Social determinants of health (SDOH)external icon are conditions in the places where people live, learn, work, and play that affect a wide range of health risks and outcomes. Show
Healthy People 2030 uses a place-based framework that outlines five key areas of SDOH: The World Health Organizationexternal icon also provides a definition of social determinants of health. Social determinants of health as the conditions in which people are born, grow, live, work and age. These circumstances are shaped by the distribution of money, power, and resources at global, national, and local levels. They state social determinants of health are mostly responsible for health inequities – the unfair and avoidable differences in health status seen within and between countries. Resources that enhance quality of life can have a significant influence on population health outcomes. Examples of these resources include safe and affordable housing, access to education, public safety, availability of healthy foods, local emergency/health services, and environments free of life-threatening toxins. Healthy People 2030 highlights the importance of addressing SDOH by including “social and physical environments that promote good health for all” as one of the four overarching goals for the decade. We also know that poverty limits access to healthy foods and safe neighborhoods and that more education is a predictor of better health. Differences in health are striking in communities with poor SDOH such as unstable housing, low income, unsafe neighborhoods, or substandard education. By applying what we know about SDOH, we can not only improve individual and population health but also advance health equity. Find CDC programs and tools to address SDOH. If you’d like to learn more about SDOH or what is included on this page, contact us at . Author: Dr. Jean-Paul Rodrigue
Human activities are dependent on the usage of several forms and sources of energy to perform work. The more available and affordable energy sources are, the more capabilities and opportunities can be mobilized. The energy content (or energy density) of an energy source is the available energy per unit of weight or volume, but the challenge is to extract and use this energy effectively. Thus, the more energy consumed, the greater the amount of work realized, with economic development correlated with higher levels of energy consumption. There are four types of physical work related to human activities:
Lower energy prices in terms of efforts to extract and ease of application involve more opportunities to perform physical work. There are enormous reserves of energy able to meet the future needs of humanity. However, one of the leading contemporary issues is that many of these reserves are not necessarily widely available at competitive costs, such as solar energy, or are unevenly distributed around the world, such as oil and wind energy. The geography of energy reveals complex differences in the availability of energy sources, and supply and demand patterns. Still, the availability or the competitiveness of an energy source can improve with technological development, implying dynamics in the geography of energy. Even if some energy sources are extracted far from where they are consumed, the massification of transportation enables their mobility, which is particularly the case for petroleum and coal. Sources of EnergyChemical Energy Content of some Fuels (in MJ/kg)Primary Energy Consumption, Selected Countries, 1965-2020Primary Energy Consumption and GPD Per Capita, 2019Energy and WorkThroughout the history of energy use, the choice of an energy source depended on several utility factors that involved a transition in energy systems from solid, liquid, and eventually to gas sources. Since the industrial revolution, efforts have been made for work to be performed by machines, which considerably improved industrial productivity. The energy sources used for this mechanization substantially impacted energy demand patterns. The development of the steam engine and the generation and distribution of electric energy over considerable distances have also altered the spatial pattern of manufacturing industries by liberating production from a direct connection to a fixed power system. While in the earlier stages of the industrial revolution, factories located close to sources of energy (a waterfall or a coalfield) or raw materials, mass conveyances, and new energy sources (petroleum and electricity) enabled much greater locational flexibility. Industrialization placed considerable demands on fossil fuels through its processes and outcomes. At the turn of the 20th century, the invention and commercial development of the internal combustion engine, notably in transport equipment, expanded the mobility of passengers and freight and incited the development of a global trade network. The setting of industrial and energy systems is interrelated. With globalization, transportation accounts for a growing share of the total amount of energy spent on implementing, operating, and maintaining the international range and scope of economic and social activities. Energy consumption has a strong correlation with the level of development, with transportation accounting for between 20 and 25% of consumed energy among developed economies. The benefits conferred by additional mobility, notably in terms of better comparative advantages and access to resources, have required a growing amount of energy spent to support this expanded spatial system. At the beginning of the 21st century, the transition reached a stage where fossil fuels, such as petroleum, are dominant. Out of the world’s total power production, 87% is derived from fossil fuels, but this share is expected to steadily decline in the coming years. Evolution of Energy SourcesAnnual Energy Consumption in England and Wales, 1560s to 1850sPower Generated by Steam Machines, Europe, 1840-1888Global Energy Systems Transition World Energy Consumption, 1965-2020World Energy Production, 20192. Transportation and Energy ConsumptionTransportation and energy can be seen from a cost-benefit perspective where giving momentum to a mass (passengers, vehicles, cargo, etc.) requires a proportional amount of energy. The matter is how effectively this energy is captured to practical use, which has a strong modal characteristic. The relationship between transport and energy is direct but subject to different interpretations since it concerns different transport modes, each having its utility and level of performance. There is often a compromise between speed and energy consumption related to the desired economic returns. Passengers and high-value goods can be transported by fast but energy-intensive modes since the time component of their mobility tend to have a high value, which conveys the willingness to use more energy. Economies of scale, mainly those achieved by maritime transportation, are linked to low energy consumption per unit of mass being transported, but at a slower speed. This fits relatively well freight transport imperatives, particularly for bulk, where time is less critical and where buffer stock can be accumulated. Comparatively, air freight has high energy consumption levels linked to high-speed services where there are limited buffer stocks. The transportation market has a broad spectrum of energy consumption which is particularly impacted by three issues:
