PATH TO A SUSTAINABLE EARTH
EVEN IF THERE WAS NO CLIMATE CHANGE WE HAVE TO START NOW TO BECOME INDEPENDENT OF FOSSIL FUELS !
It is predicted that we will run out of fossil fuels in this century. Oil can last up to 50 years, natural gas up to 53 years, and coal up to 114 years.
The only way I know to understand the priorities in reducing fossil fuel use is to make it personal, and to separate reducing energy use from converting to renewable sources. A useful measure of energy use is megawatt hours per person per year (MWh/person/year), and the ourworldindata web site provides useful world and country wide averages.
World energy use average 20 MWh/person/year
US energy use average 80 MWh/person/year
US electricity generation 13 MWh/person/year or 16% of US use.
The disparities between the developed countries and the rest of the world are critical, any solution to the energy puzzle has to include the reality that the rest of the world expect the benefits of development.
There are statistics for the behavior of the "average" american.
Your car is used to travel 14,000 miles a year at 24 mpg. A gallon of gasoline has an energy content of 34 KWh. Your car uses 20 MWh/person/year or 25% of your total energy use.
Air travel is a smaller contributer compared to cars. US uses jet fuel 1000 thousand barrels a day , and gasoline 8000 thousand barrels a day. Based on the amount of jet fuel we use, the average american consumes about 2 MWh a year travelling by air, about 3% of your carbon footprint . Planes are about as efficient as hybrids, so we travel 4000 miles in two 1000 mile round trips. Air travel is estimated as 2x more polluting per gallon from depositing additional greenhouse gases.
The retail sales of electricity to major consuming sectors and percentage share of total electricity retail sales in 2021 were:
residential 38.9% or 7% of carbon footprint = 6 MWh/y/p
The are published breakdowns for greenhouse gases cab be combined with electric power, and I am assuming that these are approximately interchangeable.
Personal carbon footprint for an "average" american
Carbon footprint %
Personal Car travel 25 14,000 miles a year @ 24mpg
Residential Elec 3 Double in Texas
Residential fuel 3 Higher in the North Air travel 3 4,000 miles a year
Corporate Industrial fuel 21
Commercial elec 17
Commercial fuel 9
Industrial elec 8
Roughly half your footprint is under your personal purchase control, and half under corporate control. Electrical supplies 30% of the energy.
Obviously these vary with location, family size etc. so "your mileage may differ" applies to all these percentages. However they do provide a framework for thinking about what you can do.
Whatever we choose to do, social pressure and financial incentives are much more effective than political mandates. Sustainability needs to be part of our obligation as trustees of the planet to future generations.
The strategy has 3 elements; use less, convert fossil fuel uses to electricity, and change to renewable electricity. Focus on highest leverage items.
The first step is solving a problem is to not make it worse. This means a fertility rate of no more than 2 children per couple, we must get to zero population growth. The good news is that in many developed countries we are already at zero growth, and all the trends show poorer countries are headed that way.
Renewable electric power generation 30% of footprint
Renewable electrical power generation will reduce your footprint by around 30% , and we are reliant on changing most of the national grid to renewables to reduce its carbon footprint. This is the item that requires national political commitment and resources to make happen. It require an "all of the above" approach to the different technologies. It will also mean that we will need some spare on demand capacity from fossil fuels or nuclear to manage variations in generation.
In 2021 about 15% of generation in the US came from renewables up from 5% 7 years ago, compound growth at this rate could get to 100% as soon as 20 years. If we just add constant capacity it would take 60 year, 40 years is probably more realistic.
Domestic cars 25% of footprint
To reduce your carbon footprint, it is obvious that your car is the biggest line item, and is more than other countries because we drive a lot and our cars are larger and less efficient. Gas cars are 30% efficient at generating motion power, compared to 95% for electric motors.
Hybrid cars are roughly twice as efficient as conventional gasoline motors, so changing to a hybrid will halve your gas bill and reduce your carbon footprint by 13%.
Electric cars (Nissan Leaf) have a range of 200 miles on a charge of 62 KWh, or 4.3 MWh/person/year. Electric motors are much more energy efficient than gasoline engines, and the cars are smaller and lighter. Roof top solar in Texas can generate enough for a 2 car family, so changing to an electric car will eliminate gas use, reduce maintenance costs by roughly 50%, and adding roof top solar can reduce your carbon footprint by 35%.
