary to practically meet most demand, as well as to realistically compete with fossil fuels. Solar PV has the highest theoretical potential, by far, among renewable energy sources (see chart below).
Image courtesy: Pacific Integrated Energy, Inc.

An important and often ignored factor is Area Power Density, a measure of how much area must be committed to generate the energy (kWh per acre or MWh per square km or mile). Fossil fuels are very energy dense, and solar has the highest area power densities of renewables, as shown in the graph below.

Image courtesy Pacific Integrated Energy, Inc.

Taking into account the criteria applied, solar PV gets the high score so far:

If we look at solar PV as the potential priority for a clean energy transition, we must take a closer look, as PV comes in many types. Here are the different generations of PV technologies:

  • First generation PV (1941–current): This was the first commercial PV technology. Traditional crystalline silicon PV still dominates, with about 96% of solar module sales globally. Today it is the reliable standard, though it does have significant energy costs and carbon footprint for manufacturing, and it is limited to certain markets because of its weight and rigidity.
  • Second generation PV (CdTe and CIGS), first commercialized in the 1990s: These are thin film materials, which contain scarce elements (indium, gallium, tellurium) and in most cases also toxic elements (e.g., cadmium). Gallium arsenide is an exotic PV solar cell, which provides higher efficiency, but also contains scarce and toxic elements, and is prohibitively expensive for most applications.
  • Third generation PV includes:
    •  Perovskites: currently not stable and contain water-soluble lead.
    •  Quantum dot: are in development infancy, contain lead or cadmium, or have not been commercially available.
  • New generation PV: Novel PV with the potential for good and stable performance, using nontoxic earth-abundant elements. PI Energy is developing a proprietary thin and flexible nontoxic solar PV that uses significantly less energy to produce than first-generation solar PV.

4. Made from earth-abundant nontoxic elements for global scalability.

Global scalability of clean energy excludes significant use and deployment of scarce and toxic elements, which means that only c-silicon and Fourth Generation PV meet this requirement.

5. Low-cost. This is the last step in the criteria, and it includes the manufacture and installation of renewable energy. Crystalline silicon is the global leader for renewable energy installations over the past years, yet solar PV only provides less than 0.4% of global energy consumed6. As the current dominant technology, c-Si is limited in where it can be installed, due to its rigidity and weight, which increases its installation costs. The ideal solar materials, according to MIT, is a lightweight and flexible PV module, made of earth-abundant elements, so that they can be installed on new applications, including most building exteriors and even electric and hybrid vehicles.

While current c-Si appears to be the best solar energy solution today, we need to do a lot better to address climate change and make clean technology and energy a market choice, based on cost-competitiveness and globally deployability, so it can be ramped up quickly. PI Energy is a New Generation PV technology currently in development. The Company plans to provide a far better PV solution that expands where solar can be used based on economics and functionality. For more information visit

This article is supported by PI Energy.

1 “The Paradox of Choice – Why More is Less”, by Barry Schwartz, PhD. 2004 .(ISBN 0-06-000568-8)

2 “Harnessing The Power Of The Tides In Scotland”, by Steve Hanley — CleanTechnica, Nov. 15, 2021





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