Thursday, March 12, 2009

The obstacles to Alternative Energy implementation are in our heads. Are they?

Everybody is talking about how the economy is affecting the inertia of Greentech by (a) limiting investment and (b) having to compete with lower fuel costs

I believe that we are closer to implementable solutions than what most people think and I will try to make the calculations to prove this point. Please feel free to correct me wherever you think I might be wrong (I am no expert on this specific subject).

The average home in the US consumed 936 kWh per month in 2007 (according to the US Department of Energy), that represents $99.70 spent per month in electricity ($1,196.40 per year).

If we were to buy an alternative energy technology we could spend in that technology the equivalent capital for which annual payments equal $1,196.40 (for interest and principal – mortgage style)

Let’s assume we can get a loan at 4% for 20 years. The capital for annual payments of $1,196.40 at 4% over 20 years is $16,259.47 (at the end of 20 years the debt will be zero).

Now, let's see what we can afford with this money!

Perhaps we could buy a wind turbine. In order to calculate the capacity (and the cost) of a turbine able to cover 100% of our energy needs we need to bring the monthly kWh into a 10 hour day wind energy production. Therefore, 936 kWh divided by 30 days gives us 31.2 kWh per day. We then divide by 10 hours and obtain 3.12 kWh (per hour). In short, we need to generate 3.12 kWh for 10 hours every day to cover 100% of our electricity needs (this is achievable in almost any state with wind turbines that have a 5 m/s or 11MPH minimum wind capacity)

After a lot of web searching I found that the cost of a 3.5 kW wind turbine runs around the $12,000 mark (installed). There are additional charges for maintenance, but the "extra" $4,259.47 (remember we had $16,259.47 as total capital available) should more than suffice for those expenses.

An alternative for the wind turbine is solar power. In this case we need to convert the 31.2 kWh per day into 5 hour days of sun. Therefore, we need 6.24 kW solar panels tied to the grid (31.2 kWh per day divided by 5). According to my research these will run for around $40,000 ($23,740.53 over our budget)

But wait! We have not counted the rebates and incentives we could get from state and federal entities. I do not have enough time or energy to calculate the applicable rebates, because each county and each state and each technology has a different rebate quantity and procedure. I will risk saying that the available rebates range between 20% to 50% (perhaps making the solar panels affordable!)

Can the same principle be applied to water? Could we start by calculating the cost of water and sewer in a typical house and then find technologies that could replace either the water sourcing or the waste water removal service? The answer: I don’t know (perhaps I will explore this in a future article)

Some of the comments I got from last week's Energy Storage:

"I believe pumped-storage hydroelectric has and is being used. I remember Northfield Mountain in Massachusetts being the first that I had ever seen. Here's a Wikipedia link describing the technology and current sites using it: click"

"The gravity part is the easy part, I suspect. You will need to either find a natural land formation where you can store the water, OR, you will have to build a vessel. Perhaps that is the hidden cost. Also, you have to consider the efficiency of the system... First the primary renewable energy source cost and efficiency, then the pumping uphill efficiency, and finally, your hydro-electric generator efficiency -- that is a lot of steps and the overall efficiency, which is multiplicative, perhaps turns out to be dishearteningly low."

"This approach was implemented in Bath County, Virginia back in the 70's. It apparently worked quite well. However, it was implemented to utilize the electricity produced by coal fired turbine plants who produce a steady stream of power by day and by night, but where consumption was lower at night. So, they kept the plant at the same production level at night and used the electricity to pump the water back up the mountain above the hydro electric plant."

"The pumped hydro system suffers when you increase the scale. As the volume of water increases, the system becomes more expensive"

"That is what is being planned for Norway where there is a large hydro power industry - they are looking at having offshore wind turbines working continuously to drive pumps to release the power for peak shaving in Europe thru interconnectors."

"Last weekend I heared about a Spanish project were they haul up on a slope an 80 ton heavy concrete block when the wind was blowing, letting it make electricity when there was no wind! It is like the old clocks were you wind up the weight every day"

" It only makes sense when there are significant elevation changes, and most solar and wind farms are in the flat lands"

"1 cubic meter at the top of a 100 meter tower has a potential energy of about 0.272 kW·h for example lead-acid has power density around 100W/liter"

"A number of companies are looking at this, as well as compressed gas storage, flow batteries, etc. It looks like the maximum efficiency for pumped hydro is between 70% and 80%. Initial capital outlay for building the facility is high. It all depends on the price of fossil fuels and carbon credits..."

"Pumped hydro is severely limited in further deployment (we already have 20 GW of it in the US alone). Here's why: *Locations that have the requisite topography are very rare. *Safety issues regarding the construction of an upper aquifer at height are very real and, for the most part, insurmountable. *The politics of water make it almost completely impossible for new projects to launch. *The efficiency of pumped hydro is, at best, 78%. Batteries can achieve 85% efficiency. Right now the capital costs of batteries are far higher than pumped hydro. But placing a bet on battery prices falling due to economies of scale is smarter than placing a bet that some community somewhere will allow its water system to be interfered with."