A trend that emerged since the 1950s concerns the growing share of transportation in the world’s total oil consumption; transportation accounts for approximately 29% of world energy demand and about 61.5% of all the oil used each year. The impacts of transport on energy consumption are diverse, including activities that are necessary for the provision of transport infrastructures and facilities:
Energy consumption has substantial modal variations:
Further distinctions in the energy consumption of transport can be made between the mobility of passengers and freight, relying on different modal configurations:
3. Petroleum: The Transport FuelAlmost all transportation modes depend on variations of the internal combustion engine, with the two most salient technologies being the diesel engine and the gas turbine, since they are the linchpin of globalization. While ship and truck engines are adaptations of the diesel engine, jet engines are an adaptation of the gas turbine. Transportation is almost entirely reliant (90%) upon petroleum products, except for railways using electrical power. While the use of petroleum for other economic sectors, such as industrial and electricity generation, has remained relatively stable, the growth in oil demand is mainly attributed to the growth in transportation demand. Still, the share of oil used in the transportation sector is steadily declining with the introduction of alternative sources such as electric cars. What varies is the type and the quality of petroleum-derived fuel being used. While maritime transportation relies on low-quality bunker fuel, air transportation requires Jet-A, a specialized fuel with additives. Road transportation is highly fragmented, with 85% of the automobiles depending on gasoline, while 90% of the trucks rely on diesel. It is worth looking at the chemical combustion principle of hydrocarbons. For the majority of internal combustion engines, gasoline (C8H18; four strokes Otto-cycle engines) serves as fuel, but other sources like methane (CH4; gas turbines), diesel (mostly trucks), bunker fuel (for ships), and kerosene (turbofans of jet planes) are used. Gasoline produces around 46,000 Btu per kilogram combusted, requiring 16 to 24 kg of air. The energy released by combustion causes a rise in the temperature of combustion products. Several factors and conditions influence the level of combustion in an internal combustion engine to provide momentum and keep efficient operating conditions. The temperature attained depends on the rate of release and dissipation of the energy and the number of combustion products. Air is the most available source of oxygen, but because air also contains vast quantities of nitrogen, nitrogen becomes the principal constituent of combustion products. The combustion rate may be increased by finely dividing the fuel to increase its surface area and hence its reaction rate and by mixing it with the air to provide the necessary amount of oxygen to the fuel. If combustion was perfect, emissions and thus local environmental impacts of transportation would be negligible, except for carbon dioxide emissions. The challenge is that combustion in internal combustion engines is imperfect and incomplete for two reasons:
In addition to the imperfect and incomplete combustion of hydrocarbons, three major factors influence the rate of combustion and thus emissions of pollutants, which are the characteristics of the vehicle (where technological improvements can play a role), driving characteristics (where planning and regulation can play a role), and atmospheric conditions. The internal combustion engine converts less than a third of the energy consumed into momentum, primarily due to friction. For electric motors, this figure is above 80%. Demand for Refined Petroleum Products by Sector in the United States, 1960-2018 (in Quadrillion BTUs)Automobile Emission Factors4. Transportation and Peak OilThe extent to which conventional non-renewable fossil fuels will continue to be the primary resources for nearly all transportation fuels is subject to debate. But the gap between demand and supply, once considerable, is narrowing, an effect compounded by the possibility that global oil production will eventually peak. The steady surge in demand from developing economies, particularly China and India, requires additional outputs. This raises concerns about the capacity of major oil producers to meet this rising and enduring global demand. The producers are not running out of oil, but the existing reservoirs may not be capable of producing on a daily basis the increasing volumes of oil that the world requires. Reservoirs do not exist as underground lakes from which oil can easily be extracted. There are geological limits to the output of existing fields. This suggests that additional reserves need to be found to compensate for the declining production of existing fields. Reserves additions may not be enough to offset this growing demand, but technological improvements allowed to tap bitumen and oil shale reserves. However, extracting such reserves necessitates much energy and water. The production of 1 barrel of bitumen requires burning the equivalent of 10-20% of its energy content. Others argue that the history of the oil industry is marked by cycles of shortages and surplus. The rising price of oil will render cost-effective oil recovery in difficult areas. Deepwater drilling and extraction from tar sands and oil shale should increase the supply of oil that can be recovered and extracted. But there is a limit to the capacity of technological innovation