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Types of Energy

Nonrenewable Energy Sources:

These refer to energy sources that occur in a finite quantity and whose resources will ultimately be fully expended. While this category primarily refers to fossil fuel technologies nuclear power is also included.

Jump to one of the following sections: fossil fuels, liquid fuels, coal power, natural gas, nuclear power

Renewable Energy Sources:

These refer to energy sources that can continually be replenished. This can occur almost instantly in the case of wind and solar power or over a generation as with wood.

Jump to one of the following sections: hydroelectric power, wind energy, solar power, geothermal energy, biomass, or fuel cells


 

 

Energy usage chart

Nonrenewable Energy Sources:

Fossil Fuels:

The 19th century development of technologies that can utilize fossil fuels as a massive scale energy source changed the face of human civilization forever. Combustion engines and centralized power generation based on the combustion of fossil fuels allowed people to travel further, stay warm for longer and create economies and products on a scale that few thought imaginable throughout the centuries before. Fossil fuel extraction and the extent of its utilization has also brought a vast set of costs that have caused their continued utility to come under major scrutiny. Fossil fuel combustion releases pollutants that affect human and ecosystem health. Moreover, byproducts of their usage significantly change the composition of the Earth's atmosphere. These changes have many broad sweeping effects, including being the primary human created cause of climate change. Furthermore, since crude oil and coal are the byproducts of geologic compression, that takes millions of years to complete, fossil fuel usage has a distinct shelf life. Due to global population increase and the industrialization of the developing world some estimates predict up to a 60% increase in global energy demands by the year 2030 (1). In the face of rising energy demands and the risk to human and environmental health, the threat posed by continued use of these non-renewable resources becomes even greater.

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Liquid Fuels (Petroleum):

According to the Energy Information Administration (EIA) petroleum based liquid fuels such as gasoline and heavy fuel oils are still the most utilized source of energy by energy units produced (btu), accounting for 35% of the worlds total energy consumption (1). These fuels are used primarily for power generation, combustion engines and plastics. Nearly all motorized transportation sources are powered by petroleum based products. Known oil reserves as of 2009 were approximately 1342.21 billion barrels (2). While that may seem like a lot, the global rate of consumption as of 2009 would deplete this supply by the middle of 2052. Though comparatively cleaner than coal, oil combustion is still the second leading contributor to carbon emissions globally and is a major source of pollutants leading to human health problems and acid rain. Environmental risks of extraction may increase as land bound supplies begin to dwindle. Under these conditions, the risk of irreversable harm due to extraction only increases as seen by the impacts of the Deepwater Horizon oil spill in May of 2010.

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Coal:

Coal is the second most utilized source of energy globally, accounting for 27% of all energy consumption. It is used primarily as the fuel source for large scale power generation. Depending on how reserves are calculated, the current rate of consumption would provide coal supplies for the next 60-120 years (1). Its relative abundance and cheap extraction and refining processes continue to make it a staple of worldwide energy usage. Coal is a sedimentary rock formed primarily from compression of accumulated plant matter over the course of millions of years. Many other minerals and compounds are typically compressed within it. As currently utilized, coal contributes to environmental problems such as acid rain, air and water pollution, and climate change more than any other energy resource. Toxic heavy metals including mercury and lead, nitrous and sulfur oxides, carbon dioxide and particulate matter are among the byproducts of combustion that harm human health and environmental quality. Presence of radioactive elements in coal (2) such as uranium and thorium also increase health risks associated with it.

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Natural Gas and its Byproducts:

Vaporous gases refer here to hydrocarbon based gases such as natural gas (primarily methane), butane, and propane. As the name would suggest, natural gas refers to the compound that is extracted from the earth. Butane is one of the components of natural gas and propane is created by combining natural gas and petroleum. These gases account for 23% of global energy consumption and are primarily used for heating and energy generation in the case of natural gas and portable fuel in the case of butane (lighter fluid) and propane (camping fuel). The EIA makes little reference of dwindling reserves but reports that production output to meet demand will have to increase threefold by 2035 (1). Of the hydrocarbon options, the vaporous gas family releases the least pollutants, including carbon dioxide during combustion. Methane itself, however is a much more potent greenhouse gas than carbon dioxide. Methane's environmental footprint is greater by a good margin than renewable fuels, particularly when risks associated with the extraction of natural gases from low grade shales are also taken into account. This process referred to as hydrofracking, involves boring a hole into the reserves and forcing the gases upward by forcing liquid down the hole and into the rock (2). There is growing concern that this process will cause extensive groundwater contamination nearby and a large number of spills have added to those concerns that this process is not safe.

