From mainstream media to social media, the world is abuzz with the topic of climate change. A simple Google search on the phrase today yielded 1,100,000,00 results, and typing “gret” into Google is all it takes to bring up 107 million stories about Greta Thunberg. This 16-year-old Swedish environmental activist whose lone mission to protest climate change outside the Swedish Parliament has ignited a flame within millions of young people from more than 100 countries who have joined her with demands for climate action and a cry to “listen to the scientists.”
Even those associated with the oil industry are taking up the charge. For example, the former CEO of BP, Lord John Browne, is speaking globally about the need to clean up the atmosphere and reduce reliance on fossil fuels. His new book “Make, Think, Imagine” considers whether our demand for energy has driven the Earth’s climate to the edge of catastrophe and suggests that the same spark that triggers innovation can be used to counter its negative consequences and that it is time to “listen to the engineers.”
In many countries, visible progress demonstrates the need to switch from fossil fuel to renewable energy sources. In almost all cases, the focus seems to be on the use of electricity and the potential to displace the use of fossil fuel with renewable generation to clean up the grid. There seems to be a view that cleaning the electricity system will solve the issue.
In reality, the problem is more serious than that, and there is a need to “take stock” and go after the “low hanging fruit” to truly solve the issue.
The Big Picture
Electricity generation is certainly the largest single source of emissions in many parts of the world. It is the largest single source in the US, for example, followed closely by transportation. But there are other major sources of emissions that need to be added to the mix as well.
While electricity may be the largest single source of emissions, the electric system delivers less than 20% of total energy. The balance is almost all based on fossil fuel, and this provides for heating, industrial uses and transportation. The transportation industry alone uses more than double the energy delivered by the electric grid. And most major buildings in locations with cold winters use more energy for heating – largely natural gas – with fuel consumption taking place primarily during months when solar energy is at its low period for the year.
While storage is key to any transition to clean energy, it is also a good time to look for additional opportunities to significantly reduce emissions quickly and move onto a comprehensive plan that can be implemented over a longer period. Expansions to the electric grid may require up to 20 years for approval and construction, and this is far too long if there is to be an effective transition away from fossil fuel.
To Quickly Reduce Emissions
Consider the sources of emissions and how they may be reduced quickly. The fuel sources and the efficiency of their use is very critical. Coal, for example, produces almost double the emissions created by burning natural gas, for the same energy output. Changing all electrical coal generation to natural gas would reduce total emissions by more than 15%, but there are also some opportunities to dramatically improve efficiency by using natural gas.
A coal-fired steam turbine generating station will typically operate at about 30% efficiency. On the other hand, a natural gas combined cycle gas turbine (CCGT) can operate at as high as 60%. If a steam turbine coal generation facility was replaced with a natural gas-powered CCGT, the emissions would be reduced by almost 75%, and if the gas turbines were utilized as a “combined heat and power” (CHP) system, the efficiency can be as high as 90%, meaning that emissions from coal generation would be reduced by more than 80%.
Given that this general area is responsible for more than 1/3 of total US emissions, full implementation of such an approach would reduce US total emissions by more than 25%, a very significant change. Critics will suggest that natural gas is a fossil fuel, and that is certainly correct, but in the interest of achieving a practical solution that would make a large difference in a short time, this might be a very good start.
The Transportation Factor
The second largest source of emissions is transportation, and more than half of that source is caused by personal vehicles. There can be little doubt that efficiency plays a key role in this area. The typical gasoline-powered vehicle is less than 25% efficient, and many are less than 20%. An electric vehicle is typically better than 60%, and while this difference may appear large, it is important to consider the fuel used to generate the electricity. A coal-fired generating facility that is 30% efficient, providing electricity to an EV that is 60% efficient, would result in an overall efficiency of (0.3 x 0.6) 18%, very similar to the efficiency of the gasoline-powered car. However, if the electricity is generated from renewable sources (including hydro), nuclear or even a CCGT powered by natural gas, the overall efficiency of the EV is 2-3 times better than the gasoline-powered car.
Price of fuel is another issue. A new Tesla Model S long-range vehicle will travel 370 miles, powered by a 100 kWh battery. The average user pays $.12/kWh in the US for electricity, meaning that the cost of a full charge, done on a home charger, would be $12. By comparison, a BMW X5 is estimated to operate at 25 miles/US gallon. With an average cost of $2.90/gallon, the Tesla car could travel 370 miles for $12 in electricity, while the BMW X5 would require $42.92 in gasoline. If the electricity for the Tesla were generated from renewables or other clean sources (nuclear) the emissions would be zero, while the BMW CO2emissions would be almost 300 pounds.
If sufficient electricity can be made available to power a large portion of the vehicle fleet, the impact on emissions would be large. The combined use of coal-fired electricity and fossil-fueled personal vehicles is responsible for almost 50% of total emissions. But if conversion was driven to 100% EV use, the electric system would need to deliver far more energy than is currently delivered. This challenge cannot be met without major changes in both the vehicle fleet and the electric grid. The thought of powering vehicles with renewable capacity is idealistic, and given the very small portion of total energy that is currently powered by solar and wind, this may well prove to be beyond reach.
It is apparent that there are opportunities for significant reductions in emissions, using currently available technology -- opportunities that would not require the complete elimination of fossil fuel in a very short time. This approach could dramatically reduce emission, allowing time to rebuild our energy systems for an ultimately clean supply of energy.