by Rick O'Connor | Oct 21, 2025
Geothermal is one source of energy that has been explored, and utilized, in recent decades. It is heat which is stored beneath the earth – either in the soil, rocks, or the fluid portion of the mantle. It has been used primarily in heating our homes and producing electricity. The amount of geothermal energy within the crust leads to it having great potential for us.
How Geothermal Energy Works – EPA
Many around the world are using a geothermal heat pump system where pipes in a closed system filled with water, or another antifreeze type fluid, buried between 10-20 feet in the yard can move heat from the ground into the home during winter, and reverse the process during summer. If the house is insulated properly, the US EPA considers this method the most efficient one for heating and cooling your home.
Iceland is famous for their use of geothermal energy. Drilling pipes beneath the earth, they are using hot steam and water to heat buildings, provide hot water, grow vegetables in greenhouses, raise fish in aquaculture ponds, and spin turbines to produce electricity. The island is, of course, an active volcano – and that helps.
In 2011 over 40 countries had developed geothermal districts which were producing about 1% of the world’s electricity. The amount of electricity generated was equal to 104 nuclear power plants. In 2022 the United States had 3,965 geothermal plants in operation – the most in the world. The majority of these are in California, Nevada, Utah, and Hawaii.
In general, geothermal has less environmental impact than fossil fuels. If located near a good source, the cost is much lower to produce. However, there are two main problems. One, the cost of tapping into the system from locations far from the sources is high. Second, we could actually remove the dry or wet steam faster than the earth can replace them. Below are additional pros and cons.
| Advantages |
Disadvantages |
| Very high efficiency |
Scarcity of suitable sites |
| Moderate net energy at suitable sites |
CO2 emissions |
| Lower CO2 emissions than fossil fuels |
Moderate to high local air pollution |
| Low cost at favorable sites |
Noise and odors (hydrogen sulfide gas) |
| Low land use and disturbance |
High cost except at suitable sites |
There is one more source of energy to look at – hydrogen – and we will explore that one in the next article.
References
Geothermal Energy Fact Sheet. The Center for Sustainable Systems. University of Michigan. https://css.umich.edu/publications/factsheets/energy/geothermal-energy-factsheet.
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
by Rick O'Connor | Oct 6, 2025
This option for providing power has not been discussed as much recently as it was a decade ago. At that time many were looking at using corn waste, used cooking oil, and animal manure as a source of energy. Some universities devoted a lot of their research dollars towards the topic. But not as much today.
You might remember that our first source of energy for heating and cooking was wood. A decade ago, some communities were considering returning to this source. However, the problems that existed hundreds of years ago still exist today – mainly, is there enough wood. It is a renewable resource, but it does not grow as fast as we use it.
One of the biofuels that did get a lot of attention a decade ago, and is still popular in some countries, is ethanol and biodiesel. This has really caught on in Brazil and, to some extent, in the United States. There are several advantages to this form of energy. (1) Countries can supply their own source of fuel and are not dependent on importing from nations who have fossil fuels. (2) If managed correctly – not removing plants faster than they can replenish themselves – there would be no increase in carbon dioxide emissions. (3) They are available now, are easy to store and transport, can be distributed through existing fuel networks, and used in existing vehicles.
However, there are some problems…
Converting farmland to biofuel farms would decrease food production and overall biodiversity. Here are some advantages and disadvantages of solid biomass.
| Advantages |
Disadvantages |
| Large potential supply in some areas |
Nonrenewable if harvested unsustainably |
| Moderate costs |
Moderate to high environmental impact |
| No net CO2 increase if harvested, and replanted sustainably |
Soil erosion, water pollution, and loss of wildlife habitat |
| Can make use of agricultural, timber, and urban waste |
Farms could compete with food crops |
Biodiesel
| Advantages |
Disadvantages |
| Reduce CO2 emissions |
Increased NO2 emissions and smog |
| Reduced CO emissions |
Higher cost than regular diesel |
| High net energy for oil palm crops |
Low net energy for soybean crops |
| Better gas mileage |
May compete with food crops and raise food prices |
| Potentially renewable |
Can make engines hard to start in cold weather |
Ethanol
| Advantages |
Disadvantages |
| High octane |
Lower driving range |
| Some reduction in CO2 emissions |
Lower net energy |
| Potentially renewable |
Higher cost |
|
Competing with food crops |
|
Higher NO2 emissions and more smog |
|
Corrosive |
|
Can make engines hard to start in cold weather |
The potential of using biofuels is still here. There are definitely some pros and cons to this form of energy for us to think about. In our next article we will look at another that has been discussed a lot – geothermal.
