An Overview on Green Energy Technologies
vZenergy designs and implements systems and products with a focus on the commercialization of Advanced Green Energy and Power System technology. With both, state-of-the-art power conversion systems utilizing inverter, rectifier and DC converter building blocks, and controls and information technology, Green Energy technologies can be integrated into Smart Grid Systems that manage power flow, improve power quality, and provide back-up power. In short, Green Energy technologies can supply intelligent reliable power when you need it.
Energy Systems & Products
Renewable Energy
1.6MW Solar PV Installation at Google’s corporate headquarters. Complements of Suntech Power Systems.
The Earth receives vast amounts of energy from the sun that can be captured in various forms. Solar technologies directly convert this energy to electricity, while wind, hydro and bioenergy technologies do so indirectly. Energy from the sun is limitless for many generations to come; hence it is referred to as “Renewable Energy”.
SOLAR
There are two primary classes of solar technologies for generation of electricity, Solar Photovoltaic (Solar PV) and Concentrated Solar Power (CSP).
Solar PV systems produce electricity directly from sunlight, typically using crystalline silicon semiconductors or thin-film cells based on cadmium telluride or other materials. Crystalline silicon is used extensively in rooftop systems, while thin-film is almost exclusively used in utility-scale power systems. A critical component in these systems is the type of power conversion system used. The power conversion technology deployed has a significant impact on safety, energy production and reliability. vZenergy is a globally recognized expert in power conversion systems, and provides unique insights to its clients on how to maximize project performance.
Concentrated Solar Power utilizes reflectors or lenses to focus the sun's rays on a small area. The resulting heat is used to drive steam turbines or sterling engines, which in turn drive generators producing electricity. CSP systems are typically found in utility-scale power systems in the lower latitudes.
WIND
Civilizations have been harvesting energy from the wind for centuries, to grind grain and pump water. Today, modern wind turbines are efficient electricity generators using state-of-the-art technology, and continue to be perfected to maximize the amount of energy harvested from the wind, improve reliability and lower maintenance and capital cost.
Wind turbines are constructed from light-weight and resilient composite materials and are equipped with sensors that anticipate wind speed and direction changes, altering their yaw, pitch, and speed for optimum power output.
Standing on towers a hundred meters high in either urban centers, open country or the open sea, wind turbines can produce more than three (3) megawatts of power per turbine.
HYDRO
Like wind, civilizations have been harvesting energy from river falls for centuries. Today hydro power is primarily derived from waterfalls alone, but increasingly hydro power is also being generated from waves, ocean currents, tides and the flow of rivers (referred to as “run-of-river”). A number of designs to harvest these various new forms of hydro energy are still in their infancy, but commercial projects are being implemented.
BIOENERGY
Using biomass as fuel is one of the oldest examples of renewable energy, initiated when our ancestors burned wood for heat, light, and cooking. The technology has come a long way with sources for biomass feedstock ranging from municipal solid waste and forestry residue to food crops such as corn and sugarcane, and dedicated energy crops like switch-grass and ecowillow. Rather than just burning the fuel, the biomass is converted to a gas or biofuel using enzymatic, bacteriological, and chemical agents. The Biogas or Biofuel is then converted to mechanical power to propel vehicles or produce electricity.
Each renewable energy technology has its own set of nuances, and vZenergy will provide you with insights to successfully account for these nuances in your power plant design to maximize economic returns.
"The European Photovoltaic Technology Platform estimates that the PV industry has the potential to create more than 200,000 jobs in the European Union by 2020 and ten times this number worldwide."
- European Photovoltaic Industry Association
"Wind power is one of the fastest growing forms of new electricity generation in the U.S. In recent years, around 40% of all new generation capacity added to the electric grid in the U.S. was from wind power projects."
- American Wind Energy Association
Alternative Energy
Block Diagram of a Hydrogen Fuel Cell System Generating Electricity from Natural Gas or BioFuel.
Alternative Energy is a broad term for energy from non-conventional sources that is not renewable. Fuel cells, low-impact combustion engines, and hydrogen systems are often included in this category.
FUEL CELLS
A technology first widely used in space applications, there are numerous types of fuel cell, which produce electricity directly from a fuel. Hydrogen fuel is often used in conjunction with Fuel Cells, but a variety of fuels can be converted such as natural gas and biofuels (fuel cells converting a biofuel would be classified as a Renewable Energy generator). While fuel cells are currently expensive to manufacture, they have the advantage of silent operation with lower harmful emissions compared to combustion engines.
Recent advances in fuel cell design and materials science promise lower manufacturing costs, a wider range of fuels and higher efficiencies, making the fuel cell a viable option for numerous niche applications.
LOW-IMPACT COMBUSTION ENGINES
Under threat, the combustion engine technology is rapidly evolving. Engines today are more efficient, have fewer emissions, and can operate with a number of biofuels. There low-capital cost will continue to make them a preferred choice in many applications.
