Tidal energy is little used around the world. In order for electricity to be generated, differences between high and low tides must consistently reach 16 feet. There are few regions in the world where this occurs. There are currently no tidal energy facilities in the United States although there is potential in the Pacific Northwest and the Atlantic Northeast.

Harnessing Tidal Energy.

Barrage or Dam. There are only three barrage tidal plants in the world. Essentially, a barrage is built which forces tidal flows through turbines, creating electricity. When the water levels on both sides of the barrage are significantly different, gates are opened, allowing water to flow through and activate the turbines. The Rance Tidal Plant in France is a prime example of the barrage method of tidal energy.

Tidal Turbines. A relatively new technology, tidal turbines are very similar to wind turbines but underwater. They are positioned strategically at entrances to bays or rivers, among others, where currents are fast. Because seawater is much denser than air, a single tidal turbine can produce significantly more energy than a wind turbine of the same size.

Environmental Impact.

Tidal energy is a renewable resource, but the classic, barrage method of harnessing tidal energy has some negative environmental impacts. Most notably, tidal power plants upset fish migrations and, by disrupting water flows, can upset entire estuarine ecosystems. Tidal turbines however, because they do not block water flow, may be a viable answer to these concerns.

How Tidal Compares to Solar.

Tidal turbines are a very efficient source of energy, and that is an advantage over solar to this point. However, there are only 40 locations in the world where tidal power is feasible. The sun shines everywhere. Nonetheless, they are both certainly part of the solution. While I support solar energy wholeheartedly, tidal power could be a great source for green energy. Especially for northern coastal regions where the sun is not as prevalent. I live in Oregon and I’ve personally witnessed the dramatic turn of tides (I’m talking about starfish clinging on at eye-level during low tide!)

image credit:Tidalstream Partners

1. Determine the type of panels you need. There are two main types right now: PV, mono-crystalline panels and thin-film, amorphous silicon panels. The former have the higher efficiency at the moment, which may be necessary if you have a small roof space. The latter have the aesthetic value, especially if you have a large roof space or partial shading. Yet efficiency is not the only factor. Your location, climate, position relative to the sun, and roof type are just some.
2. Panel certifications will be vital to getting approved for state or federal rebates. Many states have a certain set of standards which all solar panels must meet. These standards will likely vary in some way from state to state. You can check this site to find your state’s incentives and appropriate links to find solar panel requirements.
3. Calculate your needs. Grab your past electric bills out of your files. You can use these to calculate your daily energy usage. Different solar panels have different outputs in watts. Using available space and panel output, you can figure out which panels and how many of them you’ll need.
4. Mounting system. Depending on the pitch of your roof and the position of your home, you may choose a ground mount system. This will mean PV panels and some extra money for the mounting system itself. However, you will have the advantage of choosing the proper tilt and, if you so choose, a solar tracker to follow the sun across the sky.
5. Warranties are a vital factor when buying panels. Solar panels require very little maintenance and use no controls to run. Therefore they have very long lives and usually come with substantial warrantees. When comparing solar panel providers, check their warranties against each other. It is not atypical for panels to have a 25 year warranty.

So is nuclear power clean? Is it sustainable? How does solar power compare? These are just a few questions that immediately popped into my head. So now, I’ll try to answer them:

Is Nuclear Power Sustainable?

Nuclear Power, which is derived from the fission of uranium, plutonium, or thorium, is sustainable in that we have hundreds to thousands of years of usable uranium available. Although, I imagine that number might diminish over the years as demand increased (especially if we were to adopt nuclear as our primary power source). I should note that nuclear energy is not a renewable energy source…it’s just that there’s a lot of it.

Is Nuclear Power Clean?

Nuclear power, in terms of carbon dioxide emissions, is quite clean. It does not directly emit any greenhouse gases. However, the nuclear fuel cycle produces them indirectly, but at a drastically slower rate than fossil fuel sources.

Much of the debate over nuclear power has surrounded waste disposal. In the U.S. the solution has been to box it up and store it beneath the state of Nevada. This waste ranges from high-level to low-level waste, high-level being the stuff we all hear about, and low-level being clothes, gloves, materials used in the power plants, and other items exposed to radiation. Uranium can be reprocessed (for the plutonium) and used as a fuel in the plant itself. However, it is this reprocessing that facilitates the making of nuclear bombs.