References
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
by Rick O'Connor | Sep 22, 2025
Wind power has become more popular across the planet. Though some regions of the Earth get more wind than others – it blows basically everywhere. The concept behind wind energy is the same as hydroelectric power. In hydroelectric moving water turns the turbines to generate electricity – with wind power it is moving air.
photo: Sam Ho 2022
One study conducted at Stanford by C.I. Archer and M.Z. Jacobsen in 2004 mapped the global potential for wind energy. Their data suggested that capturing only 20% of this potential energy from the world’s best sites could generate seven times more energy than was being developed in 2011 and thus could help phase out coal and nuclear power sources. Offshore wind production looks promising as well. Out there – the wind can be stronger and steadier than winds over land. Many countries have already developed offshore wind farms. Over land within the U.S., areas near the Rocky Mountains show the best promise – and many of these areas have already developed wind farms. In 2011 scientists estimated that wind farms in North Dakota, South Dakota, Kansas, and Texas alone could generate three times more energy than all of the power plants operating at that time. This looks like a promising option for fossil fuels, but there are challenges.
- Areas where wind energy is most promising have few people – the energy would have to transported to more urban sites.
- Winds do die down and a backup source will be needed in many locations.
- Studies have found that rotating wind turbines kill as many as 40,000 birds and bats each year in the U.S. alone.
- Many urban and coastal communities resist them because they are unsightly and noisy.
Others
| Advantages |
Disadvantages |
| Moderate to high energy yield |
Steady winds needed |
| High energy efficiency |
Backup systems needed during low wind events |
| Moderate capital costs |
High land use required |
| Low electricity costs |
“Visual” pollution |
| Very low environmental impact |
Noise when located near populated areas |
| No carbon dioxide emissions |
Can kill birds and bats |
| Can be located at sea |
|
| Land below turbines can be used for agriculture |
|
In the next article we will look at using biomass as an energy source.
Reference
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
by Rick O'Connor | Sep 15, 2025
This form of renewable energy has been used for decades. Water at higher elevations flows towards the sea. Placing a hydroelectric dam on such a waterway the flowing water can turn the turbines and generate electricity. It is the number one source of renewable energy around the world, and – when including environmental costs – one of the least expensive way to generate electricity.
In 2011 much of the world was looking towards increasing hydroelectric power. Today it is the number one form of renewable energy around the world and growth is predicted to remain stable through 2030. One issue of hydropower is droughts generated by climate change. The are other concerns as well – such as the production of methane from anaerobic decomposition from submerged plants on the bottom of the reservoirs, and the build up of silt within the turbines coming from the rivers flowing through them.
| Advantages |
Disadvantages |
| Moderate to high net energy |
High construction costs |
| High efficiency (80%) |
High environmental impact from flooding due to the reservoir |
| Low-cost electricity |
High CO2 emissions from rapid biomass decay in shallow tropical reservoirs |
| Long life span |
Danger of collapse |
| No CO2 emissions during operation in temperate areas |
Uproots people |
| Provides irrigation water |
Decreases fish harvest below dam |
| Reservoir useful for recreation |
Decreases need silt below dam |
Hydroelectric power has its pros and cons.
Photo: Energytheory.
References
Projected Costs of Generating Electricity by 2020. International Energy Agency. https://www.iea.org/reports/projected-costs-of-generating-electricity-2020.
Hydroelectricity. International Energy Agency. https://www.iea.org/energy-system/renewables/hydroelectricity.
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
by Rick O'Connor | Sep 8, 2025
We will begin our look at solar energy by explaining there are two forms – passive and active. In passive solar energy the well insulated building is heated directly from the sun without the need for additional technologies. In active solar energy the build has solar panels. These panels have a heat-absorbing fluid which collects solar energy and can use it directly within the house or store it for later use. Here are some advantages and disadvantages of passive or solar heating.
| Advantages |
Disadvantages |
| Energy is free |
Need access to the sun 60% of the time |
| Quick installation |
Sun can be blocked by trees and other structures |
| No CO2 emissions |
Need a heat storage system |
| Very low air and water pollution |
High cost |
| Very low land disturbance |
Active systems need maintenance and repairs |
|
Active collectors can be unattractive |
Another problem is that most solar energy designs are designed to heat the buildings, not cool – but there are technologies that can help with this – such as:
- Block summer sun with window overhangs and awnings.
- Use a light-colored roof to reflect as much as 80% of the sun’s heat.
- Suspend reflective insulating foil in the attic to block heat from radiating into the house.
- Place plastic earth tubes into the ground where the earth is cool year-round. Tiny fans can pipe cool air into the house when needed.
- Use geothermal heat pumps.
Can solar energy be used for high-temperature heat demands – such heating water and generating steam for electricity?
