Abstract: In some embodiments, a light emitting structure comprises a layered semiconductor stack comprising a first set of doped layers, a second layer, a light emitting layer positioned between the first set of doped layers and the second layer, and an electrical contact to the first set of doped layers. The first set of doped layers can comprise a first sub-layer, a second sub-layer, and a third sub-layer, wherein the third sub-layer is adjacent to the light emitting layer. The electrical contact can be coupled to the second sub-layer. The first, second and third sub-layers can be doped n-type, and an electrical conductivity of the second sub-layer can be higher than an electrical conductivity of the first and third sub-layers. The first, second and third sub-layers, the light emitting layer, and the second layer can each comprise a superlattice.

Abstract: An energy system includes a turbine flue heat exchanger feeding a storage tank arranged to deliver water on a high temperature (90° C.) line to supply circuits. A heat pump and storage tank are arranged to deliver lower temperature (45° C.) water on a low temperature line to the supply circuits. A number of the supply circuits are each arranged to receive high temperature water, receive low temperature water, and use these flows to deliver a process water supply at a desired high, low or intermediate temperature (65° C.). In some each supply circuits the blending is controlled by control of a low temperature line pump according to temperature of the process outlet. The low temperature tank is supplied by a heat pump the inlet of which is fed by a heat recovery heat exchanger which recovers waste heat from a plant, and so it is more efficient than if it received cold water. Electrical energy for the heat pump is at least partly supplied by the high temperature heater gas turbine.

Abstract: A heating system (1) has a turbine (20) for burning a fuel to provide flue gas and electrical energy. A flue gas heat exchanger (25) receives the flue gas and uses it to heat water in three of stages. An air conduit (2) receives inlet air (3) and gases from secondary inlets (5, 26) from within the system to elevate the temperature in the main conduit (2) above ambient. An evaporator (8) recovering heat from the air flow of the main conduit, and provides energy via an evaporator coil to an air source heat pump ASHP (50). A water source heat pump WSHP (60) receives a water feed at an elevated temperature from the ASHP (50), and it cools the flue gas in a third heat exchanger stage (25(c)).