Optimizing power plant performance for energy efficiency
How power plants can save on electricity consumption that they work so hard to produce.
Power producers are looking for ways to reduce carbon emissions without compromising their market competitiveness. To meet this challenge, classic base load fossil-fuel burning power plants are diversifying electricity production by enhancing renewables in the mix.
The huge potential of improved efficiency of power plant assets is often underestimated in pursuing this objective. Power plant optimization is often also associated with upgrading the performance of combustion and steam processes, but another prime candidate for efficiency improvement are the plant’s electrical systems, better known as the electrical balance of plant (or EBoP).
A conventional power plant uses up to 7 percent of its own electrical output to operate its electrical systems. In a 600 megawatt (MW) power plant, this means the electrical systems consume around 40 MW of the electricity produced by it. This is power that is generated but never reaches the grid.
There are of course obvious ways to reduce this power drain, like installing energy efficient lighting and motion detectors. But even bigger energy savings are possible by making the plant`s own major electricity consumption elements more efficient.
As in many other industries, the biggest consumption points in a power station are typically the motors that operate pumps, mills, fans and auxiliary systems. Older motors are often inefficient by today`s standards, and in addition many systems are still controlled by throttling. This means the motor driving a pump or a fan runs at constant power regardless of load requirements. The flow of water or air is controlled with bypasses, resulting in significant energy waste.
An integrated solution that combines variable speed drives with high efficiency motors can easily stem the energy waste. ABB motors and drive combinations can save 30 to 60 percent of the energy used by throttle valves and guide vanes to adjust air and water flow. And these energy savers are a mere fraction of the plant’s total investment.
By implementing such measures, electricity that was previously wasted can be sold to the grid, or the fuel wasted generating it can be saved. Depending on the application and local energy prices, the payback time of such an investment is typically under two years, and in some cases, just a few months.
EBoP systems can also significantly improve the safety of plant equipment. Modern switchgear equipped with appropriate circuitbreakers and the latest numerical protection systems provide a safer operating environment for both electrical equipment and personnel. ABB provides upgrades for many types of switchgear which can extend equipment life and reduce both investment costs and required shutdown times.
Sometimes components, for instance an excitation system, simply reach the end of their useful life and can no longer be operated reliably because of lack of spare parts or know-how. This poses a threat to the overall production process, and while upgrading such components doesn`t change the plant`s nominal figures, increased availability of all processes contributes to its overall efficiency.
It is topics such as these that the service team addresses to optimize power plants and their electrical systems to enable energy efficiency and save on consumption that they work so hard to produce.