This post on the Transsolar ‘Green & Sexy’ blog features two Sankey diagrams. The “climate engineers” at Transsolar use them to model heat flows inside a building based on outside temperature and solar radiation.

No absolute values are given in these demo Sankey diagrams, but one can still get a general idea by observing proportions. Flows are color-coded with solor radiation in yellow, convection in blue, and heat losses in red.

The second Sankey diagram shown is a timeline made 24 frames – one per hour over a full-day. As the outside temperature rises and solar radiation increases around noon, the inside temperature and cooling demand increases.

(via tumblr)

Sankey diagram timeline by Transsolar

The authors explain:

“These Sankey diagrams allow us to see the proportion of how much energy is hitting the facade, how much energy is being radiated into the walls, how much energy is being convected into the air, and how much heating or cooling is actually needed to maintain an acceptable indoor air temperature. The animation is the first example we’ve ever seen of a Sankey diagram that represents the dynamic, ever-changing relationship of heat flows in a building with time.”

From a slideshow by Convion (Finland) on its fuel cell technology.

Using a feed of 8,42 kg natural gas per hour with an energy content of 114,75 KW (based on the lower heating value) the CHP equipment yields 59,5 KW electric energy and heat. Biogas or hydrogen can also be used as fuel.

Electrical efficiency is between 53 and 65% net AC, the total energy efficiency is larger 85%.

Interesting comparative Sankey diagram on page 16 of the 2012 environmental declaration of Rosenheim Stadtwerke (Rosenheim City Power?).

The city is building or already running a wood gasification plant. Instead of just using the heat from directly burning wood (with 30% energy loss), they decided to work with a wood gas carburetor and use the wood gas to run a gas motor. This is somewhat similar to CHP where heat and electric power can be produced. Overall loss of energy (“Verluste”) in the system is only 23%.

The green box at the bottom displays the avoided fossil GHG emissions per tonne of wood for both technologies.

Flows are in MWh, but only some selected arrows are labeled. Unfortunately the flows are not always to scale: yellow arrow “W√§rme” (heat) in figure at top representing 3,15 MWh, but shown as half the width of the blue arrow 4,5 MWh. I reckon the diagram was build manually from rectangles and triangles.

This Sankey diagram is from a research project at Bayreuth University (Germany) on latent thermal storage and heat pumps. Read the project summary here (in German).

Flows show percentage shares, not absolute values. LTTT watermark in the background is from the insitute where the project was run.

The summary of a research project under participation of Kempten University of Applied Sciences is presented on a project webpage. It also features this comparison Sankey diagram.

These are in fact two Sankey diagrams “mirrored” at an imaginary horizontal center line. The bottom one facing upwards is the diagram for the baseline representing convential energy systems. The upper one with flows pointing downwards has the same amounts of useful energy (trigeneration 30 % electricity, 47 % heat und 23 % cold), but using 31% less primary energy (see black dashed lines).

Via CarbonSignal blog comes the following post and Sankey diagram:

“Tri-generation, also known as combined cooling, heat and power (CCHP), is a combination of co-generation, known as combined heat and power (CHP) with an adsorption or absorption chiller to provide water chilling. More information of co-generation can be found here. The chilled water can then be used in refrigeration or air conditioning systems. The engine is connected to a generator which can supply electricity to the site or export electricity to the grid. Typically about 38% of the energy supplied as fuel to the engine is converted to electrical energy.

The rest of the energy leaves the engine as heat via the hot exhaust gases, the coolant system and the oil system. A large amount of the waste heat can be recovered through heat exchangers and can be used to supply all hot water to heat domestic hot water, supply heat to a HVAC system, or supply a chiller to provide all chilled water.

Alternatively the system can be designed to supply a mix of both hot and chilled water to match the site loads. The use of a heat recovery system and chiller can increase the efficiency to between 67- 85% depending on the mix of chilled and hot water required.”

Architect Ziya Buluch has a comprehensive description of his project ‘The Nest’ on his blog. The Nest is a green building which is planned to have no external primary head demand.

Scroll down to the end to find this Sankey diagram:

The flows represent the heat energy. Overall demand for heat 37.46 kWh per square meter per year. 12.08 kWh/m2a is from solar panels, 25.38 kWh/m2a from an air-source heat pump (whaterver that is…).

Untypical Sankey diagram, but nevertheless interesting. Flows are not really to scale (compare the 12 kWh inflow and the 6 kWh losses outflow, which should have half the width, or to the 25 kWh inflow that should be roughly twice as wide). Unicolor grey flows with a slight gradient from left to right.

I had to stop posting for a few days because I had trouble with page hijacking. Set up WP anew with the help of a friend (thanks Chris!). To get going again after this break, here’s a misc Sankey diagram from my collection:

The upper part depicts a process diagram of a gas-powered steam boiler system. Below are the energy flows as a Sankey diagram. Values are in percent, showing the yield. Out of the input energy (100%) we have 31.5% of the energy in low presseure steam and 42% in electric energy. Don’t know where I picked this duiagram from, will have to check if I find the source of this.