to find and extract more oil around the world, and the related risks can be very high. Adding oil extraction, distribution, and refinery capacity are slow, complex, capital intensive, and highly regulated. If technically and economically viable, carbon sequestration in the form of CO2 capture and storage could enhance the recovery of oil from conventional wells and prolong the life of partially depleted oil fields well into the next century. High fuel prices usually stimulate the development of alternatives, but automotive fuel oil demand is relatively inelastic. Higher prices result in very marginal changes in demand for fuel. The equivalent of $100 per barrel was considered a threshold that would limit demand for automotive fuel and lead to a decline in passenger and freight-km. Evidence suggests that higher oil prices had a limited impact on the average annual growth rate of global motorization. The analysis of the evolution of the use of fossil fuels suggests that in a market economy, the introduction of alternative fuels is leading to an increase in the global consumption of both fossil and alternative fuels and not to the substitution of crude oil by alternative fuels. This suggests that in the initial phase of an energy transition cycle, the introduction of a new source of energy complements the existing supply until the new source of energy becomes price competitive to be an alternative. The presence of renewable and non-renewable fuels stimulates the energy market with the concomitant increase in greenhouse gas emissions. The production of alternative fuels adds up to the existing fossil fuels and does not replace them. The main concern is the amount of oil that can be pumped to the surface on a daily basis, especially where major oil fields have reached peak capacity. Under such circumstances, oil prices are bound to rise in the medium to long term, sending significant price signals to the transport market. How the transport system responds and adapts to higher energy prices is subject to much debate and interpretation in terms of the scale and timing of the transition. The following potential consequences can be noted:
Higher energy prices can trigger notable changes in usage, modes, networks, and supply chain management. From a macro perspective, and since transportation is a very complex system, assessing the outcome of higher energy prices remains hazardous. What appears very likely is a strong rationalization, a shift towards more energy-efficient modes, as well as a higher level of integration between modes to create multiplying effects in energy efficiency. As higher transport costs play in, namely for containers, many manufacturing activities will reconsider the locations of production facilities to sites closer to markets (near-sourcing). While cheap and efficient transport systems favored globalization, the new relationships between transport and energy are likely to restructure the global structure of production and distribution towards regionalization. This process is also favored by less acute differences in labor costs and a push towards automation. 5. Transportation and Alternative FuelsThe energy source with the lowest cost is usually preferred. The dominance of petroleum-derived fuels results from the relative simplicity with which they can be stored and used in internal combustion engines. Other fossil fuels (natural gas, propane, and methanol) can be used as transportation fuels as well but require a more complicated storage system. The main issue concerning the large-scale uses of alternative vehicle fuels is the significant capital investments required in distribution facilities compared with conventional fuels. Another issue is that in terms of energy density, these alternative fuels have lower efficiency than gasoline and thus require a greater volume of onboard storage to cover the equivalent distance as gasoline-propelled vehicles if performance is kept constant. Alternative fuels in the form of non-crude oil resources are drawing considerable attention as a result of the non-renewable character of fossil fuels and the need to reduce emissions of harmful pollutants and carbon. The most prevalent alternatives being considered are:
The diffusion of non-fossil fuels in the transportation sector has serious limitations. While oil prices have increased over time, they have been subject to significant fluctuations. The comparative costs of alternative energy sources to fossil fuels are higher in the transportation sector than in other types of economic activities. This suggests higher competitive advantages for the industrial, household, commercial, electricity, and heat sectors to shift away from oil and to rely on solar, wind, or hydro-power. Transportation fuels based on renewable energy sources might not be competitive with petroleum fuels unless significant price increases as well as substantial technological improvements. An emerging trend involves decarbonizing transport intending to make transportation systems carbon neutral. Achieving such an outcome requires measures that have been advocated for decades, such as low carbon fuels, vehicle and equipment efficiency, and modal shift. It remains unclear if carbon-neutral transportation is achievable in the medium term since it involves capital-intensive energy transitions. Modes such as maritime shipping have a much lower potential, mainly for technical reasons, as ship engines are massive. This power level cannot be readily provided by technology other than the internal combustion engine. Urban transportation with a shorter lifespan of vehicles and a reliance on public transit has a better potential to become carbon neutral. Related Topics
Bibliography
Which of the following modes of transportation has low fixed and high variable cost?Some of these aircraft include helicopters, passenger aircraft, and cargo aircraft. The correct answer is Air. Air transportation is the most expensive and costly of all modes of transportations. It has low fixed and high variable costs.
Which type of material handling system typically has the highest fixed cost?Which type of material handling system typically has the highest fixed cost and the lowest variable cost? Automated.
Which of the following is a combination of weight and volume?Density can be expressed in any combination of mass and volume units; the most commonly seen units are grams per mL (g mL–1, g cm–3), or kilograms per liter.
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