Daily Archives: October 14, 2018

Tidal energy

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Tidal energy is a type of hydropower that depends on the kinetic energy in the tides to create energy, mostly for electricity. It works by taking advantage of the rising and falling of the tides. During high tide, the rising water spins turbines and as the tide goes out the turbines spin again and collect the kinetic energy from the water. Currently, the Sihwa Lake Tidal Power Station in South Korea is the largest tidal power installation. The Sihwa plant has a total power output capacity of 245 MW. Because collecting tidal energy depends on the gravitational pull between the earth and moon, it is a renewable energy and will not run out.

Tidal energy, however, has many downfalls. The equipment is very expensive initially, although it can be installed on already-present buildings in the water such as bridges. Another downside is its possible negative affect on marine life. Fish and animals may get stuck in the turbines, or they could also be affected by the noise generated by the turbines, if they depend on echo-location. However, this does not affect the entire water supply, just in the proximity of the equipment.

Although tidal energy is not going to be our primary energy source anytime soon, technological advances may make the economical and ecological cost go down soon. Tidal energy may be worth the investment of research because tides are more constant and predictable than other alternative renewable energy sources such as solar or wind energy.

Going Nuclear

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Theoretically speaking, nuclear energy seems like the perfect alternative.

Let’s not get into the confusing physics behind it too much. You take “stuff”, and you either smash it together to make larger stuff (fusion) or you split it up to make smaller stuff (fission). That’s about as simple as I can make it.

But there’s a catch: nuclear energy production produces waste. And it has the potential to go really, really wrong.

Nuclear energy doesn’t just produce waste, it produces radioactive waste. And right now, our solution to what to do with that radioactive waste is to store it underneath a mountain in the middle of nowhere. Seems sustainable…

Additionally, we’ve all seen some of the catastrophic consequences of nuclear energy generation gone wrong. Three Mile Island, Chernobyl, Fukushima.

In terms of energy produced compared to resources devoted, nuclear energy does seem perfect. After all, it seems like there’s an endless supply of “stuff”. A study conducted by the World Nuclear Association finds that energy devoted to production represents a mere 1-3% of the total energy produced post-production.

The issue, of course is long-term feasibility and sustainability. It seems like the perfect alternative until it goes wrong and leaves a no-man land of 1000 square miles in its wake (Chernobyl).

Despite all the benefits, the return on resources, the endless power generation, the effects are simply too severe for nuclear energy to be a long-term, sustainable alternative energy source.

Ultimately, ask yourself: Would you want a nuclear power plant near your town?

Geothermal Energy Production: Not the Most Sustainable Option

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I learned a lot about geothermal energy production through my mini-term to New Zealand. There, geothermal energy is ideal because of New Zealand’s geographic location, which is located near where two tectonic plates meet. Geothermal energy production works via using the heat and thus energy from inside the Earth to make power. This works by pumping geothermal fluid out of the ground, converting the heat into steam, and having this steam go through turbines and turn the turbines so create energy. This is done on a large scale in New Zealand to create electricity, but there is also smaller-scale geothermal energy that people can use to heat their homes. The New Zealand geothermal practices are so successful due to the location near tectonic plates that have heat closer to the Earth’s surface, which means that other locations are much less ideal for geothermal energy production and make this practice less efficient. Geothermal energy production can be quite problematic due to the geothermal fluid itself–prior to the late 1990s, geothermal fluid was dumped into rivers after the fluid was used to create steam. This ended up polluting a lot of rivers and raising the river temperature as well as allowing for harmful, poisonous bacteria and algae to grow in rivers, killing off the wildlife. The Resource Management Act has thus put restrictions on how geothermal fluid is dealt with after the energy production process. Fluid is now pumped back into the ground after the fluid is used, to attempt to recycle the geothermal fluid. This is still quite problematic because the fluid can build up in certain locations and erupt out of the ground. Another problem that occurs is the shifting levels of the ground. When the geothermal fluid is placed back in the ground, this can also contaminate the ground water and thus our crops, since the crops are now interacting with harmful, toxic materials. Pumping the fluid back into the ground can get quite expensive, and the cleanup of the rivers in New Zealand that have been previously destroyed by this practice is extremely expensive. This is definitely not a widely commercialized practice, and I really don’t think it should be (alternatives such as solar and wind power are much better for the environment with fewer negative drawbacks). In terms of long-term sustainability, I don’t see this practice being incredibly sustainable due to the negative environmental drawbacks. However, the fluid can keep being re-used, which is a slight positive when compared to things such as coal burning or fossil fuel usage.

