# 1. A general hospital located in Mediterranean region can achieve carbon neutrality due to energy use using locally available renewable energies.

Characteristics of the hospital.

Parameter Value
Beds 400
Covered surface 26,172 m2
Annual electricity consumption 4,895 KWhel/year
Energy used Grid electricity
Annual heat consumption 2,444 MWhheat/year
Fuel used Heating oil
Total annual energy consumption 7,339 MWh/year
Annual energy consumption per bed 18.35 MWh/bed year
Annual daily consumption per bed 50.27 KWh/bed day
Annual energy consumption per covered surface 280.4 KWh/m2 year
Average daily energy consumption 20.11 MWh/day
Annual energy consumption in space heating 2,495 MWh/year
Annual energy consumption for DHW production 954 MWh/year
Annual energy consumption in space cooling 1,321 MWh/year
Annual energy consumption in lighting 1,028 MWh/year
Annual energy consumption in the operation of several devices, machinery and apparatus including the kitchen 1,541 MWh/year
Total annual CO2 emissions due to energy use 4,396.9 tnCO2/year
Total daily CO2 emissions due to energy use 12.05 tnCO2/day
Annual CO2 emissions per covered surface due to energy use 168 kgCO2/m2 year
Annual CO2 emissions per bed due to energy use 11 tnCO2/bed year

 

Taking into account that in the location of the hospital the solar irradiance is high and that there is satisfactory availability of solid biomass nearby, the hospital could zero its net annual CO2 emissions using the following benign energy systems and green energies sources:

  1. Installing solar thermal panels on the roof terrace of its buildings,
  2. Installing solar-PV modules on the roof terrace of its buildings,
  3. Replacing the heating oil used with solid biomass and changing the heating system,
  4. Installing a ground source heat pump (GSHP),
  5. Installing electric batteries for electricity storage, and
  6. Installing a re-charging system for the batteries of electric vehicles including the electric ambulances. Electricity can be generated with solar-PV panels installed on the top of car parks.

The abovementioned energy systems can generate heat, cooling and electricity covering all the annual energy requirements in the abovementioned grid connected hospital.

  1. Domestic hot water will be produced by the solar thermal panels, the GSHP and the solid biomass,
  2. Space heating will be achieved with the use of solid biomass and the GSHP,
  3. Space cooling will be provided by the GSHP,
  4. All the annual electricity requirements for lighting and the operation of several devices, and apparatus including the GSHP will be provided by the solar-PV system,
  5. The electric batteries will provide electricity in emergency cases, and
  6. The electric vehicles of the hospital, the staff and the visitors will be re-charged with the on-site installed re-charging station while the batteries will be re-charged with solar electricity generated by the solar-PV system.

Heating oil will not be used anymore while the net annual electricity balance with the electric grid will be zero.

The energy systems used in the hospital are:

  1. A solar thermal system,
  2. A solar-PV system,
  3. A solid biomass heating system,
  4. A ground source heat pump,
  5. An electric battery, and
  6. A re-charging station for the batteries of electric vehicles including the electric ambulances.

The benign energy sources used in the hospital are:

  1. Solar energy
  2. Solid biomass, and
  3. Ambient heat.

 

#2. A general hospital located in USA achieving carbon neutrality due to energy use

 Characteristics of the hospital

Location: North, approximate latitude 33o

Covered surface 11,313 m2

Annual total specific energy consumption 764 KWh/m2

Fuels used: grid electricity (49.08%) and natural gas (50.92%)

Average annual solar radiation: between 3.5-6.5 KWh/day

The local solar irradiance is attractive and cost-effective, at this latitude, for the use of solar thermal energy for hot water production and solar photovoltaics for electricity generation

Table 1. Energy consumption in various sectors in the hospital

Hospital’s sector Distribution of energy consumption (%) Annual specific energy consumption (KWh/m2)
Space heating 29 221.56
Space cooling 11 84.04
Ventilation 12 91.68
Water heating 11 84.04
Lighting 9 68.76
Cooking 7 53.48
Refrigeration 3 22.92
Office equipment 2 15.28
Computers 5 38.20
Other 11 84.04
Total 100 764

 

Step 1. Reduction of heat and electricity consumption at 15%, on average, using various energy saving techniques

Analysis of energy consumption in each sector in the hospital is necessary by an experienced energy expert for choosing the areas where energy savings can be achieved in a cost-effective way. Usually energy savings at around 15-20% can be obtained in a cost-effective way.

Step 2. Changes regarding the fuels and energies Grid electricity will not be used. used for reducing the carbon footprint in the hospital

  1. Grid electricity will not be used. Electricity will be generated in-situ with: a) solar photovoltaic panels installed on the roof of the buildings, and b) with a heat and power co-generation system using natural gas. Additionally, green electricity will be purchased from an external energy provider having a 100% renewable energy portofolio.
  2. Steam will be produced with natural gas burning.
  3. Heat will be produced a) from the heat and power co-generation system using natural gas while b) hot water will be also produced with a solar thermal system using flat plate solar collectors placed on the roof of the buildings.
  4. Energy for cooking will be produced partly by natural gas and partly with electricity provided that some appliances in the kitchen will be replaced with electric appliances.
  5. An electric battery can be used for electricity storage increasing the energy stability, security and resilience in the hospital.
  6. Additionally, a battery charging system can be installed in the hospital for re-charging the batteries of electric vehicles of the staff, the patients and the hospital’s electric ambulances and other vehicles, if any.

Table 2. Energy and fuels used in the hospital

Energy Production system Fuel used
Heat Solar thermal system Solar energy
High temperature heat (steam production) Gas burning Natural gas
Heat Heat and power co-generation system Natural gas
Electricity generation Solar photovoltaic Solar energy
Electricity generation Heat and power co-generation system Natural gas
Electricity generation Purchase from an external provider with a 100% renewable energy portofolio Various renewable energies
Electricity storage Electric battery storage system Electricity generated by several fuels

 

Step 3. Estimation of carbon emissions

The only fossil fuel used in the hospital is natural gas. The annual CO2 emissions due to natural gas use can be estimated using appropriate coefficients as follows:

1 kg natural gas = 1.21 m3 emits 2.75 kg CO2 and

Natural gas at 1 GJ=239 Mcal emits 50 kg CO2

Step 4. Offsetting any remaining carbon emissions

The carbon emissions due to natural gas use in the hospital can be offset using a carbon offsetting scheme. The hospital can buy carbon credits either from the compliance market or from the voluntary market. It is advisable to cooperate with a certified carbon credit provider choosing a nature-based project which is certified by an external reliable organization.