The Engineering News Record(ENR) last week wrote an informative story about renewable energy. They focused on how the renewable energy generation has matured and some of the problems the industry has had as it has expanded. The three types of renewable energy that were investigated were wind, solar and geothermal. I was surprised to find out that wind energy has the most sustained momentum with regards to growth as well as operations, while solar represents a small fraction of the energy portfolio.
Here are some of the things I really found interesting.
- Wind: The steel towers have grown exponentially in size, with their fiberglass-reinforced rotors increasing from 10 to 120 meters in diameter since 1981. Safety is now an issue because the workers constructing the turbines are working in a more dangerous environment.
- Solar: Photo Voltaic efficiency ranges from 8% to 22%, depending on the cell’s architecture. SunPower last month announced it had produced a full-scale, 5-in. prototype cell that is 23.4% efficient, claiming a world record for a large-area solar cell.
- Geothermal has high start up costs but benefits from cheap generation costs. They are estimated to be 5¢ to 7.5¢ per kilowatt-hour. Estimates for the new nuclear plants can be more than $6,300 per installed kW.
In California much of the renewable energy comes from the Mojave Desert. Grassroots coalitions formed to fight the projects. One group, the California Desert Coalition, opposes the Green Path project and points out the people who will be most directly affected by the project will benefit the least.
Photo by Brionv
2 comments:
This is a great summary of the subject. The problems with transmitting green energy to the consumers is evident, and as a long term solution I think that we need to shift the focus from building large industrial solar, wind or geothermal "farms", to a smaller, individual energy harvesting equipment. In the future, each consumer should produce most of his energy by himself, using a roof solar panels or near-by wind turbine. In that way, we will solve the transmission problem,and we will save many public lands from being covered with solar panels.
Hi Charles -
Thanks for the article. I think some clarification is in order because there has been some misinformation about our energy needs and options in the press.
First, the transmission situation is much more complex than the utility industry says, and there are many options for addressing transmission problems then just building new lines. For example, existing transmission lines can be used much more efficiently than utilities say. A utility group just released a study required by the State of Minnesota that found that 600 MW of wind energy could be installed on existing power lines in the state without the need for any new lines or upgrades, and this after years of utility insistence that this was not possible. Moreover, the study indicates that some simple, inexpensive transmission equipment upgrades could increase the amount of wind energy installed in the state much more cost effectively than building whole new lines.
Further, sometimes transmission lines are "constrained" because of how the contracts to use them work and not because they are actually running at capacity. Thus, a big fossil fuel plant might have contracted for firm rights to transmission capacity and use only a portion of those rights a substantial amount of the time, such that renewable energy cannot use this capacity even when it's not used. This is a problem with regulation and bureaucracy that tends to result in building more lines.
Also, transmission line capacity is based on how the heat of transmitting power affects them, but heat build up is highly dependent on daily weather conditions. Ever since transmission lines were first rated their rating has been based on a worst-case climatic assumption, regardless of the actual conditions. This is called "static" rating. Now, a number of companies make affordable equipment that can measure real-time transmission line capacity so that we can use a line's physical capacity more fully. If this real-time capacity is measured a line can have be rated using what is called a "dynamic" rating. The distinction between dynamic and static ratings is important for wind energy development because when the wind is blowing and turbines are spinning, the wind is also cooling the transmission lines thereby allowing them to carry far more capacity then their "static" capacity. A DOE engineer said that this could be up to 60% more capacity, but perhaps 25% to 40% is more probable. Given the size of the investments in large transmission lines and their costs, it makes sense to use them as efficiently as possible.
Many areas of engineering have learned how to get more out of less, because this saves money and resources. Vehicles are lighter, electronics are more efficient, etc. We need to use intelligent engineering to make sure that our existing transmission system is used efficiently, rather than just build new lines using old techniques and technology.
The reason that the utility transmission sector has been so slow to innovate is because utilities make a lot of money on new transmission lines and less on using what they have more efficiently, so they have a strong incentive to build new lines. Unfortunately, this perverse incentive structure means that ratepayers and the environment tend to lose.
Also, I suggest caution in putting too much credence in complaints about the lack of new transmission capacity built in the past couple of decades, because this lack of new construction is part of past normal utility building cycles. Essentially, the utility construction cycle is "lumpy" (this is the industry’s word for it). By "lumpy" they mean that it is not built incrementally but in big blocks of equipment. In the past, most power was generated by large central power generating stations that required large transmission lines. So, what would happen is that when a utility decided it needed more power it would build a big power plant (or two or three or more) and then also build all the transmission capacity needed by this new generating capacity. This all happened at about the same time because of the interconnected nature of transmission systems. If a big change is added anywhere in a power system, many other things needed to change as well, and the impacts of big changes can ripple for many hundreds of miles in all directions. As a consequence, the utility industry built a great deal of new capacity in the late '70s and early '80s. The downside to this sort of development is that the new power plants and transmission lines needed to be sized to accommodate growth well into the future, such that when the new equipment was first brought on-line only a small portion of its capacity was needed. Now, after decades this excess capacity is being used, but new technology and more expensive energy indicate that this "lumpy" process is no longer the best approach to power system capacity management. This "lumpy" growth is financially inefficient (it cost ratepayers a lot of money) and it doesn't address the reality that many forms of renewable energy can fossil fuel power can now be installed incrementally, and that our technology allows us to use power and transmission lines more efficiently.
So, there is a paradigm shift going on here, but the utility industry is resisting it because it could keep more ratepayer dollars in ratepayer pockets.
Further, while some press alleges that the opposition to the transmission lines in southern California is based primarily on concerns about impacts to nature, this is simply not true. Impacts to nature are one reason, but the primary thrust of the opposition's arguments is that it will be cheaper and less impactful to install "in-basin" power generation capacity (of many types) using new technologies and the new paradigm described above rather than build generation far away AND a NEW $1.5 billion transmission line. This way, San Diego can get less expensive more reliable power while helping the environment.
Recent technical advances in solar PV mean that the price is coming down rapidly. Importantly, this price is getting low enough to be cheaper than solar power generated by big solar farms in the desert, many of which also require cooling water. Moreover, since each of us can own solar PV we can also benefit financially from this ownership.
When one looks at the entire cost of these competing options, the in-basin alternatives are simply less expensive and more reliable than out-of-basin alternatives. You might want to check out San Diego Smart Energy 2020, a plan prepared by a power engineer on behalf of local citizen groups:
http://www.sdsmartenergy.org/20-may-08_Smart%20Energy%202020_2nd%20printing_complete.pdf
Southern California Edison (SCE) recently announced a 250MW solar PV project, similar to what is proposed by Smart Energy 2020 plan, it's just that Smart Energy 2020 proposes how to expand the model shown by SCE's individual project into a regional plan that can meet regional energy needs.
Also, some say that we need to have all types of renewable energy. I think this is a somewhat simplistic statement. Obviously, some type of renewable energy work better in some locations than in others. Also, we should use our renewable energy dollars wisely as they are not unlimited. In other words, while we need to study all options, we should plan to use the most appropriate and cost-effective options and not just fling resources willy-nilly at all options. Thanks for listening.
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