Hydroelectricity–not the future move

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On hearing how important hydroelectricity is to New York State and their green energy initiatives, I wanted to understand what draw backs may come with the sustainable energy option. In the book “Sustainable Energy–without the hot air”, the author explores what is necessary to make hydroelectricity and he states that all “you need [is] altitude, and you need rainfall” (55, MacKay). He goes in further with an anecdote rooted in math to prove that hydroelectricity is not compatible with all countries rain flows, and ultimately their ability to create a sustainable amount of hydroelectricity to account for the populations energy demands.

The country that showcases the shortcomings of this issue in Britain, a country notorious for its’ rainfall, by estimating the gravitational power of the rain in both the low and high lands by multiplying the rainfall, by the density of the water, by the strength of gravity, and the typical altitude of the lands above the sea. Once the calculations for both the low lands and high lands gravitational power of rain, independently of each other, and then added up together, the author was able to show that the limits of the hydroelectric energy production you can create/capture in a day is 1.5 kWh/d.

This is a minute amount of energy relative to what biomass, solar heating, and wind energy are able to produce about over fifteen times the amount of energy over the same period of time. The author also explains that, “The actual power from hydroelectricity in the UK today is 0.2 kWh/d per person, so this 1.5kWh/d per person would require a seven-fold in- crease in hydroelectric power” (56, MacKay). Hydroelectricity seems to have some major set backs and ultimately seems like an investment of time and energy that may not be worth it fiscally compared to other renewable energy sources.

Efficiency of wind turbines

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One of the largest ways of creating wind power is through wind turbines. To generate wind power, one needs an apparatus that enables air flow to provide the mechanical power to turn electric generators. Wind turbines acts as an alternative to burning fossil fuels. There are a surplus of wind turbines in this country, they are “renewable, widely distributed, clean, produce no greenhouse gas emissions during operation, consume no water, and use little land.” They are overall extremely sustainable and a wonderful option instead of burning fossil fuels to power generators.

Though wind turbines obviously rely on certain weather conditions, they produce more than enough power for how much they save the environment. A single wind turbine can produce energy for nearly 500 homes. As for cost, “Wind turbines under 100 kilowatts cost roughly $3,000 to $8,000 per kilowatt of capacity. A 10 kilowatt machine (the size needed to power a large home) might have an installed cost of $50,000-$80,000 (or more). Wind turbines have significant economies of scale. Smaller farm or residential scale turbines cost less overall, but are more expensive per kilowatt of energy producing capacity. Oftentimes there are tax and other incentives that can dramatically reduce the cost of a wind project.”

Though this may seem like a hefty financial necessity, the amount of good that these wind turbines are doing for the environment is undoubtedly worth the cost.

 

Wave Energy

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Wave energy forms from wind. The amount of energy is dependent on the speed of the wind. According to the EIA, the annual energy potential of waves off the coasts of the U.S. is estimated to be 2.64 Kilowatt-hours, which could produce 66% of energy generation. There are several ways to channel wind power: Wave energy can be harnessed into a narrow channel to increase their size and power which can spin turbines that generate electricity. It also can be channeled into a catch basin or reservoir where the water flows into a turbine. This is similar to the way a hydropower dam operates.

According to the New York Times, in Western, Australia they have buoys that generate waves into electricity for a nearby military base. The buoys started supplying 240 kilowatts each to the electricity grid for this base, roughly about 5% of its electricity. This is proving to be a successful experiment and source of renewable energy because it does not use any fossil fuels.

The biggest challenge facing wave energy is the cost. If you want to test an idea, it costs millions. Additionally, once generated it is at a cost of 40 cents per kilowatt-hour. While it is expensive, improvements are being made in order to improve the equipment and ensure it is not destroyed by storms. In order to make this a more consistent form of energy used, the government will need to assist in the funding of these projects.

