In the battle against climate change, cities will play a decisive role. Without a targeted policy for cities to reduce their greenhouse gas emissions, climate mitigation policies cannot be successful. Renewables play contribute significantly to reduce the use of fossil fuel in cities. The reduction of greenhouse gas emissions, energy security and development of new jobs in Europe are key arguments in favor of renewables. Renewables have the potential to become a pillar in the future energy portfolio of cities.
The deployment of renewable energies is becoming a major political issue on the global, national and community levels. The city of Stockholm is one of the leading examples of widespread deployment of renewables. This European experience can also be transferred to cities in East Asia and North America, as well as to cities in South and South-East Asia and right across countries south of the equator.
The City of Stockholm, the capital of Sweden, has 0.9 million inhabitants and the greater region of Stockholm has 2.1 million. District heating, by cogeneration of heat and power, is the dominating heating system in Stockholm. Less than 20 % of the energy comes from fossil sources. The rest is from biomass, waste and heat-pumps.
Besides heating, the system generates 20 TWh of electricity. The heat-pumps also provide district cooling.
Stockholm is also a pioneer city in using renewable energy for transport. Public buses run on upgraded biogas, biodiesel or ethanol. Also, cars run on biofuels and at present almost 20 % of all fuel used is renewable. Hydrogenated Vegetable Oil (HVO) dominates the market, replacing fossil diesel to an increasing extent.
Biogas is produced using wet organic wastes, principally sewage but soon also organic household waste. Ethanol is produced from cereals or is imported from abroad, and the biodiesel is largely made from rapeseed oil and other vegetable oils.
Decision makers in cities dealing with the issues of the sources of future heat supply and solutions for the transport sector should consider a few key criteria such as:
- Impact on greenhouse gas emissions
- Security of supply
- Regional development by regional energy solutions
All these criteria favor solutions based on biomass and other renewables. Cities should take into account these criteria and direct all new investment toward renewable energy solutions and improved energy efficiency, and avoid new investment in fossil structures.