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Nuclear Power:

Nuclear power refers to power generation by harnessing the released energy from a controlled nuclear fission reaction - the splitting of uranium 235 into smaller atomic particles. Nuclear power makes up about 5% of all energy generated worldwide, is used exclusively for electrical power generation and 50% of nuclear power production occurs in the United States, Japan, and France. The major advantages to nuclear power are that it has a carbon footprint near zero relative to other non-renewable sources and makes no major contribution to air pollution. Further, uranium stocks are high enough to last into the foreseeable future. Localized and regional environmental impacts can be significant and have the potential to be truly hazardous. Thermal pollution from the release of water used in cooling towers into natural bodies of water can pose a threat to fish and wildlife and without good design, water entering the towers can suck in large quantities of young fish. Uranium 235 is a radioactive particle and exposure to this radioactivity can have dramatic impacts even with limited exposure. When a reactor fails and radiation is released, as happened in Japan after the March 2011 earthquake (2), worker safety as well as local and regional communities can be put at serious risk. Last, nuclear fission has always been at the center of the debate because even if risks of reactor failure are mitigated, there is no true method of safe disposal for the radioactive waste products of these reactions. Though efforts to reprocess these waste products have progressed (2), ultimate disposal sites still remain an issue.

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Renewable Energy Sources:

Today, humankind is on the cusp of implementing new technologies for energy production that have the potential to impact society every bit as substantially as fossil fuels once did, while mitigating to eliminating many of the net negatives that fossil fuel energy extraction and combustion create. Unlike fossil fuels, whose stocks are finite, renewable energy sources can continually be replenished. This can occur almost instantly in the case of wind and solar power or over a generation as with wood. While all renewable technologies still only account for 10% of all global energy consumption, these technologies are increasingly becoming a vital part of energy plans both domestically and globally.

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Hydro Power:

Hydropower refers to the utilization of the water flow to generate electrical power and is currently the most commonly used form of renewable energy (1). The typical image that most associate with hydropower is that of a dammed river that directs water down into a turbine and spins a generator; however, other forms of hydropower have been developed. Turbines can also be installed in naturally occurring areas of increased flow such as large waterfalls or high flow rapids and do not require the construction of a dam. Devices that are turned from tidal movement have been developed as well. Dammed hydropower is a clean and very cost effective form of power generation. Though initial construction and permitting costs can be quite significant, once the facility is built, the cost of upkeep of the facility is fairly minimal and the fuel is free and consistent for the foreseeable future. Startup cost considerations have to date prevented tidal and natural river flow technologies from becoming more prevalent. Construction of new dams is often a contentious issue. A dammed river site can create new opportunities for recreation and can have the dual benefit of flood control, but dam construction also has significant ecological consequences. Dams can be very detrimental to aquatic migrating species moving to and from breeding/spawning grounds if the dam impedes that migration. In some cases the environmental impacts can be reduced by installing a device such as a fish ladder that fish and other wildlife can use to climb the dam. Many aquatic species are very sensitive to temperature changes as well. The change from free flowing water to standing water behind a dam can effect changes in water temperature, this can also impact the downstream ecology. Aside from these considerations, a main limitation of hydropower is the finite number of places that facilities can be cited.

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Wind:

Similar to hydropower, wind power is generated from movement of wind spinning turbines that power generators. Wind energy is the fastest growing source of energy worldwide (1) with more large offshore projects getting installed each year and numerous smaller scale projects providing power more locally. Windpower only provides about 2% of all energy nationally (2). Power generation from wind is a no-pollutant energy source and cost considerations are fairly similar overall to fossil fuel powered plants (3). Siting of turbines is critical not only to find areas where the wind is strong and consistent, but also where there is enough suitable land area to build the turbines while disturbing the least habitat space. Wind power takes up significantly more land area/KWh than fossil fuel or hydropower facilities. Piecing together large land areas with no trees or other impediments, with limited ecological impact or finding offshore space is a significant barrier. Critics of wind power harp on the unpredictability of wind intensity at any given moment to be a reliable major contributor to the grid. Last, the impact of wind turbines on migrating bird populations has been an ongoing concern, although new technologies, careful siting of projects and research that downplays the impacts have calmed many in the mainstream to this issue (4). Last, advocates often need to contend with a public that simply find the turbines unattractive and campaign against their construction "in their own backyard".

