Green Zephyr Co.Ltd ™

Renewable Energy Capture, Transformation & Storage

 All fossil fuel sources (oil, coal, gas) are finite and will run out. The same applies to materials required for nuclear fission energy sources (Uranium etc). Expect total depletion in 100 years max. Low grade coal in difficult extractions may last longer.

Bio fuels (wood, ethanol, bio diesel, biogas) are one way of RECTS without releasing new fossil carbon into the atmosphere, but attention is required to ensure that there is actually a net energy output (output exceeds input); and a balance with food cropping land requirements is maintained. Bio by-product from other processes and effluents which may otherwise be wasted (producing rogue methane) are the most attractive sources.

The poor efficiencies in hydrogen production and utilisation, along with difficult storage make this "media darling" a specialized-only solution for power generation storage, and similar problems exist for it as a transport fuel.

In evaluating potential RECTS contributors, a close eye must kept on in-built demand for, or dependence on, other "buried treasure" materials such as platinum (hydrogen) and vanadium (flow batteries). These may render the solution a limited life, and an environmentally difficult present.

It is of course possible to capture usable energy from opportunistic renewable sources (wind, wave, tide, ocean currents, rainfall, snowfall etc). Two of these (rainfall/snowfall) are already well served by hydro storage for subsequent electricity production on demand. Wind, which is the most volatile opportunistic renewable, can be partnered with hydro storage generation on an either/or basis where hydro makes up the short-fall in wind generation.

Wind fluctuations are more rapid than large hydro or other contingent generation can contend with, so that some trimming and dumping of wind power potential is still required (or a larger non-generating variable/switchable "spinning reserve" of wind turbines maintained) to smooth the output adequately.

Most of the negative publicity surrounding windpower generation (other than visual) relate to the variability of output and non-guaranteed output. this can be mitigated over short to long time scales by introducing more and more storage. The storage mechanism itself, however needs to be dynamically suited to wind variability and available in bulk. Major hydro currently fills this role by default, but the dynamic matching is poor, and the connection between too long.

Intrinsic embedded storage is required at the wind turbine, preferably on a flow-through basis allowing full integration and averaging. Side-arm overflow and reinjection storage mechanisms can work if dynamics match, but control is more complex (storage may however be smaller for the same effect).

It is possible to use electrically pumped hydro storage to adsorb excess wind power generation to raise water on hydro dams when supply exceeds demand. This is later used to make up shortfall if wind drops or demand increases. This is an example of a side-arm mechanism. The round-trip efficiency of the stored/destored component is reduced by the number of steps involved.

Batteries (various types) and flywheels, already serve to dynamically match wind turbines to diesel contingent generation in small "island" grids, but do not scale up (presently) as practical bulk storage.

Compressed air systems may one day be the common bulk energy storage. This technology is currently in its infancy as far as systems and equipment are concerned, with most requiring combined natural gas (or other thermal fuel) to partially assist the actual generation step following the destorage. Real progress may depend on development of air pumping wind turbines (no electrical intermediary) with a recycle of compressing heat directly to drive assistance. Useful deployment of some of the cooling effects associated with multi stage expansion reheat are also required for full viability (refrigeration and airconditioning). This in affect creates a whole new utillity with in-transit storage. Offshore wind generation could be an early uptake since landing and injection could benefit in practical terms as well as in storage effects.

Short/medium term some experimentation with embedded flywheel technology onboard wind turbines can be expected since any decrease in output variability can reduce electrical generator size required. The constructors have demonstrated mechanical capabilities giving some confidence in outcome. The short term 1 to 5 minute storage capability is still a major step forward from present.

In the immediate term however, storage of energy is in raised water, since the destorage and generation mechanisms either already exist (existing hydro-dam) or are purchasable as mature technology.

What was required was direct step wind-power-to-water-pumping without any multi step losses. While wind pumping of water in itself is hardly a radical concept, what was missing was a means of integrating much higher than normal wind turbine density with an onboard water storage capability; built in simply engineered modular cell format; allowing most economies to participate in local manufacture and assembly.

Hence was born the "Energy Storing Wind Dam" (ESWD).