Microturbines for distributed power generation and sludge drying

Electricity today in Brazil is one of the main inputs of industries and represents about 40% of production costs. In the last 20 years, electricity has increased by 131% above inflation, including causing some industries to almost disappear, such as the aluminum industry, and other industries to migrate to other countries, such as Paraguay, which has a very low cost of electricity. electricity.

Contrary to electricity, the supply of natural gas has increased over the last few years, as has the distribution network in large cities, and its cost has been decreasing.

The current scenario of increasing the cost of electricity and decreasing the cost of natural gas becomes the ideal scenario for the use of Distributed Generation, where electricity is generated directly by the final consumer.

Since 2008, Fluxo has been an authorized distributor for the North American company Capstone Turbine Corporation, a manufacturer of microturbines that generate electrical and thermal energy from a single fuel source, such as natural gas.

Among its 30, 65 and 200 kW models, Capstone currently has more than 9,000 microturbines operating in 73 countries, and in Brazil there are more than 60 units installed and some have been in continuous operation for almost 10 years, stopping on average only one day a year for preventive maintenance, as the microturbines are lubricated and cooled only with ambient air (patented technology by Capstone).

Another important point about microturbines is that, in addition to producing electrical energy, they convert 50 to 60% of the fuel into thermal energy with a temperature of up to 300°C, which makes them perfect for drying applications, where burners are usually used. .

A burner can be replaced by the exhaust of one or more microturbines and the user benefits from the electricity generated even with a reduced cost of fuel, as natural gas distributors have reduced tariffs for generation or cogeneration. “In this type of scenario, the investment in microturbines can quickly return to the user, sometimes in a period of less than 1 year”, says Capstone's Product Manager at Fluxo Rafael Amarante.

Another type of fuel that can be used by microturbines is the biogas generated in sewage, effluent and landfill treatment processes. Microturbines are the perfect solution for the use of this gas, as they bring technical and economic feasibility, and also minimize a problem that has been increasing exponentially in large cities, which is the residual sludge from these processes, usually discarded with a high percentage of humidity (80 to 90%).

With the use of biogas, microturbines can generate electrical and thermal energy to feed sludge dryers – which require a high amount of heat to evaporate its moisture – but also promote a reduction in its final weight and volume by up to five times. This process brings an excellent economic benefit to the companies that generate the sludge, as it drastically reduces the space needed for its disposal, and also makes it possible to use dry sludge as a fertilizer, transforming it from waste to an economically exploited product, with excellent environmental gain.