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Solar:

Solar technologies convert energy from the sun into usable forms of energy for human consumption. Solar energy most commonly conjures up images of bluish hued rectangular panels, but there are several different distinct types of technology. Passive solar simply uses building design to best assist in heating and cooling needs by capturing heat and light from the sun. Passive solar is merely a supplement to any HVAC system, but building design requires no additional technologies. Active solar methods include photovoltaic and thermal technologies. Photovoltaic solar energy converts sunpower directly to electricity by way of solar cells bound in a weatherproof shell. Solar thermal technology utilizes mirrors in its panels that generate heat. This heat can be used as heat such as for HVAC systems or water heating or it can be converted into electricity by way of a generator. In total, active solar energy still only accounts for less than 1% of all energy consumed nationally (1). While the environmental impacts of solar power generation are negligible, there are impacts in production including degradation in mining for silica, the use of storage batteries and potential human exposure to silica dust in manufacturing plants. Once used primarily for small scale projects such as individual home installations, solar power is becoming more viable for generating power on a large scale because of increased capacity for power storage and fuel cells that more efficiently capture sunlight year round. Siting is still important but not as limiting as it once was. Though costs for solar power have come down considerably, the price is still the major consideration that keeps solar power from proliferating more broadly. Between 3-4 times as expensive as coal or oil, it is still one of the more expensive technologies to install and maintain (2).

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Geothermal Energy:

Geothermal energy refers to the capture of heat energy from beneath the earth's surface for energy production. The main type of geothermal energy production is referred to as hydrothermal energy - the trapping of hot water or steam. These resources can be used to power generators and create electricity or steam, or hot water can be used directly to heat a building. Geothermal energy harnesses a miniscule percentage of all heat energy in the earth's crust and as such is considered a renewable energy source. Excess water or steam is typically pumped back into the ground in closed loop systems or from and to wells in an open loop system. Any toxic elements from the earth, such as lead, ammonia, and mercury can be released in an open loop system whereas they are reinjected back into the ground in a closed loop system. One challenge in large scale production is that significant heat resources are not universally available within cost effective drilling depth. Those places that are suitable are often in remote areas or areas highly valued as tourist destinations such as Yellowstone National Park and thus any intervention would be subject to outcry and legal opposition (1). Exploration for suitable places and drilling are the most cost intensive part of geothermal power production, but total costs are comparable to fossil fuel production(2).

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Biomass:

Biomass refers to the conversion of biological material, typically plants, into an energy source. In traditional cultures around the world, wood is by a large margin the most significantly utilized example of biomass and is still the most widely used biomass fuel. Power generation through combustion of pulp or solid waste is a larger scale form (1). Biofuels such as ethanol, biodiesel and algae based fuels also fall under the blanket of biomass. These fuels, primarily used as additives or substitutes for gasoline are different forms of alcohol created from different kinds of biomass. Nearly all fuel in the United States currently has up to a 10% composition of ethanol (2). Though combustion releases high amounts of carbon emissions, with sound land management practices, biomass combustion can be a net carbon neutral endeavor since a similar amount of plant matter is being recultivated. While other air pollutants such as heavy metals and nitrous and sulfur oxides are non-existent with biomass combustion, released particulate matter is very high. Allocation of large parcels of land is critical for large scale biomass operations since a lot of plant matter is needed and, without plans for forest regeneration, the carbon neutral aspect of biomass combustion is lost.

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Fuel Cells:

Fuel cells are an emerging technology that could ultimately be used instead of batteries, particularly in transportation, but also including laptop and backup generators. Since hydrogen is the primary fuel source they leave a relatively minimal environmental footprint compared with gasoline powered engines. They also are more efficient at converting input fuel into electricity, meaning fuel cell powered vehicles would run more efficiently than combustion engines. Cost considerations and longevity are the major obstacles for fuel cells to overcome to become more prolific on the market.

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Quantal Energy would like to recognize the efforts of Dan Zinder in the preparation of the material above.