TL/DR:
Overall more reasonable pollution
Solid burners efficiency is now less terrible
Diesel = best energy density
Gas = lowest pollution
Oil boilers are viable at scale (low pollution)
Solid fuels have emission multipliers (higher tiers = lower emissions)

Long version:

Fuel Values/Emissions:
- Crude Oil 1.4 MJ -> 0.48 MJ / 1.4 -> 1.4
- Light Oil 1.5 MJ -> 1.08 MJ / 1.2 -> 1.1
- Heavy Oil 1.0 MJ -> 0.60 MJ / 1.3 -> 1.3
- Petro Gas 1.5 MJ -> 0.90 MJ / 1.0 -> 0.5
- Diesel 2.0 MJ -> 1.50 MJ / 0.8 -> 0.7

Non-fluid Emissions (instead of 1.0):
Wood 1.1, Coal 1.0, Solid fuel 0.9, Rocket fuel 0.8, Nuclear fuel 0.7
Solid fuel fuel value 12 MJ -> 10.8 MJ
Diesel fuel recipe now takes 10 Petroleum gas instead of 20

Entities:

• ... Small Burner:
  Efficiency: 25% -> 70%
  Emissions: 60/MW -> 22/MW
  Power: 0.5 MW -> 0.7 MW

• ... Big Burner:
  Efficiency: 50% -> 80%
  Emissions: 20/MW -> 18/MW

• ... Diesel Generator:
  Efficiency: 100% -> 85%
  Emissions: 12.5/MW -> 8.25/MW (multiplied with fuel emissions)
  4 MW Power only with Diesel fuel, less dense fuel types = less power and emissions

• ... Oil Boiler:
  Still 100% efficiency
  Emissions: 7.4/MW -> 3.7/MW (multiplied with fuel emissions)
  Now only needs 2 steam engines or 1 steam turbine instead of +1 each (165 -> 240° temperature)

• ... Steam Engine:
  Now accepts 240° hot steam instead of 165. With vanilla boilers it may not appear saturated because those only produce 165° hot steam, but they still produce the same with them

• ... Other Changes: (OPTIONAL ! Check startup Settings)
  Disabled wind turbine (k2-wind-turbine looks better, or my "windturbines" mod is more realistic. pick one of those)
  Burner Cars and tanks and hovercrafts pollute 1/20000 of their base fuel consumption per minute. 600kW -> 30 pollution/min for example (tank)
  Trains (seperate setting) pollute 25 per minute (15 for diesel trains if that mod ever gets updated)

Example calculations:

• Vanilla boiler (unchanged)
  provides 1.8 MW for 1.8 MW fuel consumption. Pollution: 16.66/MW

• Big burner
  provides 50 MW for 62.5 MW fuel consumption. Pollution = 18/MW

• Burner
  provides 0.7 MW for 1 MW fuel consumption. Pollution = 22/MW

• Diesel Generator
  Light Oil: 2.9 MW for 3.13 fluid/s. Pollution: 9.1/MW
  Diesel: 4 MW for 3.13 fluid/s. Pollution: 5.82/MW
  Gas: 2.4 MW for 3.13 fluid/s. Pollution: 4.16/MW

• Oil Boiler:
  Light Oil: 2.7 MW for 2.5 fluid/s. Pollution: 4.07/MW
  Diesel: 2.7 MW for 1.8 fluid/s. Pollution: 2.58/MW
  Gas: 2.7 MW for 3 fluid/s. Pollution: 1.85/MW