Is it renewable energy, sustainable energy, or clean energy – why it’s important to know

Is it renewable energy, sustainable energy, or clean energy – why it’s important to know

by Sean Burke, CEO and Co-founder, Enteligent, Inc.

When we formed Enteligent to develop higher efficiency solar products, I wasn’t very aware of the macro-level energy picture. We hear terms like “renewable”, “sustainable”, and “clean” energy used almost interchangeably all the time but do we really understand what they mean? Probably not. They are typically used as lingo grouping together several promising energy candidates without distinguishing that need to be prioritized as the world pivots from fossil fuels. 

It’s important to make the correct distinctions early on, in order to make the best decisions possible. As an example, compact fluorescent lamps (CFL) were selected as the world’s first change from inefficient incandescent lighting ten years ago, which was a dramatic false start. While more energy-efficient than incandescent bulbs, the mercury content of CFLs was an environmental disposal nightmare, and their well-intentioned adoption only derailed the eventual rightful successor, light-emitting diode (LED) technology. CFL rollouts, once the darling of government-sponsored utility incentives, were abruptly abandoned once consumers learned of the issues with the disposal of spent CFL bulbs, or the health concerns associated with their in-situ fracture. If we had just moved directly to LED and had otherwise invested all those resources wasted on CFLs, we could have improved the cost curve of LED manufacturing, achieved even greater energy savings through accelerated adoption, and avoided the environmental issues and health concerns.

We can think of "renewables" as sources of energy that are replenished but not necessarily at the rate that we are using them. "Sustainable" energy comes from sources that can be replenished as fast as we use them. However, neither renewable nor sustainable descriptions say anything about how "clean" the energy is from a pollution or carbon emissions standpoint. You'll often see marketing messages with terms like "renewable" and "sustainable" used in such a way as to deliberately make you think their products are clean when they are not.

We can all agree that burning petroleum-based fuels like gasoline and diesel are not clean, nor are they sustainable or renewable – once we use them, these fuels are gone forever. It’s even more complicated for some sources like nuclear power, which provides up to 20% of the electricity in the United States. Nuclear power is not considered renewable, but it is a zero-carbon source, emitting low or no CO2. It’s also noteworthy that thirty to forty years ago there was considerable dialogue and mass demonstrations protesting nuclear power because of the potential operational risks and environmental impacts of radioactive waste containment. Now, public debate has largely shifted to greater concern over carbon-based energy sources and fewer people protest nuclear power even though it continues to supply a significant portion of electrical generation.

Fifty years ago, there was a big effort to reduce the burning of coal because of its contribution to acid rain caused by high sulphur content and high particulate count causing smog and other atmospheric pollutants. Natural gas was hailed as a miracle alternative as it became cost-effective with new drilling technologies, readily available with cross-continent pipeline installations, cleaner with fewer impurities than coal, and easily converted to energy with high-efficiency combustion technologies. 

From that time, there was a slow but steady decline in coal use and substitution with natural gas where now there are innumerable natural gas electric generation plants all over the world. The increase in availability also allowed natural gas to fuel our furnaces, power our air conditioners, heat our stoves, and supply backyard firepits all around the country. However, natural gas is still a carbon-emissions energy source and around the country, there are efforts to eliminate its use. In fact, my own city passed an ordinance banning natural gas hookups for new home construction. 

Therefore, if we are going to talk about the elimination of carbon fuels we need to take into account total energy consumption and not just that portion that is currently consumed to generate electricity.

Add to the fact that the world is at the precipice of a transition from internal combustion engines to electric vehicles (EVs). General Motors Corporation has announced that it will cease selling gas-powered vehicles by 2035. The state of California has mandated that all new car sales be zero emissions by 2035. Effectively, this is a conversion from non-electrical to electrical means of energy consumption. The point of all this is that when we size the true future electrical demand, its baseline is beyond simply the current electrical generation demand. It is really the total energy market, and that baseline is approximately 60,000 terawatts of electricity equivalent. That’s in stark contrast to the current total global electrical generation capacity of approximately 25,000 terawatts. 

The list of common renewable energies include:

  • Wind;
  • Solar;
  • Hydroelectric;
  • Biomass;
  • Geothermal; and
  • Tidal

While appearing to be more than plentiful, the sources on the list provide only 26% of the world’s total current electrical generation capacity and only 11% of our total energy consumption (which includes heating, vehicles, industrial consumption and other uses). Of this, less than 0.5% is supplied by biomass, geothermal and tidal, which are unlikely to become any more significant in the near- or mid-term based on cost efficiencies or other issues of viability. The vast majority of clean electrical generation is by wind, solar and hydroelectric. 

While hydroelectric provides the bulk of the current clean electricity generation, it is commonly agreed that hydroelectric dam construction is environmentally damaging, causes massive displacement of people, and disruption to surroundings. Construction of large-scale hydro-electric projects are incredibly capital intensive and can take decades to complete. While hydro produces clean energy, it is not viable for the scale that we will need.

Solar and wind energy are the only two viable sources that are clean, renewable, sustainable, and scalable. While both of these sources have the promise to expand significantly, solar is half the cost and, in most regions of the world, the most reliable – the sun’s rays shine for a very predictable schedule whereas wind is highly variable. Over time, solar generation is approximately half the cost of wind power installations. Solar’s cost advantage, with its Moore’s Law governed silicon-based architecture and electronics-based component design, will widen over time compared to the largely mechanical-based technologies of wind energy. Photovoltaic cell advancements solar power infrastructure improvements will also continue to improve solar energy’s efficiencies, all of which align to make it the most expandable and efficient electrical source for our future.

I would also like to point out that our world includes almost one billion people who have no access to electricity. Electricity is one of the major necessities that improve health, education, and their standard of living. Solar, combined with energy storage and microgrids, is one of the best ways to bring this vast number of people a better life. As this happens, there will be an even more electricity demand – kind of like growing overall demand for solar products while improving the world. 

Currently, solar provides only 2% of global electricity generation. All global clean energy sources provide only about 5,000 terawatts of electricity whereas the total energy demand (including heating sources and automotive petroleum products) is about 60,000 terawatts of electricity equivalent, as I stated earlier. While there is a long way to go before we completely power the world on clean energy, solar is the most cost-effective and scalable clean energy candidate available to get us there. As an industry, solar can grow at an amazing 15% CAGR (Compounded Annual Growth Rate) for the next 30 years and yet leave 46% of the global supply to other energy sources. The future for solar is bright indeed.

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