How does Solar Compare to Nuclear Power?

Solar and Nuclear power each have their advantages. Although, at this time nuclear power would probably run away with the trophy if not for the environmental and political holdups. Here are their respective advantages, as I see them:

• Nuclear
  • would have an easier transition to a centralized grid system.already provides a good portion of our electricity
  • does not emit greenhouse gases
  • plenty of resource available
  • presently cheaper than solar power

• Solar
  • is a renewable energy source
  • available to anyone with a home (ignoring cost inhibitions)
  • has no volatile waste (other than panels which could likely be recycled)
  • several emerging technologies that can improve efficiency and central station generation abilities.

These are the advantages, put simply, that I can see right now. There are proponents of one, the other, or both. I see a brighter future for solar for three reasons:

1. It is completely, even daily, renewable.

2. Solar is fast advancing. We are likely on the cusp of a technological windfall for solar power.

3. The risks for nuclear power are high and unlikely to get resolved soon. So far it seems that, in an attempt to stop polluting the sky, we would throw our toxins into the ground.

Ethanol is the same type of alcohol you’ll find in your beer or whiskey. Ethanol, as a biofuel, is relatively easy to manufacture and process and is a native crop to the Americas; perhaps why you find it blended with gasoline at pumps across the nation. Ethanol can be produced from sugar cane and maize (corn). Logically then, it is no surprise that the United States (corn) and Brazil (sugar cane) are the far-and-away world leaders in ethanol production and use.

So, if ethanol is a biofuel and, when it is burnt, does not give off greenhouse gases, why is there so much controversy surrounding it here in the United States? The first and most recognizable reason is that it requires so much arable land to grow that it competes with corn used for food. Secondly, the life-cycle of ethanol is not as green as you might think. Corn ethanol has a rather mediocre energy balance. In other words, for every 1 unit of fossil fuel energy put into ethanol’s production, only 1.34 units of energy are released when the fuel burns. There is minimal displacement of negative energy. To be fair, there are contradictory reports regarding ethanol’s energy balance. Nonetheless, I have found none that are exceptionally favorable (although ethanol produced from sugar cane has a much better energy balance (1:8), check out Brazil’s fascinating achievements.)

For these reasons ethanol has fallen out of favor with many clean energy supporters. But don’t count it out just yet. Cellulosic ethanol, a biofuel made from wood, grasses, and non-edible portions of plants, may be the fuel’s saving grace. This type of fuel can be made from corn stover (corn stalks and leaves) and wood chips. In other words, it need not compete with the food supply and reduces greenhouse gas emissions by a considerably higher amount than standard corn ethanol.

So what about solar energy and ethanol? At this point in time, there is not much competition between the two. Ethanol, in some form, is already poised to be a big source of fuel for cars. Solar energy can also power cars and, as you can imagine, in a very clean way. But as of yet solar cars are still very much a niche market, if a market at all. They are reserved mostly for competitions and university studies, although some car makers are getting ready to put solar powered cars in storefronts around the world.

For now, solar and ethanol are both working toward the same goal. There are cleaner sources of biofuels, such as biodiesel, and but for cellulosic ethanol I might claim ethanol as a dying fuel source (at least in North America). But we shall see. At this point in time ethanol, and biodiesel, represent ways to clean up the millions of existing cars on the road while solar cars may become our grand transition to eco-friendly transit.

With just some plastic sheeting, salvaged lumber, and scrap parts from an old gas furnace, the two men built the system in just a few weeks. Using the south-facing wall of the shop, and battling temperatures that often fall to near-zero degrees, their simply-designed heating system can provide nearly all the heat necessary to work comfortably in the shop, even on the coldest of days.

They detail the building process step-by-step and really do a great job of exposing the feasibility of the project. They kept the project inexpensive and effective through four “secrets:”

1. Use the south-facing side of the shop for the collector.
2. Use cheap plastic film instead of glass or plexi-glass as glazing.
3. Do not use any heat storage system.
4. Salvage as much product as possible.

For a detailed description of the work and to learn how they succeeded at following their four secret rules, check out the full article at Mother Earth News.