• converting industrial waste energy streams into heat and power with on-site generation plants; and
• building CHP facilities near thermal energy users to enable recycling of normally wasted thermal energy from the production of electric power to displace host boiler fuel.

Industrial Waste Energy Recycling

Many industrial processes produce byproduct energy streams such as (i) hot exhaust gases, (ii) flare gases and (iii) high pressure gases. Hot exhaust gases are generated by facilities such as coke ovens, glass furnaces, petroleum refineries and hot rolled steel ovens, which all have high temperature exhaust that can be converted into electricity and thermal energy. Flare gases are typically created by blast furnaces, which reduce iron ore to molten iron and produce byproduct gas that must be flared for cleanup. Finally, energy in the form of pressure drop energy is created when gases, including steam and natural gas, flow from high pressure pipes to low pressure points of use. Electric power and thermal energy can be produced by capturing and recycling these forms of waste energy produced by industrial processes.

The following diagram depicts a typical industrial site, which purchases electricity and fuel, uses the energy to produce finished goods, and emits significant waste energy from the processes.

Primary Energy designs, builds and operates energy recycling facilities to convert some of the waste energy into electricity and useful thermal energy. The following diagram shows the original industrial site with energy recycling added. The site purchases less electricity and less fuel to produce the same quantity of finished goods and, as a result, vents less waste energy.

Recycling with On-site Combined Heat & Power Plants

In a typical electric power generation plant, input fuel is used to create electricity while excess thermal energy (in the form of steam) is wasted in the process. Many facilities, both commercial and industrial, require a substantial amount of thermal energy for heating, cooling and other low temperature processes. By locating an electric generation plant on-site at a facility that has a significant demand for thermal energy, steam that is typically wasted can be used by the host. Such CHP plants reduce their hosts’ energy costs and reduce emissions as compared to buying power off of the grid and producing steam with boilers.

The following diagram depicts the estimated average energy conversion efficiency of all fuel-fired central generation in the United States for 2003, reported by the United States Energy Information Agency. Fuel to the central power plant is used to produce electricity only. The average central generation plant converted 36% of the input energy into electricity entering the transmission grid. In the United States approximately 9% of this energy is lost, on average, before reaching the end user. Therefore, only 33% of the energy in the fuel arrives as power.

To improve efficiency, Primary Energy designs, constructs, and operates CHP plants at the thermal user’s site. The following diagram depicts this process, such as Primary Energy’s Portside Project. Fuel is burned in a gas turbine at the user’s site to produce electricity and steam, which drives a second electric generator. Some steam is extracted for use in the industrial processes after giving up much of its pressure to produce added electricity. The exhaust steam from the steam turbine is then used to produce hot water or steam. These CHP plants convert 60% to 80% of the fuel’s energy to useful energy, more than double the efficiency of conventional central generation.