Saturday, May 21, 2016

Brief Info as Distributed at 2016 Maker Faire

Ultra-Linear Hydraulic Accumulator

What is a “Hydraulic Accumulator”? Hydraulic accumulators have been in use in systems utilizing hydraulic oil to power equipment for well over one hundred years. It is basically a reservoir of pressurized oil, integrated into a hydraulic pump and hydraulic motor system to perform heavy-duty work (think backhoe, and other earth-moving equipment, as well as oil drilling/oil platform equipment). The accumulator acts to smooth the oil pressure in the hydraulic system.

There are several methods used to pressurize the oil in a hydraulic accumulator. Most typically, compressed nitrogen gas is used. Note that springs are used, but all these methods (save the weight loaded reservoir) have a problem: power decreases rapidly, if more than 20% of the oil stored is used.

Here is a link to a file published by hydraulics specialist company Hydac description of high-pressure accumulators that use a bladder:

This gives you some insight into what an "accumulator".  Here are two pictures of a large array of accumulators, as well as smaller, varied accumulators:

Bolenz & Schaefer Accumulator Station Image result for hydraulic accumulator pictures

What do you mean by “Ultra-Linear?” Most hydraulic accumulators are small in size. My proposed device would be approximately five feet high, three feet wide, and stretch in a line (not particularly straight, not particularly level) for a half-mile, or more.

Why not use “pumped hydro” reservoirs to store renewable energy? Unfortunately, constructing two large reservoirs to contain the vast amounts of water needed to make an economic system of energy storage, is constrained by geography and geology. Useful sites for pumped storage are almost never near urban centers demanding significant amounts of power. This hydraulic system could be located in straight line locations, such as along metropolitan freeway land.

Why have no hydraulic accumulators heretofore been used to store energy from wind, solar, tidal, and other renewables? Note the drawing above. Most accumulators use compressed gas, and the problem with compressed gas is that it heats up, and energy is lost as the heat dissipates. There are very few places where compressed gas is used to store megawatts of electricity. You have to use springs, or a heavy weight, to avoid Carnot Efficiency losses. Even then, a large volume of oil is required, and converting that oil under pressure to electricity has been not very efficient up to now.

What has changed? Are there more efficient hydraulic motors now?
Enter Artemis Intelligent Power ( By using computer controls, Artemis has achieved 90%+ "Overall Efficiency" (blue line) in converting pressurized oil to rotating power.

Using a rotating generator offers the best quality power for a wider set of businesses and homes.

Where are the springs in your system? I am using fiberglass springs, which outperform steel springs over time. The latest Chevrolet Corvettes use a front fiberglass leaf spring in place of steel, as it gives better performance (millions of cycles before replacement) and weight savings.

Why use leaf springs? The sheets of fiberglass, configured as multiple sheets, give a more constant spring rate if designed correctly. The fiberglass sheet also functions as an enclosure, protecting against weather, as well as performing to store energy.

What about individual battery power in homes? (e.g., Tesla Home Battery) It should prove 25% cheaper to use this “Ultra-Linear” grid-scale system, powering four to five hundred homes for eight hours, than installing individual battery systems in every individual household. The Independent System Operator that distributes utility electricity throughout California could better utilize solar power plants and wind turbine farms if larger entities were consistently available to absorb excessive renewables generation.

System Build Comparison Building lithium batteries requires specialized employees, and high engineering costs, as does the construction of Pumped Hydro facilities. The Ultra-Linear Hydraulic Accumulator could be produced anywhere with limited training, and shipped to urban as well as remote locations (think Western Alaskan villages) where local residents could be trained to both build the system as well as maintain its operation.

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