Energy Savings, not Warming, will Sell Renewables

Vern Scott
6 min readMar 18, 2021

Often, I meet climate change deniers who argue that global warming is a “hoax”. I counter that apart from CO2 release, renewables and electrification are more efficient, representing a more economical future in addition to a cleaner and simpler one. But what is the evidence for this?

This Japanese high speed mag-lev train is the fastest in the world, and incredibly energy efficient

There are two competing arguments that you often see in print, regarding the efficiency of electric cars versus gasoline cars. Left-leaning articles “rightly” state that electric cars are 60%+- efficient, while gasoline cars are 20%+- efficient (efficiency being measured by the amount of onboard “fuel” utilized while the rest is “wasted”). Right-leaning articles say that when the efficiency of the electricity source is considered (usually around 33%, in the conversion of natural gas or coal), electric cars are often not more efficient than gas cars. Some quick math reveals there is a partial truth to that last statement, since for electrics 0.33 x 0.60 = 0.20 which equals the gas car efficiency. However, gasoline production has efficiency issues too (it requires energy to be brought from the ground and processed) and increasingly electricity is being produced by renewables (with much higher efficiency rates) while electric cars are getting more efficient, so it is an evolving argument. Let’s examine some of the details. (Hanley,2018),(Skowron,2019),(Deb,2016)

The chart below is one of my favorites. It shows the various energy sources by percentage in the US (as of 2017), and how much of that energy is utilized or wasted. Since renewables are getting ever better, cheaper, and more efficient, while fossil fuel is getting ever harder to get out of the ground (not to mention harder to clean up), there seems to be a growing efficiency advantage to non fossil-fuel options (it depends on your efficiency sample points). However, energy utility is not always about energy efficiency. The easiest way to explain this is to examine fuel densities. Energy density is sometimes needed to make a fuel portable, and so a trade-off is made between efficiency and portability. A rocket ship, for instance, uses liquid oxygen which is very energy dense, portable, and expensive. A jet fighter or tank may use kerosene and diesel, respectively, and we are a long ways from battery-powering either one of them (batteries currently have a relatively low energy density and energy/weight problem). Hydrogen is one of the best bets to power these jets or tanks cleanly, due to a decent energy density and especially a high energy/weight ratio. However, hydrogen takes a fair amount of energy to produce, and is thus not highly energy efficient or even cost effective. Ethanol made from corn is also a notoriously inefficient process (it takes more energy to make it than it produces), but other societal values are at work (the processing of biomass waste to make a clean/portable fuel). (Roberts,2018)

Energy Usage in the US in 2017, showing the various energy utilizations and losses for a given application. Note how much energy is lost in combustion and transmission of power!

Internal combustion engines are relatively complex and will probably never be highly efficient. The combustion needed to power them produces heat, which is typically wasted. If this heat could somehow be recovered (there have been attempts to use this heat to augment the power train or alternator, called exhaust heat recovery), cars would be more efficient, but it may be a losing battle. Fossil fuel burning at a power plant, on the other hand, can (and does) use this waste heat more effectively (called cogeneration), plus is in a much better position to “scrub” CO2. All this is pretty much why burning natural gas and coal at the plant are 30% efficient and cars 20% efficient. Remember that internal combustion engines were designed around the relative abundance of fossil fuels 100 years ago, which were at the time practically leaking out of the ground. Now that fossil fuel is getting harder to find (and fracking tends to pollute groundwater or create unintended methane releases), it is getting less efficient to produce all the time. Renewables, on the other hand, are getting more efficient by the day, especially as photovoltaics are producing more with cheaper materials and manufacturing processes, and batteries are becoming more energy dense and less pricey. Economy of scale and public interest will continue this trend.

At this point, we need to point out that electrification is not always efficient either. Electricity travelling over long distances through traditional HVAC (High Voltage Alternating Current) wires (plus the transformers that step down the voltage) can create up to 50% line losses. Electric motors (which power electric cars or home heating/cooling systems) can also produce waste heat. There are four major avenues being explored/implemented that could greatly reduce this electrical waste: 1) Electric cars with regenerative braking (where the energy used to “brake” is fed back into charging the batteries, or some other onboard utility) 2) HVDC (High Voltage Direct Current) power, direct current (often from renewables) that suffers much less energy line loss than HVAC, and can be used to “share” energy between regions and offset “time of use” problems (renewables generally produce during the day, and expanding their daytime markets reduces the need to store energy in expensive devices) 3) Air-source heat pumps are the hope of electrifying heating/cooling in a highly efficient manner, so as to replace relatively inefficient gas heat (these heat pumps “draw” hot or cold out of ambient air, and can be highly efficient) 4) Electrified light rail and high speed rail could be much more energy efficient than air or car travel, if filled to capacity with riders. Maglev high speed rail is extremely energy efficient (because it rides on an air cushion and has little resistance), but is expensive to build. Of course there are other electrification applications too numerous to mention, but the general idea often involves direct DC transfer from renewables to the application, with some kind of energy storage (battery or fuel cell) if necessary. This eliminates the relatively inefficient AC power delivery and standby waste heat (like when your internal combustion engine idles at a stop light). The holy grail of electrification is superconductivity, in which there is no waste heat and potential 100% efficiencies (sounds too good to be true, but they have recently engineered superconductive materials that operate at room temperature, quite a breakthrough). The next challenge is to make these relatively brittle materials into some kind of wire! (Molina,2019),(Daware,2016)

Nuclear power plant with adjacent power line. Conversion of electrical transmission from HVAC to HVDC will cut line loss, waste heat from nuclear or fossil fuel power plants can be recaptured by cogeneration, though this may be moot if renewables take over.

It’s best to conclude that energy efficiency is something to strive for when possible, such as in controlled conditions like ordinary transportation, energy delivery, and home heating. In situations where a large load is being moved in a remote place (such as a truck, jet, rocket, or tank), energy densities come into play and efficiency may take a back seat, but over time (and with new technology) these should become the exceptions. So now that you know all this, the next time you’re at a cocktail party and some ignoramus says “global warming is a hoax!”, tell them “no, it’s not…but even if it was, switching from fossil fuels to renewables and electrification generally offers greater efficiencies that are already proving to save energy, while being easier, and cheaper to use. At the same time, society should acknowledge that hydrogen may be the less efficient, more energy dense and portable fuel for remote/high horsepower needs such as jets and tanks”.

See how all that rolls off the tongue?

Enjoy these other Vern Scott Energy and Transportation Articles:

What a National Infrastructure Upgrade Should Be

CO2 Contribution will Destroy our Planet-or Maybe Not!

Fighting Cow Flatulence

Affordable 3D Printed Structures

Who Will Invent the Catalytic Converter of the Global Warming Age?

The Far-Off Future of Renewables

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Vern Scott

Scott lives in the SF Bay Area and writes confidently about Engineering, History, Politics, and Health