Distributed generation

Big power plants make electricity for many people.

They are often very far away. These plants send power over long lines.

Small tools can make power too. These tools sit close to where we live. They can even stay on your roof. Some use the sun or the wind.

These small tools can also store power. This keeps the power ready for later. Using small tools can keep our air clean. It also helps keep our power safe.

Small tools can work in a group. They can form a tiny power grid. This helps a whole town stay bright.

It is exciting to see how we make power!

Most electricity comes from big power plants. These plants are often far away from cities. They send power over very long lines. This is called centralized power.

Other ways to make power are closer to home. We call these distributed energy resources, or DERs. These are small tools that make or store power. They might be on a roof or in a yard. DERs are often small. They usually make 10 megawatts or less. A megawatt is a way to measure power.

Many DERs use renewable energy. This means power from nature. Some use the sun with solar panels. Others use wind or heat from the earth. Some use small dams or even gas.

Using DERs can help the planet. They make less pollution. They also save power. When power travels long distances, some is lost. DERs make power right where it is used. This means less power is wasted.

Sometimes, small tools work together in a microgrid. A microgrid is a tiny, local power grid. It can work on its own if the main grid breaks. This helps keep the lights on during a storm.

Electricity can be made in two different ways. Most of our power comes from huge central plants. These plants might use coal, gas, or nuclear energy. They are often built far away from the people who use the power. This is because big plants need space or specific resources. For example, coal plants are often built near coal mines. Hydroelectric plants must be built where there is flowing water. This way of making power is called centralized generation.

Distributed generation is a different way to work. It uses small devices called distributed energy resources, or DERs. These devices are located close to where the power is needed. They are much smaller than big power plants. Most DER systems make 10 megawatts or less. They can use many different kinds of energy. Some use the sun, wind, or heat from the earth. Others use small amounts of water, gas, or even plants.

In the past, big central plants were the only main choice. It was cheaper to build one giant plant than many small ones. This changed as technology grew and costs shifted. By the start of the 21st century, the old way had problems. The long power lines used to carry electricity were getting old. Sometimes, the lines caused power quality problems for digital tools. Experts began to see that smaller units could be very helpful. They found that making small tools in large amounts was efficient.

There are many specific technologies used in these systems. One type is called photovoltaics, which uses solar panels to catch sunlight. Another is cogeneration, which makes both electricity and heat. This is very useful for heating buildings or water. Some systems use fuel cells to create power. In 2012, fuel cell systems were very popular in Japan. The Ene Farm project sold 20,000 units there that year. These units can last between ten and fifteen years.

Using these small tools can change how our world works. When power is made right where it is used, less energy is lost. This happens because the electricity does not have to travel long paths. It can even be made in the same building where it is used. Some people use microgrids to connect these small tools together. A microgrid is a small, local power grid. It can work all by itself if the main grid has a problem. This helps keep the lights on even during big disturbances.

Electricity can be produced through two very different methods. Most of our power comes from centralized generation. This method uses massive power stations to create bulk electricity. These stations might use coal, natural gas, or nuclear energy. They also include large hydroelectric dams and massive solar farms. Because these plants are so large, they are often built far from cities. For example, coal plants are built near mines to save on transport costs. Hydroelectric plants must be located where there is enough water flow. This electricity then travels over long distances through a massive transmission and distribution grid.

Distributed generation offers a different approach to powering our lives. This method uses small, modular devices called distributed energy resources, or DERs. These devices are located very close to the people or buildings that use the power. A DER system typically has a capacity of 10 megawatts (MW) or less. Some systems use multiple different parts to work together. When they combine different types of energy and storage, they are called hybrid power systems. These systems can be grid-connected or even function as part of a local microgrid.

Distributed energy resources use many different types of fuel and technology. Many DERs rely on renewable energy sources. These include solar power, wind power, and geothermal power. They can also use small-scale hydro, biomass, or biogas. Some systems use natural gas through processes like cogeneration. Cogeneration, or combined heat and power (CHP), uses steam turbines or engines to make electricity. It also captures the hot exhaust to provide heat for water or buildings. Some advanced systems even use that heat to provide cooling through an absorptive chiller.

Historically, the world relied almost entirely on large central plants. It was much cheaper to build one giant facility than many small ones. However, this changed around the late 1960s. By the start of the 21st century, central plants faced new challenges. The long-distance grid was aging and sometimes caused power quality issues. Digital equipment requires extremely reliable electricity to function correctly. Experts found that making small units in large amounts was becoming very efficient. This is known as the economy of mass production.

Distributed generation provides several important benefits to the energy system. One major benefit is efficiency. When electricity is generated in the same building where it is used, very little energy is lost. In centralized systems, energy is lost as it travels over long power lines. Distributed systems also help the environment. They often use clean, renewable energy instead of fossil fuels. This can reduce the total amount of carbon emitted. Another benefit is security. If the main power grid has a problem, a microgrid can disconnect and operate autonomously. This helps keep the lights on during a disturbance.

There are specific technologies that make these systems work. Photovoltaic systems, or solar PV, use solar cells to turn sunlight into electricity. Fuel cells are another important tool. In 2012, Japan's Ene Farm project sold 20,000 fuel cell units. These PEM fuel cell units have a lifetime of about 60,000 hours. This means they can last between ten and fifteen years. Other technologies include microturbines, reciprocating engines, and small wind power systems. Some people even combine solar, fuel cells, and batteries to power a single home.

While the benefits are many, integrating these resources is complex. Because wind and solar depend on the weather, their output is uncertain. This makes it harder to balance the supply of power with the demand. It can also put pressure on the transmission network. Sometimes, it even causes "reverse power flow" from the local system back to the main grid. There are also cybersecurity concerns. If many small devices use the same control software, a single attacker could potentially disable them. This is why new rules, like the EU NIS2 directive, are being created to protect energy systems.

Finally, we can look at the concept of grid parity. Grid parity happens when an energy source becomes as cheap as the electricity from the main grid. When a technology reaches grid parity, it does not need government subsidies to grow. Since the 2010s, solar and wind power have reached grid parity in many places. This includes parts of the United States, Europe, and Australia. As technology improves and more people use it, the costs continue to fall. This makes distributed generation a key part of a diverse and clean energy future.