by Brian T. Lynch, MSW*
A discussion with an engineer friend of mine regarding electric vehicles and electric energy production in the United States prompted me to do a brief survey of thermal efficiency rates for various carbon-producing and carbon-free electric power generation options. The results are below.
For me, the whole discussion is animated by the nearly unanimous conclusion of hundreds of climate scientists that we have only six years left to make carbon dioxide reductions sufficient enough to avoid the worst impacts of global warming. We lost a half-century of time to a well-funded disinformation campaign by the fossil fuel industries, whose corporate leaders were the first to discover that their products would eventually lead to a global warming crisis.
Can a rapid transition to electric vehicles save us from global warming?
No! This was never the case. At any rate, it is already too late for half-measures. There are many other major sources of carbon dioxide emissions that need to be brought under control. There are other factors that expedite the problem as well, such as the loss of jungles and forests that capture carbon dioxide from the atmosphere. Added to other much-needed actions, however, transitioning to electric vehicles is STILL a necessary step.
For me, the whole discussion is animated by the nearly unanimous conclusion of hundreds of climate scientists that we have only six years left to make carbon dioxide reductions sufficient enough to avoid the worst impacts of global warming. We lost a half-century of time to a well-funded disinformation campaign by the fossil fuel industries, whose corporate leaders were the first to discover that their products would eventually lead to a global warming crisis.
Can a rapid transition to electric vehicles save us from global warming?
No! This was never the case. At any rate, it is already too late for half-measures. There are many other major sources of carbon dioxide emissions that need to be brought under control. There are other factors that expedite the problem as well, such as the loss of jungles and forests that capture carbon dioxide from the atmosphere. Added to other much-needed actions, however, transitioning to electric vehicles is STILL a necessary step.
RENEWABLE ELECTRIC ENERGY
I confirmed that currently, about 60% of our electricity generation is from fossil fuels—coal, natural gas, petroleum, and other gases. About 18% was from nuclear energy, and about 21% was from renewable energy sources. Our renewable energy sources increase by about 1.5 percentage points per year at this time. So, the current energy mix on our electric grid is about 60% carbon-based and 40% alternative sources. In six years, at the present growth rate of renewable energy sources, it will be about 49% carbon-based and 51% alternative sources. This is still bad news for Earth's climate. It's way too slow to be a determinative factor at this point.
EV vs. ICE
"Electric vehicles (EVs) are generally 60–73% efficient, depending on the drive cycle. However, when you include the energy recaptured from regenerative braking, EVs can be over 77% efficient. This is because regenerative braking captures energy that would otherwise be lost as heat."
"Modern gasoline engines (ICE) have a maximum thermal efficiency of more than 50%, but most road-legal cars are only about 20% to 40% [efficient] when used to power a car."
CARBON FOOTPRINT OF EV AND ICE VEHICLES:
"The researchers found that, on average, gasoline cars emit more than 350 grams of CO2 per mile driven over their lifetimes. The hybrid and plug-in hybrid versions scored around 260 grams of carbon dioxide per mile, while the fully battery-electric vehicle created just 200 grams. Stats from the U.S. Department of Energy tell a similar story: Using the nationwide average of different energy sources, DOE found that EVs create 3,932 lbs. of CO2 equivalent per year, compared to 5,772 lbs. for plug-in hybrids, 6,258 lbs. for typical hybrids, and 11,435 lbs. for gasoline vehicles."
Thermal Efficiency in Electric Power Generation
ZERO CARBON DIOXIDE EMISSIONS OPTIONS
Wind
What is the ultimate efficiency of wind power generation?
That number is 16/27, or 59.3%. On a practical level with utility-scale wind turbines, the best turbines achieve roughly 75–85% of this 59.3% value, meaning roughly 44–50% efficiency. This is under the most optimal operating conditions.
Solar Thermal
Solar thermal energy is around 70–80% effective at converting solar energy into heat. Solar water heaters are the most common method for converting solar energy into thermal energy. Solar thermal collectors convert solar radiation into heat, which can be used in industrial, residential, and governmental sectors.
Solar Photoelectric
Though most commercial panels have efficiencies from 17% to 20%, researchers have developed PV cells with efficiencies approaching 50%.
Nuclear
New nuclear plants have a thermal efficiency of around 34–36%, while new reactor designs can reach 39%.
Hydro
The efficiency of today's hydroelectric plant is about 90 percent. Hydroelectric plants do not create air pollution, the fuel--falling water--is not consumed, projects have long lives relative to other forms of energy generation, and hydroelectric generators respond quickly to changing system conditions.
CARBON DIOXIDE EMISSION OPTIONS
Coal
New coal-fired plants are about 40% efficient, while CCGT plants can reach 60%.
Natural gas
Natural gas plants can be 39–60% efficient, depending on the type of plant. A simple cycle natural gas power plant is usually 33–43% efficient.
Gas turbine
A simple cycle gas turbine can achieve 20–35% energy conversion efficiency.
Fossil fuel
State-of-the-art fossil fuel plants can reach 46% efficiency.
Combined-cycle systems
Combined-cycle systems can reach higher values, such as over 60% efficiency.
Thermal Efficiency in Electric Power Generation
ZERO CARBON DIOXIDE EMISSIONS OPTIONS
Wind
What is the ultimate efficiency of wind power generation?
That number is 16/27, or 59.3%. On a practical level with utility-scale wind turbines, the best turbines achieve roughly 75–85% of this 59.3% value, meaning roughly 44–50% efficiency. This is under the most optimal operating conditions.
Solar Thermal
Solar thermal energy is around 70–80% effective at converting solar energy into heat. Solar water heaters are the most common method for converting solar energy into thermal energy. Solar thermal collectors convert solar radiation into heat, which can be used in industrial, residential, and governmental sectors.
Solar Photoelectric
Though most commercial panels have efficiencies from 17% to 20%, researchers have developed PV cells with efficiencies approaching 50%.
Nuclear
New nuclear plants have a thermal efficiency of around 34–36%, while new reactor designs can reach 39%.
Hydro
The efficiency of today's hydroelectric plant is about 90 percent. Hydroelectric plants do not create air pollution, the fuel--falling water--is not consumed, projects have long lives relative to other forms of energy generation, and hydroelectric generators respond quickly to changing system conditions.
CARBON DIOXIDE EMISSION OPTIONS
Coal
New coal-fired plants are about 40% efficient, while CCGT plants can reach 60%.
Natural gas
Natural gas plants can be 39–60% efficient, depending on the type of plant. A simple cycle natural gas power plant is usually 33–43% efficient.
Gas turbine
A simple cycle gas turbine can achieve 20–35% energy conversion efficiency.
Fossil fuel
State-of-the-art fossil fuel plants can reach 46% efficiency.
Combined-cycle systems
Combined-cycle systems can reach higher values, such as over 60% efficiency.
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* The main reason I put my degree (MSW) after my name on this blog is because there are so many people named Brian T. Lynch on the internet.
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