HYDROGEN SYSTEMS
Hydrogen represents a promising means of storing and transmitting energy, and is often referred to as an “energy carrier” in the same way that electricity is. When converted through fuel cells or combustion engines, it finds use as a fuel. Hydrogen can be readily produced from Renewable Energy sources, and is envisioned as an economical means to consume excess wind or solar power instead of wasting (or shedding) it.
Storage of hydrogen is typically achieved either physically ― under high pressure or in extreme cold ― or chemically, in metal or complex hydrides.
Electrical Energy Storage
To realize on the UN’s vision of achieving 80% Renewable Energy by 2050, Energy Storage will be a necessary component of the Electrical Grid to Balance Intermittent Power Generation with Demand.
Energy storage is a crucial component of any practical electrical power systems utilizing Renewable or Alternative Energy. Energy storage is required to manage power from variable and unpredictable energy sources like solar and wind, and maintain a fixed power output on fuel cells that cannot cycle up or down. There are many Energy Storage technologies, and they are typically classified by duration in which they can charge and discharge energy. Two broad categories are Daily Storage used for power smoothing and energy shifting within the period of a day, and Bulk Storage for storage of energy for use beyond a day. Daily technologies include Batteries, Super/Ultra Capacitors, and Flywheels. Bulk Storage includes conventional Hydro Dams (pumping water into a reservoir) and Compressed Air.
BATTERIES - FLOW / HYBRID FLOW / NON-FLOW (DAILY STORAGE)
Batteries store electrical energy by means of an electro-chemical reaction. There are three basics types of batteries, classical non-flow batteries that typically plate a metal onto an electrode such as lead-acid batteries, flow batteries which are bi-directional fuel cells (regenerative fuel cells), and hybrid batteries that have characteristics of both. Some batteries are suitable for power applications such as smoothing renewable energy, while others are more suitable for energy applications where energy is stored for use during periods of high-demand (energy shifting). In selecting a battery technology there are many attributes to consider that impact health and safety, efficiency, longevity and life-cycle costs.
Each type of battery offers costs and characteristics that make it suitable for different environments and applications.
Representing Ecoult, Clemens van Zeyl provided systems engineering and project management for Ecoult’s Valve-Regulated Lead-Acid and UltraBattery™ energy storage solution incorporated with a 500 kW solar photovoltaic power plant at Public Service Co. of New Mexico's Prosperity Energy Storage Project in Albuquerque, New Mexico.
SUPER/ULTRA CAPACITORS (DAILY STORAGE)
Super or Ultra Capacitors are designed to deliver very high-power as a burst of energy. Classic super or ultra batteries technology use electrochemical storage, but recent technologies developments are focused on electro-statically storing energy through use of nano-technology. Other advancements include combining battery technology with ultra capacitors, such as the UltraBatteryTM being commercialized by Ecoult.
Although the energy density of an Ultra Capacitor is lower than that of conventional batteries, their power density is much greater, thanks to their rapid charge and discharge cycles. Further, their operational lifespan is many times that of conventional batteries.
These characteristics make them suited to short duration power smoothing applications in renewable energy systems, as well as providing short-term storage for regenerative braking systems in electric and hybrid-electric vehicles.
FLYWHEELS (DAILY STORAGE)
Vacuum enclosures, carbon fibre composite rotors, high-temperature super conductors, and magnetic bearings have made the flywheel an energy storage option, but there are many considerations when applying these systems, such as health and safety, standby losses, and temperature management.
PUMPED HYDRO AND COMPRESSED AIR (BULK STORAGE)
Pumped Hydro and Compressed Air are typically used for Bulk Energy Storage where energy is stored for use over several days. Pumped Hydro stores energy by pumping water into an elevated reservoir by utilizing the hydraulic turbine as a pump, and energy is discharged when water is released through the hydraulic turbine. Mechanical energy from the turbine is converted to electricity, and vice versa, by means of an electromechanical generator/motor.
Compressed air systems work in a similar manner to pumped hydro as both utilize turbines and motor/generates to convert energy. In this case, energy is stored by compressing air in into an underground cavern by using the turbine as a compressor, and energy is discharged when pressurized air is released through the turbine.
Both of these technologies are very competitive on a large scale, and are typically deployed by utilities at the transmission level to manage energy flow on the electric grid.
“When we create a firm, dispatchable renewable resource - when we can dispatch exactly when we need electric power - then we can firmly state that we can preclude the future use of fossil fuel peaking resources”. “The batteries are doing a couple things. They’re dedicated to smoothing the output of PV”, and they “address the need to shift that energy to deliver it to the grid when it’s much more beneficial.”
- Steve Willard, Prosperity project leader, Public Service of New Mexico