The average life of a car in the US is 11 years, so in 20 years the change to electric cars could have a major impact on fossil fuel use. The good news is that car companies are used to a annual design changes. Battery infrastructure may be the limiting factor.
Plug-in vehicles are predicted to make up 23% of new passenger vehicle sales globally in 2025, up from just under 10% in 2021. A this rate, 50% of all sales by 2035 seems likely.
Industrial fossil fuel use 21 %
As we learn how to build much larger systems, general industrial uses will convert to electricity, with carbon capture as an option for large facilities. A carbon tax that should be used to add financial pressure on commercial and industrial facilities. Building codes are a well established process for ensuring new and upgrade construction meet societies needs, it should be used to enforce footprint requirements.
Many industrial processes emit CO2 through fossil fuel consumption. Several processes also produce CO2 emissions through chemical reactions that do not involve combustion, and examples include the production of mineral products such as cement, the production of metals such as iron and steel, and the production of chemicals. The fossil fuel combustion component of various industrial processes accounted for about 16% of total U.S. CO2 emissions and 13% of total U.S. greenhouse gas emissions in 2020.
The cement industry accounts for around 5 percent of global carbon dioxide (CO2) emissions. While some estimate that energy efficiency improvements could achieve emission reductions of up to 40 percent, some industry analyses suggest that producers may have already exhausted this potential. Reducing emissions from the calcination process means looking to a material other than limestone. Blended cement could reduce CO2 emissions by as much as 20 percent, but its widespread use is limited by other environmental regulations (these substitutes can contain toxic heavy metals); the limited availability of substitute material; and some building code restrictions (blended cement can take longer to set).
Finally, CO2 emissions can be captured after they are produced through carbon capture and storage (CCS). CO2 penetrates concrete and reacts with calcium hydroxide in the presence of water to form calcium carbonate; the result is stable, long-term CO2 storage. As a mitigation technology, accelerated carbonation can be achieved by exposing freshly mixed concrete to flue gases with high CO2 concentrations.
Household and commercial fossil fuel use 12% of footprint
The next items under personal purchasing control are residential and commercial fossil fuel use. There is EIA data on over 70 households in the southwest US, which shows energy use of 13 MWh/y + 4 KWh/squft/y for new single family residences with 3.5 occupants. The average single family home from 2000-4000 squft has an average total energy consumption from 15-20 MWh/y +-30% or +- 1% of your footprint, giving an idea of the energy saving opportunity.
The use breakdown for a typical residence.
Energy use is 6% of energy footprint for US average resident.
Cool 17% - 1% of energy footprint
Heat 29% - 2% of energy footprint
Water 14% - 1% of energy footprint
Appliances 13% - 1% of energy footprint
Most water and space heat combined use fossil fuel @ 3% of your footprint.
In Texas, a 3000 squft single family house with 2 people uses 7 MWh/y/p electricity and 6 MWh/y/p natural gas. Slightly above average for a single family house, over 2x US average per person.
Assuming that electricity is converted to renewable, the additional potential savings are from conversion from fossil fuel to renewable electricity, which produces a 3% decrease in carbon footprint. Energy savings alone can produce a 1% reduction.
Commercial facilities have similar heating, cooling and lighting issues to houses, the immediate strategy is improving insulation and moving to electric as much as possible. Large area solar should be a requirement. The trend to working from home should reduce the need for commercial space, with savings all round.
Agriculture 9% of footprint
One of the current hot issues is "they are coming for our beef". Beef is uses much more fossil fuel than other protein sources, so moving to a veggies oriented diet is probably better for you and will reduce footprint.
At least as important is the impact of agriculture on land use in the planet from the demand for food and palm oil in particular. Palm oils are easier to stabilize and maintain quality of flavor and consistency in processed foods, so are frequently favored by food manufacturers. Demand has also increased for other uses, such as cosmetics and biofuels, encouraging the growth of palm oil plantations in tropical countries. Growing bio-fuels is a uniquely poor use of agriculture.
We can choose to change the balance of our diets. The use of non-essential but useful oils will only be changed if the users pay the full cost of growing. This needs to include the loss of CO2 absorption, loss of bio-diverse habitat, CO2 creation from burning the native forest.
Air travel 3% impact
Air travel is a minor problem compared to your car when you fly 4000 miles a year. Add a few international flights and it becomes a significant contribution. The most likely long term solution is to use hydrogen as a fuel source.
In February 2022, Airbus announced a demonstration of a liquid hydrogen-fueled Turbofan, with a first flight expected within five years.