"When I worked for an electric utility we had two pumped storage facilities that worked well but had the many of the problems indicated in previous posts. Another promising storage medium is compressed air energy storage (CAES) where air is pumped into an old salt mine (like the ones under several Great Lakes cities) and released to generate power. Like pumped hydro, the pumps turn into turbines and the motors turn into generators"

"Moving water from one place to the other in the wild raises all sorts of environmental questions. Better not done"

Until next week: SHALOM!

Tuesday, March 3, 2009

Energy storage

The best way to store energy is gravity.

You heard right! The best way to store energy is perhaps by pumping water upstream (or up to a large container) and letting Potential Energy take over.

If this is the case then, why are we not setting up renewable energy plants next to water sources and pumping water upstream? to then have hydro-electric generation to recuperate the stored energy?

Is it that we are not yet producing enough renewable energy to have to store it? or perhaps its the fact that no one has been able to coordinate power source, high storage and water source?

I have heard a million times that the biggest obstacle to renewable energy was power storage. Everyone points to the battery to be the "next big thing" in clean energy. Why is gravity and potential energy left in the dark?

In the previous weeks I wrote about the electric grid, one of the biggest dilemmas on power generation is weather to have local or centralized power. Many people responded to my post and the more I heard the more I am leaning towards distributed power generation. With distributed power it will be more feasible to have a "full renewable system" in place.

In a "full renewable system" energy generation is not a stand alone solution. We could have power generated from wind (for a small group of houses) and a reservoir to pump water up when the wind provides more than the necessary power. In change, we could use the water reservoir to generate power in low wind conditions and also as a receptacle of recycled water from the same community. This way we will link water recycling with power generation: True Sustainability!


Perhaps this is not the right combination of green technologies, perhaps there is a better formula using solar power and water heating solutions. The point is that we are very limited if with think of solutions in a one dimensional aspect (e.g. power generation) versus thinking on multi dimensional levels (e.g. the "full renewable system").

Here are some interesting comments from last week's question regarding the power grid:

"The growth of micro-wind turbines built as vertical axis turbines and mounted onto roof tops of commercial office blocks will do a lot for distributed power"

"Interestingly there have been some recent developments in high voltage dc systems - to ship power between different countries - but so far it's still not a proven technology as far as I can tell."

"The driver for sizing a power plant is the historic consumption and projected consumption for the future. Really it is based on the power markets in the area and pricing. Another large driver is transmission availability"

"I think that the crux of the problem is that you can't have a generator without a load, you can't put power into the grid that no one is going to consume, you must have always a load, that is the reason for having a smart grid that switch on more generators when the power requested from the grid increase and switch off the generators when the requested power decrease."

"Electric grid operators and power plants try to meet the demand of a given region but the real factor is cost and time to bring on new power plants and resources"

"Perhaps DC is the answer to all who are concerned with the fact that you can generate wind power, but you cannot get it to where the heavy electric load is located"

"There is actually a high-voltage, high-power DC line running from the Bonneville Power Authority in the Columbia Gorge to California"

"Generally, there are two types of power plants. Baseload and Peaking. Baseload plants, as you would expect, tend to run at full or nearly full capacity all the time. They tend to be designed for steady efficient power output, like a diesel truck engine. The peakers tend to be less efficient, sometimes much less, but can start up quickly and operate over a wide range of output levels. The respective capacities reflect the somewhat local needs for each type of power. Big transmission can modify that, but only within limits unless you go to.... DC transmission. This IS in use around the world, including the US. The limitations tend to be in the costs of converting from AC to DC and back to AC for final delivery so you only want to use it (generally) for long haul applications"

"Capacity of a power plant to produce power is defined by the total of the MCR (Maximum Continuous Rating) of each of the generators installed at specific conditions. The capacity needs of the power plant in the old regulated days was the capacity required to exceed the predicted load plus an allowance for the shutdown of one or more of the largest generators. This typically meant that 5 to 10 % of reserve capacity was to be available on the peak day to meet the peak load. This peak load is much smaller than the total of all potential loads installed by the various users including homes, businesses, and industry. For example a typical home will only use 10 to 15 % of all the capacity installed within the home on average. The peak demand might be larger and will coincide with other users peak demands on very hot days in the summer. The challenge with matching the electrical production with demand is that the transportation system does not store the electrical energy. Fossil fuel transport systems including natural gas pipelines or even the fuel tank in your car have considerable capacity to buffer difference in production and demand"

"The amount of power generated must exactly match the amount of power being consumed (used or wasted) or the mismatch will increase or decrease the system frequency. The frequency difference is usually very very small but still everyone tries very hard to prevent it. The utility or Independent System Operators (ISO) power dispatchers have a good idea (from historical data and from weather forecasts, etc.) how much power they will need and the time of day they will need it. Then they go to great lengths to measure how much power is going into their bulk power stations, how much is flowing in or out of their interconnection lines and how much is being generated at each plant and by each generator connected to their part of the grid. All of this is fed into a system modeling program in a computer which determines how much power should be generated for the next few seconds and which generator in which plant can generate it most economically"

"Actually, there are quite a few DC grids in the world. Most are found in Europe. On the distribution loss side, DC does not suffer skin effect loss so it does have an advantage there. With the advent of modern DC conversion technology, the argument that it is "harder" to convert DC levels has lost some of it's basis. Finally, after all of the conversion, distributions, and storage - the critical loads are always DC."

Well, I believe this is enough reading for one week. Until next week: SHALOM!