Clean Energy on Construction Sites
There is much discussion about clean energy on construction sites with construction managers keen to adopt newer, cleaner solutions. The default power source to date has been diesel generators but using these generate considerable CO2 which is a known greenhouse gas and also NO2 and Particulate Matter which contributes to poor air quality in urban areas. Climate changing greenhouse gases and poor urban air quality are driving the shift from diesel to alternatives.
Campbell Associates supply environmental monitoring solutions for construction sites and are working with partners to reduce our carbon footprint and improve urban air quality with cleaner power options. This article discusses the options, their suitability and how clean they really are:
Hydrogen Fuel Cells
Hydrogen (H2) is a clean zero emission fuel which is commercially available as a power source for construction sites. It is used in a hydrogen fuel cell to generate power to charge batteries to store and distribute power. They are often combined with solar and wind generation to share the load of charging batteries.
Note: The generation of hydrogen creates greenhouse gases. Most hydrogen (95%) is produced by a thermal process where steam reacts with a hydrocarbon fuel (normally natural gas). H2 produced this way is normally referred to a grey hydrogen. It is estimated that grey hydrogen production creates 3 times the greenhouse gases compared diesel. However when used hydrogen produces zero NO2, whereas diesel generates a considerable amount. The net result is that the complete process of production and consumption is that H2 produces about 50% of the CO2 emissions compared to Diesel.
Hydrogen produced by electrolysis of water generates hydrogen without the release of any CO2. This is referred to as Green hydrogen. It is currently expensive to produce H2 in this way and green hydrogen is produces in small volumes.
Benefits vs diesel:
· Reduction in greenhouse gas/CO2 emissions by up to 100% at point of use.
· Improves local air quality - Reduction in NOx and Particulate Matter emissions by 100%
· Compressed hydrogen bottles are widely available and can be delivered to sites.
· Very low noise emission
· It can be easily combined with wind and solar solutions to reduce H2 consumption.
The disadvantages vs diesel:
· It can be more expensive – This depends on the application.
· Requires investment in new hardware.
· Generation of Hydrogen creates greenhouse gases.
Summary:
Hydrogen fuel cell systems offer reliable energy for sites with significant savings in CO2 emissions. It offers huge advantages for local urban air quality with zero emissions of NOx and Particulate matter.
Local Solar/ Wind
Off grid power systems using solar panels and small wind turbines are a popular solution. There is an investment to purchase but when in place they offer emission free energy for site.
Advantages vs diesel:
· Zero emissions
· Near zero running costs
Disadvantages vs diesel
· With extended poor light/ wind, systems will turn off.
· The size of panels required for year-round use prohibits solar panels on many sites.
· Additional power generation normally needed as backup.
Summary
Solar and wind offers emission free low-cost power for construction sites. Unless people on site are willing to change backup batteries in winter months then solar is only part of the solution and it should be combined with another source such as hydrogen.
HVO fuel (Hydrotreated Vegetable Oil) is a fossil free, renewable and sustainable fuel produced by hydrotreatment of vegetable oils and/or animal fats.
The chemical structure almost identical to regular diesel and can therefore can fully replace fossil diesel. Meets EN 15940 standards and Fuel Quality Directive 2009/30/EC
The benefits vs diesel:
· Reduction in greenhouse gas/CO2 emissions by up to 90% compared to standard diesel.
· Improves local air quality - Reduction in NOx and Particulate Matter emissions by up to 30%
· It will work with current power generators – No modifications.
· Long shelf life – Can be stored in existing diesel tanks.
The disadvantages vs diesel:
· Price- Typically 15% more expensive than regular diesel.
· Limited availability in the UK.
· To be commercial production requires harvesting crops, with the preferred being palm oil that has documented problems with rainforest clearance causing increased carbon emissions.
· Producing HVO using Hydrogen as part of the process. Hydrogen is primarily made using fossil fuels.
· With price and availability issues it is possible sites will revert to using standard diesel.
Summary:
HVO offers an easy solution with big reductions in CO2, although the overall process of producing the HVO will reduce the greenhouse gas savings. There is a moderate improvement in local air quality emissions.