Resource efficiency with useful heat or electricity
|SE|
One way to determine which energy source that is best for the environment is to assess the benefit in the form of heat or electricity a power source can provide. The tables below can be read as 1 unit of fuel provides X heating and Y electricity. Higher number is better.
Note that "useful heat out" greater than 100 means that the end result is more heat energy than if the fuel were burned directly for heating.
All types of power sources
| Power source 100% in |
% Electricity out | % Heat out | % Useful heat out with HP COP 4 |
Net effect electricity contribution by % of fuel energy in |
|---|---|---|---|---|
| Direct combustion for heating (wood burning, pellets, oil, gas) |
0 | 100 | 100 | 25 |
| Internal combustion engine with gas/liquid fuel (Gen set) |
35 | 0 | 140 | 35 |
| Solid fuel in condensation power plant | 40 | 0 | 160 | 40 |
| Combustion engine with gas/liquid fuel with district heating | 35 | 65 | 205 | 51 |
| Solid fuel in cogeneration plants | 40 | 60 | 220 | 55 |
| Gas/liquid fuel in gas combined cycle power plant without district heating | 60 | 0 | 240 | 60 |
| Gas/liquid fuel in gas combined heat and power plants with district heating | 60 | 40 | 280 | 70 |
Relative energy demand for heating with combinations of electricity production and electric heating/heat pumps
| Examples of power source | Electric Efficiency | System efficiency during heating | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Solar collector | 0% | 200-143% | |||||||
| Combustion for heating
(oil, gas, firewood) |
0% | 111% | |||||||
| Electric heat | 2 | 3 | 4 | 5 | 6 | 7 | <=COP | ||
| Solar cell | 15% | 667% | 333% | 222% | 167% | 133% | 111% | 95% | |
| Nuclear power, Old coal power, oil power, good petrol engine | 30% | 333% | 167% | 111% | 83% | 67% | 56% | 48% | |
| Efficient coal power, modern diesel engine | 40% | 250% | 125% | 83% | 63% | 50% | 42% | 36% | |
| Very large diesel engines | 50% | 200% | 100% | 67% | 50% | 40% | 33% | 29% | |
| Efficient gas combined cycle power plants | 60% | 167% | 83% | 56% | 42% | 33% | 28% | 24% | |
| 70% | 143% | 71% | 48% | 36% | 29% | 24% | 20% | ||
Underlined system efficiencies are combinations with a lower efficiency than combustion or optimal heat capture for heating (eg oil boiler, wood burning).
Bold is the dividing line where the combination gives a higher efficiency than the theoretical maximum for combustion alone or heat capture for heating (100%).
Conclusions
- Resistive electric heating corresponds to COP 1. It gives that it is more efficient to burn the fuel directly for heating than resistive electric heating.
- For the combination gas combined cycle power plant and heat pump with heat factor (COP) 4, the total energy requirement is reduced to 42% compared to direct combustion with a theoretical 100% efficiency.
- Conversion from gas heating to heat pumps (SCOP 4) is very efficient.
- Conversion from coal burning to heat pumps (SCOP 4) with coal condensate is also effective.
- Thermal power has an electrical efficiency of up to 60%. An efficient combustion boiler up to approx. 90%. Local heating as peak heating for heat pumps, (wood, oil, gas, etc.) then results in lower total energy use and carbon dioxide emissions.
- By combining high-efficiency power units with heat pumps with a high heating factor, the fuel requirement can be reduced.
Electric car compared to ICE petrol car
An electric car cuts carbon dioxide emissions in half compared to a petrol car if the electricity is produced with petrol.
If gasoline is used in a car engine, a maximum of 30% can become electricity = kinetic energy under optimal conditions.
If gasoline is used to produce electricity in a gas combined cycle power plant with a combined cycle, you can get about 60% electricity = kinetic energy.
Solid fuels
| Power source 100% in |
% Electricity out | % Heat out | % Useful heat out with HP COP 4 |
Net effect electricity contribution by % of fuel energy in |
|---|---|---|---|---|
| Direct combustion for heat (wood burning, pellets, oil, gas) |
0 | 100 | 100 | 25 |
| Solid fuel in condensation power plant | 40 | 0 | 160 | 40 |
| Solid fuel in cogeneration plants | 40 | 60 | 220 | 55 |
Gas and liquid fuels
| Power source 100% in |
% Electricity out | % Heat out | % Useful heat out with HP COP 4 |
Net effect electricity contribution by % of fuel energy in |
|---|---|---|---|---|
| Direct combustion for heat (wood burning, pellets, oil, gas) |
0 | 100 | 100 | 25 |
| Internal combustion engine with gas/liquid fuel (Gen set) |
35 | 0 | 140 | 35 |
| Combustion engine with gas/liquid fuel with district heating | 35 | 65 | 205 | 51 |
| Gas/liquid fuel in gas combined cycle power plant without district heating | 60 | 0 | 240 | 60 |
| Gas/liquid fuel in gas combined heat and power plants with district heating | 60 | 40 | 280 | 70 |