It can, but there are trade-offs.
| Advantages |
Disadvantages |
| Moderate net energy |
Low efficiency |
| Moderate environmental impact |
High costs |
| No CO2 emissions |
Needs back up and storage systems |
| Fast construction (1-2 years) |
Needs access to the sun most of the time |
|
Vulnerable to sabotage |
|
Land use that could be used for other resources |
Solar cells can be used to produce electricity directly. This electricity can be used directly within the building or stored for later use. This electricity can be connected to the grid and some countries require power companies to purchase excess electricity produced by homes placed on the grid. These solar cells have no moving parts, are safe and quiet, require little maintenance, produce no pollution, and last as long as conventional fossil fuel and nuclear energy sources. There are some issues…
| Advantages |
Disadvantages |
| Fairly high net energy yield |
Need access to the sun |
| They work on cloudy days |
Need storage and back up systems |
| Quick installation |
High costs |
| Easily expanded or moved |
High land use |
| No CO2 emissions |
DC current must be converted to AC |
| Low environmental impact |
|
| Last 20-40 years |
|
As many already know, Florida Power and Light has already invested in this technology – as has the U.S. military. In our next article we will look at producing electricity from the water cycle.
References
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
by Rick O'Connor | Aug 25, 2025
Over the last couple of articles, we have seen how humans moved from a wood-based energy source to coal and from coal to oil. With the onset of the industrial revolution, new innovations such as electricity and transportation, our energy needs have increased – along with our population.
In Part 16 we looked at the advantages and disadvantages of continuing using fossil fuels for our energy needs. We also looked at nuclear energy. Many feel that these pros and cons are sufficient enough to continue with fossil fuels – for now. Others, including some energy companies, believe it is time to look for other alternatives. It is estimated that fossil fuels will last another 200-500 years, and as we get closer to those deadlines, prices will go up. And then there is the concern surrounding the environmental impacts of burning fossil fuels. Enter the renewables.
We can begin by making our homes, businesses, and vehicles more energy efficient.
Photo: UF IFAS
Miller and Spoolman1 begin their chapter on this topic but discussing energy efficiency – the idea of using our current energy sources more wisely and, possibly, extending the deadline. Many of us already use energy efficient appliances, energy efficient building designs, and energy efficient cars. Some of this is forced on us. Some are to help us reduce our energy costs. But this movement has already begun. Data from the U.S. Department of Energy in 2011 stated that fossil fuels accounted for 85% of our energy input. 84% of that energy became unavoidable energy waste (41%) and unnecessary energy waste (43%). Only 9% were converted into useful energy. The incandescent light bulb uses only 5-10% of its energy to produce light, the rest is lost as heat. 94% of the energy in the internal combustion engine is lost as heat. Only 34% of the energy used to burn coal actually becomes electricity.
In 2011 industry accounted for 30% of the worlds, and 38% of the U.S., energy consumption. Miller and Spoolman provide methods in which industry can become more energy efficient.
- Replace energy-wasting electric motors.
- Recycle materials like steel and other metals.
- Switch from low-efficient incandescent to fluorescent or LED lighting.
Many industries have already made such changes.
In 2011, transportation accounted for 67% of the oil consumption in the U.S. During the 1970s the federal government began requiring fuel efficient cars and trucks. Fuel efficiency increased until about 1985 were it peaked – it has remained at this level since. Though vehicles are more fuel efficient than they were in the 1960s, U.S. consumers still prefer large trucks and SUVs to more fuel-efficient vehicles. There has been recent interest in electric vehicles. But recent reports suggest some automakers may be reducing their inventory of such cars and trucks.
There is a whole new industry in energy efficient buildings – “green buildings”. Most of our buildings were not designed with energy efficiency in mind. For those there are some things we can do to improve energy efficiency.
- Insulate and plug leaks. Over 30% of American homes lose their heated air through holes, cracks, and single paned windows.
- Energy efficient windows. This can reduce heat/AC loss by over 50%.
- Use more energy efficient appliances.
- Use more energy efficient lighting.
Other suggestions within the home include;
- The attic. Hang reflective foil to reflect heat. Use a house fan. Be sure attic insulation is at least 12 inches thick.
- Install water saving toilets, faucets, and shower heads. Repair water leaks.
- Use microwave as much as possible. Run only full loads in the dishwater and use low – or no-heat – drying. Clean refrigerator coils regularly.
- Other rooms. Use compact fluorescent lighting and LED lighting. Turn off lights, TV, computers when not in use. Set the thermostat as low as possible in the winter, and as high as possible in the summer. Weather strip and caulk doors and windows. Use fans.
- Plant trees to shade/cool house.
In our next article we will begin looking at new forms of energy that could replace fossil fuels.
References
Miller, G.T., Spoolman, S.E. 2011. Living in the Environment. Brooks/Cole Cengage Learning. Belmont CA. pp. 674.