Wood as a Power Source

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For this post, I wanted to look at a power source that has become less prevalent over time, simply because more efficient energy sources have been found.  Wood is the first energy source humans ever discovered and used, primarily as a source of light and to cook food.  It was never intended to power cars, or power homes on a large scale.  Gas, Oil, and Electricity now make up the bulk of our energy, as they are more convenient and effective for our needs.  However, after doing some research, I learned that wood is still the primary power source for a lot of people around the globe, primarily in the developing world.  According to the food and agriculture organization of the united nations “more than two billion people depend on wood energy for cooking and heating.”  In countries where electricity isn’t widely available wood is the easiest source of energy to use, as all it requires is people finding trees and cutting them down.  (Source)

Wood is a renewable source since it is something that is planted and can obviously regrow over and over again.  Using wood as one of the primary power sources for developed countries at a huge scale is probably not feasible.  However, if countries want to use more renewable energy, wood could certainly play a role in this.  According to forestry focus, “wood from sustainably managed forests, when used as an energy source, does not add extra carbon to the atmosphere as the carbon released through its combustion and/or decay is taken up by replacement trees. The net effect is that wood is carbon neutral if it comes from well managed forests.” One developed country, Ireland, is currently trying to increase its reliance on wood as a power source, and is exploring several options to do so.  The Irish government is funding research that looks at how wood can be used on a larger scale logistically, and having test runs on supply chains, alongside promoting the use of wood as a renewable source.  (Source)

Go with the Wind?

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Wind energy refers to the process of creating electricity using the wind, or air flows that occur naturally in the earth’s atmosphere. Wind turbines are used to capture kinetic energy from the wind and generate electricity.

Wind energy projects have created many economic benefits to the U.S.. The projects have created jobs, created a new source of revenue for farmers and ranchers in the form of land lease payments, and increased local tax base. Wind energy can also lower electricity bills for those who neighbor the wind turbines.

In terms of employment, wind energy projects create new jobs in rural communities in manufacturing, transportation, and project construction. At the end of 2016, the U.S. wind energy industry accounted for 101,000 full-time jobs.

The US Department of Energy projects that we’ll have 404 gigawatts of wind energy capacity across the country by 2050, up from 89 gigawatts today. Because the overall electricity demand is projected to remain consistent, wind energy would soon help provide one-third of the country’s needs.

Currently, the major incentive to invest in wind is the renewable portfolio standard, which mandates a minimum amount of electricity to come from renewable resources. Another incentive is the federal production tax credit, which benefits wind energy installations across the entire country. Overall, wind energy is one of the fastest growing forms of electricity generation in the United States, with the largest share renewable electricity generating capacity in the country.

 

Hydroelectricity

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In order to make hydroelectric power, you need altitude and rainfall. Using the power of moving water to generate electricity is the largest source of emissions-free, renewable electricity in the United States and worldwide. To increase the volume of moving water, impoundments or dams are used to collect the water. An opening in the dam uses gravity to drop water down a pipe called a penstock. The moving water causes the turbine to spin, which causes magnets inside a generator to rotate and create electricity. In 2011, hydropower provided 16% of the world’s electricity, second only to fossil fuels. Worldwide capacity in 2011 was 950 gigawatts, with 24% in the China, 8% in the United States, and 9% in Brazil. In the U.S., hydropower is produced for an average of 0.85 cents per kilowatt-hour, and convert 90% of the available energy into electricity (kwh).

Since hydropower depends on rivers and streams for generation, the potential to use hydropower as a source of electricity varies across the country. For example, the Pacific Northwest (Oregon and Washington) generates more than two-thirds of its electricity from hydroelectric dams. The Grand Coulee dam on the Columbia River in Washington is one of the largest dams in the world, with a capacity of more than 6,750 megawatts. Hydropower is a tool for developing countries and can serve as a long-term energy source. However, the flooding of land to create reservoirs can also eliminate areas where people live or grow crops.

Hydroelectricity

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Hydroelectricity uses the energy from moving water to create electricity. Using natural sources of water like rivers, dams and rainfall, hydro power seems to be a feasible option for renewable energy. I found a page that discusses the gravitational power of rainfall in Britain per year. Taking the total amount of rainfall (584 mm per year), times the density of water (1000 kg/m^3), the altitude above sea level (100 m), and the strength of gravity (10 m/s^2), we would get about 0.02 W/m^2 of power per unit at best. This number represents the amount of power per unit land area that the rainfall landed.

(584 mm / year * 1000 kg/m^3 * 10 m/s^2 * 100 m = 0.02 W/m^2)

When we multiply the amount of power per land unit by the area per person, in this region of Britain (0.02 W/m^2 * 2700m^2 / 60 million people) we would be left with about 1 kWh per day per person, at max rainfall. Right away we can see that this is nowhere near the amount of energy needed to sustain even one person for a day.

A major roadblock for hydroelectric power is that it never uses water’s full potential energy due to high rates of evaporation as well as scarcity of hydro power/electric plants. It is clear that hydroelectric power itself cannot power our everyday lives, though perhaps through further experimentation and research we may see an increase in hydroelectricity usage worldwide.